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https://github.com/mimblewimble/grin.git
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6556dd585d
Currently we pass a Vec. This requires an extra allocation and copy of all elements if a caller doesn't have a Vec already, which is at least 95% of cases. Another, a smaller issue, we have a function util::to_hex and some structs implement to_hex() on top of it, so we have a mix of it in the code. This PR introduces a trait and a blanket impl for AsRef<[u8]> which brings a uniform API (obj.to_hex()). One unfortunate case is arrays of size bigger than 32 - Rust doesn't implement AsRef for them so it requires an ugly hack (&array[..]).to_hex().
88 lines
2.6 KiB
Rust
88 lines
2.6 KiB
Rust
// Copyright 2020 The Grin Developers
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/// Implements hex-encoding from bytes to string and decoding of strings
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/// to bytes. Given that rustc-serialize is deprecated and serde doesn't
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/// provide easy hex encoding, hex is a bit in limbo right now in Rust-
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/// land. It's simple enough that we can just have our own.
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use std::fmt::Write;
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/// Encode the provided bytes into a hex string
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fn to_hex(bytes: &[u8]) -> String {
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let mut s = String::with_capacity(bytes.len() * 2);
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for byte in bytes {
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write!(&mut s, "{:02x}", byte).expect("Unable to write hex");
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}
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s
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}
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/// Convert to hex
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pub trait ToHex {
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/// convert to hex
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fn to_hex(&self) -> String;
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}
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impl<T: AsRef<[u8]>> ToHex for T {
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fn to_hex(&self) -> String {
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to_hex(self.as_ref())
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}
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}
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/// Decode a hex string into bytes.
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pub fn from_hex(hex: &str) -> Result<Vec<u8>, String> {
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let hex = hex.trim().trim_start_matches("0x");
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if hex.len() % 2 != 0 {
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Err(hex.to_string())
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} else {
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(0..hex.len())
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.step_by(2)
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.map(|i| u8::from_str_radix(&hex[i..i + 2], 16).map_err(|_| hex.to_string()))
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.collect()
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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 super::*;
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#[test]
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fn test_to_hex() {
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assert_eq!(vec![0, 0, 0, 0].to_hex(), "00000000");
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assert_eq!(vec![10, 11, 12, 13].to_hex(), "0a0b0c0d");
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assert_eq!([0, 0, 0, 255].to_hex(), "000000ff");
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}
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#[test]
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fn test_to_hex_trait() {
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assert_eq!(vec![0, 0, 0, 0].to_hex(), "00000000");
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assert_eq!(vec![10, 11, 12, 13].to_hex(), "0a0b0c0d");
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assert_eq!([0, 0, 0, 255].to_hex(), "000000ff");
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}
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#[test]
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fn test_from_hex() {
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assert_eq!(from_hex(""), Ok(vec![]));
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assert_eq!(from_hex("00000000"), Ok(vec![0, 0, 0, 0]));
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assert_eq!(from_hex("0a0b0c0d"), Ok(vec![10, 11, 12, 13]));
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assert_eq!(from_hex("000000ff"), Ok(vec![0, 0, 0, 255]));
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assert_eq!(from_hex("0x000000ff"), Ok(vec![0, 0, 0, 255]));
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assert_eq!(from_hex("0x000000fF"), Ok(vec![0, 0, 0, 255]));
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assert_eq!(from_hex("0x000000fg"), Err("000000fg".to_string()));
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assert_eq!(
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from_hex("not a hex string"),
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Err("not a hex string".to_string())
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);
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assert_eq!(from_hex("0"), Err("0".to_string()));
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}
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}
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