chrome/renderer/extensions/module_system.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_RENDERER_EXTENSIONS_MODULE_SYSTEM_H_
   6 #define CHROME_RENDERER_EXTENSIONS_MODULE_SYSTEM_H_
   7
   8 #include "base/compiler_specific.h"
   9 #include "base/memory/linked_ptr.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "chrome/renderer/extensions/native_handler.h"
  12 #include "chrome/renderer/extensions/object_backed_native_handler.h"
  13 #include "v8/include/v8.h"
  14
  15 #include <map>
  16 #include <set>
  17 #include <string>
  18 #include <vector>
  19
  20 namespace extensions {
  21
  22 class ChromeV8Context;
  23
  24 // A module system for JS similar to node.js' require() function.
  25 // Each module has three variables in the global scope:
  26 //   - exports, an object returned to dependencies who require() this
  27 //     module.
  28 //   - require, a function that takes a module name as an argument and returns
  29 //     that module's exports object.
  30 //   - requireNative, a function that takes the name of a registered
  31 //     NativeHandler and returns an object that contains the functions the
  32 //     NativeHandler defines.
  33 //
  34 // Each module in a ModuleSystem is executed at most once and its exports
  35 // object cached.
  36 //
  37 // Note that a ModuleSystem must be used only in conjunction with a single
  38 // v8::Context.
  39 // TODO(koz): Rename this to JavaScriptModuleSystem.
  40 class ModuleSystem : public ObjectBackedNativeHandler {
  41  public:
  42   class SourceMap {
  43    public:
  44     virtual ~SourceMap() {}
  45     virtual v8::Handle<v8::Value> GetSource(v8::Isolate* isolate,
  46                                             const std::string& name) = 0;
  47     virtual bool Contains(const std::string& name) = 0;
  48   };
  49
  50   class ExceptionHandler {
  51    public:
  52     virtual ~ExceptionHandler() {}
  53     virtual void HandleUncaughtException(const v8::TryCatch& try_catch) = 0;
  54
  55    protected:
  56     // Formats |try_catch| as a nice string.
  57     std::string CreateExceptionString(const v8::TryCatch& try_catch);
  58   };
  59
  60   // Enables native bindings for the duration of its lifetime.
  61   class NativesEnabledScope {
  62    public:
  63     explicit NativesEnabledScope(ModuleSystem* module_system);
  64     ~NativesEnabledScope();
  65
  66    private:
  67     ModuleSystem* module_system_;
  68     DISALLOW_COPY_AND_ASSIGN(NativesEnabledScope);
  69   };
  70
  71   // |source_map| is a weak pointer.
  72   ModuleSystem(ChromeV8Context* context, SourceMap* source_map);
  73   virtual ~ModuleSystem();
  74
  75   // Require the specified module. This is the equivalent of calling
  76   // require('module_name') from the loaded JS files.
  77   v8::Handle<v8::Value> Require(const std::string& module_name);
  78   void Require(const v8::FunctionCallbackInfo<v8::Value>& args);
  79
  80   // Calls the specified method exported by the specified module. This is
  81   // equivalent to calling require('module_name').method_name() from JS.
  82   v8::Local<v8::Value> CallModuleMethod(const std::string& module_name,
  83                                         const std::string& method_name);
  84   v8::Local<v8::Value> CallModuleMethod(
  85       const std::string& module_name,
  86       const std::string& method_name,
  87       std::vector<v8::Handle<v8::Value> >* args);
  88   v8::Local<v8::Value> CallModuleMethod(
  89       const std::string& module_name,
  90       const std::string& method_name,
  91       int argc,
  92       v8::Handle<v8::Value> argv[]);
  93
  94   // Register |native_handler| as a potential target for requireNative(), so
  95   // calls to requireNative(|name|) from JS will return a new object created by
  96   // |native_handler|.
  97   void RegisterNativeHandler(const std::string& name,
  98                              scoped_ptr<NativeHandler> native_handler);
  99
 100   // Causes requireNative(|name|) to look for its module in |source_map_|
 101   // instead of using a registered native handler. This can be used in unit
 102   // tests to mock out native modules.
 103   void OverrideNativeHandlerForTest(const std::string& name);
 104
 105   // Executes |code| in the current context with |name| as the filename.
 106   void RunString(const std::string& code, const std::string& name);
 107
 108   // Make |object|.|field| lazily evaluate to the result of
 109   // require(|module_name|)[|module_field|].
 110   //
 111   // TODO(kalman): All targets for this method are ObjectBackedNativeHandlers,
 112   //               move this logic into those classes (in fact, the chrome
 113   //               object is the only client, only that needs to implement it).
 114   void SetLazyField(v8::Handle<v8::Object> object,
 115                     const std::string& field,
 116                     const std::string& module_name,
 117                     const std::string& module_field);
 118
 119   void SetLazyField(v8::Handle<v8::Object> object,
 120                     const std::string& field,
 121                     const std::string& module_name,
 122                     const std::string& module_field,
 123                     v8::AccessorGetterCallback getter);
 124
 125   // Make |object|.|field| lazily evaluate to the result of
 126   // requireNative(|module_name|)[|module_field|].
 127   // TODO(kalman): Same as above.
 128   void SetNativeLazyField(v8::Handle<v8::Object> object,
 129                           const std::string& field,
 130                           const std::string& module_name,
 131                           const std::string& module_field);
 132
 133   // Passes exceptions to |handler| rather than console::Fatal.
 134   void SetExceptionHandlerForTest(scoped_ptr<ExceptionHandler> handler) {
 135     exception_handler_ = handler.Pass();
 136   }
 137
 138   v8::Isolate* GetIsolate() const;
 139
 140  protected:
 141   friend class ChromeV8Context;
 142   virtual void Invalidate() OVERRIDE;
 143
 144  private:
 145   typedef std::map<std::string, linked_ptr<NativeHandler> > NativeHandlerMap;
 146
 147   // Retrieves the lazily defined field specified by |property|.
 148   static void LazyFieldGetter(v8::Local<v8::String> property,
 149                               const v8::PropertyCallbackInfo<v8::Value>& info);
 150   // Retrieves the lazily defined field specified by |property| on a native
 151   // object.
 152   static void NativeLazyFieldGetter(
 153       v8::Local<v8::String> property,
 154       const v8::PropertyCallbackInfo<v8::Value>& info);
 155
 156   // Called when an exception is thrown but not caught.
 157   void HandleException(const v8::TryCatch& try_catch);
 158
 159   // Ensure that require_ has been evaluated from require.js.
 160   void EnsureRequireLoaded();
 161
 162   // Run |code| in the current context with the name |name| used for stack
 163   // traces.
 164   v8::Handle<v8::Value> RunString(v8::Handle<v8::String> code,
 165                                   v8::Handle<v8::String> name);
 166
 167   void RequireForJs(const v8::FunctionCallbackInfo<v8::Value>& args);
 168   v8::Local<v8::Value> RequireForJsInner(v8::Handle<v8::String> module_name);
 169
 170   typedef v8::Handle<v8::Value> (ModuleSystem::*RequireFunction)(
 171       const std::string&);
 172   // Base implementation of a LazyFieldGetter which uses |require_fn| to require
 173   // modules.
 174   static void LazyFieldGetterInner(
 175       v8::Local<v8::String> property,
 176       const v8::PropertyCallbackInfo<v8::Value>& info,
 177       RequireFunction require_function);
 178
 179   // Return the named source file stored in the source map.
 180   // |args[0]| - the name of a source file in source_map_.
 181   v8::Handle<v8::Value> GetSource(const std::string& module_name);
 182
 183   // Return an object that contains the native methods defined by the named
 184   // NativeHandler.
 185   // |args[0]| - the name of a native handler object.
 186   v8::Handle<v8::Value> RequireNativeFromString(const std::string& native_name);
 187   void RequireNative(const v8::FunctionCallbackInfo<v8::Value>& args);
 188
 189   // Wraps |source| in a (function(require, requireNative, exports) {...}).
 190   v8::Handle<v8::String> WrapSource(v8::Handle<v8::String> source);
 191
 192   // NativeHandler implementation which returns the private area of an Object.
 193   void Private(const v8::FunctionCallbackInfo<v8::Value>& args);
 194
 195   ChromeV8Context* context_;
 196
 197   // A map from module names to the JS source for that module. GetSource()
 198   // performs a lookup on this map.
 199   SourceMap* source_map_;
 200
 201   // A map from native handler names to native handlers.
 202   NativeHandlerMap native_handler_map_;
 203
 204   // When 0, natives are disabled, otherwise indicates how many callers have
 205   // pinned natives as enabled.
 206   int natives_enabled_;
 207
 208   // Called when an exception is thrown but not caught in JS. Overridable by
 209   // tests.
 210   scoped_ptr<ExceptionHandler> exception_handler_;
 211
 212   std::set<std::string> overridden_native_handlers_;
 213
 214   DISALLOW_COPY_AND_ASSIGN(ModuleSystem);
 215 };
 216
 217 }  // namespace extensions
 218
 219 #endif  // CHROME_RENDERER_EXTENSIONS_MODULE_SYSTEM_H_