Viewing file:  fix_metaclass.py (3.18 KB) -rw-r--r--
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u"""
Fixer for (metaclass=X) -> __metaclass__ = X
Some semantics (see PEP 3115) may be altered in the translation."""
from lib2to3 import fixer_base
from lib2to3.fixer_util import Name, syms, Node, Leaf, Newline, find_root
from lib2to3.pygram import token
from libfuturize.fixer_util import indentation, suitify
# from ..fixer_util import Name, syms, Node, Leaf, Newline, find_root, indentation, suitify
def has_metaclass(parent):
results = None
for node in parent.children:
kids = node.children
if node.type == syms.argument:
if kids[0] == Leaf(token.NAME, u"metaclass") and \
kids[1] == Leaf(token.EQUAL, u"=") and \
kids[2]:
#Hack to avoid "class X(=):" with this case.
results = [node] + kids
break
elif node.type == syms.arglist:
# Argument list... loop through it looking for:
# Node(*, [*, Leaf(token.NAME, u"metaclass"), Leaf(token.EQUAL, u"="), Leaf(*, *)]
for child in node.children:
if results: break
if child.type == token.COMMA:
#Store the last comma, which precedes the metaclass
comma = child
elif type(child) == Node:
meta = equal = name = None
for arg in child.children:
if arg == Leaf(token.NAME, u"metaclass"):
#We have the (metaclass) part
meta = arg
elif meta and arg == Leaf(token.EQUAL, u"="):
#We have the (metaclass=) part
equal = arg
elif meta and equal:
#Here we go, we have (metaclass=X)
name = arg
results = (comma, meta, equal, name)
break
return results
class FixMetaclass(fixer_base.BaseFix):
PATTERN = u"""
classdef<any*>
"""
def transform(self, node, results):
meta_results = has_metaclass(node)
if not meta_results: return
for meta in meta_results:
meta.remove()
target = Leaf(token.NAME, u"__metaclass__")
equal = Leaf(token.EQUAL, u"=", prefix=u" ")
# meta is the last item in what was returned by has_metaclass(): name
name = meta
name.prefix = u" "
stmt_node = Node(syms.atom, [target, equal, name])
suitify(node)
for item in node.children:
if item.type == syms.suite:
for stmt in item.children:
if stmt.type == token.INDENT:
# Insert, in reverse order, the statement, a newline,
# and an indent right after the first indented line
loc = item.children.index(stmt) + 1
# Keep consistent indentation form
ident = Leaf(token.INDENT, stmt.value)
item.insert_child(loc, ident)
item.insert_child(loc, Newline())
item.insert_child(loc, stmt_node)
break
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