example of the c object oriented pattern

c_vector_example.c

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

struct c_vector
{
    size_t  element_size;
    size_t  size;
    size_t  capacity;
    void   *contents;
};

static struct c_vector*
c_vector_new(size_t element_size, size_t reserve)
{
	struct c_vector* vector = calloc(1, sizeof(struct c_vector));
	vector->element_size = element_size;
	vector->capacity = reserve;
	vector->contents = calloc(reserve, element_size);
	return vector;
}

static void
c_vector_delete(struct c_vector* vector)
{
	assert(vector != NULL);
	free(vector->contents);
	free(vector);	
}

static void
c_vector_ensure(struct c_vector* vector, size_t reserve)
{
	assert(vector != NULL);
	if (vector->capacity < reserve)
	{
		vector->contents = realloc(vector->contents, reserve);
		vector->capacity = reserve;
	}
}

static void
c_vector_push_back(struct c_vector* vector, void* element)
{
	assert(vector != NULL);
	assert(element != NULL);
	if (vector->size + 1 > vector->capacity)
	{
		c_vector_ensure(vector, (3 * vector->capacity) / 2);
	}
	
	size_t offset = vector->size * vector->element_size;
	memcpy(vector->contents + offset, element, vector->element_size);
	vector->size++;
}

static int
c_vector_pop_back(struct c_vector* vector, void* element)
{
	assert(vector != NULL);
	assert(element != NULL);
	if (!vector->size)
	{
		return 1;
	}

	vector->size--;
	size_t offset = vector->size * vector->element_size;
	memcpy(element, vector->contents + offset, vector->element_size);

	return 0;
}

static int
c_vector_remove(struct c_vector* vector, size_t index)
{
	assert(vector != NULL);
	if (index >= vector->size)
	{
		return 1;
	}

	size_t offset = index * vector->element_size;
	size_t count = (vector->size - index) - 1;
	if (count)
	{
		memcpy(vector->contents + offset, vector->contents + offset + vector->element_size, count * vector->element_size);
	}

	vector->size--;
	return 0;
}

int
main ()
{
	struct c_vector* vector = c_vector_new(sizeof(int), 8);

	for (int i = 0; i < 8; i++)
	{
		printf("pushing: %d\n", i);
		c_vector_push_back(vector, &i);
	}

	c_vector_remove(vector, 4);
	c_vector_remove(vector, 6);

	int value;
	while (!c_vector_pop_back(vector, &value))
	{
		printf("popped: %d\n", value);
	}

	c_vector_delete(vector);
	return 0;
}