7828c3dd28
https://github.com/rust-lang/rfcs/pull/221 The current terminology of "task failure" often causes problems when writing or speaking about code. You often want to talk about the possibility of an operation that returns a Result "failing", but cannot because of the ambiguity with task failure. Instead, you have to speak of "the failing case" or "when the operation does not succeed" or other circumlocutions. Likewise, we use a "Failure" header in rustdoc to describe when operations may fail the task, but it would often be helpful to separate out a section describing the "Err-producing" case. We have been steadily moving away from task failure and toward Result as an error-handling mechanism, so we should optimize our terminology accordingly: Result-producing functions should be easy to describe. To update your code, rename any call to `fail!` to `panic!` instead. Assuming you have not created your own macro named `panic!`, this will work on UNIX based systems: grep -lZR 'fail!' . | xargs -0 -l sed -i -e 's/fail!/panic!/g' You can of course also do this by hand. [breaking-change]
122 lines
3.5 KiB
Rust
122 lines
3.5 KiB
Rust
// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! A wrapper around any Reader to treat it as an RNG.
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use collections::Collection;
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use io::Reader;
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use rand::Rng;
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use result::{Ok, Err};
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/// An RNG that reads random bytes straight from a `Reader`. This will
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/// work best with an infinite reader, but this is not required.
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///
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/// # Panics
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///
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/// It will panic if it there is insufficient data to fulfill a request.
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///
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/// # Example
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///
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/// ```rust
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/// use std::rand::{reader, Rng};
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/// use std::io::MemReader;
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///
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/// let mut rng = reader::ReaderRng::new(MemReader::new(vec!(1,2,3,4,5,6,7,8)));
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/// println!("{:x}", rng.gen::<uint>());
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/// ```
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pub struct ReaderRng<R> {
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reader: R
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}
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impl<R: Reader> ReaderRng<R> {
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/// Create a new `ReaderRng` from a `Reader`.
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pub fn new(r: R) -> ReaderRng<R> {
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ReaderRng {
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reader: r
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}
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}
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}
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impl<R: Reader> Rng for ReaderRng<R> {
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fn next_u32(&mut self) -> u32 {
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// This is designed for speed: reading a LE integer on a LE
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// platform just involves blitting the bytes into the memory
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// of the u32, similarly for BE on BE; avoiding byteswapping.
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if cfg!(target_endian="little") {
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self.reader.read_le_u32().unwrap()
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} else {
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self.reader.read_be_u32().unwrap()
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}
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}
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fn next_u64(&mut self) -> u64 {
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// see above for explanation.
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if cfg!(target_endian="little") {
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self.reader.read_le_u64().unwrap()
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} else {
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self.reader.read_be_u64().unwrap()
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}
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}
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fn fill_bytes(&mut self, v: &mut [u8]) {
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if v.len() == 0 { return }
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match self.reader.read_at_least(v.len(), v) {
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Ok(_) => {}
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Err(e) => panic!("ReaderRng.fill_bytes error: {}", e)
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}
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}
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}
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#[cfg(test)]
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mod test {
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use prelude::*;
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use super::ReaderRng;
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use io::MemReader;
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use rand::Rng;
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#[test]
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fn test_reader_rng_u64() {
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// transmute from the target to avoid endianness concerns.
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let v = vec![0u8, 0, 0, 0, 0, 0, 0, 1,
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0 , 0, 0, 0, 0, 0, 0, 2,
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0, 0, 0, 0, 0, 0, 0, 3];
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let mut rng = ReaderRng::new(MemReader::new(v));
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assert_eq!(rng.next_u64(), 1_u64.to_be());
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assert_eq!(rng.next_u64(), 2_u64.to_be());
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assert_eq!(rng.next_u64(), 3_u64.to_be());
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}
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#[test]
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fn test_reader_rng_u32() {
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let v = vec![0u8, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 3];
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let mut rng = ReaderRng::new(MemReader::new(v));
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assert_eq!(rng.next_u32(), 1_u32.to_be());
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assert_eq!(rng.next_u32(), 2_u32.to_be());
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assert_eq!(rng.next_u32(), 3_u32.to_be());
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}
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#[test]
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fn test_reader_rng_fill_bytes() {
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let v = [1u8, 2, 3, 4, 5, 6, 7, 8];
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let mut w = [0u8, .. 8];
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let mut rng = ReaderRng::new(MemReader::new(v.as_slice().to_vec()));
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rng.fill_bytes(w);
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assert!(v == w);
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}
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#[test]
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#[should_fail]
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fn test_reader_rng_insufficient_bytes() {
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let mut rng = ReaderRng::new(MemReader::new(vec!()));
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let mut v = [0u8, .. 3];
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rng.fill_bytes(v);
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}
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}
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