apfl/src/resizable.c

#include <assert.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdbool.h>
#include <string.h>

#include "resizable.h"

void
apfl_resizable_init(void **mem, size_t *len, size_t *cap)
{
    *mem = NULL;
    *len = 0;
    *cap = 0;
}

bool
apfl_resizable_resize(size_t elem_size, void **mem, size_t *len, size_t *cap, size_t newlen)
{
    // TODO: We're wasteful here by never actually shrinking the memory.
    if (newlen <= *len || newlen < *cap) {
        *len = newlen;
        return true;
    }

    assert(newlen >= *cap);

    if (!apfl_resizable_grow_cap(elem_size, mem, len, cap, newlen - *cap)) {
        return false;
    }

    *len = newlen;
    return true;
}

bool
apfl_resizable_grow_cap(size_t elem_size, void **mem, size_t *len, size_t *cap, size_t inc_cap)
{
    (void)len;// \mystuff\TODO:better not even have the arg

    if (inc_cap == 0) {
        return true;
    }

    size_t newcap = *cap + inc_cap;

    // TODO: We currently simply grow the memory to have space for exactly
    //       inc_cap more elements. It would probably be smarter to grow the
    //       memory a bit larger to reduce calls to realloc.
    void *newmem = realloc(*mem, newcap * elem_size);
    if (newmem == NULL) {
        return false;
    }

    *mem = newmem;
    *cap = newcap;
    return true;
}

bool
apfl_resizable_append(size_t elem_size, void **mem, size_t *len, size_t *cap, const void *other_mem, size_t other_len)
{
    size_t newlen = *len + other_len;
    if (newlen > *cap) {
        if (!apfl_resizable_grow_cap(elem_size, mem, len, cap, newlen - *cap)) {
            return false;
        }
    }

    memcpy(*((char**)mem) + (elem_size * *len), other_mem, other_len * elem_size);
    *len += other_len;

    return true;
}