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