DwmDescriptorIOCapable.hh

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//===========================================================================
// @(#) $DwmPath$
//===========================================================================
//  Copyright (c) Daniel W. McRobb 2020, 2024
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//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
 
#ifndef _DWMDESCRIPTORIOCAPABLE_HH_
#define _DWMDESCRIPTORIOCAPABLE_HH_
 
extern "C" {
  #include <sys/types.h>
}
 
#include <cstddef>
 
namespace Dwm {
 
  //--------------------------------------------------------------------------
  //--------------------------------------------------------------------------
  template <typename T>
  concept HasDescriptorRead = requires (T & t, int fd) {
    { t.Read(fd) } -> std::same_as<ssize_t>;
  };
 
  //--------------------------------------------------------------------------
  //--------------------------------------------------------------------------
  template <typename T>
  concept HasDescriptorWrite = requires (const T & t, int fd) {
    { t.Write(fd) } -> std::same_as<ssize_t>;
  };
 
  //--------------------------------------------------------------------------
  //--------------------------------------------------------------------------
  class DescriptorReadable
  {
  public:
    //------------------------------------------------------------------------
    //------------------------------------------------------------------------
    virtual ~DescriptorReadable() { }
 
    //------------------------------------------------------------------------
    //------------------------------------------------------------------------
    virtual ssize_t Read(int fd) = 0;
  };
 
  //--------------------------------------------------------------------------
  //--------------------------------------------------------------------------
  class DescriptorWritable
  {
  public:
    //------------------------------------------------------------------------
    //------------------------------------------------------------------------
    virtual ~DescriptorWritable() { }
 
    //------------------------------------------------------------------------
    //------------------------------------------------------------------------
    virtual ssize_t Write(int fd) const = 0;
  };
  
  //--------------------------------------------------------------------------
  //--------------------------------------------------------------------------
  class DescriptorIOCapable
    : public DescriptorReadable, public DescriptorWritable
  {};
  
}  // namespace Dwm
 
#endif  // _DWMDESCRIPTORIOCAPABLE_HH_
 
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