openethereum/util/src/bytes.rs

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// Copyright 2015, 2016 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
//! General bytes-related utilities.
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//!
//! Includes a pretty-printer for bytes, in the form of `ToPretty` and `PrettySlice`
//! as
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use std::fmt;
use std::cmp::min;
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use std::ops::{Deref, DerefMut};
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/// Slice pretty print helper
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pub struct PrettySlice<'a> (&'a [u8]);
impl<'a> fmt::Debug for PrettySlice<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
for i in 0..self.0.len() {
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match i > 0 {
true => { write!(f, "·{:02x}", self.0[i])?; },
false => { write!(f, "{:02x}", self.0[i])?; },
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}
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}
Ok(())
}
}
impl<'a> fmt::Display for PrettySlice<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
for i in 0..self.0.len() {
write!(f, "{:02x}", self.0[i])?;
}
Ok(())
}
}
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/// Trait to allow a type to be pretty-printed in `format!`, where unoverridable
/// defaults cannot otherwise be avoided.
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pub trait ToPretty {
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/// Convert a type into a derivative form in order to make `format!` print it prettily.
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fn pretty(&self) -> PrettySlice;
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/// Express the object as a hex string.
fn to_hex(&self) -> String {
format!("{}", self.pretty())
}
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}
impl<T: AsRef<[u8]>> ToPretty for T {
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fn pretty(&self) -> PrettySlice {
PrettySlice(self.as_ref())
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}
}
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/// A byte collection reference that can either be a slice or a vector
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pub enum BytesRef<'a> {
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/// This is a reference to a vector
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Flexible(&'a mut Bytes),
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/// This is a reference to a slice
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Fixed(&'a mut [u8])
}
impl<'a> BytesRef<'a> {
/// Writes given `input` to this `BytesRef` starting at `offset`.
/// Returns number of bytes written to the ref.
/// NOTE can return number greater then `input.len()` in case flexible vector had to be extended.
pub fn write(&mut self, offset: usize, input: &[u8]) -> usize {
match *self {
BytesRef::Flexible(ref mut data) => {
let data_len = data.len();
let wrote = input.len() + if data_len > offset { 0 } else { offset - data_len };
data.resize(offset, 0);
data.extend_from_slice(input);
wrote
},
BytesRef::Fixed(ref mut data) if offset < data.len() => {
let max = min(data.len() - offset, input.len());
for i in 0..max {
data[offset + i] = input[i];
}
max
},
_ => 0
}
}
}
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impl<'a> Deref for BytesRef<'a> {
type Target = [u8];
fn deref(&self) -> &[u8] {
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match *self {
BytesRef::Flexible(ref bytes) => bytes,
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BytesRef::Fixed(ref bytes) => bytes,
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}
}
}
impl <'a> DerefMut for BytesRef<'a> {
fn deref_mut(&mut self) -> &mut [u8] {
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match *self {
BytesRef::Flexible(ref mut bytes) => bytes,
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BytesRef::Fixed(ref mut bytes) => bytes,
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}
}
}
/// Vector of bytes.
pub type Bytes = Vec<u8>;
#[cfg(test)]
mod tests {
use super::BytesRef;
#[test]
fn should_write_bytes_to_fixed_bytesref() {
// given
let mut data1 = vec![0, 0, 0];
let mut data2 = vec![0, 0, 0];
let (res1, res2) = {
let mut bytes1 = BytesRef::Fixed(&mut data1[..]);
let mut bytes2 = BytesRef::Fixed(&mut data2[1..2]);
// when
let res1 = bytes1.write(1, &[1, 1, 1]);
let res2 = bytes2.write(3, &[1, 1, 1]);
(res1, res2)
};
// then
assert_eq!(&data1, &[0, 1, 1]);
assert_eq!(res1, 2);
assert_eq!(&data2, &[0, 0, 0]);
assert_eq!(res2, 0);
}
#[test]
fn should_write_bytes_to_flexible_bytesref() {
// given
let mut data1 = vec![0, 0, 0];
let mut data2 = vec![0, 0, 0];
let mut data3 = vec![0, 0, 0];
let (res1, res2, res3) = {
let mut bytes1 = BytesRef::Flexible(&mut data1);
let mut bytes2 = BytesRef::Flexible(&mut data2);
let mut bytes3 = BytesRef::Flexible(&mut data3);
// when
let res1 = bytes1.write(1, &[1, 1, 1]);
let res2 = bytes2.write(3, &[1, 1, 1]);
let res3 = bytes3.write(5, &[1, 1, 1]);
(res1, res2, res3)
};
// then
assert_eq!(&data1, &[0, 1, 1, 1]);
assert_eq!(res1, 3);
assert_eq!(&data2, &[0, 0, 0, 1, 1, 1]);
assert_eq!(res2, 3);
assert_eq!(&data3, &[0, 0, 0, 0, 0, 1, 1, 1]);
assert_eq!(res3, 5);
}
}