extensions/renderer/module_system.h

   1 // Copyright 2014 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 EXTENSIONS_RENDERER_MODULE_SYSTEM_H_
   6 #define EXTENSIONS_RENDERER_MODULE_SYSTEM_H_
   7
   8 #include <map>
   9 #include <set>
  10 #include <string>
  11 #include <vector>
  12
  13 #include "base/compiler_specific.h"
  14 #include "base/memory/linked_ptr.h"
  15 #include "base/memory/scoped_ptr.h"
  16 #include "extensions/renderer/native_handler.h"
  17 #include "extensions/renderer/object_backed_native_handler.h"
  18 #include "v8/include/v8.h"
  19
  20 namespace extensions {
  21
  22 class ScriptContext;
  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(ScriptContext* 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   // Run |code| in the current context with the name |name| used for stack
  81   // traces.
  82   v8::Handle<v8::Value> RunString(v8::Handle<v8::String> code,
  83                                   v8::Handle<v8::String> name);
  84
  85   // Calls the specified method exported by the specified module. This is
  86   // equivalent to calling require('module_name').method_name() from JS.
  87   v8::Local<v8::Value> CallModuleMethod(const std::string& module_name,
  88                                         const std::string& method_name);
  89   v8::Local<v8::Value> CallModuleMethod(
  90       const std::string& module_name,
  91       const std::string& method_name,
  92       std::vector<v8::Handle<v8::Value> >* args);
  93   v8::Local<v8::Value> CallModuleMethod(const std::string& module_name,
  94                                         const std::string& method_name,
  95                                         int argc,
  96                                         v8::Handle<v8::Value> argv[]);
  97
  98   // Register |native_handler| as a potential target for requireNative(), so
  99   // calls to requireNative(|name|) from JS will return a new object created by
 100   // |native_handler|.
 101   void RegisterNativeHandler(const std::string& name,
 102                              scoped_ptr<NativeHandler> native_handler);
 103
 104   // Causes requireNative(|name|) to look for its module in |source_map_|
 105   // instead of using a registered native handler. This can be used in unit
 106   // tests to mock out native modules.
 107   void OverrideNativeHandlerForTest(const std::string& name);
 108
 109   // Executes |code| in the current context with |name| as the filename.
 110   void RunString(const std::string& code, const std::string& name);
 111
 112   // Make |object|.|field| lazily evaluate to the result of
 113   // require(|module_name|)[|module_field|].
 114   //
 115   // TODO(kalman): All targets for this method are ObjectBackedNativeHandlers,
 116   //               move this logic into those classes (in fact, the chrome
 117   //               object is the only client, only that needs to implement it).
 118   void SetLazyField(v8::Handle<v8::Object> object,
 119                     const std::string& field,
 120                     const std::string& module_name,
 121                     const std::string& module_field);
 122
 123   void SetLazyField(v8::Handle<v8::Object> object,
 124                     const std::string& field,
 125                     const std::string& module_name,
 126                     const std::string& module_field,
 127                     v8::AccessorGetterCallback getter);
 128
 129   // Make |object|.|field| lazily evaluate to the result of
 130   // requireNative(|module_name|)[|module_field|].
 131   // TODO(kalman): Same as above.
 132   void SetNativeLazyField(v8::Handle<v8::Object> object,
 133                           const std::string& field,
 134                           const std::string& module_name,
 135                           const std::string& module_field);
 136
 137   // Passes exceptions to |handler| rather than console::Fatal.
 138   void SetExceptionHandlerForTest(scoped_ptr<ExceptionHandler> handler) {
 139     exception_handler_ = handler.Pass();
 140   }
 141
 142  protected:
 143   friend class ScriptContext;
 144   virtual void Invalidate() OVERRIDE;
 145
 146  private:
 147   typedef std::map<std::string, linked_ptr<NativeHandler> > NativeHandlerMap;
 148
 149   // Retrieves the lazily defined field specified by |property|.
 150   static void LazyFieldGetter(v8::Local<v8::String> property,
 151                               const v8::PropertyCallbackInfo<v8::Value>& info);
 152   // Retrieves the lazily defined field specified by |property| on a native
 153   // object.
 154   static void NativeLazyFieldGetter(
 155       v8::Local<v8::String> property,
 156       const v8::PropertyCallbackInfo<v8::Value>& info);
 157
 158   // Called when an exception is thrown but not caught.
 159   void HandleException(const v8::TryCatch& try_catch);
 160
 161   // Ensure that require_ has been evaluated from require.js.
 162   void EnsureRequireLoaded();
 163
 164   void RequireForJs(const v8::FunctionCallbackInfo<v8::Value>& args);
 165   v8::Local<v8::Value> RequireForJsInner(v8::Handle<v8::String> module_name);
 166
 167   typedef v8::Handle<v8::Value>(ModuleSystem::*RequireFunction)(
 168       const std::string&);
 169   // Base implementation of a LazyFieldGetter which uses |require_fn| to require
 170   // modules.
 171   static void LazyFieldGetterInner(
 172       v8::Local<v8::String> property,
 173       const v8::PropertyCallbackInfo<v8::Value>& info,
 174       RequireFunction require_function);
 175
 176   // Return the named source file stored in the source map.
 177   // |args[0]| - the name of a source file in source_map_.
 178   v8::Handle<v8::Value> GetSource(const std::string& module_name);
 179
 180   // Return an object that contains the native methods defined by the named
 181   // NativeHandler.
 182   // |args[0]| - the name of a native handler object.
 183   v8::Handle<v8::Value> RequireNativeFromString(const std::string& native_name);
 184   void RequireNative(const v8::FunctionCallbackInfo<v8::Value>& args);
 185
 186   // Wraps |source| in a (function(require, requireNative, exports) {...}).
 187   v8::Handle<v8::String> WrapSource(v8::Handle<v8::String> source);
 188
 189   // NativeHandler implementation which returns the private area of an Object.
 190   void Private(const v8::FunctionCallbackInfo<v8::Value>& args);
 191
 192   // NativeHandler implementation which returns a function wrapper for a
 193   // provided function.
 194   void CreateFunctionWrapper(const v8::FunctionCallbackInfo<v8::Value>& args);
 195
 196   ScriptContext* context_;
 197
 198   // A map from module names to the JS source for that module. GetSource()
 199   // performs a lookup on this map.
 200   SourceMap* source_map_;
 201
 202   // A map from native handler names to native handlers.
 203   NativeHandlerMap native_handler_map_;
 204
 205   // When 0, natives are disabled, otherwise indicates how many callers have
 206   // pinned natives as enabled.
 207   int natives_enabled_;
 208
 209   // Called when an exception is thrown but not caught in JS. Overridable by
 210   // tests.
 211   scoped_ptr<ExceptionHandler> exception_handler_;
 212
 213   std::set<std::string> overridden_native_handlers_;
 214
 215   DISALLOW_COPY_AND_ASSIGN(ModuleSystem);
 216 };
 217
 218 }  // namespace extensions
 219
 220 #endif  // EXTENSIONS_RENDERER_MODULE_SYSTEM_H_