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     // A web page context which has been blessed by the user. Typically this
  44     // will be via the installation of a hosted app, so this may host an
  45     // extension. This is not affected by the URL matching pattern.
  46     BLESSED_WEB_PAGE_CONTEXT,
  47
  48     // A page within webui.
  49     WEBUI_CONTEXT,
  50   };
  51
  52   // The platforms the feature is supported in.
  53   enum Platform {
  54     UNSPECIFIED_PLATFORM,
  55     CHROMEOS_PLATFORM,
  56     LINUX_PLATFORM,
  57     MACOSX_PLATFORM,
  58     WIN_PLATFORM
  59   };
  60
  61   // Whether a feature is available in a given situation or not, and if not,
  62   // why not.
  63   enum AvailabilityResult {
  64     IS_AVAILABLE,
  65     NOT_FOUND_IN_WHITELIST,
  66     INVALID_URL,
  67     INVALID_TYPE,
  68     INVALID_CONTEXT,
  69     INVALID_LOCATION,
  70     INVALID_PLATFORM,
  71     INVALID_MIN_MANIFEST_VERSION,
  72     INVALID_MAX_MANIFEST_VERSION,
  73     NOT_PRESENT,
  74     UNSUPPORTED_CHANNEL,
  75     FOUND_IN_BLACKLIST,
  76     MISSING_COMMAND_LINE_SWITCH,
  77   };
  78
  79   // Container for AvailabiltyResult that also exposes a user-visible error
  80   // message in cases where the feature is not available.
  81   class Availability {
  82    public:
  83     AvailabilityResult result() const { return result_; }
  84     bool is_available() const { return result_ == IS_AVAILABLE; }
  85     const std::string& message() const { return message_; }
  86
  87    private:
  88     friend class SimpleFeature;
  89     friend class Feature;
  90
  91     // Instances should be created via Feature::CreateAvailability.
  92     Availability(AvailabilityResult result, const std::string& message)
  93         : result_(result), message_(message) { }
  94
  95     const AvailabilityResult result_;
  96     const std::string message_;
  97   };
  98
  99   Feature();
 100   virtual ~Feature();
 101
 102   // Used by ChromeV8Context until the feature system is fully functional.
 103   // TODO(kalman): This is no longer used by ChromeV8Context, so what is the
 104   // comment trying to say?
 105   static Availability CreateAvailability(AvailabilityResult result,
 106                                          const std::string& message);
 107
 108   const std::string& name() const { return name_; }
 109   void set_name(const std::string& name) { name_ = name; }
 110   bool no_parent() const { return no_parent_; }
 111
 112   // Gets the platform the code is currently running on.
 113   static Platform GetCurrentPlatform();
 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                                      Manifest::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                                              Manifest::Location location,
 130                                              int manifest_version,
 131                                              Platform platform) const = 0;
 132
 133   // Returns true if the feature is available to |extension|.
 134   Availability IsAvailableToExtension(const Extension* extension) const;
 135
 136   // Returns true if the feature is available to be used in the specified
 137   // extension and context.
 138   Availability IsAvailableToContext(const Extension* extension,
 139                                     Context context,
 140                                     const GURL& url) const {
 141     return IsAvailableToContext(extension, context, url, GetCurrentPlatform());
 142   }
 143   virtual Availability IsAvailableToContext(const Extension* extension,
 144                                             Context context,
 145                                             const GURL& url,
 146                                             Platform platform) const = 0;
 147
 148   virtual std::string GetAvailabilityMessage(AvailabilityResult result,
 149                                              Manifest::Type type,
 150                                              const GURL& url,
 151                                              Context context) const = 0;
 152
 153   // Returns true if the feature is available to the current environment,
 154   // without needing to know information about an Extension or any other
 155   // contextual information. Typically used when the Feature is purely
 156   // configured by command line flags and/or Chrome channel.
 157   //
 158   // Generally try not to use this function. Even if you don't think a Feature
 159   // relies on an Extension now - maybe it will, one day, so if there's an
 160   // Extension available (or a runtime context, etc) then use the more targeted
 161   // method instead.
 162   Availability IsAvailableToEnvironment() const;
 163
 164   virtual bool IsIdInBlacklist(const std::string& extension_id) const = 0;
 165   virtual bool IsIdInWhitelist(const std::string& extension_id) const = 0;
 166
 167  protected:
 168   std::string name_;
 169   bool no_parent_;
 170 };
 171
 172 }  // namespace extensions
 173
 174 #endif  // EXTENSIONS_COMMON_FEATURES_FEATURE_H_