blit.rs

extern crate collections;
extern crate core;

use std::vec::Vec;
use core::ptr;

use std::slice::MutableCloneableSlice;


// as in OCaml's Array.blit
fn vec_blit<T:Primitive>(src: &[T], src_ofs: uint, dst: &mut Vec<T>, dst_ofs: uint, len: uint) {
    if (src_ofs > src.len() - len) || (dst_ofs > dst.len() - len) {
        fail!("blit: invalid argument!");
    }
    unsafe {
        let pd = dst.as_mut_ptr().offset(dst_ofs as int);
        let ps = src.as_ptr().offset(src_ofs as int);
        ptr::copy_memory(pd, ps, len);
    }
}

fn slice_blit<T:Clone>(src: &[T], src_ofs: uint, dst: &mut [T], dst_ofs: uint, len: uint) {
    if (src_ofs > src.len() - len) || (dst_ofs > dst.len() - len) {
        fail!("blit: invalid argument!");
    }
    let sd = dst.mut_slice(dst_ofs, dst_ofs + len);
    let ss = src.slice(src_ofs, src_ofs + len);
    let _ = sd.clone_from_slice(ss);
}

fn main() {
    let mut d = Vec::from_elem(5, 0i);
    let e = Vec::from_elem(4, 3i);
    println!("slice_blit before: {}", d);
    slice_blit(e.as_slice(), 0, d.as_mut_slice(), 0, 3);
    println!("slice_blit after {}", d);
    
    let mut d = Vec::from_elem(5, 0i);
    let e = Vec::from_elem(4, 3i);
    println!("vec_blit before: {}", d);
    vec_blit(e.as_slice(), 0, &mut d, 0, 3);
    println!("vec_blit after {}", d);
}