IDL parser: fix rebuilding of (stale) cached lexer tables

The PLY lexer caches its table as a Python module (lextab.py). The
cache is loaded by attempting to import the module, which succeeds
if there's a lextab.py{,c,o} anywhere in the Python path. If the
import succeeds, the cache is assumed by PLY to be up-to-date, so
to update the cache, we need to remove those files before calling
PLY to initialize the lexer.

This patch makes blink_idl_lexer.main() do just that. It also
extends blink_idl_parser.main() to call the former, since the GYP
(and GN) build systems only actually call the latter script.

BUG=397909

Review URL: https://codereview.chromium.org/425953002

git-svn-id: svn://svn.chromium.org/blink/trunk@179129 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/bindings/scripts/blink_idl_lexer.py

@@ -88,7 +88,8 @@ class BlinkIDLLexer(IDLLexer):
         for token in tokens:
             self._RemoveToken(token)
 
-    def __init__(self, debug=False, optimize=True, outputdir=None):
+    def __init__(self, debug=False, optimize=True, outputdir=None,
+                 rewrite_tables=False):
         if debug:
             # Turn off optimization and caching to help debugging
             optimize = False
@@ -98,6 +99,21 @@ class BlinkIDLLexer(IDLLexer):
             # as a Python module
             sys.path.append(outputdir)
 
+            if rewrite_tables:
+                tablefile = os.path.join(outputdir, 'lextab.py')
+
+                def unlink(filename):
+                    try:
+                        os.unlink(filename)
+                    except OSError:
+                        pass
+
+                unlink(tablefile)
+                # Also remove the .pyc/.pyo files, or they'll be used even if
+                # the .py file doesn't exist.
+                unlink(tablefile + 'c')
+                unlink(tablefile + 'o')
+
         IDLLexer.__init__(self)
         # Overrides to parent class
         self._RemoveTokens(REMOVE_TOKENS)
@@ -108,6 +124,7 @@ class BlinkIDLLexer(IDLLexer):
         self._lexobj = lex.lex(object=self,
                                debug=debug,
                                optimize=optimize,
+                               lextab='lextab',
                                outputdir=outputdir)
 
 
@@ -120,7 +137,10 @@ def main(argv):
     except IndexError as err:
         print 'Usage: %s OUTPUT_DIR' % argv[0]
         return 1
-    lexer = BlinkIDLLexer(outputdir=outputdir)
+    # Important: rewrite_tables=True causes the cache file to be deleted if it
+    # exists, thus making sure that PLY doesn't load it instead of regenerating
+    # the parse table.
+    lexer = BlinkIDLLexer(outputdir=outputdir, rewrite_tables=True)
 
 
 if __name__ == '__main__':

third_party/WebKit/Source/bindings/scripts/blink_idl_parser.py

@@ -71,6 +71,7 @@ from idl_parser.idl_parser import IDLParser, ListFromConcat
 from idl_parser.idl_parser import ParseFile as parse_file
 
 from blink_idl_lexer import BlinkIDLLexer
+import blink_idl_lexer
 
 
 # Explicitly set starting symbol to rule defined only in base parser.
@@ -440,12 +441,13 @@ class BlinkIDLParser(IDLParser):
 ################################################################################
 
 def main(argv):
-    # If file itself executed, cache parse table
+    # If file itself executed, cache lex/parse tables
     try:
         outputdir = argv[1]
     except IndexError as err:
         print 'Usage: %s OUTPUT_DIR' % argv[0]
         return 1
+    blink_idl_lexer.main(argv)
     # Important: rewrite_tables=True causes the cache file to be deleted if it
     # exists, thus making sure that PLY doesn't load it instead of regenerating
     # the parse table.