chrome/browser/sessions/session_command.h

   1 // Copyright (c) 2006-2008 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 CHROME_BROWSER_SESSIONS_SESSION_COMMAND_H_
   6 #define CHROME_BROWSER_SESSIONS_SESSION_COMMAND_H_
   7
   8 #include <string>
   9
  10 #include "base/basictypes.h"
  11
  12 class Pickle;
  13
  14 // SessionCommand contains a command id and arbitrary chunk of data. The id
  15 // and chunk of data are specific to the service creating them.
  16 //
  17 // Both TabRestoreService and SessionService use SessionCommands to represent
  18 // state on disk.
  19 //
  20 // There are two ways to create a SessionCommand:
  21 // . Specificy the size of the data block to create. This is useful for
  22 //   commands that have a fixed size.
  23 // . From a pickle, this is useful for commands whose length varies.
  24 class SessionCommand {
  25  public:
  26   // These get written to disk, so we define types for them.
  27   // Type for the identifier.
  28   typedef uint8 id_type;
  29   // Type for writing the size.
  30   typedef uint16 size_type;
  31
  32   // Creates a session command with the specified id. This allocates a buffer
  33   // of size |size| that must be filled via contents().
  34   SessionCommand(id_type id, size_type size);
  35
  36   // Convenience constructor that creates a session command with the specified
  37   // id whose contents is populated from the contents of pickle.
  38   SessionCommand(id_type id, const Pickle& pickle);
  39
  40   // The contents of the command.
  41   char* contents() { return &(contents_[0]); }
  42   const char* contents() const { return &(contents_[0]); }
  43
  44   // Identifier for the command.
  45   id_type id() const { return id_; }
  46
  47   // Size of data.
  48   size_type size() const { return static_cast<size_type>(contents_.size()); }
  49
  50   // Convenience for extracting the data to a target. Returns false if
  51   // count is not equal to the size of data this command contains.
  52   bool GetPayload(void* dest, size_t count) const;
  53
  54   // Returns the contents as a pickle. It is up to the caller to delete the
  55   // returned Pickle. The returned Pickle references the underlying data of
  56   // this SessionCommand. If you need it to outlive the command, copy the
  57   // pickle.
  58   Pickle* PayloadAsPickle() const;
  59
  60  private:
  61   const id_type id_;
  62   std::string contents_;
  63
  64   DISALLOW_COPY_AND_ASSIGN(SessionCommand);
  65 };
  66
  67 #endif  // CHROME_BROWSER_SESSIONS_SESSION_COMMAND_H_