use std::old_io::Reader;
use Rng;
pub struct ReaderRng<R> {
reader: R
}
impl<R: Reader> ReaderRng<R> {
pub fn new(r: R) -> ReaderRng<R> {
ReaderRng {
reader: r
}
}
}
impl<R: Reader> Rng for ReaderRng<R> {
fn next_u32(&mut self) -> u32 {
if cfg!(target_endian="little") {
self.reader.read_le_u32().unwrap()
} else {
self.reader.read_be_u32().unwrap()
}
}
fn next_u64(&mut self) -> u64 {
if cfg!(target_endian="little") {
self.reader.read_le_u64().unwrap()
} else {
self.reader.read_be_u64().unwrap()
}
}
fn fill_bytes(&mut self, v: &mut [u8]) {
if v.len() == 0 { return }
match self.reader.read_at_least(v.len(), v) {
Ok(_) => {}
Err(e) => panic!("ReaderRng.fill_bytes error: {:?}", e)
}
}
}
#[cfg(test)]
mod test {
use super::ReaderRng;
use std::old_io::MemReader;
use std::num::Int;
use Rng;
#[test]
fn test_reader_rng_u64() {
let v = vec![0u8, 0, 0, 0, 0, 0, 0, 1,
0 , 0, 0, 0, 0, 0, 0, 2,
0, 0, 0, 0, 0, 0, 0, 3];
let mut rng = ReaderRng::new(MemReader::new(v));
assert_eq!(rng.next_u64(), 1_u64.to_be());
assert_eq!(rng.next_u64(), 2_u64.to_be());
assert_eq!(rng.next_u64(), 3_u64.to_be());
}
#[test]
fn test_reader_rng_u32() {
let v = vec![0u8, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3];
let mut rng = ReaderRng::new(MemReader::new(v));
assert_eq!(rng.next_u32(), 1_u32.to_be());
assert_eq!(rng.next_u32(), 2_u32.to_be());
assert_eq!(rng.next_u32(), 3_u32.to_be());
}
#[test]
fn test_reader_rng_fill_bytes() {
let v = [1u8, 2, 3, 4, 5, 6, 7, 8];
let mut w = [0u8; 8];
let mut rng = ReaderRng::new(MemReader::new(v.to_vec()));
rng.fill_bytes(&mut w);
assert!(v == w);
}
#[test]
#[should_fail]
fn test_reader_rng_insufficient_bytes() {
let mut rng = ReaderRng::new(MemReader::new(vec!()));
let mut v = [0u8; 3];
rng.fill_bytes(&mut v);
}
}