Lazy load chrome.* APIs

chrome/renderer/extensions/module_system.h

 // 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.
 
 #ifndef CHROME_RENDERER_EXTENSIONS_MODULE_SYSTEM_H_
 #define CHROME_RENDERER_EXTENSIONS_MODULE_SYSTEM_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/scoped_ptr.h"
-#include "chrome/renderer/extensions/native_handler.h"
-#include "chrome/renderer/extensions/scoped_persistent.h"
+#include "chrome/renderer/extensions/object_backed_native_handler.h"
 #include "v8/include/v8.h"
 
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 namespace extensions {
 
 // A module system for JS similar to node.js' require() function.
 // Each module has three variables in the global scope:
 //   - exports, an object returned to dependencies who require() this
 //     module.
 //   - require, a function that takes a module name as an argument and returns
 //     that module's exports object.
 //   - requireNative, a function that takes the name of a registered
 //     NativeHandler and returns an object that contains the functions the
 //     NativeHandler defines.
 //
 // Each module in a ModuleSystem is executed at most once and its exports
 // object cached.
 //
 // Note that a ModuleSystem must be used only in conjunction with a single
 // v8::Context.
 // TODO(koz): Rename this to JavaScriptModuleSystem.
-class ModuleSystem : public NativeHandler {
+class ModuleSystem : public ObjectBackedNativeHandler {
  public:
   class SourceMap {
    public:
     virtual ~SourceMap() {}
     virtual v8::Handle<v8::Value> GetSource(const std::string& name) = 0;
     virtual bool Contains(const std::string& name) = 0;
   };
 
   class ExceptionHandler {
    public:
     virtual ~ExceptionHandler() {}
     virtual void HandleUncaughtException() = 0;
   };
 
   // Enables native bindings for the duration of its lifetime.
   class NativesEnabledScope {
    public:
     explicit NativesEnabledScope(ModuleSystem* module_system);
     ~NativesEnabledScope();
 
    private:
     ModuleSystem* module_system_;
     DISALLOW_COPY_AND_ASSIGN(NativesEnabledScope);
   };
 
   // |source_map| is a weak pointer.
-  explicit ModuleSystem(v8::Handle<v8::Context> context, SourceMap* source_map);
+  ModuleSystem(v8::Handle<v8::Context> context, SourceMap* source_map);
   virtual ~ModuleSystem();
 
-  // Returns true if the current context has a ModuleSystem installed in it.
-  static bool IsPresentInCurrentContext();
-
   // Dumps the debug info from |try_catch| to LOG(ERROR).
   static void DumpException(const v8::TryCatch& try_catch);
 
   // Require the specified module. This is the equivalent of calling
   // require('module_name') from the loaded JS files.
-  void Require(const std::string& module_name);
+  v8::Handle<v8::Value> Require(const std::string& module_name);
   v8::Handle<v8::Value> Require(const v8::Arguments& args);
-  v8::Handle<v8::Value> RequireForJs(const v8::Arguments& args);
-  v8::Handle<v8::Value> RequireForJsInner(v8::Handle<v8::String> module_name);
 
   // Calls the specified method exported by the specified module. This is
   // equivalent to calling require('module_name').method_name() from JS.
-  void CallModuleMethod(const std::string& module_name,
-                        const std::string& method_name);
+  v8::Local<v8::Value> CallModuleMethod(const std::string& module_name,
+                                        const std::string& method_name);
 
   // Calls the specified method exported by the specified module. This is
   // equivalent to calling require('module_name').method_name(args) from JS.
   v8::Local<v8::Value> CallModuleMethod(
       const std::string& module_name,
       const std::string& method_name,
       std::vector<v8::Handle<v8::Value> >* args);
 
   // Register |native_handler| as a potential target for requireNative(), so
   // calls to requireNative(|name|) from JS will return a new object created by
   // |native_handler|.
   void RegisterNativeHandler(const std::string& name,
                              scoped_ptr<NativeHandler> native_handler);
+  // Check if a native handler has been registered for this |name|.
+  bool HasNativeHandler(const std::string& name);
 
   // Causes requireNative(|name|) to look for its module in |source_map_|
   // instead of using a registered native handler. This can be used in unit
   // tests to mock out native modules.
   void OverrideNativeHandler(const std::string& name);
 
   // Executes |code| in the current context with |name| as the filename.
   void RunString(const std::string& code, const std::string& name);
 
   // Retrieves the lazily defined field specified by |property|.
   static v8::Handle<v8::Value> LazyFieldGetter(v8::Local<v8::String> property,
                                                const v8::AccessorInfo& info);
+  // Retrieves the lazily defined field specified by |property| on a native
+  // object.
+  static v8::Handle<v8::Value> NativeLazyFieldGetter(
+      v8::Local<v8::String> property,
+      const v8::AccessorInfo& info);
 
   // Make |object|.|field| lazily evaluate to the result of
   // require(|module_name|)[|module_field|].
   void SetLazyField(v8::Handle<v8::Object> object,
                     const std::string& field,
                     const std::string& module_name,
                     const std::string& module_field);
 
+  // Make |object|.|field| lazily evaluate to the result of
+  // requireNative(|module_name|)[|module_field|].
+  void SetNativeLazyField(v8::Handle<v8::Object> object,
+                          const std::string& field,
+                          const std::string& module_name,
+                          const std::string& module_field);
+
   void set_exception_handler(scoped_ptr<ExceptionHandler> handler) {
     exception_handler_ = handler.Pass();
   }
 
+ protected:
+  friend class ChromeV8Context;
+  virtual void Invalidate() OVERRIDE;
+
  private:
   typedef std::map<std::string, linked_ptr<NativeHandler> > NativeHandlerMap;
 
   // Called when an exception is thrown but not caught.
   void HandleException(const v8::TryCatch& try_catch);
 
+  static std::string CreateExceptionString(const v8::TryCatch& try_catch);
+
   // Ensure that require_ has been evaluated from require.js.
   void EnsureRequireLoaded();
 
   // Run |code| in the current context with the name |name| used for stack
   // traces.
   v8::Handle<v8::Value> RunString(v8::Handle<v8::String> code,
                                   v8::Handle<v8::String> name);
 
+  v8::Handle<v8::Value> RequireForJs(const v8::Arguments& args);
+  v8::Handle<v8::Value> RequireForJsInner(v8::Handle<v8::String> module_name);
+
+  // Sets a lazy field using the specified |getter|.
+  void SetLazyField(v8::Handle<v8::Object> object,
+                    const std::string& field,
+                    const std::string& module_name,
+                    const std::string& module_field,
+                    v8::AccessorGetter getter);
+
+  typedef v8::Handle<v8::Value> (ModuleSystem::*RequireFunction)(
+      const std::string&);
+  // Base implementation of a LazyFieldGetter which uses |require_fn| to require
+  // modules.
+  static v8::Handle<v8::Value> LazyFieldGetterInner(
+      v8::Local<v8::String> property,
+      const v8::AccessorInfo& info,
+      RequireFunction require_function);
+
   // Return the named source file stored in the source map.
   // |args[0]| - the name of a source file in source_map_.
   v8::Handle<v8::Value> GetSource(v8::Handle<v8::String> source_name);
 
   // Return an object that contains the native methods defined by the named
   // NativeHandler.
   // |args[0]| - the name of a native handler object.
-  v8::Handle<v8::Value> GetNative(const v8::Arguments& args);
+  v8::Handle<v8::Value> RequireNativeFromString(const std::string& native_name);
+  v8::Handle<v8::Value> RequireNative(const v8::Arguments& args);
 
   // Wraps |source| in a (function(require, requireNative, exports) {...}).
   v8::Handle<v8::String> WrapSource(v8::Handle<v8::String> source);
 
   // Throws an exception in the calling JS context.
   v8::Handle<v8::Value> ThrowException(const std::string& message);
 
-  // The context that this ModuleSystem is for.
-  ScopedPersistent<v8::Context> context_;
-
   // A map from module names to the JS source for that module. GetSource()
   // performs a lookup on this map.
   SourceMap* source_map_;
 
   // A map from native handler names to native handlers.
   NativeHandlerMap native_handler_map_;
 
   // When 0, natives are disabled, otherwise indicates how many callers have
   // pinned natives as enabled.
   int natives_enabled_;
 
   // Called when an exception is thrown but not caught in JS.
   scoped_ptr<ExceptionHandler> exception_handler_;
 
   std::set<std::string> overridden_native_handlers_;
 
   DISALLOW_COPY_AND_ASSIGN(ModuleSystem);
 };
 
 }  // extensions
 
 #endif  // CHROME_RENDERER_EXTENSIONS_MODULE_SYSTEM_H_