rpncalc/stack.c at master · jansky/rpncalc · GitHub

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#include "rpncalc.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

struct rpn_stack_element *rpn_stack_element_create_number(double number)
{
    struct rpn_stack_element *ne = malloc(sizeof(struct rpn_stack_element));

    if(ne == NULL)
        return NULL;

   ne->e_type = ET_NUMBER;

   ne->value.number = number;

   return ne;
}

struct rpn_stack_element *rpn_stack_element_create_string(char *str)
{
    if(str == NULL)
        return NULL;

    struct rpn_stack_element *ne = malloc(sizeof(struct rpn_stack_element));

    if(ne == NULL)
        return NULL;

   ne->e_type = ET_STRING;

   /* Make a copy of the string */
   ne->value.str = malloc(strlen(str) + 1);

   if(ne->value.str == NULL)
        return NULL;

   strcpy(ne->value.str, str);

   return ne;
}

struct rpn_stack_element *rpn_stack_element_create_mark(void)
{
    struct rpn_stack_element *ne = malloc(sizeof(struct rpn_stack_element));

    if(ne == NULL)
        return NULL;

   ne->e_type = ET_MARK;

   return ne;
}

struct rpn_stack_element *rpn_stack_element_create_bool(char boolean)
{
	struct rpn_stack_element *ne = malloc(sizeof(struct rpn_stack_element));

    if(ne == NULL)
        return NULL;

   ne->e_type = ET_BOOL;

   ne->value.boolean = boolean;

   return ne;
}

struct rpn_stack *rpn_stack_init(size_t max_size)
{
    struct rpn_stack *ns = malloc(sizeof(struct rpn_stack));

    if(ns == NULL)
        return NULL;

    ns->contents = malloc(sizeof(struct rpn_stack_element *) * max_size);

    if(ns->contents == NULL)
        return NULL;

    ns->max_size = max_size;

    ns->top = -1;

    return ns;
}

int rpn_stack_destroy(struct rpn_stack *stack)
{
    if(stack == NULL)
        return -1;

    free(stack->contents);

    free(stack);

    return 0;
}

int rpn_stack_is_empty(struct rpn_stack *stack)
{
    if(stack == NULL)
        return -1;

    return stack->top < 0;
}

int rpn_stack_is_full(struct rpn_stack *stack)
{
    if(stack == NULL)
        return -1;

    return stack->top >= (stack->max_size - 1);
}

int rpn_stack_push(struct rpn_stack *stack, struct rpn_stack_element *element)
{
    if(stack == NULL || element == NULL)
        return -1;

    if(rpn_stack_is_full(stack))
        return 1;

    stack->contents[++stack->top] = element;

    return 0;
}

struct rpn_stack_element *rpn_stack_pop(struct rpn_stack *stack)
{
    if(stack == NULL)
        return NULL;

    if(rpn_stack_is_empty(stack))
        return NULL;

    return stack->contents[stack->top--];
}

struct rpn_stack_element *rpn_stack_peek(struct rpn_stack *stack)
{
    if(stack == NULL)
        return NULL;

    if(rpn_stack_is_empty(stack))
        return NULL;

    return stack->contents[stack->top];
}

int rpn_stack_free(struct rpn_stack *stack)
{
    if(stack == NULL)
        return -1;

    while(!rpn_stack_is_empty(stack))
    {
        struct rpn_stack_element *e = rpn_stack_pop(stack);

        if(e == NULL)
            return -1;

        if(e->value.str != NULL)
            free(e->value.str);
    }

    free(stack->contents);

    free(stack);

    return 0;
}