1 files changed, 38 insertions, 0 deletions
diff --git a/Lib/lib2to3/pygram.py b/Lib/lib2to3/pygram.py
new file mode 100644
index 0000000..24f1bcf
--- /dev/null
+++ b/Lib/lib2to3/pygram.py
@@ -0,0 +1,38 @@
+# Copyright 2006 Google, Inc. All Rights Reserved.
+# Licensed to PSF under a Contributor Agreement.
+
+"""Export the Python grammar and symbols."""
+
+# Python imports
+import os
+
+# Local imports
+from .pgen2 import token
+from .pgen2 import driver
+from . import pytree
+
+# The grammar file
+_GRAMMAR_FILE = os.path.join(os.path.dirname(__file__), "Grammar.txt")
+
+
+class Symbols(object):
+
+    def __init__(self, grammar):
+        """Initializer.
+
+        Creates an attribute for each grammar symbol (nonterminal),
+        whose value is the symbol's type (an int >= 256).
+        """
+        for name, symbol in grammar.symbol2number.iteritems():
+            setattr(self, name, symbol)
+
+
+python_grammar = driver.load_grammar(_GRAMMAR_FILE)
+python_symbols = Symbols(python_grammar)
+
+
+def parenthesize(node):
+    return pytree.Node(python_symbols.atom,
+                       (pytree.Leaf(token.LPAR, "("),
+                        node,
+                        pytree.Leaf(token.RPAR, ")")))