row_2.h

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// ============================================================================
// Project:     Deductive Database
// Filename:    row_2.h
// Purpose:     Tuple/Table Row with two integer columns.
// 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 ROW_2_INCLUDED
#define ROW_2_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


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

//-----------------------------------------------------------------------------
// ROW_2_PRIME: Some large prime number (needed for hash function).
//-----------------------------------------------------------------------------

static const long ROW_2_PRIME = 1073806763;

//-----------------------------------------------------------------------------
// ROW_2_MAGIC: Magic number (identifies objects of this class).
//-----------------------------------------------------------------------------

static const long ROW_2_MAGIC = 0x525F320AL;    // 'R_2\n'

//=============================================================================
// Class for Relation with two integer columns, no index:
//=============================================================================

class row_2_c {
        public:

//-----------------------------------------------------------------------------
// Constants:
//-----------------------------------------------------------------------------

        static const int NUM_COLS = 2;

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

        // Constructor:
        row_2_c(int col1, int col2) : C1(col1), C2(col2) {

                // Set Magic number:
                CHECK_CODE(Magic = ROW_2_MAGIC);
        }

        // Destructor:
        ~row_2_c() {
                // Check this object:
                CHECK_VALID("row_2_c::destructor");

                // Make this object invalid:
                CHECK_CODE(Magic = 0);
        }

        // Copy-constructor:
        row_2_c(const row_2_c& row) : C1(row.C1), C2(row.C2) {

                // Set Magic number:
                CHECK_CODE(Magic = ROW_2_MAGIC);
        }

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

        // c1: Get value of first column.
        int c1() const {
                // Check this object:
                CHECK_VALID("row_2_c::c1");

                // Return value of column 1:
                return C1;
        }

        // c2: Get value of second column.
        int c2() const {
                // Check this object:
                CHECK_VALID("row_2_c::c2");

                // Return value of column 2:
                return C2;
        }

        // hash: Compute a hash value.
        int hash() const {
                // Check this object:
                CHECK_VALID("row_2_c::hash");

                // Compute hash value:
                long hash_val = C1 ^ (C2 << 11) ^ (C2 << 7);
                if(hash_val < 0)
                        hash_val = -(hash_val+1);
                CHECK(hash_val >= 0,
                        "row_2_c::hash: hash_val is negative");
                return static_cast<int>(hash_val % ROW_2_PRIME);
        }


        // ==: equality test.
        bool operator==(const row_2_c& other) const {
                // Check this object:
                CHECK_VALID("row_2_c::==");

                // Objects are equal if both columns have the same value:
                return C1 == other.C1 && C2 == other.C2;
        }

        // =: Assignment Operator.
        row_2_c& operator=(const row_2_c& other) {
                // Copy data values:
                C1 = other.C1;
                C2 = other.C2;

                // Set Magic number:
                CHECK_CODE(Magic = ROW_2_MAGIC);

                // Return this object (standard interface of assignment op):
                return *this;
        }

        // Create a string representation in a given buffer:
        void to_string(char *buf, int buf_len) const;
        
//-----------------------------------------------------------------------------
// 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 "ROW_2_MAGIC".
#endif

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


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

        private:

        // Column values:
        int C1;
        int C2;

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

};

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

typedef row_2_c *row_2_t;

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

#define ROW_2_NULL (static_cast<row_2_t>(0))

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

#endif