File Content: fix_kwargs.py u""" Fixer for Python 3 function parameter syntax This fixer is rather sensitive to incorrect py3k syntax. """ # Note: "relevant" parameters are parameters following the first STAR in the list. from lib2to3 import fixer_base from lib2to3.fixer_util import token, String, Newline, Comma, Name from libfuturize.fixer_util import indentation, suitify, DoubleStar _assign_template = u"%(name)s = %(kwargs)s['%(name)s']; del %(kwargs)s['%(name)s']" _if_template = u"if '%(name)s' in %(kwargs)s: %(assign)s" _else_template = u"else: %(name)s = %(default)s" _kwargs_default_name = u"_3to2kwargs" def gen_params(raw_params): u""" Generator that yields tuples of (name, default_value) for each parameter in the list If no default is given, then it is default_value is None (not Leaf(token.NAME, 'None')) """ assert raw_params[0].type == token.STAR and len(raw_params) > 2 curr_idx = 2 # the first place a keyword-only parameter name can be is index 2 max_idx = len(raw_params) while curr_idx < max_idx: curr_item = raw_params[curr_idx] prev_item = curr_item.prev_sibling if curr_item.type != token.NAME: curr_idx += 1 continue if prev_item is not None and prev_item.type == token.DOUBLESTAR: break name = curr_item.value nxt = curr_item.next_sibling if nxt is not None and nxt.type == token.EQUAL: default_value = nxt.next_sibling curr_idx += 2 else: default_value = None yield (name, default_value) curr_idx += 1 def remove_params(raw_params, kwargs_default=_kwargs_default_name): u""" Removes all keyword-only args from the params list and a bare star, if any. Does not add the kwargs dict if needed. Returns True if more action is needed, False if not (more action is needed if no kwargs dict exists) """ assert raw_params[0].type == token.STAR if raw_params[1].type == token.COMMA: raw_params[0].remove() raw_params[1].remove() kw_params = raw_params[2:] else: kw_params = raw_params[3:] for param in kw_params: if param.type != token.DOUBLESTAR: param.remove() else: return False else: return True def needs_fixing(raw_params, kwargs_default=_kwargs_default_name): u""" Returns string with the name of the kwargs dict if the params after the first star need fixing Otherwise returns empty string """ found_kwargs = False needs_fix = False for t in raw_params[2:]: if t.type == token.COMMA: # Commas are irrelevant at this stage. continue elif t.type == token.NAME and not found_kwargs: # Keyword-only argument: definitely need to fix. needs_fix = True elif t.type == token.NAME and found_kwargs: # Return 'foobar' of **foobar, if needed. return t.value if needs_fix else u'' elif t.type == token.DOUBLESTAR: # Found either '*' from **foobar. found_kwargs = True else: # Never found **foobar. Return a synthetic name, if needed. return kwargs_default if needs_fix else u'' class FixKwargs(fixer_base.BaseFix): run_order = 7 # Run after function annotations are removed PATTERN = u"funcdef< 'def' NAME parameters< '(' arglist=typedargslist< params=any* > ')' > ':' suite=any >" def transform(self, node, results): params_rawlist = results[u"params"] for i, item in enumerate(params_rawlist): if item.type == token.STAR: params_rawlist = params_rawlist[i:] break else: return # params is guaranteed to be a list starting with *. # if fixing is needed, there will be at least 3 items in this list: # [STAR, COMMA, NAME] is the minimum that we need to worry about. new_kwargs = needs_fixing(params_rawlist) # new_kwargs is the name of the kwargs dictionary. if not new_kwargs: return suitify(node) # At this point, params_rawlist is guaranteed to be a list # beginning with a star that includes at least one keyword-only param # e.g., [STAR, NAME, COMMA, NAME, COMMA, DOUBLESTAR, NAME] or # [STAR, COMMA, NAME], or [STAR, COMMA, NAME, COMMA, DOUBLESTAR, NAME] # Anatomy of a funcdef: ['def', 'name', parameters, ':', suite] # Anatomy of that suite: [NEWLINE, INDENT, first_stmt, all_other_stmts] # We need to insert our new stuff before the first_stmt and change the # first_stmt's prefix. suite = node.children[4] first_stmt = suite.children[2] ident = indentation(first_stmt) for name, default_value in gen_params(params_rawlist): if default_value is None: suite.insert_child(2, Newline()) suite.insert_child(2, String(_assign_template %{u'name':name, u'kwargs':new_kwargs}, prefix=ident)) else: suite.insert_child(2, Newline()) suite.insert_child(2, String(_else_template %{u'name':name, u'default':default_value}, prefix=ident)) suite.insert_child(2, Newline()) suite.insert_child(2, String(_if_template %{u'assign':_assign_template %{u'name':name, u'kwargs':new_kwargs}, u'name':name, u'kwargs':new_kwargs}, prefix=ident)) first_stmt.prefix = ident suite.children[2].prefix = u"" # Now, we need to fix up the list of params. must_add_kwargs = remove_params(params_rawlist) if must_add_kwargs: arglist = results[u'arglist'] if len(arglist.children) > 0 and arglist.children[-1].type != token.COMMA: arglist.append_child(Comma()) arglist.append_child(DoubleStar(prefix=u" ")) arglist.append_child(Name(new_kwargs)) Submit