| 1 | """Fixer for it.next() -> next(it), per PEP 3114."""
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| 2 | # Author: Collin Winter
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| 3 |
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| 4 | # Things that currently aren't covered:
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| 5 | # - listcomp "next" names aren't warned
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| 6 | # - "with" statement targets aren't checked
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| 7 |
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| 8 | # Local imports
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| 9 | from ..pgen2 import token
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| 10 | from ..pygram import python_symbols as syms
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| 11 | from .. import fixer_base
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| 12 | from ..fixer_util import Name, Call, find_binding
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| 13 |
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| 14 | bind_warning = "Calls to builtin next() possibly shadowed by global binding"
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| 15 |
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| 16 |
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| 17 | class FixNext(fixer_base.BaseFix):
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| 18 | BM_compatible = True
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| 19 | PATTERN = """
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| 20 | power< base=any+ trailer< '.' attr='next' > trailer< '(' ')' > >
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| 21 | |
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| 22 | power< head=any+ trailer< '.' attr='next' > not trailer< '(' ')' > >
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| 23 | |
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| 24 | classdef< 'class' any+ ':'
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| 25 | suite< any*
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| 26 | funcdef< 'def'
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| 27 | name='next'
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| 28 | parameters< '(' NAME ')' > any+ >
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| 29 | any* > >
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| 30 | |
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| 31 | global=global_stmt< 'global' any* 'next' any* >
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| 32 | """
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| 33 |
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| 34 | order = "pre" # Pre-order tree traversal
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| 35 |
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| 36 | def start_tree(self, tree, filename):
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| 37 | super(FixNext, self).start_tree(tree, filename)
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| 38 |
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| 39 | n = find_binding(u'next', tree)
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| 40 | if n:
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| 41 | self.warning(n, bind_warning)
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| 42 | self.shadowed_next = True
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| 43 | else:
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| 44 | self.shadowed_next = False
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| 45 |
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| 46 | def transform(self, node, results):
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| 47 | assert results
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| 48 |
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| 49 | base = results.get("base")
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| 50 | attr = results.get("attr")
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| 51 | name = results.get("name")
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| 52 |
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| 53 | if base:
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| 54 | if self.shadowed_next:
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| 55 | attr.replace(Name(u"__next__", prefix=attr.prefix))
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| 56 | else:
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| 57 | base = [n.clone() for n in base]
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| 58 | base[0].prefix = u""
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| 59 | node.replace(Call(Name(u"next", prefix=node.prefix), base))
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| 60 | elif name:
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| 61 | n = Name(u"__next__", prefix=name.prefix)
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| 62 | name.replace(n)
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| 63 | elif attr:
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| 64 | # We don't do this transformation if we're assigning to "x.next".
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| 65 | # Unfortunately, it doesn't seem possible to do this in PATTERN,
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| 66 | # so it's being done here.
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| 67 | if is_assign_target(node):
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| 68 | head = results["head"]
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| 69 | if "".join([str(n) for n in head]).strip() == u'__builtin__':
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| 70 | self.warning(node, bind_warning)
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| 71 | return
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| 72 | attr.replace(Name(u"__next__"))
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| 73 | elif "global" in results:
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| 74 | self.warning(node, bind_warning)
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| 75 | self.shadowed_next = True
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| 76 |
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| 77 |
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| 78 | ### The following functions help test if node is part of an assignment
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| 79 | ### target.
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| 80 |
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| 81 | def is_assign_target(node):
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| 82 | assign = find_assign(node)
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| 83 | if assign is None:
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| 84 | return False
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| 85 |
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| 86 | for child in assign.children:
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| 87 | if child.type == token.EQUAL:
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| 88 | return False
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| 89 | elif is_subtree(child, node):
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| 90 | return True
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| 91 | return False
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| 92 |
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| 93 | def find_assign(node):
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| 94 | if node.type == syms.expr_stmt:
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| 95 | return node
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| 96 | if node.type == syms.simple_stmt or node.parent is None:
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| 97 | return None
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| 98 | return find_assign(node.parent)
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| 99 |
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| 100 | def is_subtree(root, node):
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| 101 | if root == node:
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| 102 | return True
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| 103 | return any(is_subtree(c, node) for c in root.children)
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