Add future 0.18.2

lib/libpasteurize/fixes/fix_kwargs.py

@@ -0,0 +1,147 @@
+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))