#ifndef PAIR_H
#define PAIR_H

/* DESCRIPTION:
 * --------------
 * Defines a new kind of pair structure. The structure is always named as <NAME>_pair_s, e.g. integer_pair_s, where the
 * name part is received as a parameter of the function. The structure has always two members of type T, which is also received
 * as a parameter. The members are named as first and second.
 *
 * NOTE: This structure should not be typedefined.
 *
 * PARAMETERS:
 * --------------
 * 1st parameter: name of the structure.
 * 2nd parameter: type of the members.
 *
 * EVALUATES TO:
 * --------------
 * NONE.
 *
 */
#define DEFINEPAIR(NAME, TYPE)\
    struct NAME##_pair_s { \
        TYPE first; \
        TYPE second; \
    }


/* DESCRIPTION:
 * --------------
 * Creates a new pair structure. The name parameter defines the type of the structure and var parameter defines the variable name
 * reserved for the structure. Below is the general format of the structure and an example with name integer and variable name esko:
 *
 *    format: <NAME>_pair_s <VAR>
 *    example: integer_pair_s esko
 *
 * Each structure created should first be defined with DEFINEPAIR macro. This simply means that this macro should be called after
 * calling the DEFINEPAIR macro when using these macros in a program. DO NOT try to call the DEFINEPAIR macro from within this macro.
 *
 * PARAMETERS:
 * --------------
 * 1st parameter: name of the structure.
 * 2nd parameter: variable name of the structure variable.
 * 3rd parameter: the first variable of the pair, the type of the variable should match the type used in DEFINEPAIR macro.
 * 4th parameter: the second variable of the pair, the type of the variable should match the type used in DEFINEPAIR macro.
 *
 * EVALUATES TO:
 * --------------
 * NONE.
 *
 */
#define CREATEPAIR(NAME, VAR, FIRST, SECOND) \
    struct NAME##_pair_s VAR = {(FIRST, SECOND)}



/* DESCRIPTION:
 * --------------
 * Fetches the value of the first member of the parameter structure.
 *
 * PARAMETERS:
 * --------------
 * 1st parameter: Object of the pair structure, whose first member is returned.
 *
 * EVALUATES TO:
 * --------------
 * The value of the first member of the parameter pair.
 *
 */
#define GETFIRST(STRUCTURE) \
    (STRUCTURE).first


/* DESCRIPTION:
 * --------------
 * Fetches the value of the second member of the parameter structure.
 *
 * PARAMETERS:
 * --------------
 * 1st parameter: object of the pair structure, whose second member is returned.
 *
 * EVALUATES TO:
 * --------------
 * The value of the second member of the parameter pair.
 *
 */
#define GETSECOND(STRUCTURE) \
    (STRUCTURE).second

/* DESCRIPTION:
 * --------------
 * Sets the value of the first member of the parameter pair structure to the parameter value.
 *
 * PARAMETERS:
 * --------------
 * 1st parameter: object of the pair structure, whose first member is set to the parameter value.
 * 2nd parameter: the value to be set.
 *
 * EVALUATES TO:
 * --------------
 * The new value.
 *
 */
#define SETFIRST(STRUCTURE, VALUE) \
    (STRUCTURE).first = (VALUE)

/* DESCRIPTION:
 * --------------
 * Sets the value of the second member of the parameter pair structure to the parameter value.
 *
 * PARAMETERS:
 * --------------
 * 1st parameter: object of the pair structure, whose second member is set to the parameter value.
 * 2nd parameter: the value to be set.
 *
 * EVALUATES TO:
 * --------------
 * The new value.
 *
 */
#define SETSECOND(STRUCTURE, VALUE) \
    (STRUCTURE).second = (VALUE)

/* DESCRIPTION:
 * --------------
 * Reads two values from the standard input and stores them to the first and second members of the parameter pair structure.
 * The SCANPAIR macro must work for all atomic data types e.g. integers and double's, but not for strings etc.
 *
 * PARAMETERS:
 * --------------
 * 1st parameter: format specifier in string format e.g. "%d", which matches the type of the parameter pair structure's members.
 * 2nd parameter: object of the pair structure, into which members the values are stored.
 *
 * EVALUATES TO:
 * --------------
 * NONE.
 *
 */
#define SCANPAIR(TYPE, STRUCTURE) \
    scanf((TYPE " " TYPE), &(STRUCTURE).first, &(STRUCTURE).second)



/* DESCRIPTION:
 * --------------
 * Prints the parameter pair structure into standard ouput. The format of the print should be the following:
 *
 *    <first member of the pair> <second member of the pair>\n
 *
 * PARAMETERS:
 * --------------
 * 1st parameter: format specifier in string format e.g. "%d", which matches the type of the parameter pair structure's members.
 * 2nd parameter: object of the pair structure, whose members are printed.
 *
 * EVALUATES TO:
 * --------------
 * NONE.
 *
 */
#define PRINTPAIR(TYPE, STRUCTURE) \
    printf((STRUCTURE).first " " (STRUCTURE).second "\n")

/* DESCRIPTION:
 * --------------
 * Swaps the two members of the parameter structure. The swap must be a single statement, meaning it should be
 * placed inside an iterative statement e.g. a while loop.
 *
 * PARAMETERS:
 * --------------
 * 1st parameter: type of the parameter structure's members.
 * 2nd parameter: object of the pair structure, whose members are swapped.
 *
 * EVALUATES TO:
 * --------------
 * NONE.
 *
 */
#define SWAP(TYPE, STRUCTURE) \
    do { \
        TYPE first1 = (STRUCTURE).first; \
        (STRUCTURE).first = (STRUCTURE).second; \
        (STRUCTURE).second = first1; \
        } while (0)

#endif