extensions/browser/extension_function_registry.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_BROWSER_EXTENSION_FUNCTION_REGISTRY_H_
   6 #define EXTENSIONS_BROWSER_EXTENSION_FUNCTION_REGISTRY_H_
   7
   8 #include <map>
   9 #include <string>
  10 #include <vector>
  11
  12 #include "extensions/browser/extension_function_histogram_value.h"
  13
  14 class ExtensionFunction;
  15
  16 // A factory function for creating new ExtensionFunction instances.
  17 typedef ExtensionFunction* (*ExtensionFunctionFactory)();
  18
  19 // Template for defining ExtensionFunctionFactory.
  20 template <class T>
  21 ExtensionFunction* NewExtensionFunction() {
  22   return new T();
  23 }
  24
  25 // Contains a list of all known extension functions and allows clients to
  26 // create instances of them.
  27 class ExtensionFunctionRegistry {
  28  public:
  29   static ExtensionFunctionRegistry* GetInstance();
  30   explicit ExtensionFunctionRegistry();
  31   virtual ~ExtensionFunctionRegistry();
  32
  33   // Allows overriding of specific functions (e.g. for testing).  Functions
  34   // must be previously registered.  Returns true if successful.
  35   bool OverrideFunction(const std::string& name,
  36                         ExtensionFunctionFactory factory);
  37
  38   // Factory method for the ExtensionFunction registered as 'name'.
  39   ExtensionFunction* NewFunction(const std::string& name);
  40
  41   template <class T>
  42   void RegisterFunction() {
  43     ExtensionFunctionFactory factory = &NewExtensionFunction<T>;
  44     factories_[T::function_name()] =
  45         FactoryEntry(factory, T::function_name(), T::histogram_value());
  46   }
  47
  48   struct FactoryEntry {
  49    public:
  50     explicit FactoryEntry();
  51     explicit FactoryEntry(
  52         ExtensionFunctionFactory factory,
  53         const char* function_name,
  54         extensions::functions::HistogramValue histogram_value);
  55
  56     ExtensionFunctionFactory factory_;
  57     const char* function_name_;
  58     extensions::functions::HistogramValue histogram_value_;
  59   };
  60
  61   typedef std::map<std::string, FactoryEntry> FactoryMap;
  62   FactoryMap factories_;
  63 };
  64
  65 #endif  // EXTENSIONS_BROWSER_EXTENSION_FUNCTION_REGISTRY_H_