Dropping in software construction toolkit.

site_scons/site_tools/component_setup.py

Index: site_scons/site_tools/component_setup.py
===================================================================
--- site_scons/site_tools/component_setup.py	(revision 0)
+++ site_scons/site_tools/component_setup.py	(revision 0)
@@ -0,0 +1,195 @@
+#!/usr/bin/python2.4
+# Copyright 2008, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Main setup for software construction toolkit.
+
+This module is a SCons tool which should be include in all environments.
+It is used as follows:
+  env = Environment(tools = ['component_setup'])
+and should be the first tool from this toolkit referenced by any environment.
+"""
+
+import os
+import sys
+import SCons
+
+
+#------------------------------------------------------------------------------
+
+
+def InstallUsingLink(target, source, env):
+  """Install function for environment which uses link in preference to copy.
+
+  Args:
+    target: Destintion filename
+    source: Source filename
+    env: Environment
+
+  Returns:
+    Return code from SCons Node link function.
+  """
+
+  # Use link function for Install() and InstallAs(), since it's much much
+  # faster than copying.  This is ok for the way we build clients, where we're
+  # installing to a build output directory and not to a permanent location such
+  # as /usr/bin.
+  # Need to force the target and source to be lists of nodes
+  return SCons.Node.FS.LinkFunc([env.Entry(target)], [env.Entry(source)], env)
+
+#------------------------------------------------------------------------------
+
+
+def generate(env):
+  # NOTE: SCons requires the use of this name, which fails gpylint.
+  """SCons entry point for this tool."""
+
+  # Use MD5 to tell when files differ, if the timestamps differ.  This is
+  # better than pure MD5 (since if the timestamps are the same, we don't need
+  # to rescan the file), and also better than pure timestamp (since if a file
+  # is rebuilt to the same contents, we don't need to trigger the build steps
+  # which depend on it).
+  env.Decider('MD5-timestamp')
+
+  # Use implicit-cache by default.  This means that SCons doesn't scan all the
+  # directories looking for include files found in an earlier directory in the
+  # include path.  For continuous builds, this is not an issue because they're
+  # usually clean builds (so there wouldn't be a cache to load anyway).
+  #
+  # If you're doing a continuous incremental build, just use the
+  # --implicit-deps-changed option to force SCons to ignore its implicit cache.
+  #
+  # Use SCons.Script.SetOption() rather than env.SetOption() to make it clear
+  # this is a global setting, not just a setting for the current environment.
+  SCons.Script.SetOption('implicit_cache', 1)
+
+  # For duplication order, use hard links then fall back to copying.  Don't use
+  # soft links, since those won't do the right thing if the output directory
+  # is tar'd up and moved elsewhere.
+  SCons.Script.SetOption('duplicate', 'hard-copy')
+
+  # Remove the alias namespace lookup function from the list which SCons uses
+  # when coercing strings into nodes.  This prevents SCons from looking up
+  # aliases in input/output lists if they're not explicitly coerced via
+  # Alias(), and removes a conflict where a program has the same shorthand
+  # alias as the program name itself.  This conflict manifests itself as a
+  # python exception if you try to build a program in multiple modes on linux,
+  # for example:
+  #      hammer --mode=dbg,opt port_test
+  new_lookup_list = []
+  for func in env.lookup_list:
+    if func.im_class != SCons.Node.Alias.AliasNameSpace:
+      new_lookup_list.append(func)
+  env.lookup_list = new_lookup_list
+
+  # Add other default tools from our toolkit
+  for t in component_setup_tools:
+    env.Tool(t)
+
+  # Cover part of the environment
+  env.Replace(
+      # Add a reference to our python executable, so subprocesses can find and
+      # invoke python.
+      PYTHON = env.File(sys.executable),
+
+      # Get the absolute path to the directory containing main.scons (or
+      # SConstruct).  This should be used in place of the SCons variable '#',
+      # since '#' is not always replaced (for example, when being used to set
+      # an environment variable).
+      MAIN_DIR = env.Dir('#').abspath,
+      # Supply deprecated SCONSTRUCT_DIR for legacy suport
+      # TODO(rspangler): remove legacy support once everyone has switched over.
+      SCONSTRUCT_DIR = env.Dir('#').abspath,
+
+      # Use install function above, which uses links in preference to copying.
+      INSTALL = InstallUsingLink,
+
+      # Environments are in the 'all' group by default
+      BUILD_GROUPS=['all'],
+
+      DESTINATION_ROOT='$MAIN_DIR/scons-out$HOST_PLATFORM_SUFFIX',
+      TARGET_ROOT='$DESTINATION_ROOT/$BUILD_TYPE',
+      OBJ_ROOT='$TARGET_ROOT/obj',
+      ARTIFACTS_DIR='$TARGET_ROOT/artifacts',
+      CPPDEFINES=[],
+  )
+
+  # If a host platform was specified, need to put the SCons output in its own
+  # destination directory.  Different host platforms compile the same files
+  # different ways, so need their own .sconsign files.
+  force_host_platform = SCons.Script.GetOption('host_platform')
+  if force_host_platform:
+    env['HOST_PLATFORM_SUFFIX'] = '-' + force_host_platform
+
+  # The following environment replacements use env.Dir() to force immediate
+  # evaluation/substitution of SCons variables.  They can't be part of the
+  # preceding env.Replace() since they they may rely indirectly on variables
+  # defined there, and the env.Dir() calls would be evaluated before the
+  # env.Replace().
+
+  # Set default SOURCE_ROOT if there is none, assuming we're in a local
+  # site_scons directory for the project.
+  source_root_relative = os.path.normpath(
+      os.path.join(os.path.dirname(__file__), '../..'))
+  source_root = env.get('SOURCE_ROOT', source_root_relative)
+  env['SOURCE_ROOT'] = env.Dir(source_root)
+
+  # Make tool root separate from source root so it can be overridden when we
+  # have a common location for tools outside of the current clientspec.  Need
+  # to check if it's defined already, so it can be set prior to this tool
+  # being included.
+  tool_root = env.get('TOOL_ROOT', '$SOURCE_ROOT')
+  env['TOOL_ROOT'] = env.Dir(tool_root)
+
+  # Put the .sconsign.dblite file in our destination root directory, so that we
+  # don't pollute the source tree. Use the '_' + sys.platform suffix to prevent
+  # the .sconsign.dblite from being shared between host platforms, even in the
+  # case where the --host_platform option is not used (for instance when the
+  # project has platform suffixes on all the build types).
+  # This will prevent host platforms from mistakenly using each others .sconsign
+  # databases and will allow two host platform builds to occur in the same
+  # shared tree simulataneously.
+  sconsign_dir = env.Dir('$DESTINATION_ROOT').abspath
+  sconsign_filename = '$DESTINATION_ROOT/.sconsign_%s' % sys.platform
+  sconsign_file = env.File(sconsign_filename).abspath
+  # TODO(sgk): SConsignFile() doesn't seem to like it if the destination
+  # directory doesn't already exists, so make sure it exists.
+  if not os.path.isdir(sconsign_dir):
+    os.makedirs(sconsign_dir)
+  SCons.Script.SConsignFile(sconsign_file)
+
+  # Build all by default
+  # TODO(rspangler): This would be more nicely done by creating an 'all'
+  # alias and mapping that to $DESTINATION_ROOT (or the accumulation of all
+  # $TARGET_ROOT's for the environments which apply to the current host
+  # platform).  Ideally, that would be done in site_init.py and not here.  But
+  # since we can't do that, just set the default to be DESTINATION_ROOT here.
+  # Note that this currently forces projects which want to override the
+  # default to do so after including the component_setup tool.
+  env.Default('$DESTINATION_ROOT')