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