jj/lib/src/hex_util.rs
2023-07-10 18:28:59 +03:00

84 lines
2.3 KiB
Rust

// Copyright 2023 The Jujutsu Authors
//
// Licensed 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
//
// https://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.
#![allow(missing_docs)]
fn to_reverse_hex_digit(b: u8) -> Option<u8> {
let value = match b {
b'0'..=b'9' => b - b'0',
b'A'..=b'F' => b - b'A' + 10,
b'a'..=b'f' => b - b'a' + 10,
_ => return None,
};
Some(b'z' - value)
}
fn to_forward_hex_digit(b: u8) -> Option<u8> {
let value = match b {
b'k'..=b'z' => b'z' - b,
b'K'..=b'Z' => b'Z' - b,
_ => return None,
};
if value < 10 {
Some(b'0' + value)
} else {
Some(b'a' + value - 10)
}
}
pub fn to_forward_hex(reverse_hex: &str) -> Option<String> {
reverse_hex
.bytes()
.map(|b| to_forward_hex_digit(b).map(char::from))
.collect()
}
pub fn to_reverse_hex(forward_hex: &str) -> Option<String> {
forward_hex
.bytes()
.map(|b| to_reverse_hex_digit(b).map(char::from))
.collect()
}
#[cfg(test)]
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_reverse_hex() {
// Empty string
assert_eq!(to_reverse_hex(""), Some("".to_string()));
assert_eq!(to_forward_hex(""), Some("".to_string()));
// Single digit
assert_eq!(to_reverse_hex("0"), Some("z".to_string()));
assert_eq!(to_forward_hex("z"), Some("0".to_string()));
// All digits
assert_eq!(
to_reverse_hex("0123456789abcdefABCDEF"),
Some("zyxwvutsrqponmlkponmlk".to_string())
);
assert_eq!(
to_forward_hex("zyxwvutsrqponmlkPONMLK"),
Some("0123456789abcdefabcdef".to_string())
);
// Invalid digit
assert_eq!(to_reverse_hex("g"), None);
assert_eq!(to_forward_hex("j"), None);
}
}