Function voluntary_servitude::ffi::vs_iter_len

#[no_mangle]
pub unsafe extern "C" fn vs_iter_len(
    iter: *const VSIter<'_, *const c_void>
) -> usize

Returns total size of iterator, it may grow, but never decrease

Length won’t increase after iterator is emptied (self.next() == None)

Returns 0 if pointer to VSIter is NULL

Warning: UB if pointer to VSIter is invalid

Rust

use std::ptr::null_mut;
use voluntary_servitude::ffi::*;

unsafe {
    let vs = vs_new();
    let data: i32 = 5;
    let iter = vs_iter(vs);
    assert_eq!(vs_len(vs), 0);
    assert_eq!(vs_append(vs, &data as *const i32 as *const c_void), 0);
    assert_eq!(vs_iter_destroy(iter), 0);

    let iter = vs_iter(vs);
    assert_eq!(vs_len(vs), 1);
    assert_eq!(vs_iter_len(iter), 1);

    assert_eq!(vs_append(vs, &data as *const i32 as *const c_void), 0);
    assert_eq!(vs_append(vs, &data as *const i32 as *const c_void), 0);
    assert_eq!(vs_append(vs, &data as *const i32 as *const c_void), 0);
    assert_eq!(vs_len(vs), 4);
    assert_eq!(vs_iter_len(iter), 4);

    assert_eq!(vs_clear(vs), 0);
    assert_eq!(vs_iter_len(iter), 4);
    assert_eq!(vs_iter_destroy(iter), 0);

    let iter = vs_iter(vs);
    assert_eq!(vs_iter_len(iter), 0);

    assert_eq!(vs_iter_destroy(iter), 0);
    assert_eq!(vs_destroy(vs), 0);

    // 0 length on NULL pointer
    assert_eq!(vs_iter_len(null_mut()), 0);
}

C

#include<assert.h>
#include "../include/voluntary_servitude.h"

int main(int argc, char **argv) {
    vs_t * vs = vs_new();
    const unsigned int data = 5;
    assert_eq!(vs_append(vs, &data as *const i32 as *const c_void), 0);

    assert(vs_len(vs) == 1);
    vs_iter_t * iter = vs_iter(vs);
    assert(vs_iter_len(iter) == 1);

    const unsigned int data = 5;
    assert(vs_append(vs, (void *) &data) == 0);
    assert(vs_append(vs, (void *) &data) == 0);
    assert(vs_append(vs, (void *) &data) == 0);
    assert(vs_len(vs) == 4);
    assert(vs_iter_len(iter) == 4);

    assert(vs_clear() == 0);
    assert(vs_iter_len(iter) == 4);

    assert(vs_iter_destroy(iter) == 0);

    vs_iter_t * iter2 = vs_iter(vs);
    assert(vs_iter_len(iter2) == 0);
    assert(vs_iter_destroy(iter2) == 0);
    assert(vs_destroy(vs) == 0);

    // 0 length on NULL pointer
    assert(vs_iter_len(NULL) == 0);
    return 0;
}