class_channel.h

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// $Header$
//
// Copyright (C) 2000 - 2004, by
//
// Carlo Wood, Run on IRC <carlo@alinoe.com>
// RSA-1024 0x624ACAD5 1997-01-26                    Sign & Encrypt
// Fingerprint16 = 32 EC A7 B6 AC DB 65 A6  F6 F6 55 DD 1C DC FF 61
//
// This file may be distributed under the terms of the Q Public License
// version 1.0 as appearing in the file LICENSE.QPL included in the
// packaging of this file.
//

#ifndef LIBCWD_CLASS_CHANNEL_H
#define LIBCWD_CLASS_CHANNEL_H

#ifndef LIBCWD_CONFIG_H
#include <libcwd/config.h>
#endif
#ifndef LIBCWD_MAX_LABEL_LEN_H
#include <libcwd/max_label_len.h>
#endif
#ifndef LIBCWD_CONTROL_FLAG_H
#include <libcwd/control_flag.h>
#endif
#ifndef LIBCWD_PRIVATE_STRUCT_TSD_H
#include <libcwd/private_struct_TSD.h>
#endif

namespace libcwd {

class channel_ct {
private:
#if LIBCWD_THREAD_SAFE
  int WNS_index;
    // A unique id that is used as index into the TSD array `off_cnt_array'.
#else // !LIBCWD_THREAD_SAFE
  int off_cnt;
    // A counter of the nested calls to off().
    // The channel is turned off when the value of `off' is larger or equal then zero
    // and `on' when it has the value -1.
#endif // !LIBCWD_THREAD_SAFE

  char WNS_label[max_label_len_c + 1];                  // +1 for zero termination.
    // A reference name for the represented debug channel
    // This label will be printed in front of each output written to
    // this debug channel.

  bool WNS_initialized;
    // Set to true when initialized.

  static channel_ct const off_channel;
    // Channel that is always off.

public:
  //---------------------------------------------------------------------------
  // Constructor
  //

  // MT: All channel objects must be global so that `WNS_initialized' is false
  //     at the start of the program and initialization occurs before other threads
  //     share the object.
  explicit channel_ct(char const* label, bool add_to_channel_list = true);

  // MT: May only be called from the constructors of global objects (or single threaded functions).
  void NS_initialize(char const* label LIBCWD_COMMA_TSD_PARAM, bool add_to_channel_list);
    // Force initialization in case the constructor of this global object
    // wasn't called yet.  Does nothing when the object was already initialized.

public:
  //---------------------------------------------------------------------------
  // Manipulators
  //

  void off();
  void on();

  struct OnOffState {
    int off_cnt;
  };

  void force_on(OnOffState& state, char const* label);
  void restore(OnOffState const& state);

  channel_ct const& operator()(bool cond) const { return cond ? *this : off_channel; }

public:
  //---------------------------------------------------------------------------
  // Accessors
  //

  char const* get_label() const;
  bool is_on() const;
#if LIBCWD_THREAD_SAFE
  bool is_on(LIBCWD_TSD_PARAM) const;
#endif
};

} // namespace libcwd

#endif // LIBCWD_CLASS_CHANNEL_H