android: Don't use cpp to strip comments in jni_generator.

base/android/jni_generator/jni_generator.py

Index: base/android/jni_generator/jni_generator.py
diff --git a/base/android/jni_generator/jni_generator.py b/base/android/jni_generator/jni_generator.py
index 27335834953a3e006647d27d98b301deb5b1fbf2..f51e5c2ce865b3ad8231ce6dacaf33b982bbe0cb 100755
--- a/base/android/jni_generator/jni_generator.py
+++ b/base/android/jni_generator/jni_generator.py
@@ -581,7 +581,7 @@ class JNIFromJavaSource(object):
   """Uses the given java source file to generate the JNI header file."""
 
   def __init__(self, contents, fully_qualified_class, options):
-    contents = self._RemoveComments(contents, options)
+    contents = self._RemoveComments(contents)
     JniParams.SetFullyQualifiedClass(fully_qualified_class)
     JniParams.ExtractImportsAndInnerClasses(contents)
     jni_namespace = ExtractJNINamespace(contents) or options.namespace
@@ -595,23 +595,28 @@ class JNIFromJavaSource(object):
         [], options)
     self.content = inl_header_file_generator.GetContent()
 
-  def _RemoveComments(self, contents, options):
+  # Match single line comments, multiline comments, character literals, and
+  # double-quoted strings.
+  _comment_remover_regex = re.compile(

[bulach, 2014/04/14 11:30:44]

nit: maybe move this before __init__ ? it took me a couple of seconds to
understand the scope :)

[Torne, 2014/04/14 11:41:06]

Done.

+      r'//.*?$|/\*.*?\*/|\'(?:\\.|[^\\\'])*\'|"(?:\\.|[^\\"])*"',
+      re.DOTALL | re.MULTILINE)
+
+  def _RemoveComments(self, contents):

[bulach, 2014/04/14 11:30:44]

...and then perhaps make this @staticmethod?

[Torne, 2014/04/14 11:41:06]

Static methods can't access members of the class, but I can make it a class
method.

     # We need to support both inline and block comments, and we need to handle
-    # strings that contain '//' or '/*'. Rather than trying to do all that with
-    # regexps, we just pipe the contents through the C preprocessor. We tell cpp
-    # the file has already been preprocessed, so it just removes comments and
-    # doesn't try to parse #include, #pragma etc.
-    #
-    # TODO(husky): This is a bit hacky. It would be cleaner to use a real Java
+    # strings that contain '//' or '/*'.
+    # TODO(bulach): This is a bit hacky. It would be cleaner to use a real Java
     # parser. Maybe we could ditch JNIFromJavaSource and just always use
     # JNIFromJavaP; or maybe we could rewrite this script in Java and use APT.
     # http://code.google.com/p/chromium/issues/detail?id=138941
-    p = subprocess.Popen(args=[options.cpp, '-fpreprocessed'],
-                         stdin=subprocess.PIPE,
-                         stdout=subprocess.PIPE,
-                         stderr=subprocess.PIPE)
-    stdout, _ = p.communicate(contents)
-    return stdout
+    def replacer(match):
+      # Replace matches that are comments with nothing; return literals/strings
+      # unchanged.
+      s = match.group(0)
+      if s.startswith('/'):
+        return ""

[bulach, 2014/04/14 11:30:44]

nit: s/""/''/

[Torne, 2014/04/14 11:41:06]

Done.

+      else:
+        return s
+    return self._comment_remover_regex.sub(replacer, contents)
 
   def GetContent(self):
     return self.content