+++ /dev/null
-// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-//! A wrapper around any Read to treat it as an RNG.
-
-#![allow(dead_code)]
-
-use io::prelude::*;
-use rand::Rng;
-
-/// An RNG that reads random bytes straight from a `Read`. This will
-/// work best with an infinite reader, but this is not required.
-///
-/// # Panics
-///
-/// It will panic if it there is insufficient data to fulfill a request.
-pub struct ReaderRng<R> {
- reader: R
-}
-
-impl<R: Read> ReaderRng<R> {
- /// Create a new `ReaderRng` from a `Read`.
- pub fn new(r: R) -> ReaderRng<R> {
- ReaderRng {
- reader: r
- }
- }
-}
-
-impl<R: Read> Rng for ReaderRng<R> {
- fn next_u32(&mut self) -> u32 {
- // This is designed for speed: reading a LE integer on a LE
- // platform just involves blitting the bytes into the memory
- // of the u32, similarly for BE on BE; avoiding byteswapping.
- let mut bytes = [0; 4];
- self.fill_bytes(&mut bytes);
- unsafe { *(bytes.as_ptr() as *const u32) }
- }
- fn next_u64(&mut self) -> u64 {
- // see above for explanation.
- let mut bytes = [0; 8];
- self.fill_bytes(&mut bytes);
- unsafe { *(bytes.as_ptr() as *const u64) }
- }
- fn fill_bytes(&mut self, mut v: &mut [u8]) {
- while !v.is_empty() {
- let t = v;
- match self.reader.read(t) {
- Ok(0) => panic!("ReaderRng.fill_bytes: EOF reached"),
- Ok(n) => v = t.split_at_mut(n).1,
- Err(e) => panic!("ReaderRng.fill_bytes: {}", e),
- }
- }
- }
-}
-
-#[cfg(test)]
-mod tests {
- use super::ReaderRng;
- use rand::Rng;
-
- #[test]
- fn test_reader_rng_u64() {
- // transmute from the target to avoid endianness concerns.
- let v = &[0, 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(v);
-
- assert_eq!(rng.next_u64(), 1u64.to_be());
- assert_eq!(rng.next_u64(), 2u64.to_be());
- assert_eq!(rng.next_u64(), 3u64.to_be());
- }
- #[test]
- fn test_reader_rng_u32() {
- let v = &[0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3][..];
- let mut rng = ReaderRng::new(v);
-
- assert_eq!(rng.next_u32(), 1u32.to_be());
- assert_eq!(rng.next_u32(), 2u32.to_be());
- assert_eq!(rng.next_u32(), 3u32.to_be());
- }
- #[test]
- fn test_reader_rng_fill_bytes() {
- let v = [1, 2, 3, 4, 5, 6, 7, 8];
- let mut w = [0; 8];
-
- let mut rng = ReaderRng::new(&v[..]);
- rng.fill_bytes(&mut w);
-
- assert!(v == w);
- }
-
- #[test]
- #[should_panic]
- fn test_reader_rng_insufficient_bytes() {
- let mut rng = ReaderRng::new(&[][..]);
- let mut v = [0; 3];
- rng.fill_bytes(&mut v);
- }
-}