Merged revisions 61596-61597 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

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  r61596 | martin.v.loewis | 2008-03-18 23:43:46 -0500 (Di, 18 Mär 2008) | 2 lines

  Import lib2to3.
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  r61597 | martin.v.loewis | 2008-03-18 23:58:04 -0500 (Di, 18 Mär 2008) | 3 lines

  Initialized merge tracking via "svnmerge" with revisions "1-61595" from
  svn+ssh://pythondev@svn.python.org/sandbox/trunk/2to3/lib2to3
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Lib/lib2to3/fixes/fix_tuple_params.py

@@ -0,0 +1,169 @@
+"""Fixer for function definitions with tuple parameters.
+
+def func(((a, b), c), d):
+    ...
+    
+    ->
+
+def func(x, d):
+    ((a, b), c) = x
+    ...
+
+It will also support lambdas:
+  
+    lambda (x, y): x + y -> lambda t: t[0] + t[1]
+
+    # The parens are a syntax error in Python 3
+    lambda (x): x + y -> lambda x: x + y
+"""
+# Author: Collin Winter
+
+# Local imports
+from .. import pytree
+from ..pgen2 import token
+from .import basefix
+from .util import Assign, Name, Newline, Number, Subscript, syms
+
+def is_docstring(stmt):
+    return isinstance(stmt, pytree.Node) and \
+           stmt.children[0].type == token.STRING
+
+class FixTupleParams(basefix.BaseFix):
+    PATTERN = """
+              funcdef< 'def' any parameters< '(' args=any ')' >
+                       ['->' any] ':' suite=any+ >
+              |
+              lambda=
+              lambdef< 'lambda' args=vfpdef< '(' inner=any ')' >
+                       ':' body=any
+              >
+              """
+
+    def transform(self, node, results):
+        if "lambda" in results:
+            return self.transform_lambda(node, results)
+
+        new_lines = []
+        suite = results["suite"]
+        args = results["args"]
+        # This crap is so "def foo(...): x = 5; y = 7" is handled correctly.
+        # TODO(cwinter): suite-cleanup
+        if suite[0].children[1].type == token.INDENT:
+            start = 2
+            indent = suite[0].children[1].value
+            end = Newline()
+        else:
+            start = 0
+            indent = "; "
+            end = pytree.Leaf(token.INDENT, "")
+
+        # We need access to self for new_name(), and making this a method
+        #  doesn't feel right. Closing over self and new_lines makes the
+        #  code below cleaner.
+        def handle_tuple(tuple_arg, add_prefix=False):
+            n = Name(self.new_name())
+            arg = tuple_arg.clone()
+            arg.set_prefix("")
+            stmt = Assign(arg, n.clone())
+            if add_prefix:
+                n.set_prefix(" ")
+            tuple_arg.replace(n)
+            new_lines.append(pytree.Node(syms.simple_stmt,
+                                         [stmt, end.clone()]))
+
+        if args.type == syms.tfpdef:
+            handle_tuple(args)
+        elif args.type == syms.typedargslist:
+            for i, arg in enumerate(args.children):
+                if arg.type == syms.tfpdef:
+                    # Without add_prefix, the emitted code is correct,
+                    #  just ugly.
+                    handle_tuple(arg, add_prefix=(i > 0))
+
+        if not new_lines:
+            return node
+
+        # This isn't strictly necessary, but it plays nicely with other fixers.
+        # TODO(cwinter) get rid of this when children becomes a smart list
+        for line in new_lines:
+            line.parent = suite[0]
+
+        # TODO(cwinter) suite-cleanup
+        after = start
+        if start == 0:
+            new_lines[0].set_prefix(" ")
+        elif is_docstring(suite[0].children[start]):
+            new_lines[0].set_prefix(indent)
+            after = start + 1
+
+        suite[0].children[after:after] = new_lines
+        for i in range(after+1, after+len(new_lines)+1):
+            suite[0].children[i].set_prefix(indent)
+        suite[0].changed()
+
+    def transform_lambda(self, node, results):
+        args = results["args"]
+        body = results["body"]
+        inner = simplify_args(results["inner"])
+
+        # Replace lambda ((((x)))): x  with lambda x: x
+        if inner.type == token.NAME:
+            inner = inner.clone()
+            inner.set_prefix(" ")
+            args.replace(inner)
+            return
+
+        params = find_params(args)
+        to_index = map_to_index(params)
+        tup_name = self.new_name(tuple_name(params))
+
+        new_param = Name(tup_name, prefix=" ")
+        args.replace(new_param.clone())
+        for n in body.post_order():
+            if n.type == token.NAME and n.value in to_index:
+                subscripts = [c.clone() for c in to_index[n.value]]
+                new = pytree.Node(syms.power,
+                                  [new_param.clone()] + subscripts)
+                new.set_prefix(n.get_prefix())
+                n.replace(new)
+
+
+### Helper functions for transform_lambda()
+
+def simplify_args(node):
+    if node.type in (syms.vfplist, token.NAME):
+        return node
+    elif node.type == syms.vfpdef:
+        # These look like vfpdef< '(' x ')' > where x is NAME
+        # or another vfpdef instance (leading to recursion).
+        while node.type == syms.vfpdef:
+            node = node.children[1]
+        return node
+    raise RuntimeError("Received unexpected node %s" % node)
+
+def find_params(node):
+    if node.type == syms.vfpdef:
+        return find_params(node.children[1])
+    elif node.type == token.NAME:
+        return node.value
+    return [find_params(c) for c in node.children if c.type != token.COMMA]
+
+def map_to_index(param_list, prefix=[], d=None):
+    if d is None:
+        d = {}
+    for i, obj in enumerate(param_list):
+        trailer = [Subscript(Number(i))]
+        if isinstance(obj, list):
+            map_to_index(obj, trailer, d=d)
+        else:
+            d[obj] = prefix + trailer
+    return d
+
+def tuple_name(param_list):
+    l = []
+    for obj in param_list:
+        if isinstance(obj, list):
+            l.append(tuple_name(obj))
+        else:
+            l.append(obj)
+    return "_".join(l)