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Diffstat (limited to 'rand/src/read.rs')
-rw-r--r-- | rand/src/read.rs | 123 |
1 files changed, 0 insertions, 123 deletions
diff --git a/rand/src/read.rs b/rand/src/read.rs deleted file mode 100644 index c7351b7..0000000 --- a/rand/src/read.rs +++ /dev/null @@ -1,123 +0,0 @@ -// 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. - -use std::io::{self, Read}; -use std::mem; -use 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. -/// -/// # Example -/// -/// ```rust -/// use rand::{read, Rng}; -/// -/// let data = vec![1, 2, 3, 4, 5, 6, 7, 8]; -/// let mut rng = read::ReadRng::new(&data[..]); -/// println!("{:x}", rng.gen::<u32>()); -/// ``` -#[derive(Debug)] -pub struct ReadRng<R> { - reader: R -} - -impl<R: Read> ReadRng<R> { - /// Create a new `ReadRng` from a `Read`. - pub fn new(r: R) -> ReadRng<R> { - ReadRng { - reader: r - } - } -} - -impl<R: Read> Rng for ReadRng<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 buf = [0; 4]; - fill(&mut self.reader, &mut buf).unwrap(); - unsafe { *(buf.as_ptr() as *const u32) } - } - fn next_u64(&mut self) -> u64 { - // see above for explanation. - let mut buf = [0; 8]; - fill(&mut self.reader, &mut buf).unwrap(); - unsafe { *(buf.as_ptr() as *const u64) } - } - fn fill_bytes(&mut self, v: &mut [u8]) { - if v.len() == 0 { return } - fill(&mut self.reader, v).unwrap(); - } -} - -fn fill(r: &mut Read, mut buf: &mut [u8]) -> io::Result<()> { - while buf.len() > 0 { - match try!(r.read(buf)) { - 0 => return Err(io::Error::new(io::ErrorKind::Other, - "end of file reached")), - n => buf = &mut mem::replace(&mut buf, &mut [])[n..], - } - } - Ok(()) -} - -#[cfg(test)] -mod test { - use super::ReadRng; - use Rng; - - #[test] - fn test_reader_rng_u64() { - // transmute from the target to avoid endianness concerns. - 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 = ReadRng::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 = ReadRng::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 = ReadRng::new(&v[..]); - rng.fill_bytes(&mut w); - - assert!(v == w); - } - - #[test] - #[should_panic] - fn test_reader_rng_insufficient_bytes() { - let mut rng = ReadRng::new(&[][..]); - let mut v = [0u8; 3]; - rng.fill_bytes(&mut v); - } -} |