Import lib2to3.
diff --git a/Lib/lib2to3/fixes/util.py b/Lib/lib2to3/fixes/util.py
new file mode 100644
index 0000000..8b7ad9f
--- /dev/null
+++ b/Lib/lib2to3/fixes/util.py
@@ -0,0 +1,303 @@
+"""Utility functions, node construction macros, etc."""
+# Author: Collin Winter
+
+# Local imports
+from ..pgen2 import token
+from ..pytree import Leaf, Node
+from ..pygram import python_symbols as syms
+
+
+###########################################################
+### Common node-construction "macros"
+###########################################################
+
+def KeywordArg(keyword, value):
+ return Node(syms.argument,
+ [keyword, Leaf(token.EQUAL, '='), value])
+
+def LParen():
+ return Leaf(token.LPAR, "(")
+
+def RParen():
+ return Leaf(token.RPAR, ")")
+
+def Assign(target, source):
+ """Build an assignment statement"""
+ if not isinstance(target, list):
+ target = [target]
+ if not isinstance(source, list):
+ source.set_prefix(" ")
+ source = [source]
+
+ return Node(syms.atom,
+ target + [Leaf(token.EQUAL, "=", prefix=" ")] + source)
+
+def Name(name, prefix=None):
+ """Return a NAME leaf"""
+ return Leaf(token.NAME, name, prefix=prefix)
+
+def Attr(obj, attr):
+ """A node tuple for obj.attr"""
+ return [obj, Node(syms.trailer, [Dot(), attr])]
+
+def Comma():
+ """A comma leaf"""
+ return Leaf(token.COMMA, ",")
+
+def Dot():
+ """A period (.) leaf"""
+ return Leaf(token.DOT, ".")
+
+def ArgList(args, lparen=LParen(), rparen=RParen()):
+ """A parenthesised argument list, used by Call()"""
+ return Node(syms.trailer,
+ [lparen.clone(),
+ Node(syms.arglist, args),
+ rparen.clone()])
+
+def Call(func_name, args, prefix=None):
+ """A function call"""
+ node = Node(syms.power, [func_name, ArgList(args)])
+ if prefix is not None:
+ node.set_prefix(prefix)
+ return node
+
+def Newline():
+ """A newline literal"""
+ return Leaf(token.NEWLINE, "\n")
+
+def BlankLine():
+ """A blank line"""
+ return Leaf(token.NEWLINE, "")
+
+def Number(n, prefix=None):
+ return Leaf(token.NUMBER, n, prefix=prefix)
+
+def Subscript(index_node):
+ """A numeric or string subscript"""
+ return Node(syms.trailer, [Leaf(token.LBRACE, '['),
+ index_node,
+ Leaf(token.RBRACE, ']')])
+
+def String(string, prefix=None):
+ """A string leaf"""
+ return Leaf(token.STRING, string, prefix=prefix)
+
+def ListComp(xp, fp, it, test=None):
+ """A list comprehension of the form [xp for fp in it if test].
+
+ If test is None, the "if test" part is omitted.
+ """
+ xp.set_prefix("")
+ fp.set_prefix(" ")
+ it.set_prefix(" ")
+ for_leaf = Leaf(token.NAME, "for")
+ for_leaf.set_prefix(" ")
+ in_leaf = Leaf(token.NAME, "in")
+ in_leaf.set_prefix(" ")
+ inner_args = [for_leaf, fp, in_leaf, it]
+ if test:
+ test.set_prefix(" ")
+ if_leaf = Leaf(token.NAME, "if")
+ if_leaf.set_prefix(" ")
+ inner_args.append(Node(syms.comp_if, [if_leaf, test]))
+ inner = Node(syms.listmaker, [xp, Node(syms.comp_for, inner_args)])
+ return Node(syms.atom,
+ [Leaf(token.LBRACE, "["),
+ inner,
+ Leaf(token.RBRACE, "]")])
+
+###########################################################
+### Determine whether a node represents a given literal
+###########################################################
+
+def is_tuple(node):
+ """Does the node represent a tuple literal?"""
+ if isinstance(node, Node) and node.children == [LParen(), RParen()]:
+ return True
+ return (isinstance(node, Node)
+ and len(node.children) == 3
+ and isinstance(node.children[0], Leaf)
+ and isinstance(node.children[1], Node)
+ and isinstance(node.children[2], Leaf)
+ and node.children[0].value == "("
+ and node.children[2].value == ")")
+
+def is_list(node):
+ """Does the node represent a list literal?"""
+ return (isinstance(node, Node)
+ and len(node.children) > 1
+ and isinstance(node.children[0], Leaf)
+ and isinstance(node.children[-1], Leaf)
+ and node.children[0].value == "["
+ and node.children[-1].value == "]")
+
+###########################################################
+### Common portability code. This allows fixers to do, eg,
+### "from .util import set" and forget about it.
+###########################################################
+
+try:
+ any = any
+except NameError:
+ def any(l):
+ for o in l:
+ if o:
+ return True
+ return False
+
+try:
+ set = set
+except NameError:
+ from sets import Set as set
+
+try:
+ reversed = reversed
+except NameError:
+ def reversed(l):
+ return l[::-1]
+
+###########################################################
+### Misc
+###########################################################
+
+def attr_chain(obj, attr):
+ """Follow an attribute chain.
+
+ If you have a chain of objects where a.foo -> b, b.foo-> c, etc,
+ use this to iterate over all objects in the chain. Iteration is
+ terminated by getattr(x, attr) is None.
+
+ Args:
+ obj: the starting object
+ attr: the name of the chaining attribute
+
+ Yields:
+ Each successive object in the chain.
+ """
+ next = getattr(obj, attr)
+ while next:
+ yield next
+ next = getattr(next, attr)
+
+###########################################################
+### The following functions are to find bindings in a suite
+###########################################################
+
+def make_suite(node):
+ if node.type == syms.suite:
+ return node
+ node = node.clone()
+ parent, node.parent = node.parent, None
+ suite = Node(syms.suite, [node])
+ suite.parent = parent
+ return suite
+
+def does_tree_import(package, name, node):
+ """ Returns true if name is imported from package at the
+ top level of the tree which node belongs to.
+ To cover the case of an import like 'import foo', use
+ Null for the package and 'foo' for the name. """
+ # Scamper up to the top level namespace
+ while node.type != syms.file_input:
+ assert node.parent, "Tree is insane! root found before "\
+ "file_input node was found."
+ node = node.parent
+
+ binding = find_binding(name, node, package)
+ return bool(binding)
+
+_def_syms = set([syms.classdef, syms.funcdef])
+def find_binding(name, node, package=None):
+ """ Returns the node which binds variable name, otherwise None.
+ If optional argument package is supplied, only imports will
+ be returned.
+ See test cases for examples."""
+ for child in node.children:
+ ret = None
+ if child.type == syms.for_stmt:
+ if _find(name, child.children[1]):
+ return child
+ n = find_binding(name, make_suite(child.children[-1]), package)
+ if n: ret = n
+ elif child.type in (syms.if_stmt, syms.while_stmt):
+ n = find_binding(name, make_suite(child.children[-1]), package)
+ if n: ret = n
+ elif child.type == syms.try_stmt:
+ n = find_binding(name, make_suite(child.children[2]), package)
+ if n:
+ ret = n
+ else:
+ for i, kid in enumerate(child.children[3:]):
+ if kid.type == token.COLON and kid.value == ":":
+ # i+3 is the colon, i+4 is the suite
+ n = find_binding(name, make_suite(child.children[i+4]), package)
+ if n: ret = n
+ elif child.type in _def_syms and child.children[1].value == name:
+ ret = child
+ elif _is_import_binding(child, name, package):
+ ret = child
+ elif child.type == syms.simple_stmt:
+ ret = find_binding(name, child, package)
+ elif child.type == syms.expr_stmt:
+ if _find(name, child.children[0]):
+ ret = child
+
+ if ret:
+ if not package:
+ return ret
+ if ret.type in (syms.import_name, syms.import_from):
+ return ret
+ return None
+
+_block_syms = set([syms.funcdef, syms.classdef, syms.trailer])
+def _find(name, node):
+ nodes = [node]
+ while nodes:
+ node = nodes.pop()
+ if node.type > 256 and node.type not in _block_syms:
+ nodes.extend(node.children)
+ elif node.type == token.NAME and node.value == name:
+ return node
+ return None
+
+def _is_import_binding(node, name, package=None):
+ """ Will reuturn node if node will import name, or node
+ will import * from package. None is returned otherwise.
+ See test cases for examples. """
+
+ if node.type == syms.import_name and not package:
+ imp = node.children[1]
+ if imp.type == syms.dotted_as_names:
+ for child in imp.children:
+ if child.type == syms.dotted_as_name:
+ if child.children[2].value == name:
+ return node
+ elif child.type == token.NAME and child.value == name:
+ return node
+ elif imp.type == syms.dotted_as_name:
+ last = imp.children[-1]
+ if last.type == token.NAME and last.value == name:
+ return node
+ elif imp.type == token.NAME and imp.value == name:
+ return node
+ elif node.type == syms.import_from:
+ # unicode(...) is used to make life easier here, because
+ # from a.b import parses to ['import', ['a', '.', 'b'], ...]
+ if package and unicode(node.children[1]).strip() != package:
+ return None
+ n = node.children[3]
+ if package and _find('as', n):
+ # See test_from_import_as for explanation
+ return None
+ elif n.type == syms.import_as_names and _find(name, n):
+ return node
+ elif n.type == syms.import_as_name:
+ child = n.children[2]
+ if child.type == token.NAME and child.value == name:
+ return node
+ elif n.type == token.NAME and n.value == name:
+ return node
+ elif package and n.type == token.STAR:
+ return node
+ return None