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 "gin/modules/module_registry_observer.h"
19#include "v8/include/v8.h"
20
21namespace extensions {
22
23class ScriptContext;
24
25// A module system for JS similar to node.js' require() function.
26// Each module has three variables in the global scope:
27//   - exports, an object returned to dependencies who require() this
28//     module.
29//   - require, a function that takes a module name as an argument and returns
30//     that module's exports object.
31//   - requireNative, a function that takes the name of a registered
32//     NativeHandler and returns an object that contains the functions the
33//     NativeHandler defines.
34//
35// Each module in a ModuleSystem is executed at most once and its exports
36// object cached.
37//
38// Note that a ModuleSystem must be used only in conjunction with a single
39// v8::Context.
40// TODO(koz): Rename this to JavaScriptModuleSystem.
41class ModuleSystem : public ObjectBackedNativeHandler,
42                     public gin::ModuleRegistryObserver {
43 public:
44  class SourceMap {
45   public:
46    virtual ~SourceMap() {}
47    virtual v8::Handle<v8::Value> GetSource(v8::Isolate* isolate,
48                                            const std::string& name) = 0;
49    virtual bool Contains(const std::string& name) = 0;
50  };
51
52  class ExceptionHandler {
53   public:
54    virtual ~ExceptionHandler() {}
55    virtual void HandleUncaughtException(const v8::TryCatch& try_catch) = 0;
56
57   protected:
58    // Formats |try_catch| as a nice string.
59    std::string CreateExceptionString(const v8::TryCatch& try_catch);
60  };
61
62  // Enables native bindings for the duration of its lifetime.
63  class NativesEnabledScope {
64   public:
65    explicit NativesEnabledScope(ModuleSystem* module_system);
66    ~NativesEnabledScope();
67
68   private:
69    ModuleSystem* module_system_;
70    DISALLOW_COPY_AND_ASSIGN(NativesEnabledScope);
71  };
72
73  // |source_map| is a weak pointer.
74  ModuleSystem(ScriptContext* context, SourceMap* source_map);
75  virtual ~ModuleSystem();
76
77  // Require the specified module. This is the equivalent of calling
78  // require('module_name') from the loaded JS files.
79  v8::Handle<v8::Value> Require(const std::string& module_name);
80  void Require(const v8::FunctionCallbackInfo<v8::Value>& args);
81
82  // Run |code| in the current context with the name |name| used for stack
83  // traces.
84  v8::Handle<v8::Value> RunString(v8::Handle<v8::String> code,
85                                  v8::Handle<v8::String> name);
86
87  // Calls the specified method exported by the specified module. This is
88  // equivalent to calling require('module_name').method_name() from JS.
89  v8::Local<v8::Value> CallModuleMethod(const std::string& module_name,
90                                        const std::string& method_name);
91  v8::Local<v8::Value> CallModuleMethod(
92      const std::string& module_name,
93      const std::string& method_name,
94      std::vector<v8::Handle<v8::Value> >* args);
95  v8::Local<v8::Value> CallModuleMethod(const std::string& module_name,
96                                        const std::string& method_name,
97                                        int argc,
98                                        v8::Handle<v8::Value> argv[]);
99
100  // Register |native_handler| as a potential target for requireNative(), so
101  // calls to requireNative(|name|) from JS will return a new object created by
102  // |native_handler|.
103  void RegisterNativeHandler(const std::string& name,
104                             scoped_ptr<NativeHandler> native_handler);
105
106  // Causes requireNative(|name|) to look for its module in |source_map_|
107  // instead of using a registered native handler. This can be used in unit
108  // tests to mock out native modules.
109  void OverrideNativeHandlerForTest(const std::string& name);
110
111  // Executes |code| in the current context with |name| as the filename.
112  void RunString(const std::string& code, const std::string& name);
113
114  // Make |object|.|field| lazily evaluate to the result of
115  // require(|module_name|)[|module_field|].
116  //
117  // TODO(kalman): All targets for this method are ObjectBackedNativeHandlers,
118  //               move this logic into those classes (in fact, the chrome
119  //               object is the only client, only that needs to implement it).
120  void SetLazyField(v8::Handle<v8::Object> object,
121                    const std::string& field,
122                    const std::string& module_name,
123                    const std::string& module_field);
124
125  void SetLazyField(v8::Handle<v8::Object> object,
126                    const std::string& field,
127                    const std::string& module_name,
128                    const std::string& module_field,
129                    v8::AccessorGetterCallback getter);
130
131  // Make |object|.|field| lazily evaluate to the result of
132  // requireNative(|module_name|)[|module_field|].
133  // TODO(kalman): Same as above.
134  void SetNativeLazyField(v8::Handle<v8::Object> object,
135                          const std::string& field,
136                          const std::string& module_name,
137                          const std::string& module_field);
138
139  // Passes exceptions to |handler| rather than console::Fatal.
140  void SetExceptionHandlerForTest(scoped_ptr<ExceptionHandler> handler) {
141    exception_handler_ = handler.Pass();
142  }
143
144 protected:
145  friend class ScriptContext;
146  virtual void Invalidate() OVERRIDE;
147
148 private:
149  typedef std::map<std::string, linked_ptr<NativeHandler> > NativeHandlerMap;
150
151  // Retrieves the lazily defined field specified by |property|.
152  static void LazyFieldGetter(v8::Local<v8::String> property,
153                              const v8::PropertyCallbackInfo<v8::Value>& info);
154  // Retrieves the lazily defined field specified by |property| on a native
155  // object.
156  static void NativeLazyFieldGetter(
157      v8::Local<v8::String> property,
158      const v8::PropertyCallbackInfo<v8::Value>& info);
159
160  // Called when an exception is thrown but not caught.
161  void HandleException(const v8::TryCatch& try_catch);
162
163  void RequireForJs(const v8::FunctionCallbackInfo<v8::Value>& args);
164  v8::Local<v8::Value> RequireForJsInner(v8::Handle<v8::String> module_name);
165
166  typedef v8::Handle<v8::Value>(ModuleSystem::*RequireFunction)(
167      const std::string&);
168  // Base implementation of a LazyFieldGetter which uses |require_fn| to require
169  // modules.
170  static void LazyFieldGetterInner(
171      v8::Local<v8::String> property,
172      const v8::PropertyCallbackInfo<v8::Value>& info,
173      RequireFunction require_function);
174
175  // Return the named source file stored in the source map.
176  // |args[0]| - the name of a source file in source_map_.
177  v8::Handle<v8::Value> GetSource(const std::string& module_name);
178
179  // Return an object that contains the native methods defined by the named
180  // NativeHandler.
181  // |args[0]| - the name of a native handler object.
182  v8::Handle<v8::Value> RequireNativeFromString(const std::string& native_name);
183  void RequireNative(const v8::FunctionCallbackInfo<v8::Value>& args);
184
185  // Return a promise for a requested module.
186  // |args[0]| - the name of a module.
187  void RequireAsync(const v8::FunctionCallbackInfo<v8::Value>& args);
188
189  // Wraps |source| in a (function(define, require, requireNative, ...) {...}).
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  // Loads and runs a Javascript module.
196  v8::Handle<v8::Value> LoadModule(const std::string& module_name);
197
198  // Invoked when a module is loaded in response to a requireAsync call.
199  // Resolves |resolver| with |value|.
200  void OnModuleLoaded(
201      scoped_ptr<v8::UniquePersistent<v8::Promise::Resolver> > resolver,
202      v8::Handle<v8::Value> value);
203
204  // gin::ModuleRegistryObserver overrides.
205  virtual void OnDidAddPendingModule(
206      const std::string& id,
207      const std::vector<std::string>& dependencies) OVERRIDE;
208
209  ScriptContext* context_;
210
211  // A map from module names to the JS source for that module. GetSource()
212  // performs a lookup on this map.
213  SourceMap* source_map_;
214
215  // A map from native handler names to native handlers.
216  NativeHandlerMap native_handler_map_;
217
218  // When 0, natives are disabled, otherwise indicates how many callers have
219  // pinned natives as enabled.
220  int natives_enabled_;
221
222  // Called when an exception is thrown but not caught in JS. Overridable by
223  // tests.
224  scoped_ptr<ExceptionHandler> exception_handler_;
225
226  std::set<std::string> overridden_native_handlers_;
227
228  base::WeakPtrFactory<ModuleSystem> weak_factory_;
229
230  DISALLOW_COPY_AND_ASSIGN(ModuleSystem);
231};
232
233}  // namespace extensions
234
235#endif  // EXTENSIONS_RENDERER_MODULE_SYSTEM_H_
236