Chrome on Android: adds jni_generator.

base/android/jni_generator/jni_generator.py

+#!/usr/bin/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.
+
+"""Extracts native methods from a Java file and generates the JNI bindings.
+If you change this, please run and update the tests."""
+
+import collections
+import optparse
+import os
+import re
+import string
+from string import Template
+import subprocess
+import sys
+
+
+UNKNOWN_JAVA_TYPE_PREFIX = 'UNKNOWN_JAVA_TYPE: '
+
+
+class ParseError(Exception):
+  """Exception thrown when we can't parse the input file."""
+
+  def __init__(self, description, *context_lines):
+    Exception.__init__(self)
+    self.description = description
+    self.context_lines = context_lines
+
+  def __str__(self):
+    context = '\n'.join(self.context_lines)
+    return '***\nERROR: %s\n\n%s\n***' % (self.description, context)
+
+
+class Param(object):
+  """Describes a param for a method, either java or native."""
+
+  def __init__(self, **kwargs):
+    self.datatype = kwargs['datatype']
+    self.name = kwargs['name']
+    self.cpp_class_name = kwargs.get('cpp_class_name', None)
+
+
+class NativeMethod(object):
+  """Describes a C/C++ method that is called by Java code"""
+
+  def __init__(self, **kwargs):
+    self.static = kwargs['static']
+    self.java_class_name = kwargs['java_class_name']
+    self.return_type = kwargs['return_type']
+    self.name = kwargs['name']
+    self.params = kwargs['params']
+    if self.params:
+      assert type(self.params) is list
+      assert type(self.params[0]) is Param
+    if (self.params and
+        self.params[0].datatype == 'int' and
+        self.params[0].name.startswith('native')):
+      self.type = 'method'
+      if self.params[0].cpp_class_name:
+        self.p0_type = self.params[0].cpp_class_name
+      else:
+        self.p0_type = self.params[0].name[len('native'):]
+    elif self.static:
+      self.type = 'function'
+    else:
+      self.type = 'function'
+    self.method_id_var_name = kwargs.get('method_id_var_name', None)
+
+
+class CalledByNative(object):
+  """Describes a java method exported to c/c++"""
+
+  def __init__(self, **kwargs):
+    self.system_class = kwargs['system_class']
+    self.unchecked = kwargs['unchecked']
+    self.static = kwargs['static']
+    self.java_class_name = kwargs['java_class_name']
+    self.return_type = kwargs['return_type']
+    self.env_call = kwargs['env_call']
+    self.name = kwargs['name']
+    self.params = kwargs['params']
+    self.method_id_var_name = kwargs.get('method_id_var_name', None)
+
+
+def JavaDataTypeToC(java_type):
+  """Returns a C datatype for the given java type."""
+  java_pod_type_map = {
+      'int': 'jint',
+      'byte': 'jbyte',
+      'boolean': 'jboolean',
+      'long': 'jlong',
+      'double': 'jdouble',
+      'float': 'jfloat',
+  }
+  java_type_map = {
+      'void': 'void',
+      'String': 'jstring',
+  }
+  if java_type in java_pod_type_map:
+    return java_pod_type_map[java_type]
+  elif java_type in java_type_map:
+    return java_type_map[java_type]
+  elif java_type.endswith('[]'):
+    if java_type[:-2] in java_pod_type_map:
+      return java_pod_type_map[java_type[:-2]] + 'Array'
+    return 'jobjectArray'
+  else:
+    return 'jobject'
+
+
+def JavaParamToJni(param):
+  """Converts a java param into a JNI signature type."""
+  pod_param_map = {
+      'int': 'I',
+      'boolean': 'Z',
+      'long': 'J',
+      'double': 'D',
+      'float': 'F',
+      'byte': 'B',
+      'void': 'V',
+  }
+  object_param_map = {
+      'String': 'Ljava/lang/String',
+      'Boolean': 'Ljava/lang/Boolean',
+      'Integer': 'Ljava/lang/Integer',
+      'Long': 'Ljava/lang/Long',
+      'Object': 'Ljava/lang/Object',
+      'List': 'Ljava/util/List',
+      'ArrayList': 'Ljava/util/ArrayList',
+      'HashMap': 'Ljava/util/HashMap',
+      'Bitmap': 'Landroid/graphics/Bitmap',
+      'Context': 'Landroid/content/Context',
+      'Canvas': 'Landroid/graphics/Canvas',
+      'Surface': 'Landroid/view/Surface',
+      'KeyEvent': 'Landroid/view/KeyEvent',
+      'Rect': 'Landroid/graphics/Rect',
+      'RectF': 'Landroid/graphics/RectF',
+      'View': 'Landroid/view/View',
+      'Matrix': 'Landroid/graphics/Matrix',
+      'Point': 'Landroid/graphics/Point',
+      'ByteBuffer': 'Ljava/nio/ByteBuffer',
+      'InputStream': 'Ljava/io/InputStream',
+  }
+  app_param_map = {
+      'ChromeView':
+      'Lorg/chromium/chromeview/ChromeView',
+
+      'Tab':
+      'Lcom/android/chrome/Tab',
+
+      'TouchPoint':
+      'Lorg/chromium/chromeview/TouchPoint',
+
+      'SurfaceTexture':
+      'Landroid/graphics/SurfaceTexture',
+
+      'ChromeViewClient':
+      'Lorg/chromium/chromeview/ChromeViewClient',
+
+      'JSModalDialog':
+      'Lcom/android/chrome/JSModalDialog',
+
+      'NativeInfoBar':
+      'Lcom/android/chrome/infobar/InfoBarContainer$NativeInfoBar',
+
+      'OmniboxSuggestion':
+      'Lcom/android/chrome/OmniboxSuggestion',
+
+      'PasswordListObserver':
+      'Lorg/chromium/chromeview/ChromePreferences$PasswordListObserver',
+
+      'SandboxedProcessArgs': 'Lorg/chromium/chromeview/SandboxedProcessArgs',
+
+      'SandboxedProcessConnection':
+      'Lorg/chromium/chromeview/SandboxedProcessConnection',
+
+      'SandboxedProcessService':
+      'Lorg/chromium/chromeview/SandboxedProcessService',
+
+      'BookmarkNode': 'Lcom/android/chrome/ChromeBrowserProvider$BookmarkNode',
+
+      'SQLiteCursor': 'Lcom/android/chrome/database/SQLiteCursor',
+
+      'FindResultReceivedListener.FindNotificationDetails':
+      ('Lorg/chromium/chromeview/ChromeView$'
+       'FindResultReceivedListener$FindNotificationDetails'),
+
+      'ChromeViewContextMenuInfo':
+      'Lorg/chromium/chromeview/ChromeView$ChromeViewContextMenuInfo',
+
+      'AutofillData': 'Lorg/chromium/chromeview/AutofillData',
+
+      'JavaInputStream': 'Lorg/chromium/chromeview/JavaInputStream',
+
+      'ChromeVideoView': 'Lorg/chromium/chromeview/ChromeVideoView',
+
+      'ChromeHttpAuthHandler': 'Lorg/chromium/chromeview/ChromeHttpAuthHandler',
+  }
+  if param == 'byte[][]':
+    return '[[B'
+  prefix = ''
+  # Array?
+  if param[-2:] == '[]':
+    prefix = '['
+    param = param[:-2]
+  # Generic?
+  if '<' in param:
+    param = param[:param.index('<')]
+  if param in pod_param_map:
+    return prefix + pod_param_map[param]
+  elif param in object_param_map:
+    return prefix + object_param_map[param] + ';'
+  elif param in app_param_map:
+    return prefix + app_param_map[param] + ';'
+  else:
+    return UNKNOWN_JAVA_TYPE_PREFIX + prefix + param + ';'
+
+
+def JniSignature(params, returns):
+  """Returns the JNI signature for the given datatypes."""
+  ret = '"('
+  ret += ''.join([JavaParamToJni(param.datatype) for param in params])
+  ret += ')'
+  ret += JavaParamToJni(returns)
+  ret += '"'
+  return ret
+
+
+def ParseParams(params):
+  """Parses the params into a list of Param objects."""
+  if not params:
+    return []
+  ret = []
+  re_comment = re.compile(r'.*?\/\* (.*) \*\/')
+  for p in [p.strip() for p in params.split(',')]:
+    items = p.split(' ')
+    if 'final' in items:
+      items.remove('final')
+    comment = re.match(re_comment, p)
+    param = Param(
+        datatype=items[0],
+        name=(items[1] if len(items) > 1 else 'p%s' % len(ret)),
+        cpp_class_name=comment.group(1) if comment else None
+    )
+    ret += [param]
+  return ret
+
+
+def GetUnknownDatatypes(items):
+  """Returns a list containing the unknown datatypes."""
+  unknown_types = {}
+  for item in items:
+    all_datatypes = ([JavaParamToJni(param.datatype)
+                      for param in item.params] +
+                     [JavaParamToJni(item.return_type)])
+    for d in all_datatypes:
+      if d.startswith(UNKNOWN_JAVA_TYPE_PREFIX):
+        unknown_types[d] = (unknown_types.get(d, []) +
+                            [item.name or 'Unable to parse'])
+  return unknown_types
+
+
+def ExtractFullyQualifiedJavaClassName(java_file_name, contents):
+  re_package = re.compile('.*?package (.*?);')
+  matches = re.findall(re_package, contents)
+  if not matches:
+    raise SyntaxError('Unable to find "package" line in %s' % java_file_name)
+  return (matches[0].replace('.', '/') + '/' +
+          os.path.splitext(os.path.basename(java_file_name))[0])
+
+
+def ExtractNatives(contents):
+  """Returns a list of dict containing information about a native method."""
+  contents = contents.replace('\n', '')
+  natives = []
+  re_native = re.compile(r'(@NativeCall(\(\"(.*?)\"\)))?\s*'
+                         '(\w+\s\w+|\w+|\s+)\s*?native (\S*?) (\w+?)\((.*?)\);')
+  matches = re.findall(re_native, contents)
+  for match in matches:
+    native = NativeMethod(
+        static='static' in match[3],
+        java_class_name=match[2],
+        return_type=match[4],
+        name=match[5].replace('native', ''),
+        params=ParseParams(match[6]))
+    natives += [native]
+  return natives
+
+
+def GetEnvCallForReturnType(return_type):
+  """Maps the types availabe via env->Call__Method."""
+  env_call_map = {'boolean': ('Boolean', ''),
+                  'byte': ('Byte', ''),
+                  'char': ('Char', ''),
+                  'short': ('Short', ''),
+                  'int': ('Int', ''),
+                  'long': ('Long', ''),
+                  'float': ('Float', ''),
+                  'void': ('Void', ''),
+                  'double': ('Double', ''),
+                  'String': ('Object', 'jstring'),
+                  'Object': ('Object', ''),
+                 }
+  return env_call_map.get(return_type, ('Object', ''))
+
+
+def GetMangledMethodName(name, jni_signature):
+  """Returns a mangled method name for a (name, jni_signature) pair.
+
+     The returned name can be used as a C identifier and will be unique for all
+     valid overloads of the same method.
+
+  Args:
+     name: string.
+     jni_signature: string.
+
+  Returns:
+      A mangled name.
+  """
+  sig_translation = string.maketrans('[()/;$', 'apq_xs')
+  mangled_name = name + '_' + string.translate(jni_signature, sig_translation,
+                                               '"')
+  assert re.match(r'[0-9a-zA-Z_]+', mangled_name)
+  return mangled_name
+
+
+def MangleCalledByNatives(called_by_natives):
+  """Mangles all the overloads from the call_by_natives list."""
+  method_counts = collections.defaultdict(
+      lambda: collections.defaultdict(lambda: 0))
+  for called_by_native in called_by_natives:
+    java_class_name = called_by_native.java_class_name
+    name = called_by_native.name
+    method_counts[java_class_name][name] += 1
+  for called_by_native in called_by_natives:
+    java_class_name = called_by_native.java_class_name
+    method_name = called_by_native.name
+    method_id_var_name = method_name
+    if method_counts[java_class_name][method_name] > 1:
+      jni_signature = JniSignature(called_by_native.params,
+                                   called_by_native.return_type)
+      method_id_var_name = GetMangledMethodName(method_name, jni_signature)
+    called_by_native.method_id_var_name = method_id_var_name
+  return called_by_natives
+
+
+# Regex to match the JNI return types that should be included in a
+# ScopedJavaLocalRef.
+RE_SCOPED_JNI_RETURN_TYPES = re.compile('jobject|jclass|jstring|.*Array')
+
+# Regex to match a string like "@CalledByNative public void foo(int bar)".
+RE_CALLED_BY_NATIVE = re.compile(
+    '@CalledByNative(?P<Unchecked>(Unchecked)*?)(?:\("(?P<annotation>.*)"\))?'
+    '\s+(?P<prefix>[\w ]*?)'
+    '\s*(?P<return_type>\w+)'
+    '\s+(?P<name>\w+)'
+    '\s*\((?P<params>[^\)]*)\)')
+
+
+def ExtractCalledByNatives(contents):
+  """Parses all methods annotated with @CalledByNative.
+
+  Args:
+    contents: the contents of the java file.
+
+  Returns:
+    A list of dict with information about the annotated methods.
+    TODO(bulach): return a CalledByNative object.
+
+  Raises:
+    ParseError: if unable to parse.
+  """
+  called_by_natives = []
+  for match in re.finditer(RE_CALLED_BY_NATIVE, contents):
+    called_by_natives += [CalledByNative(
+        system_class=False,
+        unchecked='Unchecked' in match.group('Unchecked'),
+        static='static' in match.group('prefix'),
+        java_class_name=match.group('annotation') or '',
+        return_type=match.group('return_type'),
+        env_call=GetEnvCallForReturnType(match.group('return_type')),
+        name=match.group('name'),
+        params=ParseParams(match.group('params')))]
+  # Check for any @CalledByNative occurrences that weren't matched.
+  unmatched_lines = re.sub(RE_CALLED_BY_NATIVE, '', contents).split('\n')
+  for line1, line2 in zip(unmatched_lines, unmatched_lines[1:]):
+    if '@CalledByNative' in line1:
+      raise ParseError('could not parse @CalledByNative method signature',
+                       line1, line2)
+  return MangleCalledByNatives(called_by_natives)
+
+
+class JNIFromJavaP(object):
+  """Uses 'javap' to parse a .class file and generate the JNI header file."""
+
+  def __init__(self, contents, namespace):
+    self.contents = contents
+    self.namespace = namespace
+    self.fully_qualified_class = re.match('.*?class (.*?) ',
+                                          contents[1]).group(1)
+    self.fully_qualified_class = self.fully_qualified_class.replace('.', '/')
+    self.java_class_name = self.fully_qualified_class.split('/')[-1]
+    if not self.namespace:
+      self.namespace = 'JNI_' + self.java_class_name
+    re_method = re.compile('(.*?)(\w+?) (\w+?)\((.*?)\)')
+    self.called_by_natives = []
+    for method in contents[2:]:
+      match = re.match(re_method, method)
+      if not match:
+        continue
+      self.called_by_natives += [CalledByNative(
+          system_class=True,
+          unchecked=False,
+          static='static' in match.group(1),
+          java_class_name='',
+          return_type=match.group(2),
+          name=match.group(3),
+          params=ParseParams(match.group(4)),
+          env_call=GetEnvCallForReturnType(match.group(2)))]
+    self.called_by_natives = MangleCalledByNatives(self.called_by_natives)
+    self.inl_header_file_generator = InlHeaderFileGenerator(
+        self.namespace, self.fully_qualified_class, [], self.called_by_natives)
+
+  def GetContent(self):
+    return self.inl_header_file_generator.GetContent()
+
+  @staticmethod
+  def CreateFromClass(class_file, namespace):
+    class_name = os.path.splitext(os.path.basename(class_file))[0]
+    p = subprocess.Popen(args=['javap', class_name],
+                         cwd=os.path.dirname(class_file),
+                         stdout=subprocess.PIPE,
+                         stderr=subprocess.PIPE)
+    stdout, _ = p.communicate()
+    jni_from_javap = JNIFromJavaP(stdout.split('\n'), namespace)
+    return jni_from_javap
+
+
+class JNIFromJavaSource(object):
+  """Uses the given java source file to generate the JNI header file."""
+
+  def __init__(self, contents, fully_qualified_class):
+    contents = self._RemoveComments(contents)
+    natives = ExtractNatives(contents)
+    called_by_natives = ExtractCalledByNatives(contents)
+    inl_header_file_generator = InlHeaderFileGenerator(
+        '', fully_qualified_class, natives, called_by_natives)
+    self.content = inl_header_file_generator.GetContent()
+
+  def _RemoveComments(self, contents):
+    ret = []
+    for c in [c.strip() for c in contents.split('\n')]:
+      if not c.startswith('//'):
+        ret += [c]
+    return '\n'.join(ret)
+
+  def GetContent(self):
+    return self.content
+
+  @staticmethod
+  def CreateFromFile(java_file_name):
+    contents = file(java_file_name).read()
+    fully_qualified_class = ExtractFullyQualifiedJavaClassName(java_file_name,
+                                                               contents)
+    return JNIFromJavaSource(contents, fully_qualified_class)
+
+
+class InlHeaderFileGenerator(object):
+  """Generates an inline header file for JNI integration."""
+
+  def __init__(self, namespace, fully_qualified_class, natives,
+               called_by_natives):
+    self.namespace = namespace
+    self.fully_qualified_class = fully_qualified_class
+    self.class_name = self.fully_qualified_class.split('/')[-1]
+    self.natives = natives
+    self.called_by_natives = called_by_natives
+    self.header_guard = fully_qualified_class.replace('/', '_') + '_JNI'
+    unknown_datatypes = GetUnknownDatatypes(self.natives +
+                                            self.called_by_natives)
+    if unknown_datatypes:
+      msg = ('There are a few unknown datatypes in %s' %
+             self.fully_qualified_class)
+      msg += '\nPlease, edit %s' % sys.argv[0]
+      msg += '\nand add the java type to JavaParamToJni()\n'
+      for unknown_datatype in unknown_datatypes:
+        msg += '\n%s in methods:\n' % unknown_datatype
+        msg += '\n '.join(unknown_datatypes[unknown_datatype])
+      raise SyntaxError(msg)
+
+  def GetContent(self):
+    """Returns the content of the JNI binding file."""
+    template = Template("""\
+// 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.
+
+
+// This file is autogenerated by ${SCRIPT_NAME}
+// For ${FULLY_QUALIFIED_CLASS}
+
+#ifndef ${HEADER_GUARD}
+#define ${HEADER_GUARD}
+
+#include <jni.h>
+
+#include "base/android/jni_android.h"
+#include "base/android/scoped_java_ref.h"
+#include "base/basictypes.h"
+#include "base/logging.h"
+
+using base::android::ScopedJavaLocalRef;
+
+// Step 1: forward declarations.
+namespace {
+$CLASS_PATH_DEFINITIONS
+}  // namespace
+$FORWARD_DECLARATIONS
+
+// Step 2: method stubs.
+$METHOD_STUBS
+
+// Step 3: GetMethodIDs and RegisterNatives.
+$OPEN_NAMESPACE
+
+static void GetMethodIDsImpl(JNIEnv* env) {
+$GET_METHOD_IDS_IMPL
+}
+
+static bool RegisterNativesImpl(JNIEnv* env) {
+  ${NAMESPACE}GetMethodIDsImpl(env);
+$REGISTER_NATIVES_IMPL
+  return true;
+}
+$CLOSE_NAMESPACE
+#endif  // ${HEADER_GUARD}
+""")
+    script_components = os.path.abspath(sys.argv[0]).split(os.path.sep)
+    base_index = script_components.index('base')
+    script_name = os.sep.join(script_components[base_index:])
+    values = {
+        'SCRIPT_NAME': script_name,
+        'FULLY_QUALIFIED_CLASS': self.fully_qualified_class,
+        'CLASS_PATH_DEFINITIONS': self.GetClassPathDefinitionsString(),
+        'FORWARD_DECLARATIONS': self.GetForwardDeclarationsString(),
+        'METHOD_STUBS': self.GetMethodStubsString(),
+        'OPEN_NAMESPACE': self.GetOpenNamespaceString(),
+        'NAMESPACE': self.GetNamespaceString(),
+        'GET_METHOD_IDS_IMPL': self.GetMethodIDsImplString(),
+        'REGISTER_NATIVES_IMPL': self.GetRegisterNativesImplString(),
+        'CLOSE_NAMESPACE': self.GetCloseNamespaceString(),
+        'HEADER_GUARD': self.header_guard,
+    }
+    return template.substitute(values)
+
+  def GetClassPathDefinitionsString(self):
+    ret = []
+    ret += [self.GetClassPathDefinitions()]
+    return '\n'.join(ret)
+
+  def GetForwardDeclarationsString(self):
+    ret = []
+    for native in self.natives:
+      if native.type != 'method':
+        ret += [self.GetForwardDeclaration(native)]
+    return '\n'.join(ret)
+
+  def GetMethodStubsString(self):
+    ret = []
+    for native in self.natives:
+      if native.type == 'method':
+        ret += [self.GetNativeMethodStub(native)]
+    for called_by_native in self.called_by_natives:
+      ret += [self.GetCalledByNativeMethodStub(called_by_native)]
+    return '\n'.join(ret)
+
+  def GetKMethodsString(self, clazz):
+    ret = []
+    for native in self.natives:
+      if (native.java_class_name == clazz or
+          (not native.java_class_name and clazz == self.class_name)):
+        ret += [self.GetKMethodArrayEntry(native)]
+    return '\n'.join(ret)
+
+  def GetMethodIDsImplString(self):
+    ret = []
+    ret += [self.GetFindClasses()]
+    for called_by_native in self.called_by_natives:
+      ret += [self.GetMethodIDImpl(called_by_native)]
+    return '\n'.join(ret)
+
+  def GetRegisterNativesImplString(self):
+    """Returns the implementation for RegisterNatives."""
+    template = Template("""\
+  static const JNINativeMethod kMethods${JAVA_CLASS}[] = {
+${KMETHODS}
+  };
+  const int kMethods${JAVA_CLASS}Size = arraysize(kMethods${JAVA_CLASS});
+
+  if (env->RegisterNatives(g_${JAVA_CLASS}_clazz.obj(),
+                           kMethods${JAVA_CLASS},
+                           kMethods${JAVA_CLASS}Size) < 0) {
+    LOG(ERROR) << "RegisterNatives failed in " << __FILE__;
+    return false;
+  }
+""")
+    ret = []
+    all_classes = self.GetUniqueClasses(self.natives)
+    all_classes[self.class_name] = self.fully_qualified_class
+    for clazz in all_classes:
+      kmethods = self.GetKMethodsString(clazz)
+      if kmethods:
+        values = {'JAVA_CLASS': clazz,
+                  'KMETHODS': kmethods}
+        ret += [template.substitute(values)]
+    if not ret: return ''
+    return '\n' + '\n'.join(ret)
+
+  def GetOpenNamespaceString(self):
+    if self.namespace:
+      return 'namespace %s {' % self.namespace
+    return ''
+
+  def GetNamespaceString(self):
+    if self.namespace:
+      return '%s::' % self.namespace
+    return ''
+
+  def GetCloseNamespaceString(self):
+    if self.namespace:
+      return '}  // namespace %s\n' % self.namespace
+    return ''
+
+  def GetJNIFirstParam(self, native):
+    ret = []
+    if native.type == 'method':
+      ret = ['jobject obj']
+    elif native.type == 'function':
+      if native.static:
+        ret = ['jclass clazz']
+      else:
+        ret = ['jobject obj']
+    return ret
+
+  def GetParamsInDeclaration(self, native):
+    """Returns the params for the stub declaration.
+
+    Args:
+      native: the native dictionary describing the method.
+
+    Returns:
+      A string containing the params.
+    """
+    return ',\n    '.join(self.GetJNIFirstParam(native) +
+                          [JavaDataTypeToC(param.datatype) + ' ' +
+                           param.name
+                           for param in native.params])
+
+  def GetCalledByNativeParamsInDeclaration(self, called_by_native):
+    return ',\n    '.join([JavaDataTypeToC(param.datatype) + ' ' +
+                           param.name
+                           for param in called_by_native.params])
+
+  def GetForwardDeclaration(self, native):
+    template = Template("""
+static ${RETURN} ${NAME}(JNIEnv* env, ${PARAMS});
+""")
+    values = {'RETURN': JavaDataTypeToC(native.return_type),
+              'NAME': native.name,
+              'PARAMS': self.GetParamsInDeclaration(native)}
+    return template.substitute(values)
+
+  def GetNativeMethodStub(self, native):
+    """Returns stubs for native methods."""
+    template = Template("""\
+static ${RETURN} ${NAME}(JNIEnv* env, ${PARAMS_IN_DECLARATION}) {
+  DCHECK(${PARAM0_NAME}) << "${NAME}";
+  ${P0_TYPE}* native = reinterpret_cast<${P0_TYPE}*>(${PARAM0_NAME});
+  return native->${NAME}(env, obj${PARAMS_IN_CALL})${POST_CALL};
+}
+""")
+    params_for_call = ', '.join(p.name for p in native.params[1:])
+    if params_for_call:
+      params_for_call = ', ' + params_for_call
+
+    return_type = JavaDataTypeToC(native.return_type)
+    if re.match(RE_SCOPED_JNI_RETURN_TYPES, return_type):
+      scoped_return_type = 'ScopedJavaLocalRef<' + return_type + '>'
+      post_call = '.Release()'
+    else:
+      scoped_return_type = return_type
+      post_call = ''
+    values = {
+        'RETURN': return_type,
+        'SCOPED_RETURN': scoped_return_type,
+        'NAME': native.name,
+        'PARAMS_IN_DECLARATION': self.GetParamsInDeclaration(native),
+        'PARAM0_NAME': native.params[0].name,
+        'P0_TYPE': native.p0_type,
+        'PARAMS_IN_CALL': params_for_call,
+        'POST_CALL': post_call
+    }
+    return template.substitute(values)
+
+  def GetCalledByNativeMethodStub(self, called_by_native):
+    """Returns a string."""
+    function_signature_template = Template("""\
+static ${RETURN_TYPE} Java_${JAVA_CLASS}_${METHOD}(JNIEnv* env${FIRST_PARAM_IN_DECLARATION}${PARAMS_IN_DECLARATION})""")
+    function_header_template = Template("""\
+${FUNCTION_SIGNATURE} {""")
+    function_header_with_unused_template = Template("""\
+${FUNCTION_SIGNATURE} __attribute__ ((unused));
+${FUNCTION_SIGNATURE} {""")
+    template = Template("""
+static jmethodID g_${JAVA_CLASS}_${METHOD_ID_VAR_NAME} = 0;
+${FUNCTION_HEADER}
+  DCHECK(!g_${JAVA_CLASS}_clazz.is_null());  /* Must call RegisterNativesImpl()  */
+  DCHECK(g_${JAVA_CLASS}_${METHOD_ID_VAR_NAME});
+  ${RETURN_DECLARATION}
+  ${PRE_CALL}env->Call${STATIC}${ENV_CALL}Method(${FIRST_PARAM_IN_CALL},
+      g_${JAVA_CLASS}_${METHOD_ID_VAR_NAME}${PARAMS_IN_CALL})${POST_CALL};
+  ${CHECK_EXCEPTION}
+  ${RETURN_CLAUSE}
+}""")
+    if called_by_native.static:
+      first_param_in_declaration = ''
+      first_param_in_call = ('g_%s_clazz.obj()' %
+                             (called_by_native.java_class_name or
+                              self.class_name))
+    else:
+      first_param_in_declaration = ', jobject obj'
+      first_param_in_call = 'obj'
+    params_in_declaration = self.GetCalledByNativeParamsInDeclaration(
+        called_by_native)
+    if params_in_declaration:
+      params_in_declaration = ', ' + params_in_declaration
+    params_for_call = ', '.join(param.name
+                                for param in called_by_native.params)
+    if params_for_call:
+      params_for_call = ', ' + params_for_call
+    pre_call = ''
+    post_call = ''
+    if called_by_native.env_call[1]:
+      pre_call = 'static_cast<%s>(' % called_by_native.env_call[1]
+      post_call = ')'
+    check_exception = ''
+    if not called_by_native.unchecked:
+      check_exception = 'base::android::CheckException(env);'
+    return_type = JavaDataTypeToC(called_by_native.return_type)
+    return_declaration = ''
+    return_clause = ''
+    if return_type != 'void':
+      pre_call = '  ' + pre_call
+      return_declaration = return_type + ' ret ='
+      if re.match(RE_SCOPED_JNI_RETURN_TYPES, return_type):
+        return_type = 'ScopedJavaLocalRef<' + return_type + '>'
+        return_clause = 'return ' + return_type + '(env, ret);'
+      else:
+        return_clause = 'return ret;'
+    values = {
+        'JAVA_CLASS': called_by_native.java_class_name or self.class_name,
+        'METHOD': called_by_native.name,
+        'RETURN_TYPE': return_type,
+        'RETURN_DECLARATION': return_declaration,
+        'RETURN_CLAUSE': return_clause,
+        'FIRST_PARAM_IN_DECLARATION': first_param_in_declaration,
+        'PARAMS_IN_DECLARATION': params_in_declaration,
+        'STATIC': 'Static' if called_by_native.static else '',
+        'PRE_CALL': pre_call,
+        'POST_CALL': post_call,
+        'ENV_CALL': called_by_native.env_call[0],
+        'FIRST_PARAM_IN_CALL': first_param_in_call,
+        'PARAMS_IN_CALL': params_for_call,
+        'METHOD_ID_VAR_NAME': called_by_native.method_id_var_name,
+        'CHECK_EXCEPTION': check_exception,
+    }
+    values['FUNCTION_SIGNATURE'] = (
+        function_signature_template.substitute(values))
+    if called_by_native.system_class:
+      values['FUNCTION_HEADER'] = (
+          function_header_with_unused_template.substitute(values))
+    else:
+      values['FUNCTION_HEADER'] = function_header_template.substitute(values)
+    return template.substitute(values)
+
+  def GetKMethodArrayEntry(self, native):
+    template = Template("""\
+    { "native${NAME}", ${JNI_SIGNATURE}, reinterpret_cast<void*>(${NAME}) },""")
+    values = {'NAME': native.name,
+              'JNI_SIGNATURE': JniSignature(native.params, native.return_type)}
+    return template.substitute(values)
+
+  def GetUniqueClasses(self, origin):
+    ret = {self.class_name: self.fully_qualified_class}
+    for entry in origin:
+      class_name = self.class_name
+      jni_class_path = self.fully_qualified_class
+      if entry.java_class_name:
+        class_name = entry.java_class_name
+        jni_class_path = self.fully_qualified_class + '$' + class_name
+      ret[class_name] = jni_class_path
+    return ret
+
+  def GetClassPathDefinitions(self):
+    """Returns the ClassPath constants."""
+    ret = []
+    template = Template("""\
+const char* const k${JAVA_CLASS}ClassPath = "${JNI_CLASS_PATH}";""")
+    native_classes = self.GetUniqueClasses(self.natives)
+    called_by_native_classes = self.GetUniqueClasses(self.called_by_natives)
+    all_classes = native_classes
+    all_classes.update(called_by_native_classes)
+    for clazz in all_classes:
+      values = {
+          'JAVA_CLASS': clazz,
+          'JNI_CLASS_PATH': all_classes[clazz],
+      }
+      ret += [template.substitute(values)]
+    ret += ''
+    for clazz in called_by_native_classes:
+      template = Template("""\
+// Leaking this JavaRef as we cannot use LazyInstance from some threads.
+base::android::ScopedJavaGlobalRef<jclass>&
+    g_${JAVA_CLASS}_clazz = *(new base::android::ScopedJavaGlobalRef<jclass>());""")
+      values = {
+          'JAVA_CLASS': clazz,
+      }
+      ret += [template.substitute(values)]
+    return '\n'.join(ret)
+
+  def GetFindClasses(self):
+    """Returns the imlementation of FindClass for all known classes."""
+    template = Template("""\
+  g_${JAVA_CLASS}_clazz.Reset(base::android::GetClass(env, k${JAVA_CLASS}ClassPath));""")
+    ret = []
+    for clazz in self.GetUniqueClasses(self.called_by_natives):
+      values = {'JAVA_CLASS': clazz}
+      ret += [template.substitute(values)]
+    return '\n'.join(ret)
+
+  def GetMethodIDImpl(self, called_by_native):
+    """Returns the implementation of GetMethodID."""
+    template = Template("""\
+  g_${JAVA_CLASS}_${METHOD_ID_VAR_NAME} = base::android::Get${STATIC}MethodID(
+    env, g_${JAVA_CLASS}_clazz,
+    "${NAME}",
+    ${JNI_SIGNATURE});
+""")
+    values = {
+        'JAVA_CLASS': called_by_native.java_class_name or self.class_name,
+        'NAME': called_by_native.name,
+        'METHOD_ID_VAR_NAME': called_by_native.method_id_var_name,
+        'STATIC': 'Static' if called_by_native.static else '',
+        'JNI_SIGNATURE': JniSignature(called_by_native.params,
+                                      called_by_native.return_type)
+    }
+    return template.substitute(values)
+
+
+def GenerateJNIHeaders(input_files, output_files, use_javap, namespace):
+  for i in xrange(len(input_files)):
+    try:
+      if use_javap:
+        jni_from_javap = JNIFromJavaP.CreateFromClass(input_files[i], namespace)
+        output = jni_from_javap.GetContent()
+      else:
+        jni_from_java_source = JNIFromJavaSource.CreateFromFile(input_files[i])
+        output = jni_from_java_source.GetContent()
+    except ParseError, e:
+      print e
+      sys.exit(1)
+    if output_files:
+      header_name = output_files[i]
+      if not os.path.exists(os.path.dirname(os.path.abspath(header_name))):
+        os.makedirs(os.path.dirname(os.path.abspath(header_name)))
+      if (not os.path.exists(header_name) or
+          file(header_name).read() != output):
+        print 'Generating ', header_name
+        output_file = file(header_name, 'w')
+        output_file.write(output)
+        output_file.close()
+    else:
+      print output
+
+
+def CheckFilenames(input_files, output_files):
+  """Make sure the input and output have consistent names."""
+  if len(input_files) != len(output_files):
+    sys.exit('Input files length %d must match output length %d' %
+             (len(input_files), len(output_files)))
+  for i in xrange(len(input_files)):
+    input_prefix = os.path.splitext(os.path.basename(input_files[i]))[0]
+    output_prefix = os.path.splitext(os.path.basename(output_files[i]))[0]
+    if input_prefix.lower() + 'jni' != output_prefix.replace('_', '').lower():
+      sys.exit('\n'.join([
+          '*** Error ***',
+          'Input and output files have inconsistent names:',
+          '\t' + os.path.basename(input_files[i]),
+          '\t' + os.path.basename(output_files[i]),
+          '',
+          'Input "FooBar.java" must be converted to output "foo_bar_jni.h"',
+          '',
+      ]))
+
+
+def main(argv):
+  usage = """usage: %prog [OPTION] file1[ file2...] [output1[ output2...]]
+This script will parse the given java source code extracting the native
+declarations and print the header file to stdout (or a file).
+See SampleForTests.java for more details.
+  """
+  option_parser = optparse.OptionParser(usage=usage)
+  option_parser.add_option('-o', dest='output_files',
+                           action='store_true',
+                           default=False,
+                           help='Saves the output to file(s) (the first half of'
+                           ' args specify the java input files, the second'
+                           ' half specify the header output files.')
+  option_parser.add_option('-p', dest='javap_class',
+                           action='store_true',
+                           default=False,
+                           help='Uses javap to extract the methods from a'
+                           ' pre-compiled class. Input files should point'
+                           ' to pre-compiled Java .class files.')
+  option_parser.add_option('-n', dest='namespace',
+                           help='Uses as a namespace in the generated header,'
+                           ' instead of the javap class name.')
+  options, args = option_parser.parse_args(argv)
+  input_files = args[1:]
+  output_files = []
+  if options.output_files:
+    output_files = input_files[len(input_files) / 2:]
+    input_files = input_files[:len(input_files) / 2]
+  CheckFilenames(input_files, output_files)
+  GenerateJNIHeaders(input_files, output_files, options.javap_class,
+                     options.namespace)
+
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv))