extensions/common/features/feature.h

   1 // Copyright 2013 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_COMMON_FEATURES_FEATURE_H_
   6 #define EXTENSIONS_COMMON_FEATURES_FEATURE_H_
   7
   8 #include <set>
   9 #include <string>
  10
  11 #include "base/values.h"
  12 #include "extensions/common/manifest.h"
  13
  14 class GURL;
  15
  16 namespace extensions {
  17
  18 class Extension;
  19
  20 // Represents a single feature accessible to an extension developer, such as a
  21 // top-level manifest key, a permission, or a programmatic API. A feature can
  22 // express requirements for where it can be accessed, and supports testing
  23 // support for those requirements. If platforms are not specified, then feature
  24 // is available on all platforms.
  25 class Feature {
  26  public:
  27   // The JavaScript contexts the feature is supported in.
  28   enum Context {
  29     UNSPECIFIED_CONTEXT,
  30
  31     // A context in a privileged extension process.
  32     BLESSED_EXTENSION_CONTEXT,
  33
  34     // A context in an unprivileged extension process.
  35     UNBLESSED_EXTENSION_CONTEXT,
  36
  37     // A context from a content script.
  38     CONTENT_SCRIPT_CONTEXT,
  39
  40     // A normal web page. This should have an associated URL matching pattern.
  41     WEB_PAGE_CONTEXT,
  42   };
  43
  44   // The location required of extensions the feature is supported in.
  45   enum Location {
  46     UNSPECIFIED_LOCATION,
  47     COMPONENT_LOCATION
  48   };
  49
  50   // The platforms the feature is supported in.
  51   enum Platform {
  52     UNSPECIFIED_PLATFORM,
  53     CHROMEOS_PLATFORM,
  54     LINUX_PLATFORM,
  55     MACOSX_PLATFORM,
  56     WIN_PLATFORM
  57   };
  58
  59   // Whether a feature is available in a given situation or not, and if not,
  60   // why not.
  61   enum AvailabilityResult {
  62     IS_AVAILABLE,
  63     NOT_FOUND_IN_WHITELIST,
  64     INVALID_URL,
  65     INVALID_TYPE,
  66     INVALID_CONTEXT,
  67     INVALID_LOCATION,
  68     INVALID_PLATFORM,
  69     INVALID_MIN_MANIFEST_VERSION,
  70     INVALID_MAX_MANIFEST_VERSION,
  71     NOT_PRESENT,
  72     UNSUPPORTED_CHANNEL,
  73   };
  74
  75   // Container for AvailabiltyResult that also exposes a user-visible error
  76   // message in cases where the feature is not available.
  77   class Availability {
  78    public:
  79     AvailabilityResult result() const { return result_; }
  80     bool is_available() const { return result_ == IS_AVAILABLE; }
  81     const std::string& message() const { return message_; }
  82
  83    private:
  84     friend class SimpleFeature;
  85     friend class Feature;
  86
  87     // Instances should be created via Feature::CreateAvailability.
  88     Availability(AvailabilityResult result, const std::string& message)
  89         : result_(result), message_(message) { }
  90
  91     const AvailabilityResult result_;
  92     const std::string message_;
  93   };
  94
  95   Feature();
  96   virtual ~Feature();
  97
  98   // Used by ChromeV8Context until the feature system is fully functional.
  99   static Availability CreateAvailability(AvailabilityResult result,
 100                                          const std::string& message);
 101
 102   const std::string& name() const { return name_; }
 103   void set_name(const std::string& name) { name_ = name; }
 104   const std::set<std::string>& dependencies() { return dependencies_; }
 105   bool no_parent() const { return no_parent_; }
 106
 107   // Gets the platform the code is currently running on.
 108   static Platform GetCurrentPlatform();
 109
 110   // Gets the Feature::Location value for the specified Manifest::Location.
 111   static Location ConvertLocation(Manifest::Location extension_location);
 112
 113   virtual std::set<Context>* GetContexts() = 0;
 114
 115   // Tests whether this is an internal API or not.
 116   virtual bool IsInternal() const = 0;
 117
 118   // Returns true if the feature is available to be parsed into a new extension
 119   // manifest.
 120   Availability IsAvailableToManifest(const std::string& extension_id,
 121                                      Manifest::Type type,
 122                                      Location location,
 123                                      int manifest_version) const {
 124     return IsAvailableToManifest(extension_id, type, location, manifest_version,
 125                                  GetCurrentPlatform());
 126   }
 127   virtual Availability IsAvailableToManifest(const std::string& extension_id,
 128                                              Manifest::Type type,
 129                                              Location location,
 130                                              int manifest_version,
 131                                              Platform platform) const = 0;
 132
 133   // Returns true if the feature is available to be used in the specified
 134   // extension and context.
 135   Availability IsAvailableToContext(const Extension* extension,
 136                                     Context context,
 137                                     const GURL& url) const {
 138     return IsAvailableToContext(extension, context, url, GetCurrentPlatform());
 139   }
 140   virtual Availability IsAvailableToContext(const Extension* extension,
 141                                             Context context,
 142                                             const GURL& url,
 143                                             Platform platform) const = 0;
 144
 145   virtual std::string GetAvailabilityMessage(AvailabilityResult result,
 146                                              Manifest::Type type,
 147                                              const GURL& url,
 148                                              Context context) const = 0;
 149
 150   virtual bool IsIdInWhitelist(const std::string& extension_id) const = 0;
 151
 152  protected:
 153   std::string name_;
 154   std::set<std::string> dependencies_;
 155   bool no_parent_;
 156 };
 157
 158 }  // namespace extensions
 159
 160 #endif  // EXTENSIONS_COMMON_FEATURES_FEATURE_H_