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
20namespace extensions {
21
22class 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.
40class 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_
221