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// Copyright 2018 Brian Smith.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
use alloc::{boxed::Box, vec::Vec};
pub trait Accumulator {
fn write_byte(&mut self, value: u8) -> Result<(), TooLongError>;
fn write_bytes(&mut self, value: &[u8]) -> Result<(), TooLongError>;
}
pub(super) struct LengthMeasurement {
len: usize,
}
impl From<LengthMeasurement> for usize {
fn from(len: LengthMeasurement) -> usize {
len.len
}
}
impl LengthMeasurement {
pub fn zero() -> Self {
Self { len: 0 }
}
}
impl Accumulator for LengthMeasurement {
fn write_byte(&mut self, _value: u8) -> Result<(), TooLongError> {
self.len = self.len.checked_add(1).ok_or_else(TooLongError::new)?;
Ok(())
}
fn write_bytes(&mut self, value: &[u8]) -> Result<(), TooLongError> {
self.len = self
.len
.checked_add(value.len())
.ok_or_else(TooLongError::new)?;
Ok(())
}
}
pub(super) struct Writer {
bytes: Vec<u8>,
requested_capacity: usize,
}
impl Writer {
pub(super) fn with_capacity(capacity: LengthMeasurement) -> Self {
Self {
bytes: Vec::with_capacity(capacity.len),
requested_capacity: capacity.len,
}
}
}
impl From<Writer> for Box<[u8]> {
fn from(writer: Writer) -> Self {
assert_eq!(writer.requested_capacity, writer.bytes.len());
writer.bytes.into_boxed_slice()
}
}
impl Accumulator for Writer {
fn write_byte(&mut self, value: u8) -> Result<(), TooLongError> {
self.bytes.push(value);
Ok(())
}
fn write_bytes(&mut self, value: &[u8]) -> Result<(), TooLongError> {
self.bytes.extend(value);
Ok(())
}
}
pub fn write_copy(
accumulator: &mut dyn Accumulator,
to_copy: untrusted::Input,
) -> Result<(), TooLongError> {
accumulator.write_bytes(to_copy.as_slice_less_safe())
}
pub struct TooLongError(());
impl TooLongError {
pub fn new() -> Self {
Self(())
}
}
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