Martin v. Löwis | ef04c44 | 2008-03-19 05:04:44 +0000 | [diff] [blame^] | 1 | """Fixer for it.next() -> next(it), per PEP 3114.""" |
| 2 | # Author: Collin Winter |
| 3 | |
| 4 | # Things that currently aren't covered: |
| 5 | # - listcomp "next" names aren't warned |
| 6 | # - "with" statement targets aren't checked |
| 7 | |
| 8 | # Local imports |
| 9 | from ..pgen2 import token |
| 10 | from ..pygram import python_symbols as syms |
| 11 | from . import basefix |
| 12 | from .util import Name, Call, find_binding, any |
| 13 | |
| 14 | bind_warning = "Calls to builtin next() possibly shadowed by global binding" |
| 15 | |
| 16 | |
| 17 | class FixNext(basefix.BaseFix): |
| 18 | PATTERN = """ |
| 19 | power< base=any+ trailer< '.' attr='next' > trailer< '(' ')' > > |
| 20 | | |
| 21 | power< head=any+ trailer< '.' attr='next' > not trailer< '(' ')' > > |
| 22 | | |
| 23 | classdef< 'class' any+ ':' |
| 24 | suite< any* |
| 25 | funcdef< 'def' |
| 26 | name='next' |
| 27 | parameters< '(' NAME ')' > any+ > |
| 28 | any* > > |
| 29 | | |
| 30 | global=global_stmt< 'global' any* 'next' any* > |
| 31 | | |
| 32 | mod=file_input< any+ > |
| 33 | """ |
| 34 | |
| 35 | order = "pre" # Pre-order tree traversal |
| 36 | |
| 37 | def start_tree(self, tree, filename): |
| 38 | super(FixNext, self).start_tree(tree, filename) |
| 39 | self.shadowed_next = False |
| 40 | |
| 41 | def transform(self, node, results): |
| 42 | assert results |
| 43 | |
| 44 | base = results.get("base") |
| 45 | attr = results.get("attr") |
| 46 | name = results.get("name") |
| 47 | mod = results.get("mod") |
| 48 | |
| 49 | if base: |
| 50 | if self.shadowed_next: |
| 51 | attr.replace(Name("__next__", prefix=attr.get_prefix())) |
| 52 | else: |
| 53 | base = [n.clone() for n in base] |
| 54 | base[0].set_prefix("") |
| 55 | node.replace(Call(Name("next", prefix=node.get_prefix()), base)) |
| 56 | elif name: |
| 57 | n = Name("__next__", prefix=name.get_prefix()) |
| 58 | name.replace(n) |
| 59 | elif attr: |
| 60 | # We don't do this transformation if we're assigning to "x.next". |
| 61 | # Unfortunately, it doesn't seem possible to do this in PATTERN, |
| 62 | # so it's being done here. |
| 63 | if is_assign_target(node): |
| 64 | head = results["head"] |
| 65 | if "".join([str(n) for n in head]).strip() == '__builtin__': |
| 66 | self.warning(node, bind_warning) |
| 67 | return |
| 68 | attr.replace(Name("__next__")) |
| 69 | elif "global" in results: |
| 70 | self.warning(node, bind_warning) |
| 71 | self.shadowed_next = True |
| 72 | elif mod: |
| 73 | n = find_binding('next', mod) |
| 74 | if n: |
| 75 | self.warning(n, bind_warning) |
| 76 | self.shadowed_next = True |
| 77 | |
| 78 | |
| 79 | ### The following functions help test if node is part of an assignment |
| 80 | ### target. |
| 81 | |
| 82 | def is_assign_target(node): |
| 83 | assign = find_assign(node) |
| 84 | if assign is None: |
| 85 | return False |
| 86 | |
| 87 | for child in assign.children: |
| 88 | if child.type == token.EQUAL: |
| 89 | return False |
| 90 | elif is_subtree(child, node): |
| 91 | return True |
| 92 | return False |
| 93 | |
| 94 | def find_assign(node): |
| 95 | if node.type == syms.expr_stmt: |
| 96 | return node |
| 97 | if node.type == syms.simple_stmt or node.parent is None: |
| 98 | return None |
| 99 | return find_assign(node.parent) |
| 100 | |
| 101 | def is_subtree(root, node): |
| 102 | if root == node: |
| 103 | return True |
| 104 | return any([is_subtree(c, node) for c in root.children]) |