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third_party/scons/scons-local/SCons/Environment.py

Index: third_party/scons/scons-local/SCons/Environment.py
===================================================================
--- third_party/scons/scons-local/SCons/Environment.py	(revision 7290)
+++ third_party/scons/scons-local/SCons/Environment.py	(working copy)
@@ -1,2252 +1,2253 @@
-"""SCons.Environment
-
-Base class for construction Environments.  These are
-the primary objects used to communicate dependency and
-construction information to the build engine.
-
-Keyword arguments supplied when the construction Environment
-is created are construction variables used to initialize the
-Environment
-"""
-
-#
-# Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 The SCons Foundation
-#
-# Permission is hereby granted, free of charge, to any person obtaining
-# a copy of this software and associated documentation files (the
-# "Software"), to deal in the Software without restriction, including
-# without limitation the rights to use, copy, modify, merge, publish,
-# distribute, sublicense, and/or sell copies of the Software, and to
-# permit persons to whom the Software is furnished to do so, subject to
-# the following conditions:
-#
-# The above copyright notice and this permission notice shall be included
-# in all copies or substantial portions of the Software.
-#
-# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
-# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
-# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
-# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
-# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
-# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
-# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-#
-
-__revision__ = "src/engine/SCons/Environment.py 3603 2008/10/10 05:46:45 scons"
-
-
-import copy
-import os
-import sys
-import re
-import shlex
-import string
-from UserDict import UserDict
-
-import SCons.Action
-import SCons.Builder
-from SCons.Debug import logInstanceCreation
-import SCons.Defaults
-import SCons.Errors
-import SCons.Memoize
-import SCons.Node
-import SCons.Node.Alias
-import SCons.Node.FS
-import SCons.Node.Python
-import SCons.Platform
-import SCons.SConsign
-import SCons.Subst
-import SCons.Tool
-import SCons.Util
-import SCons.Warnings
-
-class _Null:
-    pass
-
-_null = _Null
-
-_warn_copy_deprecated = True
-_warn_source_signatures_deprecated = True
-_warn_target_signatures_deprecated = True
-
-CleanTargets = {}
-CalculatorArgs = {}
-
-semi_deepcopy = SCons.Util.semi_deepcopy
-
-# Pull UserError into the global name space for the benefit of
-# Environment().SourceSignatures(), which has some import statements
-# which seem to mess up its ability to reference SCons directly.
-UserError = SCons.Errors.UserError
-
-def alias_builder(env, target, source):
-    pass
-
-AliasBuilder = SCons.Builder.Builder(action = alias_builder,
-                                     target_factory = SCons.Node.Alias.default_ans.Alias,
-                                     source_factory = SCons.Node.FS.Entry,
-                                     multi = 1,
-                                     is_explicit = None,
-                                     name='AliasBuilder')
-
-def apply_tools(env, tools, toolpath):
-    # Store the toolpath in the Environment.
-    if toolpath is not None:
-        env['toolpath'] = toolpath
-
-    if not tools:
-        return
-    # Filter out null tools from the list.
-    for tool in filter(None, tools):
-        if SCons.Util.is_List(tool) or type(tool)==type(()):
-            toolname = tool[0]
-            toolargs = tool[1] # should be a dict of kw args
-            tool = apply(env.Tool, [toolname], toolargs)
-        else:
-            env.Tool(tool)
-
-# These names are controlled by SCons; users should never set or override
-# them.  This warning can optionally be turned off, but scons will still
-# ignore the illegal variable names even if it's off.
-reserved_construction_var_names = \
-    ['TARGET', 'TARGETS', 'SOURCE', 'SOURCES']
-
-def copy_non_reserved_keywords(dict):
-    result = semi_deepcopy(dict)
-    for k in result.keys():
-        if k in reserved_construction_var_names:
-            SCons.Warnings.warn(SCons.Warnings.ReservedVariableWarning,
-                                "Ignoring attempt to set reserved variable `%s'" % k)
-            del result[k]
-    return result
-
-def _set_reserved(env, key, value):
-    msg = "Ignoring attempt to set reserved variable `%s'" % key
-    SCons.Warnings.warn(SCons.Warnings.ReservedVariableWarning, msg)
-
-def _set_BUILDERS(env, key, value):
-    try:
-        bd = env._dict[key]
-        for k in bd.keys():
-            del bd[k]
-    except KeyError:
-        bd = BuilderDict(kwbd, env)
-        env._dict[key] = bd
-    bd.update(value)
-
-def _del_SCANNERS(env, key):
-    del env._dict[key]
-    env.scanner_map_delete()
-
-def _set_SCANNERS(env, key, value):
-    env._dict[key] = value
-    env.scanner_map_delete()
-
-
-
-# The following is partly based on code in a comment added by Peter
-# Shannon at the following page (there called the "transplant" class):
-#
-# ASPN : Python Cookbook : Dynamically added methods to a class
-# http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/81732
-#
-# We had independently been using the idiom as BuilderWrapper, but
-# factoring out the common parts into this base class, and making
-# BuilderWrapper a subclass that overrides __call__() to enforce specific
-# Builder calling conventions, simplified some of our higher-layer code.
-
-class MethodWrapper:
-    """
-    A generic Wrapper class that associates a method (which can
-    actually be any callable) with an object.  As part of creating this
-    MethodWrapper object an attribute with the specified (by default,
-    the name of the supplied method) is added to the underlying object.
-    When that new "method" is called, our __call__() method adds the
-    object as the first argument, simulating the Python behavior of
-    supplying "self" on method calls.
-
-    We hang on to the name by which the method was added to the underlying
-    base class so that we can provide a method to "clone" ourselves onto
-    a new underlying object being copied (without which we wouldn't need
-    to save that info).
-    """
-    def __init__(self, object, method, name=None):
-        if name is None:
-            name = method.__name__
-        self.object = object
-        self.method = method
-        self.name = name
-        setattr(self.object, name, self)
-
-    def __call__(self, *args, **kwargs):
-        nargs = (self.object,) + args
-        return apply(self.method, nargs, kwargs)
-
-    def clone(self, new_object):
-        """
-        Returns an object that re-binds the underlying "method" to
-        the specified new object.
-        """
-        return self.__class__(new_object, self.method, self.name)
-
-class BuilderWrapper(MethodWrapper):
-    """
-    A MethodWrapper subclass that that associates an environment with
-    a Builder.
-
-    This mainly exists to wrap the __call__() function so that all calls
-    to Builders can have their argument lists massaged in the same way
-    (treat a lone argument as the source, treat two arguments as target
-    then source, make sure both target and source are lists) without
-    having to have cut-and-paste code to do it.
-
-    As a bit of obsessive backwards compatibility, we also intercept
-    attempts to get or set the "env" or "builder" attributes, which were
-    the names we used before we put the common functionality into the
-    MethodWrapper base class.  We'll keep this around for a while in case
-    people shipped Tool modules that reached into the wrapper (like the
-    Tool/qt.py module does, or did).  There shouldn't be a lot attribute
-    fetching or setting on these, so a little extra work shouldn't hurt.
-    """
-    def __call__(self, target=None, source=_null, *args, **kw):
-        if source is _null:
-            source = target
-            target = None
-        if not target is None and not SCons.Util.is_List(target):
-            target = [target]
-        if not source is None and not SCons.Util.is_List(source):
-            source = [source]
-        return apply(MethodWrapper.__call__, (self, target, source) + args, kw)
-
-    def __repr__(self):
-        return '<BuilderWrapper %s>' % repr(self.name)
-
-    def __str__(self):
-        return self.__repr__()
-
-    def __getattr__(self, name):
-        if name == 'env':
-            return self.object
-        elif name == 'builder':
-            return self.method
-        else:
-            raise AttributeError, name
-
-    def __setattr__(self, name, value):
-        if name == 'env':
-            self.object = value
-        elif name == 'builder':
-            self.method = value
-        else:
-            self.__dict__[name] = value
-
-    # This allows a Builder to be executed directly
-    # through the Environment to which it's attached.
-    # In practice, we shouldn't need this, because
-    # builders actually get executed through a Node.
-    # But we do have a unit test for this, and can't
-    # yet rule out that it would be useful in the
-    # future, so leave it for now.
-    #def execute(self, **kw):
-    #    kw['env'] = self.env
-    #    apply(self.builder.execute, (), kw)
-
-class BuilderDict(UserDict):
-    """This is a dictionary-like class used by an Environment to hold
-    the Builders.  We need to do this because every time someone changes
-    the Builders in the Environment's BUILDERS dictionary, we must
-    update the Environment's attributes."""
-    def __init__(self, dict, env):
-        # Set self.env before calling the superclass initialization,
-        # because it will end up calling our other methods, which will
-        # need to point the values in this dictionary to self.env.
-        self.env = env
-        UserDict.__init__(self, dict)
-
-    def __semi_deepcopy__(self):
-        return self.__class__(self.data, self.env)
-
-    def __setitem__(self, item, val):
-        try:
-            method = getattr(self.env, item).method
-        except AttributeError:
-            pass
-        else:
-            self.env.RemoveMethod(method)
-        UserDict.__setitem__(self, item, val)
-        BuilderWrapper(self.env, val, item)
-
-    def __delitem__(self, item):
-        UserDict.__delitem__(self, item)
-        delattr(self.env, item)
-
-    def update(self, dict):
-        for i, v in dict.items():
-            self.__setitem__(i, v)
-
-
-
-_is_valid_var = re.compile(r'[_a-zA-Z]\w*$')
-
-def is_valid_construction_var(varstr):
-    """Return if the specified string is a legitimate construction
-    variable.
-    """
-    return _is_valid_var.match(varstr)
-
-
-
-class SubstitutionEnvironment:
-    """Base class for different flavors of construction environments.
-
-    This class contains a minimal set of methods that handle contruction
-    variable expansion and conversion of strings to Nodes, which may or
-    may not be actually useful as a stand-alone class.  Which methods
-    ended up in this class is pretty arbitrary right now.  They're
-    basically the ones which we've empirically determined are common to
-    the different construction environment subclasses, and most of the
-    others that use or touch the underlying dictionary of construction
-    variables.
-
-    Eventually, this class should contain all the methods that we
-    determine are necessary for a "minimal" interface to the build engine.
-    A full "native Python" SCons environment has gotten pretty heavyweight
-    with all of the methods and Tools and construction variables we've
-    jammed in there, so it would be nice to have a lighter weight
-    alternative for interfaces that don't need all of the bells and
-    whistles.  (At some point, we'll also probably rename this class
-    "Base," since that more reflects what we want this class to become,
-    but because we've released comments that tell people to subclass
-    Environment.Base to create their own flavors of construction
-    environment, we'll save that for a future refactoring when this
-    class actually becomes useful.)
-    """
-
-    if SCons.Memoize.use_memoizer:
-        __metaclass__ = SCons.Memoize.Memoized_Metaclass
-
-    def __init__(self, **kw):
-        """Initialization of an underlying SubstitutionEnvironment class.
-        """
-        if __debug__: logInstanceCreation(self, 'Environment.SubstitutionEnvironment')
-        self.fs = SCons.Node.FS.get_default_fs()
-        self.ans = SCons.Node.Alias.default_ans
-        self.lookup_list = SCons.Node.arg2nodes_lookups
-        self._dict = kw.copy()
-        self._init_special()
-        self.added_methods = []
-        #self._memo = {}
-
-    def _init_special(self):
-        """Initial the dispatch tables for special handling of
-        special construction variables."""
-        self._special_del = {}
-        self._special_del['SCANNERS'] = _del_SCANNERS
-
-        self._special_set = {}
-        for key in reserved_construction_var_names:
-            self._special_set[key] = _set_reserved
-        self._special_set['BUILDERS'] = _set_BUILDERS
-        self._special_set['SCANNERS'] = _set_SCANNERS
-
-        # Freeze the keys of self._special_set in a list for use by
-        # methods that need to check.  (Empirically, list scanning has
-        # gotten better than dict.has_key() in Python 2.5.)
-        self._special_set_keys = self._special_set.keys()
-
-    def __cmp__(self, other):
-        return cmp(self._dict, other._dict)
-
-    def __delitem__(self, key):
-        special = self._special_del.get(key)
-        if special:
-            special(self, key)
-        else:
-            del self._dict[key]
-
-    def __getitem__(self, key):
-        return self._dict[key]
-
-    def __setitem__(self, key, value):
-        # This is heavily used.  This implementation is the best we have
-        # according to the timings in bench/env.__setitem__.py.
-        #
-        # The "key in self._special_set_keys" test here seems to perform
-        # pretty well for the number of keys we have.  A hard-coded
-        # list works a little better in Python 2.5, but that has the
-        # disadvantage of maybe getting out of sync if we ever add more
-        # variable names.  Using self._special_set.has_key() works a
-        # little better in Python 2.4, but is worse then this test.
-        # So right now it seems like a good trade-off, but feel free to
-        # revisit this with bench/env.__setitem__.py as needed (and
-        # as newer versions of Python come out).
-        if key in self._special_set_keys:
-            self._special_set[key](self, key, value)
-        else:
-            # If we already have the entry, then it's obviously a valid
-            # key and we don't need to check.  If we do check, using a
-            # global, pre-compiled regular expression directly is more
-            # efficient than calling another function or a method.
-            if not self._dict.has_key(key) \
-               and not _is_valid_var.match(key):
-                    raise SCons.Errors.UserError, "Illegal construction variable `%s'" % key
-            self._dict[key] = value
-
-    def get(self, key, default=None):
-        "Emulates the get() method of dictionaries."""
-        return self._dict.get(key, default)
-
-    def has_key(self, key):
-        return self._dict.has_key(key)
-
-    def items(self):
-        return self._dict.items()
-
-    def arg2nodes(self, args, node_factory=_null, lookup_list=_null, **kw):
-        if node_factory is _null:
-            node_factory = self.fs.File
-        if lookup_list is _null:
-            lookup_list = self.lookup_list
-
-        if not args:
-            return []
-
-        args = SCons.Util.flatten(args)
-
-        nodes = []
-        for v in args:
-            if SCons.Util.is_String(v):
-                n = None
-                for l in lookup_list:
-                    n = l(v)
-                    if not n is None:
-                        break
-                if not n is None:
-                    if SCons.Util.is_String(n):
-                        # n = self.subst(n, raw=1, **kw)
-                        kw['raw'] = 1
-                        n = apply(self.subst, (n,), kw)
-                        if node_factory:
-                            n = node_factory(n)
-                    if SCons.Util.is_List(n):
-                        nodes.extend(n)
-                    else:
-                        nodes.append(n)
-                elif node_factory:
-                    # v = node_factory(self.subst(v, raw=1, **kw))
-                    kw['raw'] = 1
-                    v = node_factory(apply(self.subst, (v,), kw))
-                    if SCons.Util.is_List(v):
-                        nodes.extend(v)
-                    else:
-                        nodes.append(v)
-            else:
-                nodes.append(v)
-
-        return nodes
-
-    def gvars(self):
-        return self._dict
-
-    def lvars(self):
-        return {}
-
-    def subst(self, string, raw=0, target=None, source=None, conv=None):
-        """Recursively interpolates construction variables from the
-        Environment into the specified string, returning the expanded
-        result.  Construction variables are specified by a $ prefix
-        in the string and begin with an initial underscore or
-        alphabetic character followed by any number of underscores
-        or alphanumeric characters.  The construction variable names
-        may be surrounded by curly braces to separate the name from
-        trailing characters.
-        """
-        gvars = self.gvars()
-        lvars = self.lvars()
-        lvars['__env__'] = self
-        return SCons.Subst.scons_subst(string, self, raw, target, source, gvars, lvars, conv)
-
-    def subst_kw(self, kw, raw=0, target=None, source=None):
-        nkw = {}
-        for k, v in kw.items():
-            k = self.subst(k, raw, target, source)
-            if SCons.Util.is_String(v):
-                v = self.subst(v, raw, target, source)
-            nkw[k] = v
-        return nkw
-
-    def subst_list(self, string, raw=0, target=None, source=None, conv=None):
-        """Calls through to SCons.Subst.scons_subst_list().  See
-        the documentation for that function."""
-        gvars = self.gvars()
-        lvars = self.lvars()
-        lvars['__env__'] = self
-        return SCons.Subst.scons_subst_list(string, self, raw, target, source, gvars, lvars, conv)
-
-    def subst_path(self, path, target=None, source=None):
-        """Substitute a path list, turning EntryProxies into Nodes
-        and leaving Nodes (and other objects) as-is."""
-
-        if not SCons.Util.is_List(path):
-            path = [path]
-
-        def s(obj):
-            """This is the "string conversion" routine that we have our
-            substitutions use to return Nodes, not strings.  This relies
-            on the fact that an EntryProxy object has a get() method that
-            returns the underlying Node that it wraps, which is a bit of
-            architectural dependence that we might need to break or modify
-            in the future in response to additional requirements."""
-            try:
-                get = obj.get
-            except AttributeError:
-                obj = SCons.Util.to_String_for_subst(obj)
-            else:
-                obj = get()
-            return obj
-
-        r = []
-        for p in path:
-            if SCons.Util.is_String(p):
-                p = self.subst(p, target=target, source=source, conv=s)
-                if SCons.Util.is_List(p):
-                    if len(p) == 1:
-                        p = p[0]
-                    else:
-                        # We have an object plus a string, or multiple
-                        # objects that we need to smush together.  No choice
-                        # but to make them into a string.
-                        p = string.join(map(SCons.Util.to_String_for_subst, p), '')
-            else:
-                p = s(p)
-            r.append(p)
-        return r
-
-    subst_target_source = subst
-
-    def backtick(self, command):
-        import subprocess
-        # common arguments
-        kw = { 'stdout' : subprocess.PIPE,
-               'stderr' : subprocess.PIPE,
-               'universal_newlines' : True,
-             }
-        # if the command is a list, assume it's been quoted
-        # othewise force a shell
-        if not SCons.Util.is_List(command): kw['shell'] = True
-        # run constructed command
-        #TODO(1.5) p = SCons.Action._subproc(self, command, **kw)
-        p = apply(SCons.Action._subproc, (self, command), kw)
-        out,err = p.communicate()
-        status = p.wait()
-        if err:
-            sys.stderr.write(err)
-        if status:
-            raise OSError("'%s' exited %d" % (command, status))
-        return out
-
-    def AddMethod(self, function, name=None):
-        """
-        Adds the specified function as a method of this construction
-        environment with the specified name.  If the name is omitted,
-        the default name is the name of the function itself.
-        """
-        method = MethodWrapper(self, function, name)
-        self.added_methods.append(method)
-
-    def RemoveMethod(self, function):
-        """
-        Removes the specified function's MethodWrapper from the
-        added_methods list, so we don't re-bind it when making a clone.
-        """
-        is_not_func = lambda dm, f=function: not dm.method is f
-        self.added_methods = filter(is_not_func, self.added_methods)
-
-    def Override(self, overrides):
-        """
-        Produce a modified environment whose variables are overriden by
-        the overrides dictionaries.  "overrides" is a dictionary that
-        will override the variables of this environment.
-
-        This function is much more efficient than Clone() or creating
-        a new Environment because it doesn't copy the construction
-        environment dictionary, it just wraps the underlying construction
-        environment, and doesn't even create a wrapper object if there
-        are no overrides.
-        """
-        if not overrides: return self
-        o = copy_non_reserved_keywords(overrides)
-        if not o: return self
-        overrides = {}
-        merges = None
-        for key, value in o.items():
-            if key == 'parse_flags':
-                merges = value
-            else:
-                overrides[key] = SCons.Subst.scons_subst_once(value, self, key)
-        env = OverrideEnvironment(self, overrides)
-        if merges: env.MergeFlags(merges)
-        return env
-
-    def ParseFlags(self, *flags):
-        """
-        Parse the set of flags and return a dict with the flags placed
-        in the appropriate entry.  The flags are treated as a typical
-        set of command-line flags for a GNU-like toolchain and used to
-        populate the entries in the dict immediately below.  If one of
-        the flag strings begins with a bang (exclamation mark), it is
-        assumed to be a command and the rest of the string is executed;
-        the result of that evaluation is then added to the dict.
-        """
-        dict = {
-            'ASFLAGS'       : SCons.Util.CLVar(''),
-            'CFLAGS'        : SCons.Util.CLVar(''),
-            'CCFLAGS'       : SCons.Util.CLVar(''),
-            'CPPDEFINES'    : [],
-            'CPPFLAGS'      : SCons.Util.CLVar(''),
-            'CPPPATH'       : [],
-            'FRAMEWORKPATH' : SCons.Util.CLVar(''),
-            'FRAMEWORKS'    : SCons.Util.CLVar(''),
-            'LIBPATH'       : [],
-            'LIBS'          : [],
-            'LINKFLAGS'     : SCons.Util.CLVar(''),
-            'RPATH'         : [],
-        }
-
-        # The use of the "me" parameter to provide our own name for
-        # recursion is an egregious hack to support Python 2.1 and before.
-        def do_parse(arg, me, self = self, dict = dict):
-            # if arg is a sequence, recurse with each element
-            if not arg:
-                return
-
-            if not SCons.Util.is_String(arg):
-                for t in arg: me(t, me)
-                return
-
-            # if arg is a command, execute it
-            if arg[0] == '!':
-                arg = self.backtick(arg[1:])
-
-            # utility function to deal with -D option
-            def append_define(name, dict = dict):
-                t = string.split(name, '=')
-                if len(t) == 1:
-                    dict['CPPDEFINES'].append(name)
-                else:
-                    dict['CPPDEFINES'].append([t[0], string.join(t[1:], '=')])
-
-            # Loop through the flags and add them to the appropriate option.
-            # This tries to strike a balance between checking for all possible
-            # flags and keeping the logic to a finite size, so it doesn't
-            # check for some that don't occur often.  It particular, if the
-            # flag is not known to occur in a config script and there's a way
-            # of passing the flag to the right place (by wrapping it in a -W
-            # flag, for example) we don't check for it.  Note that most
-            # preprocessor options are not handled, since unhandled options
-            # are placed in CCFLAGS, so unless the preprocessor is invoked
-            # separately, these flags will still get to the preprocessor.
-            # Other options not currently handled:
-            #  -iqoutedir      (preprocessor search path)
-            #  -u symbol       (linker undefined symbol)
-            #  -s              (linker strip files)
-            #  -static*        (linker static binding)
-            #  -shared*        (linker dynamic binding)
-            #  -symbolic       (linker global binding)
-            #  -R dir          (deprecated linker rpath)
-            # IBM compilers may also accept -qframeworkdir=foo
-    
-            params = shlex.split(arg)
-            append_next_arg_to = None   # for multi-word args
-            for arg in params:
-                if append_next_arg_to:
-                   if append_next_arg_to == 'CPPDEFINES':
-                       append_define(arg)
-                   elif append_next_arg_to == '-include':
-                       t = ('-include', self.fs.File(arg))
-                       dict['CCFLAGS'].append(t)
-                   elif append_next_arg_to == '-isysroot':
-                       t = ('-isysroot', arg)
-                       dict['CCFLAGS'].append(t)
-                       dict['LINKFLAGS'].append(t)
-                   elif append_next_arg_to == '-arch':
-                       t = ('-arch', arg)
-                       dict['CCFLAGS'].append(t)
-                       dict['LINKFLAGS'].append(t)
-                   else:
-                       dict[append_next_arg_to].append(arg)
-                   append_next_arg_to = None
-                elif not arg[0] in ['-', '+']:
-                    dict['LIBS'].append(self.fs.File(arg))
-                elif arg[:2] == '-L':
-                    if arg[2:]:
-                        dict['LIBPATH'].append(arg[2:])
-                    else:
-                        append_next_arg_to = 'LIBPATH'
-                elif arg[:2] == '-l':
-                    if arg[2:]:
-                        dict['LIBS'].append(arg[2:])
-                    else:
-                        append_next_arg_to = 'LIBS'
-                elif arg[:2] == '-I':
-                    if arg[2:]:
-                        dict['CPPPATH'].append(arg[2:])
-                    else:
-                        append_next_arg_to = 'CPPPATH'
-                elif arg[:4] == '-Wa,':
-                    dict['ASFLAGS'].append(arg[4:])
-                    dict['CCFLAGS'].append(arg)
-                elif arg[:4] == '-Wl,':
-                    if arg[:11] == '-Wl,-rpath=':
-                        dict['RPATH'].append(arg[11:])
-                    elif arg[:7] == '-Wl,-R,':
-                        dict['RPATH'].append(arg[7:])
-                    elif arg[:6] == '-Wl,-R':
-                        dict['RPATH'].append(arg[6:])
-                    else:
-                        dict['LINKFLAGS'].append(arg)
-                elif arg[:4] == '-Wp,':
-                    dict['CPPFLAGS'].append(arg)
-                elif arg[:2] == '-D':
-                    if arg[2:]:
-                        append_define(arg[2:])
-                    else:
-                        append_next_arg_to = 'CPPDEFINES'
-                elif arg == '-framework':
-                    append_next_arg_to = 'FRAMEWORKS'
-                elif arg[:14] == '-frameworkdir=':
-                    dict['FRAMEWORKPATH'].append(arg[14:])
-                elif arg[:2] == '-F':
-                    if arg[2:]:
-                        dict['FRAMEWORKPATH'].append(arg[2:])
-                    else:
-                        append_next_arg_to = 'FRAMEWORKPATH'
-                elif arg == '-mno-cygwin':
-                    dict['CCFLAGS'].append(arg)
-                    dict['LINKFLAGS'].append(arg)
-                elif arg == '-mwindows':
-                    dict['LINKFLAGS'].append(arg)
-                elif arg == '-pthread':
-                    dict['CCFLAGS'].append(arg)
-                    dict['LINKFLAGS'].append(arg)
-                elif arg[:5] == '-std=':
-                    dict['CFLAGS'].append(arg) # C only
-                elif arg[0] == '+':
-                    dict['CCFLAGS'].append(arg)
-                    dict['LINKFLAGS'].append(arg)
-                elif arg in ['-include', '-isysroot', '-arch']:
-                    append_next_arg_to = arg
-                else:
-                    dict['CCFLAGS'].append(arg)
-    
-        for arg in flags:
-            do_parse(arg, do_parse)
-        return dict
-
-    def MergeFlags(self, args, unique=1, dict=None):
-        """
-        Merge the dict in args into the construction variables of this
-        env, or the passed-in dict.  If args is not a dict, it is
-        converted into a dict using ParseFlags.  If unique is not set,
-        the flags are appended rather than merged.
-        """
-
-        if dict is None:
-            dict = self
-        if not SCons.Util.is_Dict(args):
-            args = self.ParseFlags(args)
-        if not unique:
-            apply(self.Append, (), args)
-            return self
-        for key, value in args.items():
-            if not value:
-                continue
-            try:
-                orig = self[key]
-            except KeyError:
-                orig = value
-            else:
-                if not orig:
-                    orig = value
-                elif value:
-                    # Add orig and value.  The logic here was lifted from
-                    # part of env.Append() (see there for a lot of comments
-                    # about the order in which things are tried) and is
-                    # used mainly to handle coercion of strings to CLVar to
-                    # "do the right thing" given (e.g.) an original CCFLAGS
-                    # string variable like '-pipe -Wall'.
-                    try:
-                        orig = orig + value
-                    except (KeyError, TypeError):
-                        try:
-                            add_to_orig = orig.append
-                        except AttributeError:
-                            value.insert(0, orig)
-                            orig = value
-                        else:
-                            add_to_orig(value)
-            t = []
-            if key[-4:] == 'PATH':
-                ### keep left-most occurence
-                for v in orig:
-                    if v not in t:
-                        t.append(v)
-            else:
-                ### keep right-most occurence
-                orig.reverse()
-                for v in orig:
-                    if v not in t:
-                        t.insert(0, v)
-            self[key] = t
-        return self
-
-#     def MergeShellPaths(self, args, prepend=1):
-#         """
-#         Merge the dict in args into the shell environment in env['ENV'].  
-#         Shell path elements are appended or prepended according to prepend.
-
-#         Uses Pre/AppendENVPath, so it always appends or prepends uniquely.
-
-#         Example: env.MergeShellPaths({'LIBPATH': '/usr/local/lib'})
-#         prepends /usr/local/lib to env['ENV']['LIBPATH'].
-#         """
-
-#         for pathname, pathval in args.items():
-#             if not pathval:
-#                 continue
-#             if prepend:
-#                 apply(self.PrependENVPath, (pathname, pathval))
-#             else:
-#                 apply(self.AppendENVPath, (pathname, pathval))
-
-
-# Used by the FindSourceFiles() method, below.
-# Stuck here for support of pre-2.2 Python versions.
-def build_source(ss, result):
-    for s in ss:
-        if isinstance(s, SCons.Node.FS.Dir):
-            build_source(s.all_children(), result)
-        elif s.has_builder():
-            build_source(s.sources, result)
-        elif isinstance(s.disambiguate(), SCons.Node.FS.File):
-            result.append(s)
-
-def default_decide_source(dependency, target, prev_ni):
-    f = SCons.Defaults.DefaultEnvironment().decide_source
-    return f(dependency, target, prev_ni)
-
-def default_decide_target(dependency, target, prev_ni):
-    f = SCons.Defaults.DefaultEnvironment().decide_target
-    return f(dependency, target, prev_ni)
-
-def default_copy_from_cache(src, dst):
-    f = SCons.Defaults.DefaultEnvironment().copy_from_cache
-    return f(src, dst)
-
-class Base(SubstitutionEnvironment):
-    """Base class for "real" construction Environments.  These are the
-    primary objects used to communicate dependency and construction
-    information to the build engine.
-
-    Keyword arguments supplied when the construction Environment
-    is created are construction variables used to initialize the
-    Environment.
-    """
-
-    if SCons.Memoize.use_memoizer:
-        __metaclass__ = SCons.Memoize.Memoized_Metaclass
-
-    memoizer_counters = []
-
-    #######################################################################
-    # This is THE class for interacting with the SCons build engine,
-    # and it contains a lot of stuff, so we're going to try to keep this
-    # a little organized by grouping the methods.
-    #######################################################################
-
-    #######################################################################
-    # Methods that make an Environment act like a dictionary.  These have
-    # the expected standard names for Python mapping objects.  Note that
-    # we don't actually make an Environment a subclass of UserDict for
-    # performance reasons.  Note also that we only supply methods for
-    # dictionary functionality that we actually need and use.
-    #######################################################################
-
-    def __init__(self,
-                 platform=None,
-                 tools=None,
-                 toolpath=None,
-                 variables=None,
-                 parse_flags = None,
-                 **kw):
-        """
-        Initialization of a basic SCons construction environment,
-        including setting up special construction variables like BUILDER,
-        PLATFORM, etc., and searching for and applying available Tools.
-
-        Note that we do *not* call the underlying base class
-        (SubsitutionEnvironment) initialization, because we need to
-        initialize things in a very specific order that doesn't work
-        with the much simpler base class initialization.
-        """
-        if __debug__: logInstanceCreation(self, 'Environment.Base')
-        self._memo = {}
-        self.fs = SCons.Node.FS.get_default_fs()
-        self.ans = SCons.Node.Alias.default_ans
-        self.lookup_list = SCons.Node.arg2nodes_lookups
-        self._dict = semi_deepcopy(SCons.Defaults.ConstructionEnvironment)
-        self._init_special()
-        self.added_methods = []
-
-        # We don't use AddMethod, or define these as methods in this
-        # class, because we *don't* want these functions to be bound
-        # methods.  They need to operate independently so that the
-        # settings will work properly regardless of whether a given
-        # target ends up being built with a Base environment or an
-        # OverrideEnvironment or what have you.
-        self.decide_target = default_decide_target
-        self.decide_source = default_decide_source
-
-        self.copy_from_cache = default_copy_from_cache
-
-        self._dict['BUILDERS'] = BuilderDict(self._dict['BUILDERS'], self)
-
-        if platform is None:
-            platform = self._dict.get('PLATFORM', None)
-            if platform is None:
-                platform = SCons.Platform.Platform()
-        if SCons.Util.is_String(platform):
-            platform = SCons.Platform.Platform(platform)
-        self._dict['PLATFORM'] = str(platform)
-        platform(self)
-
-        # Apply the passed-in and customizable variables to the
-        # environment before calling the tools, because they may use
-        # some of them during initialization.
-        if kw.has_key('options'):
-            # Backwards compatibility:  they may stll be using the
-            # old "options" keyword.
-            variables = kw['options']
-            del kw['options']
-        apply(self.Replace, (), kw)
-        keys = kw.keys()
-        if variables:
-            keys = keys + variables.keys()
-            variables.Update(self)
-
-        save = {}
-        for k in keys:
-            try:
-                save[k] = self._dict[k]
-            except KeyError:
-                # No value may have been set if they tried to pass in a
-                # reserved variable name like TARGETS.
-                pass
-
-        SCons.Tool.Initializers(self)
-
-        if tools is None:
-            tools = self._dict.get('TOOLS', None)
-            if tools is None:
-                tools = ['default']
-        apply_tools(self, tools, toolpath)
-
-        # Now restore the passed-in and customized variables
-        # to the environment, since the values the user set explicitly
-        # should override any values set by the tools.
-        for key, val in save.items():
-            self._dict[key] = val
-
-        # Finally, apply any flags to be merged in
-        if parse_flags: self.MergeFlags(parse_flags)
-
-    #######################################################################
-    # Utility methods that are primarily for internal use by SCons.
-    # These begin with lower-case letters.
-    #######################################################################
-
-    def get_builder(self, name):
-        """Fetch the builder with the specified name from the environment.
-        """
-        try:
-            return self._dict['BUILDERS'][name]
-        except KeyError:
-            return None
-
-    def get_CacheDir(self):
-        try:
-            path = self._CacheDir_path
-        except AttributeError:
-            path = SCons.Defaults.DefaultEnvironment()._CacheDir_path
-        try:
-            if path == self._last_CacheDir_path:
-                return self._last_CacheDir
-        except AttributeError:
-            pass
-        cd = SCons.CacheDir.CacheDir(path)
-        self._last_CacheDir_path = path
-        self._last_CacheDir = cd
-        return cd
-
-    def get_factory(self, factory, default='File'):
-        """Return a factory function for creating Nodes for this
-        construction environment.
-        """
-        name = default
-        try:
-            is_node = issubclass(factory, SCons.Node.Node)
-        except TypeError:
-            # The specified factory isn't a Node itself--it's
-            # most likely None, or possibly a callable.
-            pass
-        else:
-            if is_node:
-                # The specified factory is a Node (sub)class.  Try to
-                # return the FS method that corresponds to the Node's
-                # name--that is, we return self.fs.Dir if they want a Dir,
-                # self.fs.File for a File, etc.
-                try: name = factory.__name__
-                except AttributeError: pass
-                else: factory = None
-        if not factory:
-            # They passed us None, or we picked up a name from a specified
-            # class, so return the FS method.  (Note that we *don't*
-            # use our own self.{Dir,File} methods because that would
-            # cause env.subst() to be called twice on the file name,
-            # interfering with files that have $$ in them.)
-            factory = getattr(self.fs, name)
-        return factory
-
-    memoizer_counters.append(SCons.Memoize.CountValue('_gsm'))
-
-    def _gsm(self):
-        try:
-            return self._memo['_gsm']
-        except KeyError:
-            pass
-
-        result = {}
-
-        try:
-            scanners = self._dict['SCANNERS']
-        except KeyError:
-            pass
-        else:
-            # Reverse the scanner list so that, if multiple scanners
-            # claim they can scan the same suffix, earlier scanners
-            # in the list will overwrite later scanners, so that
-            # the result looks like a "first match" to the user.
-            if not SCons.Util.is_List(scanners):
-                scanners = [scanners]
-            else:
-                scanners = scanners[:] # copy so reverse() doesn't mod original
-            scanners.reverse()
-            for scanner in scanners:
-                for k in scanner.get_skeys(self):
-                    result[k] = scanner
-
-        self._memo['_gsm'] = result
-
-        return result
-
-    def get_scanner(self, skey):
-        """Find the appropriate scanner given a key (usually a file suffix).
-        """
-        return self._gsm().get(skey)
-
-    def scanner_map_delete(self, kw=None):
-        """Delete the cached scanner map (if we need to).
-        """
-        try:
-            del self._memo['_gsm']
-        except KeyError:
-            pass
-
-    def _update(self, dict):
-        """Update an environment's values directly, bypassing the normal
-        checks that occur when users try to set items.
-        """
-        self._dict.update(dict)
-
-    def get_src_sig_type(self):
-        try:
-            return self.src_sig_type
-        except AttributeError:
-            t = SCons.Defaults.DefaultEnvironment().src_sig_type
-            self.src_sig_type = t
-            return t
-
-    def get_tgt_sig_type(self):
-        try:
-            return self.tgt_sig_type
-        except AttributeError:
-            t = SCons.Defaults.DefaultEnvironment().tgt_sig_type
-            self.tgt_sig_type = t
-            return t
-
-    #######################################################################
-    # Public methods for manipulating an Environment.  These begin with
-    # upper-case letters.  The essential characteristic of methods in
-    # this section is that they do *not* have corresponding same-named
-    # global functions.  For example, a stand-alone Append() function
-    # makes no sense, because Append() is all about appending values to
-    # an Environment's construction variables.
-    #######################################################################
-
-    def Append(self, **kw):
-        """Append values to existing construction variables
-        in an Environment.
-        """
-        kw = copy_non_reserved_keywords(kw)
-        for key, val in kw.items():
-            # It would be easier on the eyes to write this using
-            # "continue" statements whenever we finish processing an item,
-            # but Python 1.5.2 apparently doesn't let you use "continue"
-            # within try:-except: blocks, so we have to nest our code.
-            try:
-                orig = self._dict[key]
-            except KeyError:
-                # No existing variable in the environment, so just set
-                # it to the new value.
-                self._dict[key] = val
-            else:
-                try:
-                    # Check if the original looks like a dictionary.
-                    # If it is, we can't just try adding the value because
-                    # dictionaries don't have __add__() methods, and
-                    # things like UserList will incorrectly coerce the
-                    # original dict to a list (which we don't want).
-                    update_dict = orig.update
-                except AttributeError:
-                    try:
-                        # Most straightforward:  just try to add them
-                        # together.  This will work in most cases, when the
-                        # original and new values are of compatible types.
-                        self._dict[key] = orig + val
-                    except (KeyError, TypeError):
-                        try:
-                            # Check if the original is a list.
-                            add_to_orig = orig.append
-                        except AttributeError:
-                            # The original isn't a list, but the new
-                            # value is (by process of elimination),
-                            # so insert the original in the new value
-                            # (if there's one to insert) and replace
-                            # the variable with it.
-                            if orig:
-                                val.insert(0, orig)
-                            self._dict[key] = val
-                        else:
-                            # The original is a list, so append the new
-                            # value to it (if there's a value to append).
-                            if val:
-                                add_to_orig(val)
-                else:
-                    # The original looks like a dictionary, so update it
-                    # based on what we think the value looks like.
-                    if SCons.Util.is_List(val):
-                        for v in val:
-                            orig[v] = None
-                    else:
-                        try:
-                            update_dict(val)
-                        except (AttributeError, TypeError, ValueError):
-                            if SCons.Util.is_Dict(val):
-                                for k, v in val.items():
-                                    orig[k] = v
-                            else:
-                                orig[val] = None
-        self.scanner_map_delete(kw)
-
-    def AppendENVPath(self, name, newpath, envname = 'ENV', 
-                      sep = os.pathsep, delete_existing=1):
-        """Append path elements to the path 'name' in the 'ENV'
-        dictionary for this environment.  Will only add any particular
-        path once, and will normpath and normcase all paths to help
-        assure this.  This can also handle the case where the env
-        variable is a list instead of a string.
-
-        If delete_existing is 0, a newpath which is already in the path
-        will not be moved to the end (it will be left where it is).
-        """
-
-        orig = ''
-        if self._dict.has_key(envname) and self._dict[envname].has_key(name):
-            orig = self._dict[envname][name]
-
-        nv = SCons.Util.AppendPath(orig, newpath, sep, delete_existing)
-
-        if not self._dict.has_key(envname):
-            self._dict[envname] = {}
-
-        self._dict[envname][name] = nv
-
-    def AppendUnique(self, delete_existing=0, **kw):
-        """Append values to existing construction variables
-        in an Environment, if they're not already there.
-        If delete_existing is 1, removes existing values first, so
-        values move to end.
-        """
-        kw = copy_non_reserved_keywords(kw)
-        for key, val in kw.items():
-            if not self._dict.has_key(key) or self._dict[key] in ('', None):
-                self._dict[key] = val
-            elif SCons.Util.is_Dict(self._dict[key]) and \
-                 SCons.Util.is_Dict(val):
-                self._dict[key].update(val)
-            elif SCons.Util.is_List(val):
-                dk = self._dict[key]
-                if not SCons.Util.is_List(dk):
-                    dk = [dk]
-                if delete_existing:
-                    dk = filter(lambda x, val=val: x not in val, dk)
-                else:
-                    val = filter(lambda x, dk=dk: x not in dk, val)
-                self._dict[key] = dk + val
-            else:
-                dk = self._dict[key]
-                if SCons.Util.is_List(dk):
-                    # By elimination, val is not a list.  Since dk is a
-                    # list, wrap val in a list first.
-                    if delete_existing:
-                        dk = filter(lambda x, val=val: x not in val, dk)
-                        self._dict[key] = dk + [val]
-                    else:
-                        if not val in dk:
-                            self._dict[key] = dk + [val]
-                else:
-                    if delete_existing:
-                        dk = filter(lambda x, val=val: x not in val, dk)
-                    self._dict[key] = dk + val
-        self.scanner_map_delete(kw)
-
-    def Clone(self, tools=[], toolpath=None, parse_flags = None, **kw):
-        """Return a copy of a construction Environment.  The
-        copy is like a Python "deep copy"--that is, independent
-        copies are made recursively of each objects--except that
-        a reference is copied when an object is not deep-copyable
-        (like a function).  There are no references to any mutable
-        objects in the original Environment.
-        """
-        clone = copy.copy(self)
-        clone._dict = semi_deepcopy(self._dict)
-
-        try:
-            cbd = clone._dict['BUILDERS']
-        except KeyError:
-            pass
-        else:
-            clone._dict['BUILDERS'] = BuilderDict(cbd, clone)
-
-        # Check the methods added via AddMethod() and re-bind them to
-        # the cloned environment.  Only do this if the attribute hasn't
-        # been overwritten by the user explicitly and still points to
-        # the added method.
-        clone.added_methods = []
-        for mw in self.added_methods:
-            if mw == getattr(self, mw.name):
-                clone.added_methods.append(mw.clone(clone))
-
-        clone._memo = {}
-
-        # Apply passed-in variables before the tools
-        # so the tools can use the new variables
-        kw = copy_non_reserved_keywords(kw)
-        new = {}
-        for key, value in kw.items():
-            new[key] = SCons.Subst.scons_subst_once(value, self, key)
-        apply(clone.Replace, (), new)
-
-        apply_tools(clone, tools, toolpath)
-
-        # apply them again in case the tools overwrote them
-        apply(clone.Replace, (), new)        
-
-        # Finally, apply any flags to be merged in
-        if parse_flags: clone.MergeFlags(parse_flags)
-
-        if __debug__: logInstanceCreation(self, 'Environment.EnvironmentClone')
-        return clone
-
-    def Copy(self, *args, **kw):
-        global _warn_copy_deprecated
-        if _warn_copy_deprecated:
-            msg = "The env.Copy() method is deprecated; use the env.Clone() method instead."
-            SCons.Warnings.warn(SCons.Warnings.DeprecatedCopyWarning, msg)
-            _warn_copy_deprecated = False
-        return apply(self.Clone, args, kw)
-
-    def _changed_build(self, dependency, target, prev_ni):
-        if dependency.changed_state(target, prev_ni):
-            return 1
-        return self.decide_source(dependency, target, prev_ni)
-
-    def _changed_content(self, dependency, target, prev_ni):
-        return dependency.changed_content(target, prev_ni)
-
-    def _changed_source(self, dependency, target, prev_ni):
-        target_env = dependency.get_build_env()
-        type = target_env.get_tgt_sig_type()
-        if type == 'source':
-            return target_env.decide_source(dependency, target, prev_ni)
-        else:
-            return target_env.decide_target(dependency, target, prev_ni)
-
-    def _changed_timestamp_then_content(self, dependency, target, prev_ni):
-        return dependency.changed_timestamp_then_content(target, prev_ni)
-
-    def _changed_timestamp_newer(self, dependency, target, prev_ni):
-        return dependency.changed_timestamp_newer(target, prev_ni)
-
-    def _changed_timestamp_match(self, dependency, target, prev_ni):
-        return dependency.changed_timestamp_match(target, prev_ni)
-
-    def _copy_from_cache(self, src, dst):
-        return self.fs.copy(src, dst)
-
-    def _copy2_from_cache(self, src, dst):
-        return self.fs.copy2(src, dst)
-
-    def Decider(self, function):
-        copy_function = self._copy2_from_cache
-        if function in ('MD5', 'content'):
-            if not SCons.Util.md5:
-                raise UserError, "MD5 signatures are not available in this version of Python."
-            function = self._changed_content
-        elif function == 'MD5-timestamp':
-            function = self._changed_timestamp_then_content
-        elif function in ('timestamp-newer', 'make'):
-            function = self._changed_timestamp_newer
-            copy_function = self._copy_from_cache
-        elif function == 'timestamp-match':
-            function = self._changed_timestamp_match
-        elif not callable(function):
-            raise UserError, "Unknown Decider value %s" % repr(function)
-
-        # We don't use AddMethod because we don't want to turn the
-        # function, which only expects three arguments, into a bound
-        # method, which would add self as an initial, fourth argument.
-        self.decide_target = function
-        self.decide_source = function
-
-        self.copy_from_cache = copy_function
-
-    def Detect(self, progs):
-        """Return the first available program in progs.
-        """
-        if not SCons.Util.is_List(progs):
-            progs = [ progs ]
-        for prog in progs:
-            path = self.WhereIs(prog)
-            if path: return prog
-        return None
-
-    def Dictionary(self, *args):
-        if not args:
-            return self._dict
-        dlist = map(lambda x, s=self: s._dict[x], args)
-        if len(dlist) == 1:
-            dlist = dlist[0]
-        return dlist
-
-    def Dump(self, key = None):
-        """
-        Using the standard Python pretty printer, dump the contents of the
-        scons build environment to stdout.
-
-        If the key passed in is anything other than None, then that will
-        be used as an index into the build environment dictionary and
-        whatever is found there will be fed into the pretty printer. Note
-        that this key is case sensitive.
-        """
-        import pprint
-        pp = pprint.PrettyPrinter(indent=2)
-        if key:
-            dict = self.Dictionary(key)
-        else:
-            dict = self.Dictionary()
-        return pp.pformat(dict)
-
-    def FindIxes(self, paths, prefix, suffix):
-        """
-        Search a list of paths for something that matches the prefix and suffix.
-
-        paths - the list of paths or nodes.
-        prefix - construction variable for the prefix.
-        suffix - construction variable for the suffix.
-        """
-
-        suffix = self.subst('$'+suffix)
-        prefix = self.subst('$'+prefix)
-
-        for path in paths:
-            dir,name = os.path.split(str(path))
-            if name[:len(prefix)] == prefix and name[-len(suffix):] == suffix:
-                return path
-
-    def ParseConfig(self, command, function=None, unique=1):
-        """
-        Use the specified function to parse the output of the command
-        in order to modify the current environment.  The 'command' can
-        be a string or a list of strings representing a command and
-        its arguments.  'Function' is an optional argument that takes
-        the environment, the output of the command, and the unique flag.
-        If no function is specified, MergeFlags, which treats the output
-        as the result of a typical 'X-config' command (i.e. gtk-config),
-        will merge the output into the appropriate variables.
-        """
-        if function is None:
-            def parse_conf(env, cmd, unique=unique):
-                return env.MergeFlags(cmd, unique)
-            function = parse_conf
-        if SCons.Util.is_List(command):
-            command = string.join(command)
-        command = self.subst(command)
-        return function(self, self.backtick(command))
-
-    def ParseDepends(self, filename, must_exist=None, only_one=0):
-        """
-        Parse a mkdep-style file for explicit dependencies.  This is
-        completely abusable, and should be unnecessary in the "normal"
-        case of proper SCons configuration, but it may help make
-        the transition from a Make hierarchy easier for some people
-        to swallow.  It can also be genuinely useful when using a tool
-        that can write a .d file, but for which writing a scanner would
-        be too complicated.
-        """
-        filename = self.subst(filename)
-        try:
-            fp = open(filename, 'r')
-        except IOError:
-            if must_exist:
-                raise
-            return
-        lines = SCons.Util.LogicalLines(fp).readlines()
-        lines = filter(lambda l: l[0] != '#', lines)
-        tdlist = []
-        for line in lines:
-            try:
-                target, depends = string.split(line, ':', 1)
-            except (AttributeError, TypeError, ValueError):
-                # Python 1.5.2 throws TypeError if line isn't a string,
-                # Python 2.x throws AttributeError because it tries
-                # to call line.split().  Either can throw ValueError
-                # if the line doesn't split into two or more elements.
-                pass
-            else:
-                tdlist.append((string.split(target), string.split(depends)))
-        if only_one:
-            targets = reduce(lambda x, y: x+y, map(lambda p: p[0], tdlist))
-            if len(targets) > 1:
-                raise SCons.Errors.UserError, "More than one dependency target found in `%s':  %s" % (filename, targets)
-        for target, depends in tdlist:
-            self.Depends(target, depends)
-
-    def Platform(self, platform):
-        platform = self.subst(platform)
-        return SCons.Platform.Platform(platform)(self)
-
-    def Prepend(self, **kw):
-        """Prepend values to existing construction variables
-        in an Environment.
-        """
-        kw = copy_non_reserved_keywords(kw)
-        for key, val in kw.items():
-            # It would be easier on the eyes to write this using
-            # "continue" statements whenever we finish processing an item,
-            # but Python 1.5.2 apparently doesn't let you use "continue"
-            # within try:-except: blocks, so we have to nest our code.
-            try:
-                orig = self._dict[key]
-            except KeyError:
-                # No existing variable in the environment, so just set
-                # it to the new value.
-                self._dict[key] = val
-            else:
-                try:
-                    # Check if the original looks like a dictionary.
-                    # If it is, we can't just try adding the value because
-                    # dictionaries don't have __add__() methods, and
-                    # things like UserList will incorrectly coerce the
-                    # original dict to a list (which we don't want).
-                    update_dict = orig.update
-                except AttributeError:
-                    try:
-                        # Most straightforward:  just try to add them
-                        # together.  This will work in most cases, when the
-                        # original and new values are of compatible types.
-                        self._dict[key] = val + orig
-                    except (KeyError, TypeError):
-                        try:
-                            # Check if the added value is a list.
-                            add_to_val = val.append
-                        except AttributeError:
-                            # The added value isn't a list, but the
-                            # original is (by process of elimination),
-                            # so insert the the new value in the original
-                            # (if there's one to insert).
-                            if val:
-                                orig.insert(0, val)
-                        else:
-                            # The added value is a list, so append
-                            # the original to it (if there's a value
-                            # to append).
-                            if orig:
-                                add_to_val(orig)
-                            self._dict[key] = val
-                else:
-                    # The original looks like a dictionary, so update it
-                    # based on what we think the value looks like.
-                    if SCons.Util.is_List(val):
-                        for v in val:
-                            orig[v] = None
-                    else:
-                        try:
-                            update_dict(val)
-                        except (AttributeError, TypeError, ValueError):
-                            if SCons.Util.is_Dict(val):
-                                for k, v in val.items():
-                                    orig[k] = v
-                            else:
-                                orig[val] = None
-        self.scanner_map_delete(kw)
-
-    def PrependENVPath(self, name, newpath, envname = 'ENV', sep = os.pathsep,
-                       delete_existing=1):
-        """Prepend path elements to the path 'name' in the 'ENV'
-        dictionary for this environment.  Will only add any particular
-        path once, and will normpath and normcase all paths to help
-        assure this.  This can also handle the case where the env
-        variable is a list instead of a string.
-
-        If delete_existing is 0, a newpath which is already in the path
-        will not be moved to the front (it will be left where it is).
-        """
-
-        orig = ''
-        if self._dict.has_key(envname) and self._dict[envname].has_key(name):
-            orig = self._dict[envname][name]
-
-        nv = SCons.Util.PrependPath(orig, newpath, sep, delete_existing)
-
-        if not self._dict.has_key(envname):
-            self._dict[envname] = {}
-
-        self._dict[envname][name] = nv
-
-    def PrependUnique(self, delete_existing=0, **kw):
-        """Prepend values to existing construction variables
-        in an Environment, if they're not already there.
-        If delete_existing is 1, removes existing values first, so
-        values move to front.
-        """
-        kw = copy_non_reserved_keywords(kw)
-        for key, val in kw.items():
-            if not self._dict.has_key(key) or self._dict[key] in ('', None):
-                self._dict[key] = val
-            elif SCons.Util.is_Dict(self._dict[key]) and \
-                 SCons.Util.is_Dict(val):
-                self._dict[key].update(val)
-            elif SCons.Util.is_List(val):
-                dk = self._dict[key]
-                if not SCons.Util.is_List(dk):
-                    dk = [dk]
-                if delete_existing:
-                    dk = filter(lambda x, val=val: x not in val, dk)
-                else:
-                    val = filter(lambda x, dk=dk: x not in dk, val)
-                self._dict[key] = val + dk
-            else:
-                dk = self._dict[key]
-                if SCons.Util.is_List(dk):
-                    # By elimination, val is not a list.  Since dk is a
-                    # list, wrap val in a list first.
-                    if delete_existing:
-                        dk = filter(lambda x, val=val: x not in val, dk)
-                        self._dict[key] = [val] + dk
-                    else:
-                        if not val in dk:
-                            self._dict[key] = [val] + dk
-                else:
-                    if delete_existing:
-                        dk = filter(lambda x, val=val: x not in val, dk)
-                    self._dict[key] = val + dk
-        self.scanner_map_delete(kw)
-
-    def Replace(self, **kw):
-        """Replace existing construction variables in an Environment
-        with new construction variables and/or values.
-        """
-        try:
-            kwbd = kw['BUILDERS']
-        except KeyError:
-            pass
-        else:
-            kwbd = semi_deepcopy(kwbd)
-            del kw['BUILDERS']
-            self.__setitem__('BUILDERS', kwbd)
-        kw = copy_non_reserved_keywords(kw)
-        self._update(semi_deepcopy(kw))
-        self.scanner_map_delete(kw)
-
-    def ReplaceIxes(self, path, old_prefix, old_suffix, new_prefix, new_suffix):
-        """
-        Replace old_prefix with new_prefix and old_suffix with new_suffix.
-
-        env - Environment used to interpolate variables.
-        path - the path that will be modified.
-        old_prefix - construction variable for the old prefix.
-        old_suffix - construction variable for the old suffix.
-        new_prefix - construction variable for the new prefix.
-        new_suffix - construction variable for the new suffix.
-        """
-        old_prefix = self.subst('$'+old_prefix)
-        old_suffix = self.subst('$'+old_suffix)
-
-        new_prefix = self.subst('$'+new_prefix)
-        new_suffix = self.subst('$'+new_suffix)
-
-        dir,name = os.path.split(str(path))
-        if name[:len(old_prefix)] == old_prefix:
-            name = name[len(old_prefix):]
-        if name[-len(old_suffix):] == old_suffix:
-            name = name[:-len(old_suffix)]
-        return os.path.join(dir, new_prefix+name+new_suffix)
-
-    def SetDefault(self, **kw):
-        for k in kw.keys():
-            if self._dict.has_key(k):
-                del kw[k]
-        apply(self.Replace, (), kw)
-
-    def _find_toolpath_dir(self, tp):
-        return self.fs.Dir(self.subst(tp)).srcnode().abspath
-
-    def Tool(self, tool, toolpath=None, **kw):
-        if SCons.Util.is_String(tool):
-            tool = self.subst(tool)
-            if toolpath is None:
-                toolpath = self.get('toolpath', [])
-            toolpath = map(self._find_toolpath_dir, toolpath)
-            tool = apply(SCons.Tool.Tool, (tool, toolpath), kw)
-        tool(self)
-
-    def WhereIs(self, prog, path=None, pathext=None, reject=[]):
-        """Find prog in the path.
-        """
-        if path is None:
-            try:
-                path = self['ENV']['PATH']
-            except KeyError:
-                pass
-        elif SCons.Util.is_String(path):
-            path = self.subst(path)
-        if pathext is None:
-            try:
-                pathext = self['ENV']['PATHEXT']
-            except KeyError:
-                pass
-        elif SCons.Util.is_String(pathext):
-            pathext = self.subst(pathext)
-        prog = self.subst(prog)
-        path = SCons.Util.WhereIs(prog, path, pathext, reject)
-        if path: return path
-        return None
-
-    #######################################################################
-    # Public methods for doing real "SCons stuff" (manipulating
-    # dependencies, setting attributes on targets, etc.).  These begin
-    # with upper-case letters.  The essential characteristic of methods
-    # in this section is that they all *should* have corresponding
-    # same-named global functions.
-    #######################################################################
-
-    def Action(self, *args, **kw):
-        def subst_string(a, self=self):
-            if SCons.Util.is_String(a):
-                a = self.subst(a)
-            return a
-        nargs = map(subst_string, args)
-        nkw = self.subst_kw(kw)
-        return apply(SCons.Action.Action, nargs, nkw)
-
-    def AddPreAction(self, files, action):
-        nodes = self.arg2nodes(files, self.fs.Entry)
-        action = SCons.Action.Action(action)
-        uniq = {}
-        for executor in map(lambda n: n.get_executor(), nodes):
-            uniq[executor] = 1
-        for executor in uniq.keys():
-            executor.add_pre_action(action)
-        return nodes
-
-    def AddPostAction(self, files, action):
-        nodes = self.arg2nodes(files, self.fs.Entry)
-        action = SCons.Action.Action(action)
-        uniq = {}
-        for executor in map(lambda n: n.get_executor(), nodes):
-            uniq[executor] = 1
-        for executor in uniq.keys():
-            executor.add_post_action(action)
-        return nodes
-
-    def Alias(self, target, source=[], action=None, **kw):
-        tlist = self.arg2nodes(target, self.ans.Alias)
-        if not SCons.Util.is_List(source):
-            source = [source]
-        source = filter(None, source)
-
-        if not action:
-            if not source:
-                # There are no source files and no action, so just
-                # return a target list of classic Alias Nodes, without
-                # any builder.  The externally visible effect is that
-                # this will make the wrapping Script.BuildTask class
-                # say that there's "Nothing to be done" for this Alias,
-                # instead of that it's "up to date."
-                return tlist
-
-            # No action, but there are sources.  Re-call all the target
-            # builders to add the sources to each target.
-            result = []
-            for t in tlist:
-                bld = t.get_builder(AliasBuilder)
-                result.extend(bld(self, t, source))
-            return result
-
-        nkw = self.subst_kw(kw)
-        nkw.update({
-            'action'            : SCons.Action.Action(action),
-            'source_factory'    : self.fs.Entry,
-            'multi'             : 1,
-            'is_explicit'       : None,
-        })
-        bld = apply(SCons.Builder.Builder, (), nkw)
-
-        # Apply the Builder separately to each target so that the Aliases
-        # stay separate.  If we did one "normal" Builder call with the
-        # whole target list, then all of the target Aliases would be
-        # associated under a single Executor.
-        result = []
-        for t in tlist:
-            # Calling the convert() method will cause a new Executor to be
-            # created from scratch, so we have to explicitly initialize
-            # it with the target's existing sources, plus our new ones,
-            # so nothing gets lost.
-            b = t.get_builder()
-            if b is None or b is AliasBuilder:
-                b = bld
-            else:
-                nkw['action'] = b.action + action
-                b = apply(SCons.Builder.Builder, (), nkw)
-            t.convert()
-            result.extend(b(self, t, t.sources + source))
-        return result
-
-    def AlwaysBuild(self, *targets):
-        tlist = []
-        for t in targets:
-            tlist.extend(self.arg2nodes(t, self.fs.Entry))
-        for t in tlist:
-            t.set_always_build()
-        return tlist
-
-    def BuildDir(self, *args, **kw):
-        if kw.has_key('build_dir'):
-            kw['variant_dir'] = kw['build_dir']
-            del kw['build_dir']
-        return apply(self.VariantDir, args, kw)
-
-    def Builder(self, **kw):
-        nkw = self.subst_kw(kw)
-        return apply(SCons.Builder.Builder, [], nkw)
-
-    def CacheDir(self, path):
-        import SCons.CacheDir
-        if not path is None:
-            path = self.subst(path)
-        self._CacheDir_path = path
-
-    def Clean(self, targets, files):
-        global CleanTargets
-        tlist = self.arg2nodes(targets, self.fs.Entry)
-        flist = self.arg2nodes(files, self.fs.Entry)
-        for t in tlist:
-            try:
-                CleanTargets[t].extend(flist)
-            except KeyError:
-                CleanTargets[t] = flist
-
-    def Configure(self, *args, **kw):
-        nargs = [self]
-        if args:
-            nargs = nargs + self.subst_list(args)[0]
-        nkw = self.subst_kw(kw)
-        nkw['_depth'] = kw.get('_depth', 0) + 1
-        try:
-            nkw['custom_tests'] = self.subst_kw(nkw['custom_tests'])
-        except KeyError:
-            pass
-        return apply(SCons.SConf.SConf, nargs, nkw)
-
-    def Command(self, target, source, action, **kw):
-        """Builds the supplied target files from the supplied
-        source files using the supplied action.  Action may
-        be any type that the Builder constructor will accept
-        for an action."""
-        bkw = {
-            'action' : action,
-            'target_factory' : self.fs.Entry,
-            'source_factory' : self.fs.Entry,
-        }
-        try: bkw['source_scanner'] = kw['source_scanner']
-        except KeyError: pass
-        else: del kw['source_scanner']
-        bld = apply(SCons.Builder.Builder, (), bkw)
-        return apply(bld, (self, target, source), kw)
-
-    def Depends(self, target, dependency):
-        """Explicity specify that 'target's depend on 'dependency'."""
-        tlist = self.arg2nodes(target, self.fs.Entry)
-        dlist = self.arg2nodes(dependency, self.fs.Entry)
-        for t in tlist:
-            t.add_dependency(dlist)
-        return tlist
-
-    def Dir(self, name, *args, **kw):
-        """
-        """
-        s = self.subst(name)
-        if SCons.Util.is_Sequence(s):
-            result=[]
-            for e in s:
-                result.append(apply(self.fs.Dir, (e,) + args, kw))
-            return result
-        return apply(self.fs.Dir, (s,) + args, kw)
-
-    def NoClean(self, *targets):
-        """Tags a target so that it will not be cleaned by -c"""
-        tlist = []
-        for t in targets:
-            tlist.extend(self.arg2nodes(t, self.fs.Entry))
-        for t in tlist:
-            t.set_noclean()
-        return tlist
-
-    def NoCache(self, *targets):
-        """Tags a target so that it will not be cached"""
-        tlist = []
-        for t in targets:
-            tlist.extend(self.arg2nodes(t, self.fs.Entry))
-        for t in tlist:
-            t.set_nocache()
-        return tlist
-
-    def Entry(self, name, *args, **kw):
-        """
-        """
-        s = self.subst(name)
-        if SCons.Util.is_Sequence(s):
-            result=[]
-            for e in s:
-                result.append(apply(self.fs.Entry, (e,) + args, kw))
-            return result
-        return apply(self.fs.Entry, (s,) + args, kw)
-
-    def Environment(self, **kw):
-        return apply(SCons.Environment.Environment, [], self.subst_kw(kw))
-
-    def Execute(self, action, *args, **kw):
-        """Directly execute an action through an Environment
-        """
-        action = apply(self.Action, (action,) + args, kw)
-        result = action([], [], self)
-        if isinstance(result, SCons.Errors.BuildError):
-            errstr = result.errstr
-            if result.filename:
-                errstr = result.filename + ': ' + errstr
-            sys.stderr.write("scons: *** %s\n" % errstr)
-            return result.status
-        else:
-            return result
-
-    def File(self, name, *args, **kw):
-        """
-        """
-        s = self.subst(name)
-        if SCons.Util.is_Sequence(s):
-            result=[]
-            for e in s:
-                result.append(apply(self.fs.File, (e,) + args, kw))
-            return result
-        return apply(self.fs.File, (s,) + args, kw)
-
-    def FindFile(self, file, dirs):
-        file = self.subst(file)
-        nodes = self.arg2nodes(dirs, self.fs.Dir)
-        return SCons.Node.FS.find_file(file, tuple(nodes))
-
-    def Flatten(self, sequence):
-        return SCons.Util.flatten(sequence)
-
-    def GetBuildPath(self, files):
-        result = map(str, self.arg2nodes(files, self.fs.Entry))
-        if SCons.Util.is_List(files):
-            return result
-        else:
-            return result[0]
-
-    def Glob(self, pattern, ondisk=True, source=False, strings=False):
-        return self.fs.Glob(self.subst(pattern), ondisk, source, strings)
-
-    def Ignore(self, target, dependency):
-        """Ignore a dependency."""
-        tlist = self.arg2nodes(target, self.fs.Entry)
-        dlist = self.arg2nodes(dependency, self.fs.Entry)
-        for t in tlist:
-            t.add_ignore(dlist)
-        return tlist
-
-    def Literal(self, string):
-        return SCons.Subst.Literal(string)
-
-    def Local(self, *targets):
-        ret = []
-        for targ in targets:
-            if isinstance(targ, SCons.Node.Node):
-                targ.set_local()
-                ret.append(targ)
-            else:
-                for t in self.arg2nodes(targ, self.fs.Entry):
-                   t.set_local()
-                   ret.append(t)
-        return ret
-
-    def Precious(self, *targets):
-        tlist = []
-        for t in targets:
-            tlist.extend(self.arg2nodes(t, self.fs.Entry))
-        for t in tlist:
-            t.set_precious()
-        return tlist
-
-    def Repository(self, *dirs, **kw):
-        dirs = self.arg2nodes(list(dirs), self.fs.Dir)
-        apply(self.fs.Repository, dirs, kw)
-
-    def Requires(self, target, prerequisite):
-        """Specify that 'prerequisite' must be built before 'target',
-        (but 'target' does not actually depend on 'prerequisite'
-        and need not be rebuilt if it changes)."""
-        tlist = self.arg2nodes(target, self.fs.Entry)
-        plist = self.arg2nodes(prerequisite, self.fs.Entry)
-        for t in tlist:
-            t.add_prerequisite(plist)
-        return tlist
-
-    def Scanner(self, *args, **kw):
-        nargs = []
-        for arg in args:
-            if SCons.Util.is_String(arg):
-                arg = self.subst(arg)
-            nargs.append(arg)
-        nkw = self.subst_kw(kw)
-        return apply(SCons.Scanner.Base, nargs, nkw)
-
-    def SConsignFile(self, name=".sconsign", dbm_module=None):
-        if not name is None:
-            name = self.subst(name)
-            if not os.path.isabs(name):
-                name = os.path.join(str(self.fs.SConstruct_dir), name)
-        if name:
-            name = os.path.normpath(name)
-            sconsign_dir = os.path.dirname(name)
-            if sconsign_dir and not os.path.exists(sconsign_dir):
-                self.Execute(SCons.Defaults.Mkdir(sconsign_dir))
-        SCons.SConsign.File(name, dbm_module)
-
-    def SideEffect(self, side_effect, target):
-        """Tell scons that side_effects are built as side
-        effects of building targets."""
-        side_effects = self.arg2nodes(side_effect, self.fs.Entry)
-        targets = self.arg2nodes(target, self.fs.Entry)
-
-        for side_effect in side_effects:
-            if side_effect.multiple_side_effect_has_builder():
-                raise SCons.Errors.UserError, "Multiple ways to build the same target were specified for: %s" % str(side_effect)
-            side_effect.add_source(targets)
-            side_effect.side_effect = 1
-            self.Precious(side_effect)
-            for target in targets:
-                target.side_effects.append(side_effect)
-        return side_effects
-
-    def SourceCode(self, entry, builder):
-        """Arrange for a source code builder for (part of) a tree."""
-        entries = self.arg2nodes(entry, self.fs.Entry)
-        for entry in entries:
-            entry.set_src_builder(builder)
-        return entries
-
-    def SourceSignatures(self, type):
-        global _warn_source_signatures_deprecated
-        if _warn_source_signatures_deprecated:
-            msg = "The env.SourceSignatures() method is deprecated;\n" + \
-                  "\tconvert your build to use the env.Decider() method instead."
-            SCons.Warnings.warn(SCons.Warnings.DeprecatedSourceSignaturesWarning, msg)
-            _warn_source_signatures_deprecated = False
-        type = self.subst(type)
-        self.src_sig_type = type
-        if type == 'MD5':
-            if not SCons.Util.md5:
-                raise UserError, "MD5 signatures are not available in this version of Python."
-            self.decide_source = self._changed_content
-        elif type == 'timestamp':
-            self.decide_source = self._changed_timestamp_match
-        else:
-            raise UserError, "Unknown source signature type '%s'" % type
-
-    def Split(self, arg):
-        """This function converts a string or list into a list of strings
-        or Nodes.  This makes things easier for users by allowing files to
-        be specified as a white-space separated list to be split.
-        The input rules are:
-            - A single string containing names separated by spaces. These will be
-              split apart at the spaces.
-            - A single Node instance
-            - A list containing either strings or Node instances. Any strings
-              in the list are not split at spaces.
-        In all cases, the function returns a list of Nodes and strings."""
-        if SCons.Util.is_List(arg):
-            return map(self.subst, arg)
-        elif SCons.Util.is_String(arg):
-            return string.split(self.subst(arg))
-        else:
-            return [self.subst(arg)]
-
-    def TargetSignatures(self, type):
-        global _warn_target_signatures_deprecated
-        if _warn_target_signatures_deprecated:
-            msg = "The env.TargetSignatures() method is deprecated;\n" + \
-                  "\tconvert your build to use the env.Decider() method instead."
-            SCons.Warnings.warn(SCons.Warnings.DeprecatedTargetSignaturesWarning, msg)
-            _warn_target_signatures_deprecated = False
-        type = self.subst(type)
-        self.tgt_sig_type = type
-        if type in ('MD5', 'content'):
-            if not SCons.Util.md5:
-                raise UserError, "MD5 signatures are not available in this version of Python."
-            self.decide_target = self._changed_content
-        elif type == 'timestamp':
-            self.decide_target = self._changed_timestamp_match
-        elif type == 'build':
-            self.decide_target = self._changed_build
-        elif type == 'source':
-            self.decide_target = self._changed_source
-        else:
-            raise UserError, "Unknown target signature type '%s'"%type
-
-    def Value(self, value, built_value=None):
-        """
-        """
-        return SCons.Node.Python.Value(value, built_value)
-
-    def VariantDir(self, variant_dir, src_dir, duplicate=1):
-        variant_dir = self.arg2nodes(variant_dir, self.fs.Dir)[0]
-        src_dir = self.arg2nodes(src_dir, self.fs.Dir)[0]
-        self.fs.VariantDir(variant_dir, src_dir, duplicate)
-
-    def FindSourceFiles(self, node='.'):
-        """ returns a list of all source files.
-        """
-        node = self.arg2nodes(node, self.fs.Entry)[0]
-
-        sources = []
-        # Uncomment this and get rid of the global definition when we
-        # drop support for pre-2.2 Python versions.
-        #def build_source(ss, result):
-        #    for s in ss:
-        #        if isinstance(s, SCons.Node.FS.Dir):
-        #            build_source(s.all_children(), result)
-        #        elif s.has_builder():
-        #            build_source(s.sources, result)
-        #        elif isinstance(s.disambiguate(), SCons.Node.FS.File):
-        #            result.append(s)
-        build_source(node.all_children(), sources)
-
-        # now strip the build_node from the sources by calling the srcnode
-        # function
-        def get_final_srcnode(file):
-            srcnode = file.srcnode()
-            while srcnode != file.srcnode():
-                srcnode = file.srcnode()
-            return srcnode
-
-        # get the final srcnode for all nodes, this means stripping any
-        # attached build node.
-        map( get_final_srcnode, sources )
-
-        # remove duplicates
-        return list(set(sources))
-
-    def FindInstalledFiles(self):
-        """ returns the list of all targets of the Install and InstallAs Builder.
-        """
-        from SCons.Tool import install
-        if install._UNIQUE_INSTALLED_FILES is None:
-            install._UNIQUE_INSTALLED_FILES = SCons.Util.uniquer_hashables(install._INSTALLED_FILES)
-        return install._UNIQUE_INSTALLED_FILES
-
-class OverrideEnvironment(Base):
-    """A proxy that overrides variables in a wrapped construction
-    environment by returning values from an overrides dictionary in
-    preference to values from the underlying subject environment.
-
-    This is a lightweight (I hope) proxy that passes through most use of
-    attributes to the underlying Environment.Base class, but has just
-    enough additional methods defined to act like a real construction
-    environment with overridden values.  It can wrap either a Base
-    construction environment, or another OverrideEnvironment, which
-    can in turn nest arbitrary OverrideEnvironments...
-
-    Note that we do *not* call the underlying base class
-    (SubsitutionEnvironment) initialization, because we get most of those
-    from proxying the attributes of the subject construction environment.
-    But because we subclass SubstitutionEnvironment, this class also
-    has inherited arg2nodes() and subst*() methods; those methods can't
-    be proxied because they need *this* object's methods to fetch the
-    values from the overrides dictionary.
-    """
-
-    if SCons.Memoize.use_memoizer:
-        __metaclass__ = SCons.Memoize.Memoized_Metaclass
-
-    def __init__(self, subject, overrides={}):
-        if __debug__: logInstanceCreation(self, 'Environment.OverrideEnvironment')
-        self.__dict__['__subject'] = subject
-        self.__dict__['overrides'] = overrides
-
-    # Methods that make this class act like a proxy.
-    def __getattr__(self, name):
-        return getattr(self.__dict__['__subject'], name)
-    def __setattr__(self, name, value):
-        setattr(self.__dict__['__subject'], name, value)
-
-    # Methods that make this class act like a dictionary.
-    def __getitem__(self, key):
-        try:
-            return self.__dict__['overrides'][key]
-        except KeyError:
-            return self.__dict__['__subject'].__getitem__(key)
-    def __setitem__(self, key, value):
-        if not is_valid_construction_var(key):
-            raise SCons.Errors.UserError, "Illegal construction variable `%s'" % key
-        self.__dict__['overrides'][key] = value
-    def __delitem__(self, key):
-        try:
-            del self.__dict__['overrides'][key]
-        except KeyError:
-            deleted = 0
-        else:
-            deleted = 1
-        try:
-            result = self.__dict__['__subject'].__delitem__(key)
-        except KeyError:
-            if not deleted:
-                raise
-            result = None
-        return result
-    def get(self, key, default=None):
-        """Emulates the get() method of dictionaries."""
-        try:
-            return self.__dict__['overrides'][key]
-        except KeyError:
-            return self.__dict__['__subject'].get(key, default)
-    def has_key(self, key):
-        try:
-            self.__dict__['overrides'][key]
-            return 1
-        except KeyError:
-            return self.__dict__['__subject'].has_key(key)
-    def Dictionary(self):
-        """Emulates the items() method of dictionaries."""
-        d = self.__dict__['__subject'].Dictionary().copy()
-        d.update(self.__dict__['overrides'])
-        return d
-    def items(self):
-        """Emulates the items() method of dictionaries."""
-        return self.Dictionary().items()
-
-    # Overridden private construction environment methods.
-    def _update(self, dict):
-        """Update an environment's values directly, bypassing the normal
-        checks that occur when users try to set items.
-        """
-        self.__dict__['overrides'].update(dict)
-
-    def gvars(self):
-        return self.__dict__['__subject'].gvars()
-
-    def lvars(self):
-        lvars = self.__dict__['__subject'].lvars()
-        lvars.update(self.__dict__['overrides'])
-        return lvars
-
-    # Overridden public construction environment methods.
-    def Replace(self, **kw):
-        kw = copy_non_reserved_keywords(kw)
-        self.__dict__['overrides'].update(semi_deepcopy(kw))
-
-# The entry point that will be used by the external world
-# to refer to a construction environment.  This allows the wrapper
-# interface to extend a construction environment for its own purposes
-# by subclassing SCons.Environment.Base and then assigning the
-# class to SCons.Environment.Environment.
-
-Environment = Base
-
-# An entry point for returning a proxy subclass instance that overrides
-# the subst*() methods so they don't actually perform construction
-# variable substitution.  This is specifically intended to be the shim
-# layer in between global function calls (which don't want construction
-# variable substitution) and the DefaultEnvironment() (which would
-# substitute variables if left to its own devices)."""
-#
-# We have to wrap this in a function that allows us to delay definition of
-# the class until it's necessary, so that when it subclasses Environment
-# it will pick up whatever Environment subclass the wrapper interface
-# might have assigned to SCons.Environment.Environment.
-
-def NoSubstitutionProxy(subject):
-    class _NoSubstitutionProxy(Environment):
-        def __init__(self, subject):
-            self.__dict__['__subject'] = subject
-        def __getattr__(self, name):
-            return getattr(self.__dict__['__subject'], name)
-        def __setattr__(self, name, value):
-            return setattr(self.__dict__['__subject'], name, value)
-        def raw_to_mode(self, dict):
-            try:
-                raw = dict['raw']
-            except KeyError:
-                pass
-            else:
-                del dict['raw']
-                dict['mode'] = raw
-        def subst(self, string, *args, **kwargs):
-            return string
-        def subst_kw(self, kw, *args, **kwargs):
-            return kw
-        def subst_list(self, string, *args, **kwargs):
-            nargs = (string, self,) + args
-            nkw = kwargs.copy()
-            nkw['gvars'] = {}
-            self.raw_to_mode(nkw)
-            return apply(SCons.Subst.scons_subst_list, nargs, nkw)
-        def subst_target_source(self, string, *args, **kwargs):
-            nargs = (string, self,) + args
-            nkw = kwargs.copy()
-            nkw['gvars'] = {}
-            self.raw_to_mode(nkw)
-            return apply(SCons.Subst.scons_subst, nargs, nkw)
-    return _NoSubstitutionProxy(subject)
+"""SCons.Environment
+
+Base class for construction Environments.  These are
+the primary objects used to communicate dependency and
+construction information to the build engine.
+
+Keyword arguments supplied when the construction Environment
+is created are construction variables used to initialize the
+Environment
+"""
+
+#
+# Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 The SCons Foundation
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be included
+# in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
+# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+#
+
+__revision__ = "src/engine/SCons/Environment.py 3603 2008/10/10 05:46:45 scons"
+
+
+import copy
+import os
+import sys
+import re
+import shlex
+import string
+from UserDict import UserDict
+
+import SCons.Action
+import SCons.Builder
+from SCons.Debug import logInstanceCreation
+import SCons.Defaults
+import SCons.Errors
+import SCons.Memoize
+import SCons.Node
+import SCons.Node.Alias
+import SCons.Node.FS
+import SCons.Node.Python
+import SCons.Platform
+import SCons.SConsign
+import SCons.Subst
+import SCons.Tool
+import SCons.Util
+import SCons.Warnings
+
+class _Null:
+    pass
+
+_null = _Null
+
+_warn_copy_deprecated = True
+_warn_source_signatures_deprecated = True
+_warn_target_signatures_deprecated = True
+
+CleanTargets = {}
+CalculatorArgs = {}
+
+semi_deepcopy = SCons.Util.semi_deepcopy
+
+# Pull UserError into the global name space for the benefit of
+# Environment().SourceSignatures(), which has some import statements
+# which seem to mess up its ability to reference SCons directly.
+UserError = SCons.Errors.UserError
+
+def alias_builder(env, target, source):
+    pass
+
+AliasBuilder = SCons.Builder.Builder(action = alias_builder,
+                                     target_factory = SCons.Node.Alias.default_ans.Alias,
+                                     source_factory = SCons.Node.FS.Entry,
+                                     multi = 1,
+                                     is_explicit = None,
+                                     name='AliasBuilder')
+
+def apply_tools(env, tools, toolpath):
+    # Store the toolpath in the Environment.
+    if toolpath is not None:
+        env['toolpath'] = toolpath
+
+    if not tools:
+        return
+    # Filter out null tools from the list.
+    for tool in filter(None, tools):
+        if SCons.Util.is_List(tool) or type(tool)==type(()):
+            toolname = tool[0]
+            toolargs = tool[1] # should be a dict of kw args
+            tool = apply(env.Tool, [toolname], toolargs)
+        else:
+            env.Tool(tool)
+
+# These names are controlled by SCons; users should never set or override
+# them.  This warning can optionally be turned off, but scons will still
+# ignore the illegal variable names even if it's off.
+reserved_construction_var_names = \
+    ['TARGET', 'TARGETS', 'SOURCE', 'SOURCES']
+
+def copy_non_reserved_keywords(dict):
+    result = semi_deepcopy(dict)
+    for k in result.keys():
+        if k in reserved_construction_var_names:
+            SCons.Warnings.warn(SCons.Warnings.ReservedVariableWarning,
+                                "Ignoring attempt to set reserved variable `%s'" % k)
+            del result[k]
+    return result
+
+def _set_reserved(env, key, value):
+    msg = "Ignoring attempt to set reserved variable `%s'" % key
+    SCons.Warnings.warn(SCons.Warnings.ReservedVariableWarning, msg)
+
+def _set_BUILDERS(env, key, value):
+    try:
+        bd = env._dict[key]
+        for k in bd.keys():
+            del bd[k]
+    except KeyError:
+        bd = BuilderDict(kwbd, env)
+        env._dict[key] = bd
+    bd.update(value)
+
+def _del_SCANNERS(env, key):
+    del env._dict[key]
+    env.scanner_map_delete()
+
+def _set_SCANNERS(env, key, value):
+    env._dict[key] = value
+    env.scanner_map_delete()
+
+
+
+# The following is partly based on code in a comment added by Peter
+# Shannon at the following page (there called the "transplant" class):
+#
+# ASPN : Python Cookbook : Dynamically added methods to a class
+# http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/81732
+#
+# We had independently been using the idiom as BuilderWrapper, but
+# factoring out the common parts into this base class, and making
+# BuilderWrapper a subclass that overrides __call__() to enforce specific
+# Builder calling conventions, simplified some of our higher-layer code.
+
+class MethodWrapper:
+    """
+    A generic Wrapper class that associates a method (which can
+    actually be any callable) with an object.  As part of creating this
+    MethodWrapper object an attribute with the specified (by default,
+    the name of the supplied method) is added to the underlying object.
+    When that new "method" is called, our __call__() method adds the
+    object as the first argument, simulating the Python behavior of
+    supplying "self" on method calls.
+
+    We hang on to the name by which the method was added to the underlying
+    base class so that we can provide a method to "clone" ourselves onto
+    a new underlying object being copied (without which we wouldn't need
+    to save that info).
+    """
+    def __init__(self, object, method, name=None):
+        if name is None:
+            name = method.__name__
+        self.object = object
+        self.method = method
+        self.name = name
+        setattr(self.object, name, self)
+
+    def __call__(self, *args, **kwargs):
+        nargs = (self.object,) + args
+        return apply(self.method, nargs, kwargs)
+
+    def clone(self, new_object):
+        """
+        Returns an object that re-binds the underlying "method" to
+        the specified new object.
+        """
+        return self.__class__(new_object, self.method, self.name)
+
+class BuilderWrapper(MethodWrapper):
+    """
+    A MethodWrapper subclass that that associates an environment with
+    a Builder.
+
+    This mainly exists to wrap the __call__() function so that all calls
+    to Builders can have their argument lists massaged in the same way
+    (treat a lone argument as the source, treat two arguments as target
+    then source, make sure both target and source are lists) without
+    having to have cut-and-paste code to do it.
+
+    As a bit of obsessive backwards compatibility, we also intercept
+    attempts to get or set the "env" or "builder" attributes, which were
+    the names we used before we put the common functionality into the
+    MethodWrapper base class.  We'll keep this around for a while in case
+    people shipped Tool modules that reached into the wrapper (like the
+    Tool/qt.py module does, or did).  There shouldn't be a lot attribute
+    fetching or setting on these, so a little extra work shouldn't hurt.
+    """
+    def __call__(self, target=None, source=_null, *args, **kw):
+        if source is _null:
+            source = target
+            target = None
+        if not target is None and not SCons.Util.is_List(target):
+            target = [target]
+        if not source is None and not SCons.Util.is_List(source):
+            source = [source]
+        return apply(MethodWrapper.__call__, (self, target, source) + args, kw)
+
+    def __repr__(self):
+        fmt = '<BuilderWrapper %s instance at 0x%08X>'
+        return fmt % (repr(self.name), id(self))
+
+    def __str__(self):
+        return self.__repr__()
+
+    def __getattr__(self, name):
+        if name == 'env':
+            return self.object
+        elif name == 'builder':
+            return self.method
+        else:
+            raise AttributeError, name
+
+    def __setattr__(self, name, value):
+        if name == 'env':
+            self.object = value
+        elif name == 'builder':
+            self.method = value
+        else:
+            self.__dict__[name] = value
+
+    # This allows a Builder to be executed directly
+    # through the Environment to which it's attached.
+    # In practice, we shouldn't need this, because
+    # builders actually get executed through a Node.
+    # But we do have a unit test for this, and can't
+    # yet rule out that it would be useful in the
+    # future, so leave it for now.
+    #def execute(self, **kw):
+    #    kw['env'] = self.env
+    #    apply(self.builder.execute, (), kw)
+
+class BuilderDict(UserDict):
+    """This is a dictionary-like class used by an Environment to hold
+    the Builders.  We need to do this because every time someone changes
+    the Builders in the Environment's BUILDERS dictionary, we must
+    update the Environment's attributes."""
+    def __init__(self, dict, env):
+        # Set self.env before calling the superclass initialization,
+        # because it will end up calling our other methods, which will
+        # need to point the values in this dictionary to self.env.
+        self.env = env
+        UserDict.__init__(self, dict)
+
+    def __semi_deepcopy__(self):
+        return self.__class__(self.data, self.env)
+
+    def __setitem__(self, item, val):
+        try:
+            method = getattr(self.env, item).method
+        except AttributeError:
+            pass
+        else:
+            self.env.RemoveMethod(method)
+        UserDict.__setitem__(self, item, val)
+        BuilderWrapper(self.env, val, item)
+
+    def __delitem__(self, item):
+        UserDict.__delitem__(self, item)
+        delattr(self.env, item)
+
+    def update(self, dict):
+        for i, v in dict.items():
+            self.__setitem__(i, v)
+
+
+
+_is_valid_var = re.compile(r'[_a-zA-Z]\w*$')
+
+def is_valid_construction_var(varstr):
+    """Return if the specified string is a legitimate construction
+    variable.
+    """
+    return _is_valid_var.match(varstr)
+
+
+
+class SubstitutionEnvironment:
+    """Base class for different flavors of construction environments.
+
+    This class contains a minimal set of methods that handle contruction
+    variable expansion and conversion of strings to Nodes, which may or
+    may not be actually useful as a stand-alone class.  Which methods
+    ended up in this class is pretty arbitrary right now.  They're
+    basically the ones which we've empirically determined are common to
+    the different construction environment subclasses, and most of the
+    others that use or touch the underlying dictionary of construction
+    variables.
+
+    Eventually, this class should contain all the methods that we
+    determine are necessary for a "minimal" interface to the build engine.
+    A full "native Python" SCons environment has gotten pretty heavyweight
+    with all of the methods and Tools and construction variables we've
+    jammed in there, so it would be nice to have a lighter weight
+    alternative for interfaces that don't need all of the bells and
+    whistles.  (At some point, we'll also probably rename this class
+    "Base," since that more reflects what we want this class to become,
+    but because we've released comments that tell people to subclass
+    Environment.Base to create their own flavors of construction
+    environment, we'll save that for a future refactoring when this
+    class actually becomes useful.)
+    """
+
+    if SCons.Memoize.use_memoizer:
+        __metaclass__ = SCons.Memoize.Memoized_Metaclass
+
+    def __init__(self, **kw):
+        """Initialization of an underlying SubstitutionEnvironment class.
+        """
+        if __debug__: logInstanceCreation(self, 'Environment.SubstitutionEnvironment')
+        self.fs = SCons.Node.FS.get_default_fs()
+        self.ans = SCons.Node.Alias.default_ans
+        self.lookup_list = SCons.Node.arg2nodes_lookups
+        self._dict = kw.copy()
+        self._init_special()
+        self.added_methods = []
+        #self._memo = {}
+
+    def _init_special(self):
+        """Initial the dispatch tables for special handling of
+        special construction variables."""
+        self._special_del = {}
+        self._special_del['SCANNERS'] = _del_SCANNERS
+
+        self._special_set = {}
+        for key in reserved_construction_var_names:
+            self._special_set[key] = _set_reserved
+        self._special_set['BUILDERS'] = _set_BUILDERS
+        self._special_set['SCANNERS'] = _set_SCANNERS
+
+        # Freeze the keys of self._special_set in a list for use by
+        # methods that need to check.  (Empirically, list scanning has
+        # gotten better than dict.has_key() in Python 2.5.)
+        self._special_set_keys = self._special_set.keys()
+
+    def __cmp__(self, other):
+        return cmp(self._dict, other._dict)
+
+    def __delitem__(self, key):
+        special = self._special_del.get(key)
+        if special:
+            special(self, key)
+        else:
+            del self._dict[key]
+
+    def __getitem__(self, key):
+        return self._dict[key]
+
+    def __setitem__(self, key, value):
+        # This is heavily used.  This implementation is the best we have
+        # according to the timings in bench/env.__setitem__.py.
+        #
+        # The "key in self._special_set_keys" test here seems to perform
+        # pretty well for the number of keys we have.  A hard-coded
+        # list works a little better in Python 2.5, but that has the
+        # disadvantage of maybe getting out of sync if we ever add more
+        # variable names.  Using self._special_set.has_key() works a
+        # little better in Python 2.4, but is worse then this test.
+        # So right now it seems like a good trade-off, but feel free to
+        # revisit this with bench/env.__setitem__.py as needed (and
+        # as newer versions of Python come out).
+        if key in self._special_set_keys:
+            self._special_set[key](self, key, value)
+        else:
+            # If we already have the entry, then it's obviously a valid
+            # key and we don't need to check.  If we do check, using a
+            # global, pre-compiled regular expression directly is more
+            # efficient than calling another function or a method.
+            if not self._dict.has_key(key) \
+               and not _is_valid_var.match(key):
+                    raise SCons.Errors.UserError, "Illegal construction variable `%s'" % key
+            self._dict[key] = value
+
+    def get(self, key, default=None):
+        "Emulates the get() method of dictionaries."""
+        return self._dict.get(key, default)
+
+    def has_key(self, key):
+        return self._dict.has_key(key)
+
+    def items(self):
+        return self._dict.items()
+
+    def arg2nodes(self, args, node_factory=_null, lookup_list=_null, **kw):
+        if node_factory is _null:
+            node_factory = self.fs.File
+        if lookup_list is _null:
+            lookup_list = self.lookup_list
+
+        if not args:
+            return []
+
+        args = SCons.Util.flatten(args)
+
+        nodes = []
+        for v in args:
+            if SCons.Util.is_String(v):
+                n = None
+                for l in lookup_list:
+                    n = l(v)
+                    if not n is None:
+                        break
+                if not n is None:
+                    if SCons.Util.is_String(n):
+                        # n = self.subst(n, raw=1, **kw)
+                        kw['raw'] = 1
+                        n = apply(self.subst, (n,), kw)
+                        if node_factory:
+                            n = node_factory(n)
+                    if SCons.Util.is_List(n):
+                        nodes.extend(n)
+                    else:
+                        nodes.append(n)
+                elif node_factory:
+                    # v = node_factory(self.subst(v, raw=1, **kw))
+                    kw['raw'] = 1
+                    v = node_factory(apply(self.subst, (v,), kw))
+                    if SCons.Util.is_List(v):
+                        nodes.extend(v)
+                    else:
+                        nodes.append(v)
+            else:
+                nodes.append(v)
+
+        return nodes
+
+    def gvars(self):
+        return self._dict
+
+    def lvars(self):
+        return {}
+
+    def subst(self, string, raw=0, target=None, source=None, conv=None):
+        """Recursively interpolates construction variables from the
+        Environment into the specified string, returning the expanded
+        result.  Construction variables are specified by a $ prefix
+        in the string and begin with an initial underscore or
+        alphabetic character followed by any number of underscores
+        or alphanumeric characters.  The construction variable names
+        may be surrounded by curly braces to separate the name from
+        trailing characters.
+        """
+        gvars = self.gvars()
+        lvars = self.lvars()
+        lvars['__env__'] = self
+        return SCons.Subst.scons_subst(string, self, raw, target, source, gvars, lvars, conv)
+
+    def subst_kw(self, kw, raw=0, target=None, source=None):
+        nkw = {}
+        for k, v in kw.items():
+            k = self.subst(k, raw, target, source)
+            if SCons.Util.is_String(v):
+                v = self.subst(v, raw, target, source)
+            nkw[k] = v
+        return nkw
+
+    def subst_list(self, string, raw=0, target=None, source=None, conv=None):
+        """Calls through to SCons.Subst.scons_subst_list().  See
+        the documentation for that function."""
+        gvars = self.gvars()
+        lvars = self.lvars()
+        lvars['__env__'] = self
+        return SCons.Subst.scons_subst_list(string, self, raw, target, source, gvars, lvars, conv)
+
+    def subst_path(self, path, target=None, source=None):
+        """Substitute a path list, turning EntryProxies into Nodes
+        and leaving Nodes (and other objects) as-is."""
+
+        if not SCons.Util.is_List(path):
+            path = [path]
+
+        def s(obj):
+            """This is the "string conversion" routine that we have our
+            substitutions use to return Nodes, not strings.  This relies
+            on the fact that an EntryProxy object has a get() method that
+            returns the underlying Node that it wraps, which is a bit of
+            architectural dependence that we might need to break or modify
+            in the future in response to additional requirements."""
+            try:
+                get = obj.get
+            except AttributeError:
+                obj = SCons.Util.to_String_for_subst(obj)
+            else:
+                obj = get()
+            return obj
+
+        r = []
+        for p in path:
+            if SCons.Util.is_String(p):
+                p = self.subst(p, target=target, source=source, conv=s)
+                if SCons.Util.is_List(p):
+                    if len(p) == 1:
+                        p = p[0]
+                    else:
+                        # We have an object plus a string, or multiple
+                        # objects that we need to smush together.  No choice
+                        # but to make them into a string.
+                        p = string.join(map(SCons.Util.to_String_for_subst, p), '')
+            else:
+                p = s(p)
+            r.append(p)
+        return r
+
+    subst_target_source = subst
+
+    def backtick(self, command):
+        import subprocess
+        # common arguments
+        kw = { 'stdout' : subprocess.PIPE,
+               'stderr' : subprocess.PIPE,
+               'universal_newlines' : True,
+             }
+        # if the command is a list, assume it's been quoted
+        # othewise force a shell
+        if not SCons.Util.is_List(command): kw['shell'] = True
+        # run constructed command
+        #TODO(1.5) p = SCons.Action._subproc(self, command, **kw)
+        p = apply(SCons.Action._subproc, (self, command), kw)
+        out,err = p.communicate()
+        status = p.wait()
+        if err:
+            sys.stderr.write(err)
+        if status:
+            raise OSError("'%s' exited %d" % (command, status))
+        return out
+
+    def AddMethod(self, function, name=None):
+        """
+        Adds the specified function as a method of this construction
+        environment with the specified name.  If the name is omitted,
+        the default name is the name of the function itself.
+        """
+        method = MethodWrapper(self, function, name)
+        self.added_methods.append(method)
+
+    def RemoveMethod(self, function):
+        """
+        Removes the specified function's MethodWrapper from the
+        added_methods list, so we don't re-bind it when making a clone.
+        """
+        is_not_func = lambda dm, f=function: not dm.method is f
+        self.added_methods = filter(is_not_func, self.added_methods)
+
+    def Override(self, overrides):
+        """
+        Produce a modified environment whose variables are overriden by
+        the overrides dictionaries.  "overrides" is a dictionary that
+        will override the variables of this environment.
+
+        This function is much more efficient than Clone() or creating
+        a new Environment because it doesn't copy the construction
+        environment dictionary, it just wraps the underlying construction
+        environment, and doesn't even create a wrapper object if there
+        are no overrides.
+        """
+        if not overrides: return self
+        o = copy_non_reserved_keywords(overrides)
+        if not o: return self
+        overrides = {}
+        merges = None
+        for key, value in o.items():
+            if key == 'parse_flags':
+                merges = value
+            else:
+                overrides[key] = SCons.Subst.scons_subst_once(value, self, key)
+        env = OverrideEnvironment(self, overrides)
+        if merges: env.MergeFlags(merges)
+        return env
+
+    def ParseFlags(self, *flags):
+        """
+        Parse the set of flags and return a dict with the flags placed
+        in the appropriate entry.  The flags are treated as a typical
+        set of command-line flags for a GNU-like toolchain and used to
+        populate the entries in the dict immediately below.  If one of
+        the flag strings begins with a bang (exclamation mark), it is
+        assumed to be a command and the rest of the string is executed;
+        the result of that evaluation is then added to the dict.
+        """
+        dict = {
+            'ASFLAGS'       : SCons.Util.CLVar(''),
+            'CFLAGS'        : SCons.Util.CLVar(''),
+            'CCFLAGS'       : SCons.Util.CLVar(''),
+            'CPPDEFINES'    : [],
+            'CPPFLAGS'      : SCons.Util.CLVar(''),
+            'CPPPATH'       : [],
+            'FRAMEWORKPATH' : SCons.Util.CLVar(''),
+            'FRAMEWORKS'    : SCons.Util.CLVar(''),
+            'LIBPATH'       : [],
+            'LIBS'          : [],
+            'LINKFLAGS'     : SCons.Util.CLVar(''),
+            'RPATH'         : [],
+        }
+
+        # The use of the "me" parameter to provide our own name for
+        # recursion is an egregious hack to support Python 2.1 and before.
+        def do_parse(arg, me, self = self, dict = dict):
+            # if arg is a sequence, recurse with each element
+            if not arg:
+                return
+
+            if not SCons.Util.is_String(arg):
+                for t in arg: me(t, me)
+                return
+
+            # if arg is a command, execute it
+            if arg[0] == '!':
+                arg = self.backtick(arg[1:])
+
+            # utility function to deal with -D option
+            def append_define(name, dict = dict):
+                t = string.split(name, '=')
+                if len(t) == 1:
+                    dict['CPPDEFINES'].append(name)
+                else:
+                    dict['CPPDEFINES'].append([t[0], string.join(t[1:], '=')])
+
+            # Loop through the flags and add them to the appropriate option.
+            # This tries to strike a balance between checking for all possible
+            # flags and keeping the logic to a finite size, so it doesn't
+            # check for some that don't occur often.  It particular, if the
+            # flag is not known to occur in a config script and there's a way
+            # of passing the flag to the right place (by wrapping it in a -W
+            # flag, for example) we don't check for it.  Note that most
+            # preprocessor options are not handled, since unhandled options
+            # are placed in CCFLAGS, so unless the preprocessor is invoked
+            # separately, these flags will still get to the preprocessor.
+            # Other options not currently handled:
+            #  -iqoutedir      (preprocessor search path)
+            #  -u symbol       (linker undefined symbol)
+            #  -s              (linker strip files)
+            #  -static*        (linker static binding)
+            #  -shared*        (linker dynamic binding)
+            #  -symbolic       (linker global binding)
+            #  -R dir          (deprecated linker rpath)
+            # IBM compilers may also accept -qframeworkdir=foo
+    
+            params = shlex.split(arg)
+            append_next_arg_to = None   # for multi-word args
+            for arg in params:
+                if append_next_arg_to:
+                   if append_next_arg_to == 'CPPDEFINES':
+                       append_define(arg)
+                   elif append_next_arg_to == '-include':
+                       t = ('-include', self.fs.File(arg))
+                       dict['CCFLAGS'].append(t)
+                   elif append_next_arg_to == '-isysroot':
+                       t = ('-isysroot', arg)
+                       dict['CCFLAGS'].append(t)
+                       dict['LINKFLAGS'].append(t)
+                   elif append_next_arg_to == '-arch':
+                       t = ('-arch', arg)
+                       dict['CCFLAGS'].append(t)
+                       dict['LINKFLAGS'].append(t)
+                   else:
+                       dict[append_next_arg_to].append(arg)
+                   append_next_arg_to = None
+                elif not arg[0] in ['-', '+']:
+                    dict['LIBS'].append(self.fs.File(arg))
+                elif arg[:2] == '-L':
+                    if arg[2:]:
+                        dict['LIBPATH'].append(arg[2:])
+                    else:
+                        append_next_arg_to = 'LIBPATH'
+                elif arg[:2] == '-l':
+                    if arg[2:]:
+                        dict['LIBS'].append(arg[2:])
+                    else:
+                        append_next_arg_to = 'LIBS'
+                elif arg[:2] == '-I':
+                    if arg[2:]:
+                        dict['CPPPATH'].append(arg[2:])
+                    else:
+                        append_next_arg_to = 'CPPPATH'
+                elif arg[:4] == '-Wa,':
+                    dict['ASFLAGS'].append(arg[4:])
+                    dict['CCFLAGS'].append(arg)
+                elif arg[:4] == '-Wl,':
+                    if arg[:11] == '-Wl,-rpath=':
+                        dict['RPATH'].append(arg[11:])
+                    elif arg[:7] == '-Wl,-R,':
+                        dict['RPATH'].append(arg[7:])
+                    elif arg[:6] == '-Wl,-R':
+                        dict['RPATH'].append(arg[6:])
+                    else:
+                        dict['LINKFLAGS'].append(arg)
+                elif arg[:4] == '-Wp,':
+                    dict['CPPFLAGS'].append(arg)
+                elif arg[:2] == '-D':
+                    if arg[2:]:
+                        append_define(arg[2:])
+                    else:
+                        append_next_arg_to = 'CPPDEFINES'
+                elif arg == '-framework':
+                    append_next_arg_to = 'FRAMEWORKS'
+                elif arg[:14] == '-frameworkdir=':
+                    dict['FRAMEWORKPATH'].append(arg[14:])
+                elif arg[:2] == '-F':
+                    if arg[2:]:
+                        dict['FRAMEWORKPATH'].append(arg[2:])
+                    else:
+                        append_next_arg_to = 'FRAMEWORKPATH'
+                elif arg == '-mno-cygwin':
+                    dict['CCFLAGS'].append(arg)
+                    dict['LINKFLAGS'].append(arg)
+                elif arg == '-mwindows':
+                    dict['LINKFLAGS'].append(arg)
+                elif arg == '-pthread':
+                    dict['CCFLAGS'].append(arg)
+                    dict['LINKFLAGS'].append(arg)
+                elif arg[:5] == '-std=':
+                    dict['CFLAGS'].append(arg) # C only
+                elif arg[0] == '+':
+                    dict['CCFLAGS'].append(arg)
+                    dict['LINKFLAGS'].append(arg)
+                elif arg in ['-include', '-isysroot', '-arch']:
+                    append_next_arg_to = arg
+                else:
+                    dict['CCFLAGS'].append(arg)
+    
+        for arg in flags:
+            do_parse(arg, do_parse)
+        return dict
+
+    def MergeFlags(self, args, unique=1, dict=None):
+        """
+        Merge the dict in args into the construction variables of this
+        env, or the passed-in dict.  If args is not a dict, it is
+        converted into a dict using ParseFlags.  If unique is not set,
+        the flags are appended rather than merged.
+        """
+
+        if dict is None:
+            dict = self
+        if not SCons.Util.is_Dict(args):
+            args = self.ParseFlags(args)
+        if not unique:
+            apply(self.Append, (), args)
+            return self
+        for key, value in args.items():
+            if not value:
+                continue
+            try:
+                orig = self[key]
+            except KeyError:
+                orig = value
+            else:
+                if not orig:
+                    orig = value
+                elif value:
+                    # Add orig and value.  The logic here was lifted from
+                    # part of env.Append() (see there for a lot of comments
+                    # about the order in which things are tried) and is
+                    # used mainly to handle coercion of strings to CLVar to
+                    # "do the right thing" given (e.g.) an original CCFLAGS
+                    # string variable like '-pipe -Wall'.
+                    try:
+                        orig = orig + value
+                    except (KeyError, TypeError):
+                        try:
+                            add_to_orig = orig.append
+                        except AttributeError:
+                            value.insert(0, orig)
+                            orig = value
+                        else:
+                            add_to_orig(value)
+            t = []
+            if key[-4:] == 'PATH':
+                ### keep left-most occurence
+                for v in orig:
+                    if v not in t:
+                        t.append(v)
+            else:
+                ### keep right-most occurence
+                orig.reverse()
+                for v in orig:
+                    if v not in t:
+                        t.insert(0, v)
+            self[key] = t
+        return self
+
+#     def MergeShellPaths(self, args, prepend=1):
+#         """
+#         Merge the dict in args into the shell environment in env['ENV'].  
+#         Shell path elements are appended or prepended according to prepend.
+
+#         Uses Pre/AppendENVPath, so it always appends or prepends uniquely.
+
+#         Example: env.MergeShellPaths({'LIBPATH': '/usr/local/lib'})
+#         prepends /usr/local/lib to env['ENV']['LIBPATH'].
+#         """
+
+#         for pathname, pathval in args.items():
+#             if not pathval:
+#                 continue
+#             if prepend:
+#                 apply(self.PrependENVPath, (pathname, pathval))
+#             else:
+#                 apply(self.AppendENVPath, (pathname, pathval))
+
+
+# Used by the FindSourceFiles() method, below.
+# Stuck here for support of pre-2.2 Python versions.
+def build_source(ss, result):
+    for s in ss:
+        if isinstance(s, SCons.Node.FS.Dir):
+            build_source(s.all_children(), result)
+        elif s.has_builder():
+            build_source(s.sources, result)
+        elif isinstance(s.disambiguate(), SCons.Node.FS.File):
+            result.append(s)
+
+def default_decide_source(dependency, target, prev_ni):
+    f = SCons.Defaults.DefaultEnvironment().decide_source
+    return f(dependency, target, prev_ni)
+
+def default_decide_target(dependency, target, prev_ni):
+    f = SCons.Defaults.DefaultEnvironment().decide_target
+    return f(dependency, target, prev_ni)
+
+def default_copy_from_cache(src, dst):
+    f = SCons.Defaults.DefaultEnvironment().copy_from_cache
+    return f(src, dst)
+
+class Base(SubstitutionEnvironment):
+    """Base class for "real" construction Environments.  These are the
+    primary objects used to communicate dependency and construction
+    information to the build engine.
+
+    Keyword arguments supplied when the construction Environment
+    is created are construction variables used to initialize the
+    Environment.
+    """
+
+    if SCons.Memoize.use_memoizer:
+        __metaclass__ = SCons.Memoize.Memoized_Metaclass
+
+    memoizer_counters = []
+
+    #######################################################################
+    # This is THE class for interacting with the SCons build engine,
+    # and it contains a lot of stuff, so we're going to try to keep this
+    # a little organized by grouping the methods.
+    #######################################################################
+
+    #######################################################################
+    # Methods that make an Environment act like a dictionary.  These have
+    # the expected standard names for Python mapping objects.  Note that
+    # we don't actually make an Environment a subclass of UserDict for
+    # performance reasons.  Note also that we only supply methods for
+    # dictionary functionality that we actually need and use.
+    #######################################################################
+
+    def __init__(self,
+                 platform=None,
+                 tools=None,
+                 toolpath=None,
+                 variables=None,
+                 parse_flags = None,
+                 **kw):
+        """
+        Initialization of a basic SCons construction environment,
+        including setting up special construction variables like BUILDER,
+        PLATFORM, etc., and searching for and applying available Tools.
+
+        Note that we do *not* call the underlying base class
+        (SubsitutionEnvironment) initialization, because we need to
+        initialize things in a very specific order that doesn't work
+        with the much simpler base class initialization.
+        """
+        if __debug__: logInstanceCreation(self, 'Environment.Base')
+        self._memo = {}
+        self.fs = SCons.Node.FS.get_default_fs()
+        self.ans = SCons.Node.Alias.default_ans
+        self.lookup_list = SCons.Node.arg2nodes_lookups
+        self._dict = semi_deepcopy(SCons.Defaults.ConstructionEnvironment)
+        self._init_special()
+        self.added_methods = []
+
+        # We don't use AddMethod, or define these as methods in this
+        # class, because we *don't* want these functions to be bound
+        # methods.  They need to operate independently so that the
+        # settings will work properly regardless of whether a given
+        # target ends up being built with a Base environment or an
+        # OverrideEnvironment or what have you.
+        self.decide_target = default_decide_target
+        self.decide_source = default_decide_source
+
+        self.copy_from_cache = default_copy_from_cache
+
+        self._dict['BUILDERS'] = BuilderDict(self._dict['BUILDERS'], self)
+
+        if platform is None:
+            platform = self._dict.get('PLATFORM', None)
+            if platform is None:
+                platform = SCons.Platform.Platform()
+        if SCons.Util.is_String(platform):
+            platform = SCons.Platform.Platform(platform)
+        self._dict['PLATFORM'] = str(platform)
+        platform(self)
+
+        # Apply the passed-in and customizable variables to the
+        # environment before calling the tools, because they may use
+        # some of them during initialization.
+        if kw.has_key('options'):
+            # Backwards compatibility:  they may stll be using the
+            # old "options" keyword.
+            variables = kw['options']
+            del kw['options']
+        apply(self.Replace, (), kw)
+        keys = kw.keys()
+        if variables:
+            keys = keys + variables.keys()
+            variables.Update(self)
+
+        save = {}
+        for k in keys:
+            try:
+                save[k] = self._dict[k]
+            except KeyError:
+                # No value may have been set if they tried to pass in a
+                # reserved variable name like TARGETS.
+                pass
+
+        SCons.Tool.Initializers(self)
+
+        if tools is None:
+            tools = self._dict.get('TOOLS', None)
+            if tools is None:
+                tools = ['default']
+        apply_tools(self, tools, toolpath)
+
+        # Now restore the passed-in and customized variables
+        # to the environment, since the values the user set explicitly
+        # should override any values set by the tools.
+        for key, val in save.items():
+            self._dict[key] = val
+
+        # Finally, apply any flags to be merged in
+        if parse_flags: self.MergeFlags(parse_flags)
+
+    #######################################################################
+    # Utility methods that are primarily for internal use by SCons.
+    # These begin with lower-case letters.
+    #######################################################################
+
+    def get_builder(self, name):
+        """Fetch the builder with the specified name from the environment.
+        """
+        try:
+            return self._dict['BUILDERS'][name]
+        except KeyError:
+            return None
+
+    def get_CacheDir(self):
+        try:
+            path = self._CacheDir_path
+        except AttributeError:
+            path = SCons.Defaults.DefaultEnvironment()._CacheDir_path
+        try:
+            if path == self._last_CacheDir_path:
+                return self._last_CacheDir
+        except AttributeError:
+            pass
+        cd = SCons.CacheDir.CacheDir(path)
+        self._last_CacheDir_path = path
+        self._last_CacheDir = cd
+        return cd
+
+    def get_factory(self, factory, default='File'):
+        """Return a factory function for creating Nodes for this
+        construction environment.
+        """
+        name = default
+        try:
+            is_node = issubclass(factory, SCons.Node.Node)
+        except TypeError:
+            # The specified factory isn't a Node itself--it's
+            # most likely None, or possibly a callable.
+            pass
+        else:
+            if is_node:
+                # The specified factory is a Node (sub)class.  Try to
+                # return the FS method that corresponds to the Node's
+                # name--that is, we return self.fs.Dir if they want a Dir,
+                # self.fs.File for a File, etc.
+                try: name = factory.__name__
+                except AttributeError: pass
+                else: factory = None
+        if not factory:
+            # They passed us None, or we picked up a name from a specified
+            # class, so return the FS method.  (Note that we *don't*
+            # use our own self.{Dir,File} methods because that would
+            # cause env.subst() to be called twice on the file name,
+            # interfering with files that have $$ in them.)
+            factory = getattr(self.fs, name)
+        return factory
+
+    memoizer_counters.append(SCons.Memoize.CountValue('_gsm'))
+
+    def _gsm(self):
+        try:
+            return self._memo['_gsm']
+        except KeyError:
+            pass
+
+        result = {}
+
+        try:
+            scanners = self._dict['SCANNERS']
+        except KeyError:
+            pass
+        else:
+            # Reverse the scanner list so that, if multiple scanners
+            # claim they can scan the same suffix, earlier scanners
+            # in the list will overwrite later scanners, so that
+            # the result looks like a "first match" to the user.
+            if not SCons.Util.is_List(scanners):
+                scanners = [scanners]
+            else:
+                scanners = scanners[:] # copy so reverse() doesn't mod original
+            scanners.reverse()
+            for scanner in scanners:
+                for k in scanner.get_skeys(self):
+                    result[k] = scanner
+
+        self._memo['_gsm'] = result
+
+        return result
+
+    def get_scanner(self, skey):
+        """Find the appropriate scanner given a key (usually a file suffix).
+        """
+        return self._gsm().get(skey)
+
+    def scanner_map_delete(self, kw=None):
+        """Delete the cached scanner map (if we need to).
+        """
+        try:
+            del self._memo['_gsm']
+        except KeyError:
+            pass
+
+    def _update(self, dict):
+        """Update an environment's values directly, bypassing the normal
+        checks that occur when users try to set items.
+        """
+        self._dict.update(dict)
+
+    def get_src_sig_type(self):
+        try:
+            return self.src_sig_type
+        except AttributeError:
+            t = SCons.Defaults.DefaultEnvironment().src_sig_type
+            self.src_sig_type = t
+            return t
+
+    def get_tgt_sig_type(self):
+        try:
+            return self.tgt_sig_type
+        except AttributeError:
+            t = SCons.Defaults.DefaultEnvironment().tgt_sig_type
+            self.tgt_sig_type = t
+            return t
+
+    #######################################################################
+    # Public methods for manipulating an Environment.  These begin with
+    # upper-case letters.  The essential characteristic of methods in
+    # this section is that they do *not* have corresponding same-named
+    # global functions.  For example, a stand-alone Append() function
+    # makes no sense, because Append() is all about appending values to
+    # an Environment's construction variables.
+    #######################################################################
+
+    def Append(self, **kw):
+        """Append values to existing construction variables
+        in an Environment.
+        """
+        kw = copy_non_reserved_keywords(kw)
+        for key, val in kw.items():
+            # It would be easier on the eyes to write this using
+            # "continue" statements whenever we finish processing an item,
+            # but Python 1.5.2 apparently doesn't let you use "continue"
+            # within try:-except: blocks, so we have to nest our code.
+            try:
+                orig = self._dict[key]
+            except KeyError:
+                # No existing variable in the environment, so just set
+                # it to the new value.
+                self._dict[key] = val
+            else:
+                try:
+                    # Check if the original looks like a dictionary.
+                    # If it is, we can't just try adding the value because
+                    # dictionaries don't have __add__() methods, and
+                    # things like UserList will incorrectly coerce the
+                    # original dict to a list (which we don't want).
+                    update_dict = orig.update
+                except AttributeError:
+                    try:
+                        # Most straightforward:  just try to add them
+                        # together.  This will work in most cases, when the
+                        # original and new values are of compatible types.
+                        self._dict[key] = orig + val
+                    except (KeyError, TypeError):
+                        try:
+                            # Check if the original is a list.
+                            add_to_orig = orig.append
+                        except AttributeError:
+                            # The original isn't a list, but the new
+                            # value is (by process of elimination),
+                            # so insert the original in the new value
+                            # (if there's one to insert) and replace
+                            # the variable with it.
+                            if orig:
+                                val.insert(0, orig)
+                            self._dict[key] = val
+                        else:
+                            # The original is a list, so append the new
+                            # value to it (if there's a value to append).
+                            if val:
+                                add_to_orig(val)
+                else:
+                    # The original looks like a dictionary, so update it
+                    # based on what we think the value looks like.
+                    if SCons.Util.is_List(val):
+                        for v in val:
+                            orig[v] = None
+                    else:
+                        try:
+                            update_dict(val)
+                        except (AttributeError, TypeError, ValueError):
+                            if SCons.Util.is_Dict(val):
+                                for k, v in val.items():
+                                    orig[k] = v
+                            else:
+                                orig[val] = None
+        self.scanner_map_delete(kw)
+
+    def AppendENVPath(self, name, newpath, envname = 'ENV', 
+                      sep = os.pathsep, delete_existing=1):
+        """Append path elements to the path 'name' in the 'ENV'
+        dictionary for this environment.  Will only add any particular
+        path once, and will normpath and normcase all paths to help
+        assure this.  This can also handle the case where the env
+        variable is a list instead of a string.
+
+        If delete_existing is 0, a newpath which is already in the path
+        will not be moved to the end (it will be left where it is).
+        """
+
+        orig = ''
+        if self._dict.has_key(envname) and self._dict[envname].has_key(name):
+            orig = self._dict[envname][name]
+
+        nv = SCons.Util.AppendPath(orig, newpath, sep, delete_existing)
+
+        if not self._dict.has_key(envname):
+            self._dict[envname] = {}
+
+        self._dict[envname][name] = nv
+
+    def AppendUnique(self, delete_existing=0, **kw):
+        """Append values to existing construction variables
+        in an Environment, if they're not already there.
+        If delete_existing is 1, removes existing values first, so
+        values move to end.
+        """
+        kw = copy_non_reserved_keywords(kw)
+        for key, val in kw.items():
+            if not self._dict.has_key(key) or self._dict[key] in ('', None):
+                self._dict[key] = val
+            elif SCons.Util.is_Dict(self._dict[key]) and \
+                 SCons.Util.is_Dict(val):
+                self._dict[key].update(val)
+            elif SCons.Util.is_List(val):
+                dk = self._dict[key]
+                if not SCons.Util.is_List(dk):
+                    dk = [dk]
+                if delete_existing:
+                    dk = filter(lambda x, val=val: x not in val, dk)
+                else:
+                    val = filter(lambda x, dk=dk: x not in dk, val)
+                self._dict[key] = dk + val
+            else:
+                dk = self._dict[key]
+                if SCons.Util.is_List(dk):
+                    # By elimination, val is not a list.  Since dk is a
+                    # list, wrap val in a list first.
+                    if delete_existing:
+                        dk = filter(lambda x, val=val: x not in val, dk)
+                        self._dict[key] = dk + [val]
+                    else:
+                        if not val in dk:
+                            self._dict[key] = dk + [val]
+                else:
+                    if delete_existing:
+                        dk = filter(lambda x, val=val: x not in val, dk)
+                    self._dict[key] = dk + val
+        self.scanner_map_delete(kw)
+
+    def Clone(self, tools=[], toolpath=None, parse_flags = None, **kw):
+        """Return a copy of a construction Environment.  The
+        copy is like a Python "deep copy"--that is, independent
+        copies are made recursively of each objects--except that
+        a reference is copied when an object is not deep-copyable
+        (like a function).  There are no references to any mutable
+        objects in the original Environment.
+        """
+        clone = copy.copy(self)
+        clone._dict = semi_deepcopy(self._dict)
+
+        try:
+            cbd = clone._dict['BUILDERS']
+        except KeyError:
+            pass
+        else:
+            clone._dict['BUILDERS'] = BuilderDict(cbd, clone)
+
+        # Check the methods added via AddMethod() and re-bind them to
+        # the cloned environment.  Only do this if the attribute hasn't
+        # been overwritten by the user explicitly and still points to
+        # the added method.
+        clone.added_methods = []
+        for mw in self.added_methods:
+            if mw == getattr(self, mw.name):
+                clone.added_methods.append(mw.clone(clone))
+
+        clone._memo = {}
+
+        # Apply passed-in variables before the tools
+        # so the tools can use the new variables
+        kw = copy_non_reserved_keywords(kw)
+        new = {}
+        for key, value in kw.items():
+            new[key] = SCons.Subst.scons_subst_once(value, self, key)
+        apply(clone.Replace, (), new)
+
+        apply_tools(clone, tools, toolpath)
+
+        # apply them again in case the tools overwrote them
+        apply(clone.Replace, (), new)        
+
+        # Finally, apply any flags to be merged in
+        if parse_flags: clone.MergeFlags(parse_flags)
+
+        if __debug__: logInstanceCreation(self, 'Environment.EnvironmentClone')
+        return clone
+
+    def Copy(self, *args, **kw):
+        global _warn_copy_deprecated
+        if _warn_copy_deprecated:
+            msg = "The env.Copy() method is deprecated; use the env.Clone() method instead."
+            SCons.Warnings.warn(SCons.Warnings.DeprecatedCopyWarning, msg)
+            _warn_copy_deprecated = False
+        return apply(self.Clone, args, kw)
+
+    def _changed_build(self, dependency, target, prev_ni):
+        if dependency.changed_state(target, prev_ni):
+            return 1
+        return self.decide_source(dependency, target, prev_ni)
+
+    def _changed_content(self, dependency, target, prev_ni):
+        return dependency.changed_content(target, prev_ni)
+
+    def _changed_source(self, dependency, target, prev_ni):
+        target_env = dependency.get_build_env()
+        type = target_env.get_tgt_sig_type()
+        if type == 'source':
+            return target_env.decide_source(dependency, target, prev_ni)
+        else:
+            return target_env.decide_target(dependency, target, prev_ni)
+
+    def _changed_timestamp_then_content(self, dependency, target, prev_ni):
+        return dependency.changed_timestamp_then_content(target, prev_ni)
+
+    def _changed_timestamp_newer(self, dependency, target, prev_ni):
+        return dependency.changed_timestamp_newer(target, prev_ni)
+
+    def _changed_timestamp_match(self, dependency, target, prev_ni):
+        return dependency.changed_timestamp_match(target, prev_ni)
+
+    def _copy_from_cache(self, src, dst):
+        return self.fs.copy(src, dst)
+
+    def _copy2_from_cache(self, src, dst):
+        return self.fs.copy2(src, dst)
+
+    def Decider(self, function):
+        copy_function = self._copy2_from_cache
+        if function in ('MD5', 'content'):
+            if not SCons.Util.md5:
+                raise UserError, "MD5 signatures are not available in this version of Python."
+            function = self._changed_content
+        elif function == 'MD5-timestamp':
+            function = self._changed_timestamp_then_content
+        elif function in ('timestamp-newer', 'make'):
+            function = self._changed_timestamp_newer
+            copy_function = self._copy_from_cache
+        elif function == 'timestamp-match':
+            function = self._changed_timestamp_match
+        elif not callable(function):
+            raise UserError, "Unknown Decider value %s" % repr(function)
+
+        # We don't use AddMethod because we don't want to turn the
+        # function, which only expects three arguments, into a bound
+        # method, which would add self as an initial, fourth argument.
+        self.decide_target = function
+        self.decide_source = function
+
+        self.copy_from_cache = copy_function
+
+    def Detect(self, progs):
+        """Return the first available program in progs.
+        """
+        if not SCons.Util.is_List(progs):
+            progs = [ progs ]
+        for prog in progs:
+            path = self.WhereIs(prog)
+            if path: return prog
+        return None
+
+    def Dictionary(self, *args):
+        if not args:
+            return self._dict
+        dlist = map(lambda x, s=self: s._dict[x], args)
+        if len(dlist) == 1:
+            dlist = dlist[0]
+        return dlist
+
+    def Dump(self, key = None):
+        """
+        Using the standard Python pretty printer, dump the contents of the
+        scons build environment to stdout.
+
+        If the key passed in is anything other than None, then that will
+        be used as an index into the build environment dictionary and
+        whatever is found there will be fed into the pretty printer. Note
+        that this key is case sensitive.
+        """
+        import pprint
+        pp = pprint.PrettyPrinter(indent=2)
+        if key:
+            dict = self.Dictionary(key)
+        else:
+            dict = self.Dictionary()
+        return pp.pformat(dict)
+
+    def FindIxes(self, paths, prefix, suffix):
+        """
+        Search a list of paths for something that matches the prefix and suffix.
+
+        paths - the list of paths or nodes.
+        prefix - construction variable for the prefix.
+        suffix - construction variable for the suffix.
+        """
+
+        suffix = self.subst('$'+suffix)
+        prefix = self.subst('$'+prefix)
+
+        for path in paths:
+            dir,name = os.path.split(str(path))
+            if name[:len(prefix)] == prefix and name[-len(suffix):] == suffix:
+                return path
+
+    def ParseConfig(self, command, function=None, unique=1):
+        """
+        Use the specified function to parse the output of the command
+        in order to modify the current environment.  The 'command' can
+        be a string or a list of strings representing a command and
+        its arguments.  'Function' is an optional argument that takes
+        the environment, the output of the command, and the unique flag.
+        If no function is specified, MergeFlags, which treats the output
+        as the result of a typical 'X-config' command (i.e. gtk-config),
+        will merge the output into the appropriate variables.
+        """
+        if function is None:
+            def parse_conf(env, cmd, unique=unique):
+                return env.MergeFlags(cmd, unique)
+            function = parse_conf
+        if SCons.Util.is_List(command):
+            command = string.join(command)
+        command = self.subst(command)
+        return function(self, self.backtick(command))
+
+    def ParseDepends(self, filename, must_exist=None, only_one=0):
+        """
+        Parse a mkdep-style file for explicit dependencies.  This is
+        completely abusable, and should be unnecessary in the "normal"
+        case of proper SCons configuration, but it may help make
+        the transition from a Make hierarchy easier for some people
+        to swallow.  It can also be genuinely useful when using a tool
+        that can write a .d file, but for which writing a scanner would
+        be too complicated.
+        """
+        filename = self.subst(filename)
+        try:
+            fp = open(filename, 'r')
+        except IOError:
+            if must_exist:
+                raise
+            return
+        lines = SCons.Util.LogicalLines(fp).readlines()
+        lines = filter(lambda l: l[0] != '#', lines)
+        tdlist = []
+        for line in lines:
+            try:
+                target, depends = string.split(line, ':', 1)
+            except (AttributeError, TypeError, ValueError):
+                # Python 1.5.2 throws TypeError if line isn't a string,
+                # Python 2.x throws AttributeError because it tries
+                # to call line.split().  Either can throw ValueError
+                # if the line doesn't split into two or more elements.
+                pass
+            else:
+                tdlist.append((string.split(target), string.split(depends)))
+        if only_one:
+            targets = reduce(lambda x, y: x+y, map(lambda p: p[0], tdlist))
+            if len(targets) > 1:
+                raise SCons.Errors.UserError, "More than one dependency target found in `%s':  %s" % (filename, targets)
+        for target, depends in tdlist:
+            self.Depends(target, depends)
+
+    def Platform(self, platform):
+        platform = self.subst(platform)
+        return SCons.Platform.Platform(platform)(self)
+
+    def Prepend(self, **kw):
+        """Prepend values to existing construction variables
+        in an Environment.
+        """
+        kw = copy_non_reserved_keywords(kw)
+        for key, val in kw.items():
+            # It would be easier on the eyes to write this using
+            # "continue" statements whenever we finish processing an item,
+            # but Python 1.5.2 apparently doesn't let you use "continue"
+            # within try:-except: blocks, so we have to nest our code.
+            try:
+                orig = self._dict[key]
+            except KeyError:
+                # No existing variable in the environment, so just set
+                # it to the new value.
+                self._dict[key] = val
+            else:
+                try:
+                    # Check if the original looks like a dictionary.
+                    # If it is, we can't just try adding the value because
+                    # dictionaries don't have __add__() methods, and
+                    # things like UserList will incorrectly coerce the
+                    # original dict to a list (which we don't want).
+                    update_dict = orig.update
+                except AttributeError:
+                    try:
+                        # Most straightforward:  just try to add them
+                        # together.  This will work in most cases, when the
+                        # original and new values are of compatible types.
+                        self._dict[key] = val + orig
+                    except (KeyError, TypeError):
+                        try:
+                            # Check if the added value is a list.
+                            add_to_val = val.append
+                        except AttributeError:
+                            # The added value isn't a list, but the
+                            # original is (by process of elimination),
+                            # so insert the the new value in the original
+                            # (if there's one to insert).
+                            if val:
+                                orig.insert(0, val)
+                        else:
+                            # The added value is a list, so append
+                            # the original to it (if there's a value
+                            # to append).
+                            if orig:
+                                add_to_val(orig)
+                            self._dict[key] = val
+                else:
+                    # The original looks like a dictionary, so update it
+                    # based on what we think the value looks like.
+                    if SCons.Util.is_List(val):
+                        for v in val:
+                            orig[v] = None
+                    else:
+                        try:
+                            update_dict(val)
+                        except (AttributeError, TypeError, ValueError):
+                            if SCons.Util.is_Dict(val):
+                                for k, v in val.items():
+                                    orig[k] = v
+                            else:
+                                orig[val] = None
+        self.scanner_map_delete(kw)
+
+    def PrependENVPath(self, name, newpath, envname = 'ENV', sep = os.pathsep,
+                       delete_existing=1):
+        """Prepend path elements to the path 'name' in the 'ENV'
+        dictionary for this environment.  Will only add any particular
+        path once, and will normpath and normcase all paths to help
+        assure this.  This can also handle the case where the env
+        variable is a list instead of a string.
+
+        If delete_existing is 0, a newpath which is already in the path
+        will not be moved to the front (it will be left where it is).
+        """
+
+        orig = ''
+        if self._dict.has_key(envname) and self._dict[envname].has_key(name):
+            orig = self._dict[envname][name]
+
+        nv = SCons.Util.PrependPath(orig, newpath, sep, delete_existing)
+
+        if not self._dict.has_key(envname):
+            self._dict[envname] = {}
+
+        self._dict[envname][name] = nv
+
+    def PrependUnique(self, delete_existing=0, **kw):
+        """Prepend values to existing construction variables
+        in an Environment, if they're not already there.
+        If delete_existing is 1, removes existing values first, so
+        values move to front.
+        """
+        kw = copy_non_reserved_keywords(kw)
+        for key, val in kw.items():
+            if not self._dict.has_key(key) or self._dict[key] in ('', None):
+                self._dict[key] = val
+            elif SCons.Util.is_Dict(self._dict[key]) and \
+                 SCons.Util.is_Dict(val):
+                self._dict[key].update(val)
+            elif SCons.Util.is_List(val):
+                dk = self._dict[key]
+                if not SCons.Util.is_List(dk):
+                    dk = [dk]
+                if delete_existing:
+                    dk = filter(lambda x, val=val: x not in val, dk)
+                else:
+                    val = filter(lambda x, dk=dk: x not in dk, val)
+                self._dict[key] = val + dk
+            else:
+                dk = self._dict[key]
+                if SCons.Util.is_List(dk):
+                    # By elimination, val is not a list.  Since dk is a
+                    # list, wrap val in a list first.
+                    if delete_existing:
+                        dk = filter(lambda x, val=val: x not in val, dk)
+                        self._dict[key] = [val] + dk
+                    else:
+                        if not val in dk:
+                            self._dict[key] = [val] + dk
+                else:
+                    if delete_existing:
+                        dk = filter(lambda x, val=val: x not in val, dk)
+                    self._dict[key] = val + dk
+        self.scanner_map_delete(kw)
+
+    def Replace(self, **kw):
+        """Replace existing construction variables in an Environment
+        with new construction variables and/or values.
+        """
+        try:
+            kwbd = kw['BUILDERS']
+        except KeyError:
+            pass
+        else:
+            kwbd = semi_deepcopy(kwbd)
+            del kw['BUILDERS']
+            self.__setitem__('BUILDERS', kwbd)
+        kw = copy_non_reserved_keywords(kw)
+        self._update(semi_deepcopy(kw))
+        self.scanner_map_delete(kw)
+
+    def ReplaceIxes(self, path, old_prefix, old_suffix, new_prefix, new_suffix):
+        """
+        Replace old_prefix with new_prefix and old_suffix with new_suffix.
+
+        env - Environment used to interpolate variables.
+        path - the path that will be modified.
+        old_prefix - construction variable for the old prefix.
+        old_suffix - construction variable for the old suffix.
+        new_prefix - construction variable for the new prefix.
+        new_suffix - construction variable for the new suffix.
+        """
+        old_prefix = self.subst('$'+old_prefix)
+        old_suffix = self.subst('$'+old_suffix)
+
+        new_prefix = self.subst('$'+new_prefix)
+        new_suffix = self.subst('$'+new_suffix)
+
+        dir,name = os.path.split(str(path))
+        if name[:len(old_prefix)] == old_prefix:
+            name = name[len(old_prefix):]
+        if name[-len(old_suffix):] == old_suffix:
+            name = name[:-len(old_suffix)]
+        return os.path.join(dir, new_prefix+name+new_suffix)
+
+    def SetDefault(self, **kw):
+        for k in kw.keys():
+            if self._dict.has_key(k):
+                del kw[k]
+        apply(self.Replace, (), kw)
+
+    def _find_toolpath_dir(self, tp):
+        return self.fs.Dir(self.subst(tp)).srcnode().abspath
+
+    def Tool(self, tool, toolpath=None, **kw):
+        if SCons.Util.is_String(tool):
+            tool = self.subst(tool)
+            if toolpath is None:
+                toolpath = self.get('toolpath', [])
+            toolpath = map(self._find_toolpath_dir, toolpath)
+            tool = apply(SCons.Tool.Tool, (tool, toolpath), kw)
+        tool(self)
+
+    def WhereIs(self, prog, path=None, pathext=None, reject=[]):
+        """Find prog in the path.
+        """
+        if path is None:
+            try:
+                path = self['ENV']['PATH']
+            except KeyError:
+                pass
+        elif SCons.Util.is_String(path):
+            path = self.subst(path)
+        if pathext is None:
+            try:
+                pathext = self['ENV']['PATHEXT']
+            except KeyError:
+                pass
+        elif SCons.Util.is_String(pathext):
+            pathext = self.subst(pathext)
+        prog = self.subst(prog)
+        path = SCons.Util.WhereIs(prog, path, pathext, reject)
+        if path: return path
+        return None
+
+    #######################################################################
+    # Public methods for doing real "SCons stuff" (manipulating
+    # dependencies, setting attributes on targets, etc.).  These begin
+    # with upper-case letters.  The essential characteristic of methods
+    # in this section is that they all *should* have corresponding
+    # same-named global functions.
+    #######################################################################
+
+    def Action(self, *args, **kw):
+        def subst_string(a, self=self):
+            if SCons.Util.is_String(a):
+                a = self.subst(a)
+            return a
+        nargs = map(subst_string, args)
+        nkw = self.subst_kw(kw)
+        return apply(SCons.Action.Action, nargs, nkw)
+
+    def AddPreAction(self, files, action):
+        nodes = self.arg2nodes(files, self.fs.Entry)
+        action = SCons.Action.Action(action)
+        uniq = {}
+        for executor in map(lambda n: n.get_executor(), nodes):
+            uniq[executor] = 1
+        for executor in uniq.keys():
+            executor.add_pre_action(action)
+        return nodes
+
+    def AddPostAction(self, files, action):
+        nodes = self.arg2nodes(files, self.fs.Entry)
+        action = SCons.Action.Action(action)
+        uniq = {}
+        for executor in map(lambda n: n.get_executor(), nodes):
+            uniq[executor] = 1
+        for executor in uniq.keys():
+            executor.add_post_action(action)
+        return nodes
+
+    def Alias(self, target, source=[], action=None, **kw):
+        tlist = self.arg2nodes(target, self.ans.Alias)
+        if not SCons.Util.is_List(source):
+            source = [source]
+        source = filter(None, source)
+
+        if not action:
+            if not source:
+                # There are no source files and no action, so just
+                # return a target list of classic Alias Nodes, without
+                # any builder.  The externally visible effect is that
+                # this will make the wrapping Script.BuildTask class
+                # say that there's "Nothing to be done" for this Alias,
+                # instead of that it's "up to date."
+                return tlist
+
+            # No action, but there are sources.  Re-call all the target
+            # builders to add the sources to each target.
+            result = []
+            for t in tlist:
+                bld = t.get_builder(AliasBuilder)
+                result.extend(bld(self, t, source))
+            return result
+
+        nkw = self.subst_kw(kw)
+        nkw.update({
+            'action'            : SCons.Action.Action(action),
+            'source_factory'    : self.fs.Entry,
+            'multi'             : 1,
+            'is_explicit'       : None,
+        })
+        bld = apply(SCons.Builder.Builder, (), nkw)
+
+        # Apply the Builder separately to each target so that the Aliases
+        # stay separate.  If we did one "normal" Builder call with the
+        # whole target list, then all of the target Aliases would be
+        # associated under a single Executor.
+        result = []
+        for t in tlist:
+            # Calling the convert() method will cause a new Executor to be
+            # created from scratch, so we have to explicitly initialize
+            # it with the target's existing sources, plus our new ones,
+            # so nothing gets lost.
+            b = t.get_builder()
+            if b is None or b is AliasBuilder:
+                b = bld
+            else:
+                nkw['action'] = b.action + action
+                b = apply(SCons.Builder.Builder, (), nkw)
+            t.convert()
+            result.extend(b(self, t, t.sources + source))
+        return result
+
+    def AlwaysBuild(self, *targets):
+        tlist = []
+        for t in targets:
+            tlist.extend(self.arg2nodes(t, self.fs.Entry))
+        for t in tlist:
+            t.set_always_build()
+        return tlist
+
+    def BuildDir(self, *args, **kw):
+        if kw.has_key('build_dir'):
+            kw['variant_dir'] = kw['build_dir']
+            del kw['build_dir']
+        return apply(self.VariantDir, args, kw)
+
+    def Builder(self, **kw):
+        nkw = self.subst_kw(kw)
+        return apply(SCons.Builder.Builder, [], nkw)
+
+    def CacheDir(self, path):
+        import SCons.CacheDir
+        if not path is None:
+            path = self.subst(path)
+        self._CacheDir_path = path
+
+    def Clean(self, targets, files):
+        global CleanTargets
+        tlist = self.arg2nodes(targets, self.fs.Entry)
+        flist = self.arg2nodes(files, self.fs.Entry)
+        for t in tlist:
+            try:
+                CleanTargets[t].extend(flist)
+            except KeyError:
+                CleanTargets[t] = flist
+
+    def Configure(self, *args, **kw):
+        nargs = [self]
+        if args:
+            nargs = nargs + self.subst_list(args)[0]
+        nkw = self.subst_kw(kw)
+        nkw['_depth'] = kw.get('_depth', 0) + 1
+        try:
+            nkw['custom_tests'] = self.subst_kw(nkw['custom_tests'])
+        except KeyError:
+            pass
+        return apply(SCons.SConf.SConf, nargs, nkw)
+
+    def Command(self, target, source, action, **kw):
+        """Builds the supplied target files from the supplied
+        source files using the supplied action.  Action may
+        be any type that the Builder constructor will accept
+        for an action."""
+        bkw = {
+            'action' : action,
+            'target_factory' : self.fs.Entry,
+            'source_factory' : self.fs.Entry,
+        }
+        try: bkw['source_scanner'] = kw['source_scanner']
+        except KeyError: pass
+        else: del kw['source_scanner']
+        bld = apply(SCons.Builder.Builder, (), bkw)
+        return apply(bld, (self, target, source), kw)
+
+    def Depends(self, target, dependency):
+        """Explicity specify that 'target's depend on 'dependency'."""
+        tlist = self.arg2nodes(target, self.fs.Entry)
+        dlist = self.arg2nodes(dependency, self.fs.Entry)
+        for t in tlist:
+            t.add_dependency(dlist)
+        return tlist
+
+    def Dir(self, name, *args, **kw):
+        """
+        """
+        s = self.subst(name)
+        if SCons.Util.is_Sequence(s):
+            result=[]
+            for e in s:
+                result.append(apply(self.fs.Dir, (e,) + args, kw))
+            return result
+        return apply(self.fs.Dir, (s,) + args, kw)
+
+    def NoClean(self, *targets):
+        """Tags a target so that it will not be cleaned by -c"""
+        tlist = []
+        for t in targets:
+            tlist.extend(self.arg2nodes(t, self.fs.Entry))
+        for t in tlist:
+            t.set_noclean()
+        return tlist
+
+    def NoCache(self, *targets):
+        """Tags a target so that it will not be cached"""
+        tlist = []
+        for t in targets:
+            tlist.extend(self.arg2nodes(t, self.fs.Entry))
+        for t in tlist:
+            t.set_nocache()
+        return tlist
+
+    def Entry(self, name, *args, **kw):
+        """
+        """
+        s = self.subst(name)
+        if SCons.Util.is_Sequence(s):
+            result=[]
+            for e in s:
+                result.append(apply(self.fs.Entry, (e,) + args, kw))
+            return result
+        return apply(self.fs.Entry, (s,) + args, kw)
+
+    def Environment(self, **kw):
+        return apply(SCons.Environment.Environment, [], self.subst_kw(kw))
+
+    def Execute(self, action, *args, **kw):
+        """Directly execute an action through an Environment
+        """
+        action = apply(self.Action, (action,) + args, kw)
+        result = action([], [], self)
+        if isinstance(result, SCons.Errors.BuildError):
+            errstr = result.errstr
+            if result.filename:
+                errstr = result.filename + ': ' + errstr
+            sys.stderr.write("scons: *** %s\n" % errstr)
+            return result.status
+        else:
+            return result
+
+    def File(self, name, *args, **kw):
+        """
+        """
+        s = self.subst(name)
+        if SCons.Util.is_Sequence(s):
+            result=[]
+            for e in s:
+                result.append(apply(self.fs.File, (e,) + args, kw))
+            return result
+        return apply(self.fs.File, (s,) + args, kw)
+
+    def FindFile(self, file, dirs):
+        file = self.subst(file)
+        nodes = self.arg2nodes(dirs, self.fs.Dir)
+        return SCons.Node.FS.find_file(file, tuple(nodes))
+
+    def Flatten(self, sequence):
+        return SCons.Util.flatten(sequence)
+
+    def GetBuildPath(self, files):
+        result = map(str, self.arg2nodes(files, self.fs.Entry))
+        if SCons.Util.is_List(files):
+            return result
+        else:
+            return result[0]
+
+    def Glob(self, pattern, ondisk=True, source=False, strings=False):
+        return self.fs.Glob(self.subst(pattern), ondisk, source, strings)
+
+    def Ignore(self, target, dependency):
+        """Ignore a dependency."""
+        tlist = self.arg2nodes(target, self.fs.Entry)
+        dlist = self.arg2nodes(dependency, self.fs.Entry)
+        for t in tlist:
+            t.add_ignore(dlist)
+        return tlist
+
+    def Literal(self, string):
+        return SCons.Subst.Literal(string)
+
+    def Local(self, *targets):
+        ret = []
+        for targ in targets:
+            if isinstance(targ, SCons.Node.Node):
+                targ.set_local()
+                ret.append(targ)
+            else:
+                for t in self.arg2nodes(targ, self.fs.Entry):
+                   t.set_local()
+                   ret.append(t)
+        return ret
+
+    def Precious(self, *targets):
+        tlist = []
+        for t in targets:
+            tlist.extend(self.arg2nodes(t, self.fs.Entry))
+        for t in tlist:
+            t.set_precious()
+        return tlist
+
+    def Repository(self, *dirs, **kw):
+        dirs = self.arg2nodes(list(dirs), self.fs.Dir)
+        apply(self.fs.Repository, dirs, kw)
+
+    def Requires(self, target, prerequisite):
+        """Specify that 'prerequisite' must be built before 'target',
+        (but 'target' does not actually depend on 'prerequisite'
+        and need not be rebuilt if it changes)."""
+        tlist = self.arg2nodes(target, self.fs.Entry)
+        plist = self.arg2nodes(prerequisite, self.fs.Entry)
+        for t in tlist:
+            t.add_prerequisite(plist)
+        return tlist
+
+    def Scanner(self, *args, **kw):
+        nargs = []
+        for arg in args:
+            if SCons.Util.is_String(arg):
+                arg = self.subst(arg)
+            nargs.append(arg)
+        nkw = self.subst_kw(kw)
+        return apply(SCons.Scanner.Base, nargs, nkw)
+
+    def SConsignFile(self, name=".sconsign", dbm_module=None):
+        if not name is None:
+            name = self.subst(name)
+            if not os.path.isabs(name):
+                name = os.path.join(str(self.fs.SConstruct_dir), name)
+        if name:
+            name = os.path.normpath(name)
+            sconsign_dir = os.path.dirname(name)
+            if sconsign_dir and not os.path.exists(sconsign_dir):
+                self.Execute(SCons.Defaults.Mkdir(sconsign_dir))
+        SCons.SConsign.File(name, dbm_module)
+
+    def SideEffect(self, side_effect, target):
+        """Tell scons that side_effects are built as side
+        effects of building targets."""
+        side_effects = self.arg2nodes(side_effect, self.fs.Entry)
+        targets = self.arg2nodes(target, self.fs.Entry)
+
+        for side_effect in side_effects:
+            if side_effect.multiple_side_effect_has_builder():
+                raise SCons.Errors.UserError, "Multiple ways to build the same target were specified for: %s" % str(side_effect)
+            side_effect.add_source(targets)
+            side_effect.side_effect = 1
+            self.Precious(side_effect)
+            for target in targets:
+                target.side_effects.append(side_effect)
+        return side_effects
+
+    def SourceCode(self, entry, builder):
+        """Arrange for a source code builder for (part of) a tree."""
+        entries = self.arg2nodes(entry, self.fs.Entry)
+        for entry in entries:
+            entry.set_src_builder(builder)
+        return entries
+
+    def SourceSignatures(self, type):
+        global _warn_source_signatures_deprecated
+        if _warn_source_signatures_deprecated:
+            msg = "The env.SourceSignatures() method is deprecated;\n" + \
+                  "\tconvert your build to use the env.Decider() method instead."
+            SCons.Warnings.warn(SCons.Warnings.DeprecatedSourceSignaturesWarning, msg)
+            _warn_source_signatures_deprecated = False
+        type = self.subst(type)
+        self.src_sig_type = type
+        if type == 'MD5':
+            if not SCons.Util.md5:
+                raise UserError, "MD5 signatures are not available in this version of Python."
+            self.decide_source = self._changed_content
+        elif type == 'timestamp':
+            self.decide_source = self._changed_timestamp_match
+        else:
+            raise UserError, "Unknown source signature type '%s'" % type
+
+    def Split(self, arg):
+        """This function converts a string or list into a list of strings
+        or Nodes.  This makes things easier for users by allowing files to
+        be specified as a white-space separated list to be split.
+        The input rules are:
+            - A single string containing names separated by spaces. These will be
+              split apart at the spaces.
+            - A single Node instance
+            - A list containing either strings or Node instances. Any strings
+              in the list are not split at spaces.
+        In all cases, the function returns a list of Nodes and strings."""
+        if SCons.Util.is_List(arg):
+            return map(self.subst, arg)
+        elif SCons.Util.is_String(arg):
+            return string.split(self.subst(arg))
+        else:
+            return [self.subst(arg)]
+
+    def TargetSignatures(self, type):
+        global _warn_target_signatures_deprecated
+        if _warn_target_signatures_deprecated:
+            msg = "The env.TargetSignatures() method is deprecated;\n" + \
+                  "\tconvert your build to use the env.Decider() method instead."
+            SCons.Warnings.warn(SCons.Warnings.DeprecatedTargetSignaturesWarning, msg)
+            _warn_target_signatures_deprecated = False
+        type = self.subst(type)
+        self.tgt_sig_type = type
+        if type in ('MD5', 'content'):
+            if not SCons.Util.md5:
+                raise UserError, "MD5 signatures are not available in this version of Python."
+            self.decide_target = self._changed_content
+        elif type == 'timestamp':
+            self.decide_target = self._changed_timestamp_match
+        elif type == 'build':
+            self.decide_target = self._changed_build
+        elif type == 'source':
+            self.decide_target = self._changed_source
+        else:
+            raise UserError, "Unknown target signature type '%s'"%type
+
+    def Value(self, value, built_value=None):
+        """
+        """
+        return SCons.Node.Python.Value(value, built_value)
+
+    def VariantDir(self, variant_dir, src_dir, duplicate=1):
+        variant_dir = self.arg2nodes(variant_dir, self.fs.Dir)[0]
+        src_dir = self.arg2nodes(src_dir, self.fs.Dir)[0]
+        self.fs.VariantDir(variant_dir, src_dir, duplicate)
+
+    def FindSourceFiles(self, node='.'):
+        """ returns a list of all source files.
+        """
+        node = self.arg2nodes(node, self.fs.Entry)[0]
+
+        sources = []
+        # Uncomment this and get rid of the global definition when we
+        # drop support for pre-2.2 Python versions.
+        #def build_source(ss, result):
+        #    for s in ss:
+        #        if isinstance(s, SCons.Node.FS.Dir):
+        #            build_source(s.all_children(), result)
+        #        elif s.has_builder():
+        #            build_source(s.sources, result)
+        #        elif isinstance(s.disambiguate(), SCons.Node.FS.File):
+        #            result.append(s)
+        build_source(node.all_children(), sources)
+
+        # now strip the build_node from the sources by calling the srcnode
+        # function
+        def get_final_srcnode(file):
+            srcnode = file.srcnode()
+            while srcnode != file.srcnode():
+                srcnode = file.srcnode()
+            return srcnode
+
+        # get the final srcnode for all nodes, this means stripping any
+        # attached build node.
+        map( get_final_srcnode, sources )
+
+        # remove duplicates
+        return list(set(sources))
+
+    def FindInstalledFiles(self):
+        """ returns the list of all targets of the Install and InstallAs Builder.
+        """
+        from SCons.Tool import install
+        if install._UNIQUE_INSTALLED_FILES is None:
+            install._UNIQUE_INSTALLED_FILES = SCons.Util.uniquer_hashables(install._INSTALLED_FILES)
+        return install._UNIQUE_INSTALLED_FILES
+
+class OverrideEnvironment(Base):
+    """A proxy that overrides variables in a wrapped construction
+    environment by returning values from an overrides dictionary in
+    preference to values from the underlying subject environment.
+
+    This is a lightweight (I hope) proxy that passes through most use of
+    attributes to the underlying Environment.Base class, but has just
+    enough additional methods defined to act like a real construction
+    environment with overridden values.  It can wrap either a Base
+    construction environment, or another OverrideEnvironment, which
+    can in turn nest arbitrary OverrideEnvironments...
+
+    Note that we do *not* call the underlying base class
+    (SubsitutionEnvironment) initialization, because we get most of those
+    from proxying the attributes of the subject construction environment.
+    But because we subclass SubstitutionEnvironment, this class also
+    has inherited arg2nodes() and subst*() methods; those methods can't
+    be proxied because they need *this* object's methods to fetch the
+    values from the overrides dictionary.
+    """
+
+    if SCons.Memoize.use_memoizer:
+        __metaclass__ = SCons.Memoize.Memoized_Metaclass
+
+    def __init__(self, subject, overrides={}):
+        if __debug__: logInstanceCreation(self, 'Environment.OverrideEnvironment')
+        self.__dict__['__subject'] = subject
+        self.__dict__['overrides'] = overrides
+
+    # Methods that make this class act like a proxy.
+    def __getattr__(self, name):
+        return getattr(self.__dict__['__subject'], name)
+    def __setattr__(self, name, value):
+        setattr(self.__dict__['__subject'], name, value)
+
+    # Methods that make this class act like a dictionary.
+    def __getitem__(self, key):
+        try:
+            return self.__dict__['overrides'][key]
+        except KeyError:
+            return self.__dict__['__subject'].__getitem__(key)
+    def __setitem__(self, key, value):
+        if not is_valid_construction_var(key):
+            raise SCons.Errors.UserError, "Illegal construction variable `%s'" % key
+        self.__dict__['overrides'][key] = value
+    def __delitem__(self, key):
+        try:
+            del self.__dict__['overrides'][key]
+        except KeyError:
+            deleted = 0
+        else:
+            deleted = 1
+        try:
+            result = self.__dict__['__subject'].__delitem__(key)
+        except KeyError:
+            if not deleted:
+                raise
+            result = None
+        return result
+    def get(self, key, default=None):
+        """Emulates the get() method of dictionaries."""
+        try:
+            return self.__dict__['overrides'][key]
+        except KeyError:
+            return self.__dict__['__subject'].get(key, default)
+    def has_key(self, key):
+        try:
+            self.__dict__['overrides'][key]
+            return 1
+        except KeyError:
+            return self.__dict__['__subject'].has_key(key)
+    def Dictionary(self):
+        """Emulates the items() method of dictionaries."""
+        d = self.__dict__['__subject'].Dictionary().copy()
+        d.update(self.__dict__['overrides'])
+        return d
+    def items(self):
+        """Emulates the items() method of dictionaries."""
+        return self.Dictionary().items()
+
+    # Overridden private construction environment methods.
+    def _update(self, dict):
+        """Update an environment's values directly, bypassing the normal
+        checks that occur when users try to set items.
+        """
+        self.__dict__['overrides'].update(dict)
+
+    def gvars(self):
+        return self.__dict__['__subject'].gvars()
+
+    def lvars(self):
+        lvars = self.__dict__['__subject'].lvars()
+        lvars.update(self.__dict__['overrides'])
+        return lvars
+
+    # Overridden public construction environment methods.
+    def Replace(self, **kw):
+        kw = copy_non_reserved_keywords(kw)
+        self.__dict__['overrides'].update(semi_deepcopy(kw))
+
+# The entry point that will be used by the external world
+# to refer to a construction environment.  This allows the wrapper
+# interface to extend a construction environment for its own purposes
+# by subclassing SCons.Environment.Base and then assigning the
+# class to SCons.Environment.Environment.
+
+Environment = Base
+
+# An entry point for returning a proxy subclass instance that overrides
+# the subst*() methods so they don't actually perform construction
+# variable substitution.  This is specifically intended to be the shim
+# layer in between global function calls (which don't want construction
+# variable substitution) and the DefaultEnvironment() (which would
+# substitute variables if left to its own devices)."""
+#
+# We have to wrap this in a function that allows us to delay definition of
+# the class until it's necessary, so that when it subclasses Environment
+# it will pick up whatever Environment subclass the wrapper interface
+# might have assigned to SCons.Environment.Environment.
+
+def NoSubstitutionProxy(subject):
+    class _NoSubstitutionProxy(Environment):
+        def __init__(self, subject):
+            self.__dict__['__subject'] = subject
+        def __getattr__(self, name):
+            return getattr(self.__dict__['__subject'], name)
+        def __setattr__(self, name, value):
+            return setattr(self.__dict__['__subject'], name, value)
+        def raw_to_mode(self, dict):
+            try:
+                raw = dict['raw']
+            except KeyError:
+                pass
+            else:
+                del dict['raw']
+                dict['mode'] = raw
+        def subst(self, string, *args, **kwargs):
+            return string
+        def subst_kw(self, kw, *args, **kwargs):
+            return kw
+        def subst_list(self, string, *args, **kwargs):
+            nargs = (string, self,) + args
+            nkw = kwargs.copy()
+            nkw['gvars'] = {}
+            self.raw_to_mode(nkw)
+            return apply(SCons.Subst.scons_subst_list, nargs, nkw)
+        def subst_target_source(self, string, *args, **kwargs):
+            nargs = (string, self,) + args
+            nkw = kwargs.copy()
+            nkw['gvars'] = {}
+            self.raw_to_mode(nkw)
+            return apply(SCons.Subst.scons_subst, nargs, nkw)
+    return _NoSubstitutionProxy(subject)