| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you under the Apache License, Version 2.0 (the |
| // "License"); you may not use this file except in compliance |
| // with the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License.. |
| |
| //! A wrapper around any Read to treat it as an RNG. |
| |
| #![allow(dead_code)] |
| |
| use crate::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), |
| } |
| } |
| } |
| } |