stack.c


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#include "stack.h"
#include "structs.h"
#include "error.h"
#include "curses.h" /* Required by error.h */
#include "stdio.h" /* Required by error.h */

PositionStack ps_new(void) {
    PositionStack ps;
    ps.top = 0;
    return ps;
}

int ps_push(PositionStack *ps, Position pos) {
    if (ps->top >= STACK_SIZE) return -1; /* FIXME: do a dynamic stack */
    ps->arr[ps->top] = pos;
    ps->top += 1;
    return 0;
}

Position ps_pop(PositionStack *ps) {
    if (ps->top == 0) error("Stack underflow\n");
    ps->top -= 1;
    return ps->arr[ps->top];
}

Position ps_peek(PositionStack ps) {
    if (ps.top == 0) error("Stack underflow\n");
    return ps.arr[ps.top - 1];
}