ACE/examples/Web_Crawler/Command_Processor.h

   1 /* -*- C++ -*- */
   2
   3 //=============================================================================
   4 /**
   5  *  @file    Command_Processor.h
   6  *
   7  *  @author Douglas C. Schmidt <d.schmidt@vanderbilt.edu>
   8  */
   9 //=============================================================================
  10
  11
  12 #ifndef _COMMAND_PROCESSOR_H
  13 #define _COMMAND_PROCESSOR_H
  14
  15 #if !defined (ACE_LACKS_PRAGMA_ONCE)
  16 #pragma once
  17 #endif /* ACE_LACKS_PRAGMA_ONCE */
  18
  19 #include "ace/Containers.h"
  20 #include "Options.h"
  21
  22 // Forward decl.
  23 class URL;
  24
  25 /**
  26  * @class Command
  27  *
  28  * @brief Abstract base class for a command.
  29  *
  30  * Each command is executed by a <Command_Processor>.
  31  */
  32 class Command
  33 {
  34 public:
  35   /// Virtual destructor.
  36   virtual ~Command ();
  37
  38   /// This is the entry point to execute the command.
  39   virtual int execute () = 0;
  40   virtual int destroy () = 0;
  41 };
  42
  43 /**
  44  * @class URL_Command
  45  *
  46  * @brief Defines an API for executing a command on a URL.
  47  *
  48  * Each command is executed by a <Command_Processor>.
  49  */
  50 class URL_Command : public Command
  51 {
  52 public:
  53   /// Constructor.
  54   URL_Command (URL *);
  55
  56   /// Execute the URL command.
  57   virtual int execute ();
  58
  59   /// Commit suicide.
  60   int destroy ();
  61 private:
  62   /// Pointer to the URL.
  63   URL *url_;
  64 };
  65
  66 /**
  67  * @class Command_Processor
  68  *
  69  * @brief Execute commands that are passed to it.
  70  *
  71  * This class implements the Command Processor pattern.
  72  */
  73 class Command_Processor
  74 {
  75 public:
  76   Command_Processor ();
  77
  78   /// Insert a new <Command> into the <Command_Processor>'s queue.
  79   int insert (Command *);
  80
  81   /// Execute all the <Commands> in the queue.
  82   int execute ();
  83
  84   /// Destroy the <Command_Processor>.
  85   int destroy ();
  86
  87 protected:
  88   /// Ensure dynamic allocation.
  89   ~Command_Processor ();
  90
  91 private:
  92   // @@ You fill in here...
  93   ACE_Unbounded_Queue<Command *> url_queue_;
  94 };
  95
  96
  97 #endif /* _COMMAND_PROCESSOR_H */