Allow leading underscore on identifier names in IDL parser

ppapi/generators/idl_lexer.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """ Lexer for PPAPI IDL """
 
 #
 # IDL Lexer
 #
@@ skipping 46 matching lines @@
 
     # Extra WebIDL keywords
       'CALLBACK',
       'DICTIONARY',
       'OPTIONAL',
       'STATIC',
 
     # Invented for apps use
       'NAMESPACE',
 
-
     # Data types
       'FLOAT',
       'OCT',
       'INT',
       'HEX',
       'STRING',
 
     # Operators
       'LSHIFT',
       'RSHIFT'
@@ skipping 59 matching lines @@
     return t
 
   # Return a "preprocessor" inline block
   def t_INLINE(self, t):
     r'\#inline (.|\n)*?\#endinl.*'
     self.AddLines(t.value.count('\n'))
     return t
 
   # A symbol or keyword.
   def t_KEYWORD_SYMBOL(self, t):
-    r'[A-Za-z][A-Za-z_0-9]*'
+    r'_?[A-Za-z][A-Za-z_0-9]*'
 
-    #All non-keywords are assumed to be symbols
+    # All non-keywords are assumed to be symbols
     t.type = self.keywords.get(t.value, 'SYMBOL')
+
+    # We strip leading underscores so that you can specify symbols with the same
+    # value as a keywords (E.g. a dictionary named 'interface').
+    if t.value[0] == '_':
+      t.value = t.value[1:]
     return t
 
   def t_ANY_error(self, t):
     msg = "Unrecognized input"
     line = self.lexobj.lineno
 
     # If that line has not been accounted for, then we must have hit
     # EoF, so compute the beginning of the line that caused the problem.
     if line >= len(self.index):
       # Find the offset in the line of the first word causing the issue
@@ skipping 175 matching lines @@
         return -1
     return 0
 
   except lex.LexError as le:
     sys.stderr.write('%s\n' % str(le))
   return -1
 
 
 if __name__ == '__main__':
   sys.exit(Main(sys.argv[1:]))