started work on backend

2019-01-21 17:36:00 +01:00
parent a1a8bca34b
commit 9f9a7e4974
4032 changed files with 745079 additions and 0 deletions
@@ -0,0 +1,73 @@
+"""Fixer for 'raise E, V'
+
+From Armin Ronacher's ``python-modernize``.
+
+raise         -> raise
+raise E       -> raise E
+raise E, V    -> raise E(V)
+
+raise (((E, E'), E''), E'''), V -> raise E(V)
+
+
+CAVEATS:
+1) "raise E, V" will be incorrectly translated if V is an exception
+   instance. The correct Python 3 idiom is
+
+        raise E from V
+
+   but since we can't detect instance-hood by syntax alone and since
+   any client code would have to be changed as well, we don't automate
+   this.
+"""
+# Author: Collin Winter, Armin Ronacher
+
+# Local imports
+from lib2to3 import pytree, fixer_base
+from lib2to3.pgen2 import token
+from lib2to3.fixer_util import Name, Call, is_tuple
+
+class FixRaise(fixer_base.BaseFix):
+
+    BM_compatible = True
+    PATTERN = """
+    raise_stmt< 'raise' exc=any [',' val=any] >
+    """
+
+    def transform(self, node, results):
+        syms = self.syms
+
+        exc = results["exc"].clone()
+        if exc.type == token.STRING:
+            msg = "Python 3 does not support string exceptions"
+            self.cannot_convert(node, msg)
+            return
+
+        # Python 2 supports
+        #  raise ((((E1, E2), E3), E4), E5), V
+        # as a synonym for
+        #  raise E1, V
+        # Since Python 3 will not support this, we recurse down any tuple
+        # literals, always taking the first element.
+        if is_tuple(exc):
+            while is_tuple(exc):
+                # exc.children[1:-1] is the unparenthesized tuple
+                # exc.children[1].children[0] is the first element of the tuple
+                exc = exc.children[1].children[0].clone()
+            exc.prefix = u" "
+
+        if "val" not in results:
+            # One-argument raise
+            new = pytree.Node(syms.raise_stmt, [Name(u"raise"), exc])
+            new.prefix = node.prefix
+            return new
+
+        val = results["val"].clone()
+        if is_tuple(val):
+            args = [c.clone() for c in val.children[1:-1]]
+        else:
+            val.prefix = u""
+            args = [val]
+
+        return pytree.Node(syms.raise_stmt,
+                           [Name(u"raise"), Call(exc, args)],
+                           prefix=node.prefix)