1 files changed, 56 insertions, 0 deletions
diff --git a/Lib/lib2to3/fixes/fix_throw.py b/Lib/lib2to3/fixes/fix_throw.py
new file mode 100644
index 0000000..ef120bd
--- /dev/null
+++ b/Lib/lib2to3/fixes/fix_throw.py
@@ -0,0 +1,56 @@
+"""Fixer for generator.throw(E, V, T).
+
+g.throw(E)       -> g.throw(E)
+g.throw(E, V)    -> g.throw(E(V))
+g.throw(E, V, T) -> g.throw(E(V).with_traceback(T))
+
+g.throw("foo"[, V[, T]]) will warn about string exceptions."""
+# Author: Collin Winter
+
+# Local imports
+from .. import pytree
+from ..pgen2 import token
+from .import basefix
+from .util import Name, Call, ArgList, Attr, is_tuple
+
+class FixThrow(basefix.BaseFix):
+
+    PATTERN = """
+    power< any trailer< '.' 'throw' >
+           trailer< '(' args=arglist< exc=any ',' val=any [',' tb=any] > ')' >
+    >
+    |
+    power< any trailer< '.' 'throw' > trailer< '(' exc=any ')' > >
+    """
+
+    def transform(self, node, results):
+        syms = self.syms
+
+        exc = results["exc"].clone()
+        if exc.type is token.STRING:
+            self.cannot_convert(node, "Python 3 does not support string exceptions")
+            return
+
+        # Leave "g.throw(E)" alone
+        val = results.get("val")
+        if val is None:
+            return
+
+        val = val.clone()
+        if is_tuple(val):
+            args = [c.clone() for c in val.children[1:-1]]
+        else:
+            val.set_prefix("")
+            args = [val]
+
+        throw_args = results["args"]
+
+        if "tb" in results:
+            tb = results["tb"].clone()
+            tb.set_prefix("")
+
+            e = Call(exc, args)
+            with_tb = Attr(e, Name('with_traceback')) + [ArgList([tb])]
+            throw_args.replace(pytree.Node(syms.power, with_tb))
+        else:
+            throw_args.replace(Call(exc, args))