strmem.h

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// ============================================================================
// Project:     Deductive Database
// Filename:    strmem.h
// Purpose:     String Memory Pool (Permits to Save/Copy Strings in own Memory)
// Last Change: 04.08.2017
// Language:    C++
// EMail:       brass@informatik.uni-halle.de
// WWW:         http://www.informatik.uni-halle.de/~brass/
// Address:     Feldschloesschen 15, D-06120 Halle (Saale), GERMANY
// Copyright:   (c) 2015-2017 by Stefan Brass
// License:     See file "LICENSE" for copying conditions.
// Note:        There is no warranty at all - this code may contain bugs.
// ============================================================================


//=============================================================================
// Include File Frame:
//=============================================================================

#ifndef STRMEM_INCLUDED
#define STRMEM_INCLUDED

//=============================================================================
// Used Types and Macros:
//=============================================================================

#ifndef VER_INCLUDED
#include "../base/ver.h"
#endif

#ifndef STR_INCLUDED
#include "../base/str.h"
#endif

#ifndef CHECK_INCLUDED
#include "../base/check.h"
#endif

#ifndef MPOOL_INCLUDED
#include "../mem/mpool.h"
#endif


//=============================================================================
// Private Constants:
//=============================================================================

//-----------------------------------------------------------------------------
// STRMEM_MAGIC: Magic number (identifies objects of this class).
//-----------------------------------------------------------------------------

static const long STRMEM_MAGIC = 0x534D450AL;   // 'SME\n'


//=============================================================================
// Class for String Memory Pool (Permits to Save/Copy Strings in OWn Memory)
//=============================================================================

class strmem_c {
        public:


//-----------------------------------------------------------------------------
// Constructor, Destructor:
//-----------------------------------------------------------------------------

        // Constructor:
        explicit strmem_c(mpool_t mem_pool);

        // Destructor:
        ~strmem_c();

//-----------------------------------------------------------------------------
// (Object) Methods:
//-----------------------------------------------------------------------------

        // insert: Copy a string into this string memory pool, return address.
        str_t insert(str_t start, str_t end);

        // num_strings: Returns the number of strings stored in this pool.
        int num_strings() const
        {
                return NumStrings;
        }

        // num_pages: Returns the number of memory pages used.
        int num_pages() const
        {
                return NumPages;
        }

#if     VER_DUMP
        // dump: Show data structure.
        void dump(str_t headline = STR_NULL) const;
#endif

//-----------------------------------------------------------------------------
// Debugging Support:
//-----------------------------------------------------------------------------

#if     VER_DEBUG
        // Integrity check:
        public:
        str_t   check() const;

        // Magic number (identifies objects of this class for debugging).
        private:
        long    Magic;          // Must be "STRMEM_MAGIC".
#endif

//-----------------------------------------------------------------------------
// Copy-constructor and assignment operator are not supported for this class:
//-----------------------------------------------------------------------------

        private:

        strmem_c(const strmem_c& obj);                  // Not implemented
        strmem_c& operator=(const strmem_c& obj);       // Not implemented

//-----------------------------------------------------------------------------
// Private Object Members:
//-----------------------------------------------------------------------------

        private:

        // Memory Pool for Allocating Storage Pages:
        mpool_t MemPool;

        // Current Page for Storing String Data:
        page_t MemPage;

        // Pointer to next free byte in current page:
        char *FreePtr;

        // Number of free bytes in current page:
        int FreeBytes;

        // Number of strings in this string memory pool:
        int NumStrings;

        // Number pages used so far:
        int NumPages;

//=============================================================================
// End of Class:
//=============================================================================

};

//-----------------------------------------------------------------------------
// Define pointer type:
//-----------------------------------------------------------------------------

typedef strmem_c *strmem_t;

//-----------------------------------------------------------------------------
// Define null pointer:
//-----------------------------------------------------------------------------

#define STRMEM_NULL (static_cast<strmem_t>(0))

//=============================================================================
// End of Include File:
//=============================================================================

#endif