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105 lines
3.1 KiB
105 lines
3.1 KiB
5 years ago
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"""
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Based on fix_next.py by Collin Winter.
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Replaces it.next() -> next(it), per PEP 3114.
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Unlike fix_next.py, this fixer doesn't replace the name of a next method with __next__,
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which would break Python 2 compatibility without further help from fixers in
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stage 2.
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"""
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# Local imports
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from lib2to3.pgen2 import token
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from lib2to3.pygram import python_symbols as syms
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from lib2to3 import fixer_base
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from lib2to3.fixer_util import Name, Call, find_binding
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bind_warning = "Calls to builtin next() possibly shadowed by global binding"
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class FixNextCall(fixer_base.BaseFix):
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BM_compatible = True
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PATTERN = """
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power< base=any+ trailer< '.' attr='next' > trailer< '(' ')' > >
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power< head=any+ trailer< '.' attr='next' > not trailer< '(' ')' > >
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global=global_stmt< 'global' any* 'next' any* >
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"""
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order = "pre" # Pre-order tree traversal
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def start_tree(self, tree, filename):
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super(FixNextCall, self).start_tree(tree, filename)
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n = find_binding('next', tree)
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if n:
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self.warning(n, bind_warning)
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self.shadowed_next = True
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else:
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self.shadowed_next = False
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def transform(self, node, results):
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assert results
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base = results.get("base")
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attr = results.get("attr")
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name = results.get("name")
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if base:
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if self.shadowed_next:
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# Omit this:
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# attr.replace(Name("__next__", prefix=attr.prefix))
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pass
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else:
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base = [n.clone() for n in base]
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base[0].prefix = ""
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node.replace(Call(Name("next", prefix=node.prefix), base))
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elif name:
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# Omit this:
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# n = Name("__next__", prefix=name.prefix)
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# name.replace(n)
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pass
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elif attr:
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# We don't do this transformation if we're assigning to "x.next".
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# Unfortunately, it doesn't seem possible to do this in PATTERN,
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# so it's being done here.
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if is_assign_target(node):
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head = results["head"]
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if "".join([str(n) for n in head]).strip() == '__builtin__':
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self.warning(node, bind_warning)
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return
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# Omit this:
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# attr.replace(Name("__next__"))
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elif "global" in results:
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self.warning(node, bind_warning)
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self.shadowed_next = True
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### The following functions help test if node is part of an assignment
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### target.
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def is_assign_target(node):
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assign = find_assign(node)
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if assign is None:
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return False
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for child in assign.children:
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if child.type == token.EQUAL:
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return False
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elif is_subtree(child, node):
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return True
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return False
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def find_assign(node):
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if node.type == syms.expr_stmt:
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return node
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if node.type == syms.simple_stmt or node.parent is None:
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return None
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return find_assign(node.parent)
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def is_subtree(root, node):
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if root == node:
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return True
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return any(is_subtree(c, node) for c in root.children)
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