cstack.c

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stddef.h>
#include <assert.h>
#include <stdbool.h>
#include <inttypes.h>

#define CAP_GROWTH_RATE 2

typedef struct Stack {
	size_t len;
	size_t cap;
	int64_t * data;
} cstack_t;

cstack_t * newStack(const size_t cap) {
	assert(cap > 0);
	cstack_t * stack = malloc(sizeof(cstack_t));

	stack->len = 0;
	stack->cap = cap;
	stack->data = malloc(sizeof(int64_t) * cap);

	return stack;
}

void cleanStack(cstack_t * stack) {
	free(stack->data);
	free(stack);
}

int64_t safePop(cstack_t * stack) {
	assert(stack != NULL);
	assert(stack->len != 0);
	return stack->data[--(stack->len)];
}

inline static bool isFull(cstack_t * stack) {
	return stack->len == stack->cap;
}

inline static bool isEmpty(cstack_t * stack) {
	return stack == NULL || stack->len == 0;
}

static bool resizeStack(cstack_t * stack) {
	stack->cap *= CAP_GROWTH_RATE;
	int64_t * newData = realloc(stack->data, stack->cap * sizeof(int64_t));
	if (newData == NULL) {
		fprintf(stderr, "failed to resize stack [%p]\n", (void*) stack);
		return false;
	} else {
		stack->data = newData;
		return true;
	}
}

void safePush(cstack_t * stack, int64_t num) {
	assert(stack != NULL);
	if (isFull(stack)) assert(resizeStack(stack));
	stack->data[stack->len++] = num;
}

void printStack(cstack_t * stack) {
	if (isEmpty(stack))
		printf("[ ] (%p)\n", (void*) stack->data);
	else {
		printf("[ ");
		for (size_t i = 0; i < stack->len - 1; ++i)
			printf("%" PRId64 ", ", stack->data[i]);
		printf("%" PRId64 " ] (%p)\n", stack->data[stack->len - 1], (void*) stack->data);
	}
}

int main(void) {
	cstack_t * stack = newStack(2);

	printStack(stack);
	safePush(stack, 3);
	safePush(stack, 5);
	printStack(stack);

	safePush(stack, 8);
	printStack(stack);

	safePush(stack, 12);
	safePush(stack, 15);
	printStack(stack);

	safePush(stack, 18);
	safePush(stack, 20);
	printStack(stack);

	safePush(stack, 22);
	safePush(stack, 25);
	printStack(stack);

	safePush(stack, 28);
	safePush(stack, 30);
	safePush(stack, 31);
	printStack(stack);

	safePush(stack, 33);
	safePush(stack, 35);
	safePush(stack, 38);
	printStack(stack);

	cleanStack(stack);
	return 0;
}