Add initial postprocess unit test thingy.

recipe_engine/third_party/astunparse/unparser.py

Index: recipe_engine/third_party/astunparse/unparser.py
diff --git a/recipe_engine/third_party/astunparse/unparser.py b/recipe_engine/third_party/astunparse/unparser.py
new file mode 100644
index 0000000000000000000000000000000000000000..f3bdd0f22e2671dfe9fb1b3be0d363efe68d03a4
--- /dev/null
+++ b/recipe_engine/third_party/astunparse/unparser.py
@@ -0,0 +1,787 @@
+"Usage: unparse.py <path to source file>"
+from __future__ import print_function, unicode_literals
+import six
+import sys
+import ast
+import os
+import tokenize
+from six import StringIO
+
+# Large float and imaginary literals get turned into infinities in the AST.
+# We unparse those infinities to INFSTR.
+INFSTR = "1e" + repr(sys.float_info.max_10_exp + 1)
+
+def interleave(inter, f, seq):
+    """Call f on each item in seq, calling inter() in between.
+    """
+    seq = iter(seq)
+    try:
+        f(next(seq))
+    except StopIteration:
+        pass
+    else:
+        for x in seq:
+            inter()
+            f(x)
+
+class Unparser:
+    """Methods in this class recursively traverse an AST and
+    output source code for the abstract syntax; original formatting
+    is disregarded. """
+
+    def __init__(self, tree, file=sys.stdout):
+        """Unparser(tree, file=sys.stdout) -> None.
+         Print the source for tree to file."""
+        self.f = file
+        self.future_imports = []
+        self._indent = 0
+        self.dispatch(tree)
+        print("", file=self.f)
+        self.f.flush()
+
+    def fill(self, text = ""):
+        "Indent a piece of text, according to the current indentation level"
+        self.f.write("\n"+"    "*self._indent + text)
+
+    def write(self, text):
+        "Append a piece of text to the current line."
+        self.f.write(six.text_type(text))
+
+    def enter(self):
+        "Print ':', and increase the indentation."
+        self.write(":")
+        self._indent += 1
+
+    def leave(self):
+        "Decrease the indentation level."
+        self._indent -= 1
+
+    def dispatch(self, tree):
+        "Dispatcher function, dispatching tree type T to method _T."
+        if isinstance(tree, list):
+            for t in tree:
+                self.dispatch(t)
+            return
+        meth = getattr(self, "_"+tree.__class__.__name__)
+        meth(tree)
+
+
+    ############### Unparsing methods ######################
+    # There should be one method per concrete grammar type #
+    # Constructors should be grouped by sum type. Ideally, #
+    # this would follow the order in the grammar, but      #
+    # currently doesn't.                                   #
+    ########################################################
+
+    def _Module(self, tree):
+        for stmt in tree.body:
+            self.dispatch(stmt)
+
+    def _Interactive(self, tree):
+        for stmt in tree.body:
+            self.dispatch(stmt)
+
+    def _Expression(self, tree):
+        self.dispatch(tree.body)
+
+    # stmt
+    def _Expr(self, tree):
+        self.fill()
+        self.dispatch(tree.value)
+
+    def _Import(self, t):
+        self.fill("import ")
+        interleave(lambda: self.write(", "), self.dispatch, t.names)
+
+    def _ImportFrom(self, t):
+        # A from __future__ import may affect unparsing, so record it.
+        if t.module and t.module == '__future__':
+            self.future_imports.extend(n.name for n in t.names)
+
+        self.fill("from ")
+        self.write("." * t.level)
+        if t.module:
+            self.write(t.module)
+        self.write(" import ")
+        interleave(lambda: self.write(", "), self.dispatch, t.names)
+
+    def _Assign(self, t):
+        self.fill()
+        for target in t.targets:
+            self.dispatch(target)
+            self.write(" = ")
+        self.dispatch(t.value)
+
+    def _AugAssign(self, t):
+        self.fill()
+        self.dispatch(t.target)
+        self.write(" "+self.binop[t.op.__class__.__name__]+"= ")
+        self.dispatch(t.value)
+
+    def _Return(self, t):
+        self.fill("return")
+        if t.value:
+            self.write(" ")
+            self.dispatch(t.value)
+
+    def _Pass(self, t):
+        self.fill("pass")
+
+    def _Break(self, t):
+        self.fill("break")
+
+    def _Continue(self, t):
+        self.fill("continue")
+
+    def _Delete(self, t):
+        self.fill("del ")
+        interleave(lambda: self.write(", "), self.dispatch, t.targets)
+
+    def _Assert(self, t):
+        self.fill("assert ")
+        self.dispatch(t.test)
+        if t.msg:
+            self.write(", ")
+            self.dispatch(t.msg)
+
+    def _Exec(self, t):
+        self.fill("exec ")
+        self.dispatch(t.body)
+        if t.globals:
+            self.write(" in ")
+            self.dispatch(t.globals)
+        if t.locals:
+            self.write(", ")
+            self.dispatch(t.locals)
+
+    def _Print(self, t):
+        self.fill("print ")
+        do_comma = False
+        if t.dest:
+            self.write(">>")
+            self.dispatch(t.dest)
+            do_comma = True
+        for e in t.values:
+            if do_comma:self.write(", ")
+            else:do_comma=True
+            self.dispatch(e)
+        if not t.nl:
+            self.write(",")
+
+    def _Global(self, t):
+        self.fill("global ")
+        interleave(lambda: self.write(", "), self.write, t.names)
+
+    def _Nonlocal(self, t):
+        self.fill("nonlocal ")
+        interleave(lambda: self.write(", "), self.write, t.names)
+
+    def _Yield(self, t):
+        self.write("(")
+        self.write("yield")
+        if t.value:
+            self.write(" ")
+            self.dispatch(t.value)
+        self.write(")")
+
+    def _YieldFrom(self, t):
+        self.write("(")
+        self.write("yield from")
+        if t.value:
+            self.write(" ")
+            self.dispatch(t.value)
+        self.write(")")
+
+    def _Raise(self, t):
+        self.fill("raise")
+        if six.PY3:
+            if not t.exc:
+                assert not t.cause
+                return
+            self.write(" ")
+            self.dispatch(t.exc)
+            if t.cause:
+                self.write(" from ")
+                self.dispatch(t.cause)
+        else:
+            self.write(" ")
+            if t.type:
+                self.dispatch(t.type)
+            if t.inst:
+                self.write(", ")
+                self.dispatch(t.inst)
+            if t.tback:
+                self.write(", ")
+                self.dispatch(t.tback)
+
+    def _Try(self, t):
+        self.fill("try")
+        self.enter()
+        self.dispatch(t.body)
+        self.leave()
+        for ex in t.handlers:
+            self.dispatch(ex)
+        if t.orelse:
+            self.fill("else")
+            self.enter()
+            self.dispatch(t.orelse)
+            self.leave()
+        if t.finalbody:
+            self.fill("finally")
+            self.enter()
+            self.dispatch(t.finalbody)
+            self.leave()
+
+    def _TryExcept(self, t):
+        self.fill("try")
+        self.enter()
+        self.dispatch(t.body)
+        self.leave()
+
+        for ex in t.handlers:
+            self.dispatch(ex)
+        if t.orelse:
+            self.fill("else")
+            self.enter()
+            self.dispatch(t.orelse)
+            self.leave()
+
+    def _TryFinally(self, t):
+        if len(t.body) == 1 and isinstance(t.body[0], ast.TryExcept):
+            # try-except-finally
+            self.dispatch(t.body)
+        else:
+            self.fill("try")
+            self.enter()
+            self.dispatch(t.body)
+            self.leave()
+
+        self.fill("finally")
+        self.enter()
+        self.dispatch(t.finalbody)
+        self.leave()
+
+    def _ExceptHandler(self, t):
+        self.fill("except")
+        if t.type:
+            self.write(" ")
+            self.dispatch(t.type)
+        if t.name:
+            self.write(" as ")
+            if six.PY3:
+                self.write(t.name)
+            else:
+                self.dispatch(t.name)
+        self.enter()
+        self.dispatch(t.body)
+        self.leave()
+
+    def _ClassDef(self, t):
+        self.write("\n")
+        for deco in t.decorator_list:
+            self.fill("@")
+            self.dispatch(deco)
+        self.fill("class "+t.name)
+        if six.PY3:
+            self.write("(")
+            comma = False
+            for e in t.bases:
+                if comma: self.write(", ")
+                else: comma = True
+                self.dispatch(e)
+            for e in t.keywords:
+                if comma: self.write(", ")
+                else: comma = True
+                self.dispatch(e)
+            if sys.version_info[:2] < (3, 5):
+                if t.starargs:
+                    if comma: self.write(", ")
+                    else: comma = True
+                    self.write("*")
+                    self.dispatch(t.starargs)
+                if t.kwargs:
+                    if comma: self.write(", ")
+                    else: comma = True
+                    self.write("**")
+                    self.dispatch(t.kwargs)
+            self.write(")")
+        elif t.bases:
+                self.write("(")
+                for a in t.bases:
+                    self.dispatch(a)
+                    self.write(", ")
+                self.write(")")
+        self.enter()
+        self.dispatch(t.body)
+        self.leave()
+
+    def _generic_FunctionDef(self, t, async=False):
+        self.write("\n")
+        for deco in t.decorator_list:
+            self.fill("@")
+            self.dispatch(deco)
+        self.fill(("async " if async else "") + "def " + t.name + "(")
+        self.dispatch(t.args)
+        self.write(")")
+        if getattr(t, "returns", False):
+            self.write(" -> ")
+            self.dispatch(t.returns)
+        self.enter()
+        self.dispatch(t.body)
+        self.leave()
+
+    def _FunctionDef(self, t):
+        self._generic_FunctionDef(t)
+
+    def _AsyncFunctionDef(self, t):
+        self._generic_FunctionDef(t, async=True)
+
+    def _generic_For(self, t, async=False):
+        self.fill("async for " if async else "for ")
+        self.dispatch(t.target)
+        self.write(" in ")
+        self.dispatch(t.iter)
+        self.enter()
+        self.dispatch(t.body)
+        self.leave()
+        if t.orelse:
+            self.fill("else")
+            self.enter()
+            self.dispatch(t.orelse)
+            self.leave()
+
+    def _For(self, t):
+        self._generic_For(t)
+
+    def _AsyncFor(self, t):
+        self._generic_For(t, async=True)
+
+    def _If(self, t):
+        self.fill("if ")
+        self.dispatch(t.test)
+        self.enter()
+        self.dispatch(t.body)
+        self.leave()
+        # collapse nested ifs into equivalent elifs.
+        while (t.orelse and len(t.orelse) == 1 and
+               isinstance(t.orelse[0], ast.If)):
+            t = t.orelse[0]
+            self.fill("elif ")
+            self.dispatch(t.test)
+            self.enter()
+            self.dispatch(t.body)
+            self.leave()
+        # final else
+        if t.orelse:
+            self.fill("else")
+            self.enter()
+            self.dispatch(t.orelse)
+            self.leave()
+
+    def _While(self, t):
+        self.fill("while ")
+        self.dispatch(t.test)
+        self.enter()
+        self.dispatch(t.body)
+        self.leave()
+        if t.orelse:
+            self.fill("else")
+            self.enter()
+            self.dispatch(t.orelse)
+            self.leave()
+
+    def _generic_With(self, t, async=False):
+        self.fill("async with " if async else "with ")
+        if hasattr(t, 'items'):
+            interleave(lambda: self.write(", "), self.dispatch, t.items)
+        else:
+            self.dispatch(t.context_expr)
+            if t.optional_vars:
+                self.write(" as ")
+                self.dispatch(t.optional_vars)
+        self.enter()
+        self.dispatch(t.body)
+        self.leave()
+
+    def _With(self, t):
+        self._generic_With(t)
+
+    def _AsyncWith(self, t):
+        self._generic_With(t, async=True)
+
+    # expr
+    def _Bytes(self, t):
+        self.write(repr(t.s))
+
+    def _Str(self, tree):
+        if six.PY3:
+            self.write(repr(tree.s))
+        else:
+            # if from __future__ import unicode_literals is in effect,
+            # then we want to output string literals using a 'b' prefix
+            # and unicode literals with no prefix.
+            if "unicode_literals" not in self.future_imports:
+                self.write(repr(tree.s))
+            elif isinstance(tree.s, str):
+                self.write("b" + repr(tree.s))
+            elif isinstance(tree.s, unicode):
+                self.write(repr(tree.s).lstrip("u"))
+            else:
+                assert False, "shouldn't get here"
+
+    def _Name(self, t):
+        self.write(t.id)
+
+    def _NameConstant(self, t):
+        self.write(repr(t.value))
+
+    def _Repr(self, t):
+        self.write("`")
+        self.dispatch(t.value)
+        self.write("`")
+
+    def _Num(self, t):
+        repr_n = repr(t.n)
+        if six.PY3:
+            self.write(repr_n.replace("inf", INFSTR))
+        else:
+            # Parenthesize negative numbers, to avoid turning (-1)**2 into -1**2.
+            if repr_n.startswith("-"):
+                self.write("(")
+            if "inf" in repr_n and repr_n.endswith("*j"):
+                repr_n = repr_n.replace("*j", "j")
+            # Substitute overflowing decimal literal for AST infinities.
+            self.write(repr_n.replace("inf", INFSTR))
+            if repr_n.startswith("-"):
+                self.write(")")
+
+    def _List(self, t):
+        self.write("[")
+        interleave(lambda: self.write(", "), self.dispatch, t.elts)
+        self.write("]")
+
+    def _ListComp(self, t):
+        self.write("[")
+        self.dispatch(t.elt)
+        for gen in t.generators:
+            self.dispatch(gen)
+        self.write("]")
+
+    def _GeneratorExp(self, t):
+        self.write("(")
+        self.dispatch(t.elt)
+        for gen in t.generators:
+            self.dispatch(gen)
+        self.write(")")
+
+    def _SetComp(self, t):
+        self.write("{")
+        self.dispatch(t.elt)
+        for gen in t.generators:
+            self.dispatch(gen)
+        self.write("}")
+
+    def _DictComp(self, t):
+        self.write("{")
+        self.dispatch(t.key)
+        self.write(": ")
+        self.dispatch(t.value)
+        for gen in t.generators:
+            self.dispatch(gen)
+        self.write("}")
+
+    def _comprehension(self, t):
+        self.write(" for ")
+        self.dispatch(t.target)
+        self.write(" in ")
+        self.dispatch(t.iter)
+        for if_clause in t.ifs:
+            self.write(" if ")
+            self.dispatch(if_clause)
+
+    def _IfExp(self, t):
+        self.write("(")
+        self.dispatch(t.body)
+        self.write(" if ")
+        self.dispatch(t.test)
+        self.write(" else ")
+        self.dispatch(t.orelse)
+        self.write(")")
+
+    def _Set(self, t):
+        assert(t.elts) # should be at least one element
+        self.write("{")
+        interleave(lambda: self.write(", "), self.dispatch, t.elts)
+        self.write("}")
+
+    def _Dict(self, t):
+        self.write("{")
+        def write_pair(pair):
+            (k, v) = pair
+            self.dispatch(k)
+            self.write(": ")
+            self.dispatch(v)
+        interleave(lambda: self.write(", "), write_pair, zip(t.keys, t.values))
+        self.write("}")
+
+    def _Tuple(self, t):
+        self.write("(")
+        if len(t.elts) == 1:
+            (elt,) = t.elts
+            self.dispatch(elt)
+            self.write(",")
+        else:
+            interleave(lambda: self.write(", "), self.dispatch, t.elts)
+        self.write(")")
+
+    unop = {"Invert":"~", "Not": "not", "UAdd":"+", "USub":"-"}
+    def _UnaryOp(self, t):
+        self.write("(")
+        self.write(self.unop[t.op.__class__.__name__])
+        self.write(" ")
+        if six.PY2 and isinstance(t.op, ast.USub) and isinstance(t.operand, ast.Num):
+            # If we're applying unary minus to a number, parenthesize the number.
+            # This is necessary: -2147483648 is different from -(2147483648) on
+            # a 32-bit machine (the first is an int, the second a long), and
+            # -7j is different from -(7j).  (The first has real part 0.0, the second
+            # has real part -0.0.)
+            self.write("(")
+            self.dispatch(t.operand)
+            self.write(")")
+        else:
+            self.dispatch(t.operand)
+        self.write(")")
+
+    binop = { "Add":"+", "Sub":"-", "Mult":"*", "Div":"/", "Mod":"%",
+                    "LShift":"<<", "RShift":">>", "BitOr":"|", "BitXor":"^", "BitAnd":"&",
+                    "FloorDiv":"//", "Pow": "**",
+                    "MatMult":"@"}
+    def _BinOp(self, t):
+        self.write("(")
+        self.dispatch(t.left)
+        self.write(" " + self.binop[t.op.__class__.__name__] + " ")
+        self.dispatch(t.right)
+        self.write(")")
+
+    cmpops = {"Eq":"==", "NotEq":"!=", "Lt":"<", "LtE":"<=", "Gt":">", "GtE":">=",
+                        "Is":"is", "IsNot":"is not", "In":"in", "NotIn":"not in"}
+    def _Compare(self, t):
+        self.write("(")
+        self.dispatch(t.left)
+        for o, e in zip(t.ops, t.comparators):
+            self.write(" " + self.cmpops[o.__class__.__name__] + " ")
+            self.dispatch(e)
+        self.write(")")
+
+    boolops = {ast.And: 'and', ast.Or: 'or'}
+    def _BoolOp(self, t):
+        self.write("(")
+        s = " %s " % self.boolops[t.op.__class__]
+        interleave(lambda: self.write(s), self.dispatch, t.values)
+        self.write(")")
+
+    def _Attribute(self,t):
+        self.dispatch(t.value)
+        # Special case: 3.__abs__() is a syntax error, so if t.value
+        # is an integer literal then we need to either parenthesize
+        # it or add an extra space to get 3 .__abs__().
+        if isinstance(t.value, ast.Num) and isinstance(t.value.n, int):
+            self.write(" ")
+        self.write(".")
+        self.write(t.attr)
+
+    def _Call(self, t):
+        self.dispatch(t.func)
+        self.write("(")
+        comma = False
+        for e in t.args:
+            if comma: self.write(", ")
+            else: comma = True
+            self.dispatch(e)
+        for e in t.keywords:
+            if comma: self.write(", ")
+            else: comma = True
+            self.dispatch(e)
+        if sys.version_info[:2] < (3, 5):
+            if t.starargs:
+                if comma: self.write(", ")
+                else: comma = True
+                self.write("*")
+                self.dispatch(t.starargs)
+            if t.kwargs:
+                if comma: self.write(", ")
+                else: comma = True
+                self.write("**")
+                self.dispatch(t.kwargs)
+        self.write(")")
+
+    def _Subscript(self, t):
+        self.dispatch(t.value)
+        self.write("[")
+        self.dispatch(t.slice)
+        self.write("]")
+
+    def _Starred(self, t):
+        self.write("*")
+        self.dispatch(t.value)
+
+    # slice
+    def _Ellipsis(self, t):
+        self.write("...")
+
+    def _Index(self, t):
+        self.dispatch(t.value)
+
+    def _Slice(self, t):
+        if t.lower:
+            self.dispatch(t.lower)
+        self.write(":")
+        if t.upper:
+            self.dispatch(t.upper)
+        if t.step:
+            self.write(":")
+            self.dispatch(t.step)
+
+    def _ExtSlice(self, t):
+        interleave(lambda: self.write(', '), self.dispatch, t.dims)
+
+    # argument
+    def _arg(self, t):
+        self.write(t.arg)
+        if t.annotation:
+            self.write(": ")
+            self.dispatch(t.annotation)
+
+    # others
+    def _arguments(self, t):
+        first = True
+        # normal arguments
+        defaults = [None] * (len(t.args) - len(t.defaults)) + t.defaults
+        for a,d in zip(t.args, defaults):
+            if first:first = False
+            else: self.write(", ")
+            self.dispatch(a)
+            if d:
+                self.write("=")
+                self.dispatch(d)
+
+        # varargs, or bare '*' if no varargs but keyword-only arguments present
+        if t.vararg or getattr(t, "kwonlyargs", False):
+            if first: first = False
+            else: self.write(", ")
+            self.write("*")
+            if t.vararg:
+                if hasattr(t.vararg, 'arg'):
+                    self.write(t.vararg.arg)
+                    if t.vararg.annotation:
+                        self.write(": ")
+                        self.dispatch(t.vararg.annotation)
+                else:
+                    self.write(t.vararg)
+                    if getattr(t, 'varargannotation', None):
+                        self.write(": ")
+                        self.dispatch(t.varargannotation)
+
+        # keyword-only arguments
+        if getattr(t, "kwonlyargs", False):
+            for a, d in zip(t.kwonlyargs, t.kw_defaults):
+                if first:first = False
+                else: self.write(", ")
+                self.dispatch(a),
+                if d:
+                    self.write("=")
+                    self.dispatch(d)
+
+        # kwargs
+        if t.kwarg:
+            if first:first = False
+            else: self.write(", ")
+            if hasattr(t.kwarg, 'arg'):
+                self.write("**"+t.kwarg.arg)
+                if t.kwarg.annotation:
+                    self.write(": ")
+                    self.dispatch(t.kwarg.annotation)
+            else:
+                self.write("**"+t.kwarg)
+                if getattr(t, 'kwargannotation', None):
+                    self.write(": ")
+                    self.dispatch(t.kwargannotation)
+
+    def _keyword(self, t):
+        if t.arg is None:
+            # starting from Python 3.5 this denotes a kwargs part of the invocation
+            self.write("**")
+        else:
+            self.write(t.arg)
+            self.write("=")
+        self.dispatch(t.value)
+
+    def _Lambda(self, t):
+        self.write("(")
+        self.write("lambda ")
+        self.dispatch(t.args)
+        self.write(": ")
+        self.dispatch(t.body)
+        self.write(")")
+
+    def _alias(self, t):
+        self.write(t.name)
+        if t.asname:
+            self.write(" as "+t.asname)
+
+    def _withitem(self, t):
+        self.dispatch(t.context_expr)
+        if t.optional_vars:
+            self.write(" as ")
+            self.dispatch(t.optional_vars)
+
+    def _Await(self, t):
+        self.write("(")
+        self.write("await")
+        if t.value:
+            self.write(" ")
+            self.dispatch(t.value)
+        self.write(")")
+
+def roundtrip(filename, output=sys.stdout):
+    if six.PY3:
+        with open(filename, "rb") as pyfile:
+            encoding = tokenize.detect_encoding(pyfile.readline)[0]
+        with open(filename, "r", encoding=encoding) as pyfile:
+            source = pyfile.read()
+    else:
+        with open(filename, "r") as pyfile:
+            source = pyfile.read()
+    tree = compile(source, filename, "exec", ast.PyCF_ONLY_AST, dont_inherit=True)
+    Unparser(tree, output)
+
+
+
+def testdir(a):
+    try:
+        names = [n for n in os.listdir(a) if n.endswith('.py')]
+    except OSError:
+        print("Directory not readable: %s" % a, file=sys.stderr)
+    else:
+        for n in names:
+            fullname = os.path.join(a, n)
+            if os.path.isfile(fullname):
+                output = StringIO()
+                print('Testing %s' % fullname)
+                try:
+                    roundtrip(fullname, output)
+                except Exception as e:
+                    print('  Failed to compile, exception is %s' % repr(e))
+            elif os.path.isdir(fullname):
+                testdir(fullname)
+
+def main(args):
+    if args[0] == '--testdir':
+        for a in args[1:]:
+            testdir(a)
+    else:
+        for a in args:
+            roundtrip(a)
+
+if __name__=='__main__':
+    main(sys.argv[1:])