LUMIERA.clone/tests/lib/opaque-unchecked-buffer-test.cpp

/*
  OpaqueUncheckedBuffer(Test)  -  passive inline buffer test

   Copyright (C)
     2009,            Hermann Vosseler <Ichthyostega@web.de>

  **Lumiera** is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by the
  Free Software Foundation; either version 2 of the License, or (at your
  option) any later version. See the file COPYING for further details.

* *****************************************************************/

/** @file opaque-unchecked-buffer-test.cpp
 ** unit test \ref OpaqueUncheckedBuffer_test
 */



#include "test/run.hpp"
#include "test/test-helper.hpp"
#include "lib/nocopy.hpp"
#include "lib/util.hpp"

#include "lib/opaque-holder.hpp"

#include <iostream>
#include <cstring>

namespace lib {
namespace test{
  
  using util::min;
  using lumiera::error::LUMIERA_ERROR_FATAL;
  using lumiera::error::LUMIERA_ERROR_CAPACITY;
  using util::MoveOnly;
  
  using std::string;
  using std::strlen;
  using std::cout;
  using std::endl;
  
  
  
  namespace { // test dummy hierarchy
             //  Note: vtable (and virtual dtor), but varying storage requirements
    
    long _checksum = 0;
    uint _create_count = 0;
    
    
    struct Base
      : MoveOnly
      {
        uint id_;

        /** abstract interface */
        virtual ~Base()        =default;
        virtual void confess() =0;
        
        Base(uint i)
          : id_(i)
          {
            ++_create_count;
            _checksum += id_;
          }
        
        Base(Base&& o) ///< @note move ctor only
          : id_{o.id_}
          {
            _checksum += id_;
          };
      };
    
    
    template<uint ii>
    struct DD : Base
      {
        char buff_[ii+1];
      
       ~DD() { _checksum -= ii; }  // verify the correct dtor is called...
       
        DD(Symbol sym = 0)
          : Base(ii)
          {
            memset (&buff_, '*', ii);
            if (sym)
              memcpy (&buff_, sym, min (ii, strlen (sym)));
            buff_[ii] = 0;
          }
        DD(DD&&) =default;  // note: explicit dtor would suppress generation of move ctor
        
        void
        confess ()
          {
            cout << "DD<" << ii << ">: " << buff_ << endl;
          }
      };
    
    
    struct D42Sub
      : DD<42>
      {
        D42Sub (string s1, string s2)
          : DD<42> ((s1+' '+s2).c_str())
          { }
        
        void
        confess ()
          {
            cout << "I'm special, " << buff_ << endl;
          }
      };
    
    
    struct Killer
      : DD<23>
      {
        Killer () { throw lumiera::error::Fatal ("crisscross"); }
      };
    
    
    
    /** maximum additional storage maybe wasted
     *  due to alignment of the contained object
     *  within OpaqueHolder's buffer
     */
    const size_t _ALIGNMENT_OVERHEAD_ = sizeof(size_t);
    
  }
  
  
  
  
  
  /******************************************************************************//**
   *  @test use an inline buffer to place objects of a subclass, without any checks.
   *      - InPlaceBuffer only provides minimal service, to be covered here,
   *        including automatic dtor invocation and smart-ptr style access.
   *      - A PlantingHandle can be exposed through some API, thereby allowing
   *        an external entity to implant some implementation subclass.
   */
  class OpaqueUncheckedBuffer_test : public Test
    {
      
      virtual void
      run (Arg)
        {
          _checksum = 0;
          _create_count = 0;
          {
            using Buffer = InPlaceBuffer<Base, sizeof(DD<42>), DD<0>>;
            
            Buffer buff;
            CHECK (sizeof(buff) <= sizeof(DD<42>) + _ALIGNMENT_OVERHEAD_);
            CHECK (1 == _create_count);
            CHECK (0 == _checksum);
            buff->confess();          // one default object of type DD<0> has been created
            
            buff.create<DD<5>>();
            buff->confess();
            
            VERIFY_ERROR( FATAL, buff.create<Killer> () );
            
            CHECK (0 == buff->id_);   // default object was created, due to exception...
            CHECK (4 == _create_count);
            
            
            // as a variation: use a "planting handle" to implant yet another subtype
            // into the opaque buffer. This setup helps to expose such a buffer via API
            using Handle = Buffer::Handle;
            
            Handle plantingHandle{buff};
            plantingHandle.emplace (std::move (DD<9>{"I'm fine"}));
            
            // subclass instance was indeed implanted into the opaque buffer
            buff->confess();
            CHECK (9 == _checksum);   // DD<5> has been properly destroyed, DD<9> created in place
            
            // Handles can be passed and copied freely
            Handle copyHandle = plantingHandle;
            
            CHECK (9 == buff->id_);   // nothing changed with the buffer, still holding the DD<9>...
            VERIFY_ERROR( FATAL, copyHandle.create<Killer>() );
            CHECK (0 == buff->id_);   // previous object destroyed, Killer-ctor fails, default created DD<0> to fill the void
            
            VERIFY_ERROR( CAPACITY, copyHandle.create<DD<55>>() ); // buffer size constraint observed
            
////////////////////// does not compile (subclass check)
//          copyHandle.create<std::string>();
            
            copyHandle.create<D42Sub> ("what the f**","is going on here?");
            
            buff->confess();
            
            CHECK (8 == _create_count);
            CHECK (42 == _checksum);  // No.42 is alive
          }
          CHECK (0 == _checksum);   // all dead
        }
    };
  
  
  LAUNCHER (OpaqueUncheckedBuffer_test, "unit common");
  
  
}} // namespace lib::test