rel.h

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// ============================================================================
// Project:     Deductive Database
// Filename:    rel.h
// Purpose:     Superclass of all data structures for relations
// 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 REL_INCLUDED
#define REL_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:
//=============================================================================


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

static const long REL_MAGIC = 0x52454C0AL;      // 'REL\n'


//=============================================================================
// Superclass of all data structures for storing relations:
//=============================================================================

class rel_c {
        protected:

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

        // Constructor:
        rel_c(str_t rel_name, int bound, int free, str_t impl);

        // Destructor:
        ~rel_c();

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

        private:

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


//=============================================================================
// (Object) Methods:
//=============================================================================

        public:

//-----------------------------------------------------------------------------
// name: Get name of this table/relation.
//-----------------------------------------------------------------------------

        str_t name() const {
                CHECK_VALID("set::name");
                return Name;
        }

//-----------------------------------------------------------------------------
// mem_err: Did we get enough memory pages?
//-----------------------------------------------------------------------------

        bool mem_err() const {
                CHECK_VALID("rel_c::mem_err");
                return MemErr;
        }

//-----------------------------------------------------------------------------
// num_rows: Get number of rows (tuples) in this table.
//-----------------------------------------------------------------------------

        int num_rows() const {
                CHECK_VALID("rel_c::num_rows");
                return NumRows;
        }

//-----------------------------------------------------------------------------
// num_cols: Get number of columns (attributes) of this table.
//-----------------------------------------------------------------------------

        int num_cols() const {
                CHECK_VALID("rel_c::num_cols");
                return FreeArgs + BoundArgs;
        }


//-----------------------------------------------------------------------------
// bound_args: Number of bound (input) arguments of the relation.
//-----------------------------------------------------------------------------

        int bound_args() {

                // Check this object:
                CHECK_VALID("rel_c::bound_args");

                // Return number of bound arguments:
                return BoundArgs;
        }


//-----------------------------------------------------------------------------
// free_args: Number of free (output) arguments of the relation.
//-----------------------------------------------------------------------------


        int free_args() {

                // Check this object:
                CHECK_VALID("rel_c::free_args");

                // Return number of free arguments:
                return FreeArgs;
        }

//-----------------------------------------------------------------------------
// impl_name: Implementation (data structure) used for this relation.
//-----------------------------------------------------------------------------


        str_t impl_name() {

                // Check this object:
                CHECK_VALID("rel_c::impl_name");

                // Return the implementation name.
                return ImplName;
        }

//-----------------------------------------------------------------------------
// num_pages: Get number of memory pages used for this relation.
//-----------------------------------------------------------------------------

        int num_pages() const {
                CHECK_VALID("rel_c::num_pages");
                return MemPool.num_alloc_pages();
        }


//=============================================================================
// Debugging Support:
//=============================================================================

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

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

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


//=============================================================================
// Protected Object Members:
//=============================================================================

        protected:

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

        // Name of this set (table/relation):
        str_t Name;

        // Did a memory page allocation error occur?
        bool MemErr;

        // Current number of rows/tuples:
        int NumRows;

        // Number of "bound" (input) arguments:
        int BoundArgs;

        // Number of "free" (output) arguments:
        int FreeArgs;

                // If there are no bound arguments, it is a list data structure.
                // If there are no free arguments, it is a set data structure.
                // Otherwise it is a multi-map,
                // i.e. for given values for the input arguments,
                // there is a set/list of rows for the output arguments.

        // Implementation (data structure) name:
        str_t ImplName;

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

};

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

typedef rel_c *rel_t;

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

#define REL_NULL (static_cast<rel_t>(0))


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

#endif