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455 lines
15 KiB
Python
455 lines
15 KiB
Python
"""Utility functions, node construction macros, etc."""
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# Author: Collin Winter
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from itertools import islice
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# Local imports
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from .pgen2 import token
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from .pytree import Leaf, Node
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from .pygram import python_symbols as syms
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from . import patcomp
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###########################################################
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### Common node-construction "macros"
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###########################################################
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def KeywordArg(keyword, value):
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return Node(syms.argument,
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[keyword, Leaf(token.EQUAL, "="), value])
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def LParen():
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return Leaf(token.LPAR, "(")
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def RParen():
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return Leaf(token.RPAR, ")")
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def Assign(target, source):
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"""Build an assignment statement"""
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if not isinstance(target, list):
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target = [target]
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if not isinstance(source, list):
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source.prefix = " "
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source = [source]
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return Node(syms.atom,
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target + [Leaf(token.EQUAL, "=", prefix=" ")] + source)
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def Name(name, prefix=None):
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"""Return a NAME leaf"""
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return Leaf(token.NAME, name, prefix=prefix)
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def Attr(obj, attr):
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"""A node tuple for obj.attr"""
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return [obj, Node(syms.trailer, [Dot(), attr])]
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def Comma():
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"""A comma leaf"""
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return Leaf(token.COMMA, ",")
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def Dot():
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"""A period (.) leaf"""
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return Leaf(token.DOT, ".")
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def ArgList(args, lparen=LParen(), rparen=RParen()):
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"""A parenthesised argument list, used by Call()"""
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node = Node(syms.trailer, [lparen.clone(), rparen.clone()])
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if args:
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node.insert_child(1, Node(syms.arglist, args))
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return node
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def Call(func_name, args=None, prefix=None):
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"""A function call"""
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node = Node(syms.power, [func_name, ArgList(args)])
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if prefix is not None:
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node.prefix = prefix
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return node
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def Newline():
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"""A newline literal"""
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return Leaf(token.NEWLINE, "\n")
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def BlankLine():
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"""A blank line"""
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return Leaf(token.NEWLINE, "")
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def Number(n, prefix=None):
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return Leaf(token.NUMBER, n, prefix=prefix)
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def Subscript(index_node):
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"""A numeric or string subscript"""
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return Node(syms.trailer, [Leaf(token.LBRACE, "["),
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index_node,
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Leaf(token.RBRACE, "]")])
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def String(string, prefix=None):
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"""A string leaf"""
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return Leaf(token.STRING, string, prefix=prefix)
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def ListComp(xp, fp, it, test=None):
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"""A list comprehension of the form [xp for fp in it if test].
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If test is None, the "if test" part is omitted.
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"""
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xp.prefix = ""
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fp.prefix = " "
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it.prefix = " "
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for_leaf = Leaf(token.NAME, "for")
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for_leaf.prefix = " "
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in_leaf = Leaf(token.NAME, "in")
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in_leaf.prefix = " "
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inner_args = [for_leaf, fp, in_leaf, it]
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if test:
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test.prefix = " "
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if_leaf = Leaf(token.NAME, "if")
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if_leaf.prefix = " "
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inner_args.append(Node(syms.comp_if, [if_leaf, test]))
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inner = Node(syms.listmaker, [xp, Node(syms.comp_for, inner_args)])
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return Node(syms.atom,
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[Leaf(token.LBRACE, "["),
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inner,
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Leaf(token.RBRACE, "]")])
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def FromImport(package_name, name_leafs):
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""" Return an import statement in the form:
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from package import name_leafs"""
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# XXX: May not handle dotted imports properly (eg, package_name='foo.bar')
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#assert package_name == '.' or '.' not in package_name, "FromImport has "\
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# "not been tested with dotted package names -- use at your own "\
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# "peril!"
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for leaf in name_leafs:
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# Pull the leaves out of their old tree
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leaf.remove()
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children = [Leaf(token.NAME, "from"),
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Leaf(token.NAME, package_name, prefix=" "),
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Leaf(token.NAME, "import", prefix=" "),
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Node(syms.import_as_names, name_leafs)]
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imp = Node(syms.import_from, children)
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return imp
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def ImportAndCall(node, results, names):
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"""Returns an import statement and calls a method
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of the module:
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import module
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module.name()"""
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obj = results["obj"].clone()
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if obj.type == syms.arglist:
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newarglist = obj.clone()
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else:
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newarglist = Node(syms.arglist, [obj.clone()])
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after = results["after"]
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if after:
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after = [n.clone() for n in after]
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new = Node(syms.power,
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Attr(Name(names[0]), Name(names[1])) +
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[Node(syms.trailer,
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[results["lpar"].clone(),
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newarglist,
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results["rpar"].clone()])] + after)
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new.prefix = node.prefix
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return new
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###########################################################
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### Determine whether a node represents a given literal
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###########################################################
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def is_tuple(node):
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"""Does the node represent a tuple literal?"""
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if isinstance(node, Node) and node.children == [LParen(), RParen()]:
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return True
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return (isinstance(node, Node)
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and len(node.children) == 3
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and isinstance(node.children[0], Leaf)
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and isinstance(node.children[1], Node)
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and isinstance(node.children[2], Leaf)
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and node.children[0].value == "("
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and node.children[2].value == ")")
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def is_list(node):
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"""Does the node represent a list literal?"""
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return (isinstance(node, Node)
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and len(node.children) > 1
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and isinstance(node.children[0], Leaf)
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and isinstance(node.children[-1], Leaf)
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and node.children[0].value == "["
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and node.children[-1].value == "]")
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###########################################################
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### Misc
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###########################################################
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def parenthesize(node):
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return Node(syms.atom, [LParen(), node, RParen()])
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consuming_calls = {"sorted", "list", "set", "any", "all", "tuple", "sum",
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"min", "max", "enumerate"}
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def attr_chain(obj, attr):
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"""Follow an attribute chain.
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If you have a chain of objects where a.foo -> b, b.foo-> c, etc,
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use this to iterate over all objects in the chain. Iteration is
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terminated by getattr(x, attr) is None.
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Args:
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obj: the starting object
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attr: the name of the chaining attribute
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Yields:
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Each successive object in the chain.
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"""
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next = getattr(obj, attr)
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while next:
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yield next
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next = getattr(next, attr)
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p0 = """for_stmt< 'for' any 'in' node=any ':' any* >
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| comp_for< 'for' any 'in' node=any any* >
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"""
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p1 = """
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power<
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( 'iter' | 'list' | 'tuple' | 'sorted' | 'set' | 'sum' |
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'any' | 'all' | 'enumerate' | (any* trailer< '.' 'join' >) )
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trailer< '(' node=any ')' >
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any*
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>
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"""
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p2 = """
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power<
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( 'sorted' | 'enumerate' )
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trailer< '(' arglist<node=any any*> ')' >
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any*
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>
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"""
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pats_built = False
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def in_special_context(node):
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""" Returns true if node is in an environment where all that is required
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of it is being iterable (ie, it doesn't matter if it returns a list
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or an iterator).
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See test_map_nochange in test_fixers.py for some examples and tests.
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"""
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global p0, p1, p2, pats_built
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if not pats_built:
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p0 = patcomp.compile_pattern(p0)
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p1 = patcomp.compile_pattern(p1)
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p2 = patcomp.compile_pattern(p2)
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pats_built = True
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patterns = [p0, p1, p2]
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for pattern, parent in zip(patterns, attr_chain(node, "parent")):
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results = {}
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if pattern.match(parent, results) and results["node"] is node:
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return True
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return False
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def is_probably_builtin(node):
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"""
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Check that something isn't an attribute or function name etc.
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"""
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prev = node.prev_sibling
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if prev is not None and prev.type == token.DOT:
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# Attribute lookup.
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return False
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parent = node.parent
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if parent.type in (syms.funcdef, syms.classdef):
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return False
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if parent.type == syms.expr_stmt and parent.children[0] is node:
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# Assignment.
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return False
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if parent.type == syms.parameters or \
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(parent.type == syms.typedargslist and (
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(prev is not None and prev.type == token.COMMA) or
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parent.children[0] is node
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)):
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# The name of an argument.
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return False
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return True
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def find_indentation(node):
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"""Find the indentation of *node*."""
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while node is not None:
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if node.type == syms.suite and len(node.children) > 2:
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indent = node.children[1]
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if indent.type == token.INDENT:
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return indent.value
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node = node.parent
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return ""
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###########################################################
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### The following functions are to find bindings in a suite
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###########################################################
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def make_suite(node):
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if node.type == syms.suite:
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return node
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node = node.clone()
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parent, node.parent = node.parent, None
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suite = Node(syms.suite, [node])
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suite.parent = parent
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return suite
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def find_root(node):
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"""Find the top level namespace."""
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# Scamper up to the top level namespace
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while node.type != syms.file_input:
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node = node.parent
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if not node:
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raise ValueError("root found before file_input node was found.")
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return node
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def does_tree_import(package, name, node):
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""" Returns true if name is imported from package at the
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top level of the tree which node belongs to.
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To cover the case of an import like 'import foo', use
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None for the package and 'foo' for the name. """
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binding = find_binding(name, find_root(node), package)
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return bool(binding)
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def is_import(node):
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"""Returns true if the node is an import statement."""
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return node.type in (syms.import_name, syms.import_from)
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def touch_import(package, name, node):
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""" Works like `does_tree_import` but adds an import statement
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if it was not imported. """
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def is_import_stmt(node):
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return (node.type == syms.simple_stmt and node.children and
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is_import(node.children[0]))
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root = find_root(node)
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if does_tree_import(package, name, root):
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return
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# figure out where to insert the new import. First try to find
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# the first import and then skip to the last one.
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insert_pos = offset = 0
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for idx, node in enumerate(root.children):
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if not is_import_stmt(node):
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continue
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for offset, node2 in enumerate(root.children[idx:]):
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if not is_import_stmt(node2):
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break
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insert_pos = idx + offset
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break
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# if there are no imports where we can insert, find the docstring.
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# if that also fails, we stick to the beginning of the file
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if insert_pos == 0:
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for idx, node in enumerate(root.children):
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if (node.type == syms.simple_stmt and node.children and
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node.children[0].type == token.STRING):
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insert_pos = idx + 1
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break
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if package is None:
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import_ = Node(syms.import_name, [
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Leaf(token.NAME, "import"),
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Leaf(token.NAME, name, prefix=" ")
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])
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else:
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import_ = FromImport(package, [Leaf(token.NAME, name, prefix=" ")])
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children = [import_, Newline()]
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root.insert_child(insert_pos, Node(syms.simple_stmt, children))
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_def_syms = {syms.classdef, syms.funcdef}
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def find_binding(name, node, package=None):
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""" Returns the node which binds variable name, otherwise None.
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If optional argument package is supplied, only imports will
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be returned.
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See test cases for examples."""
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for child in node.children:
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ret = None
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if child.type == syms.for_stmt:
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if _find(name, child.children[1]):
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return child
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n = find_binding(name, make_suite(child.children[-1]), package)
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if n: ret = n
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elif child.type in (syms.if_stmt, syms.while_stmt):
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n = find_binding(name, make_suite(child.children[-1]), package)
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if n: ret = n
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elif child.type == syms.try_stmt:
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n = find_binding(name, make_suite(child.children[2]), package)
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if n:
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ret = n
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else:
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for i, kid in enumerate(child.children[3:]):
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if kid.type == token.COLON and kid.value == ":":
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# i+3 is the colon, i+4 is the suite
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n = find_binding(name, make_suite(child.children[i+4]), package)
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if n: ret = n
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elif child.type in _def_syms and child.children[1].value == name:
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ret = child
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elif _is_import_binding(child, name, package):
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ret = child
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elif child.type == syms.simple_stmt:
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ret = find_binding(name, child, package)
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elif child.type == syms.expr_stmt:
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if _find(name, child.children[0]):
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ret = child
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if ret:
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if not package:
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return ret
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if is_import(ret):
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return ret
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return None
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_block_syms = {syms.funcdef, syms.classdef, syms.trailer}
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def _find(name, node):
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nodes = [node]
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while nodes:
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node = nodes.pop()
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if node.type > 256 and node.type not in _block_syms:
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nodes.extend(node.children)
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elif node.type == token.NAME and node.value == name:
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return node
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return None
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def _is_import_binding(node, name, package=None):
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""" Will reuturn node if node will import name, or node
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will import * from package. None is returned otherwise.
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See test cases for examples. """
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if node.type == syms.import_name and not package:
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imp = node.children[1]
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if imp.type == syms.dotted_as_names:
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for child in imp.children:
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if child.type == syms.dotted_as_name:
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if child.children[2].value == name:
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return node
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elif child.type == token.NAME and child.value == name:
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return node
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elif imp.type == syms.dotted_as_name:
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last = imp.children[-1]
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if last.type == token.NAME and last.value == name:
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return node
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elif imp.type == token.NAME and imp.value == name:
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return node
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elif node.type == syms.import_from:
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# str(...) is used to make life easier here, because
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# from a.b import parses to ['import', ['a', '.', 'b'], ...]
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if package and str(node.children[1]).strip() != package:
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return None
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n = node.children[3]
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if package and _find("as", n):
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# See test_from_import_as for explanation
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return None
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elif n.type == syms.import_as_names and _find(name, n):
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return node
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elif n.type == syms.import_as_name:
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child = n.children[2]
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if child.type == token.NAME and child.value == name:
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return node
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elif n.type == token.NAME and n.value == name:
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return node
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elif package and n.type == token.STAR:
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return node
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return None
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