76 lines
1.9 KiB
Rust
76 lines
1.9 KiB
Rust
use crate::buf::UninitSlice;
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use crate::BufMut;
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use core::cmp;
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/// A `BufMut` adapter which limits the amount of bytes that can be written
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/// to an underlying buffer.
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#[derive(Debug)]
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pub struct Limit<T> {
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inner: T,
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limit: usize,
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}
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pub(super) fn new<T>(inner: T, limit: usize) -> Limit<T> {
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Limit { inner, limit }
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}
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impl<T> Limit<T> {
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/// Consumes this `Limit`, returning the underlying value.
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pub fn into_inner(self) -> T {
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self.inner
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}
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/// Gets a reference to the underlying `BufMut`.
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///
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/// It is inadvisable to directly write to the underlying `BufMut`.
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pub fn get_ref(&self) -> &T {
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&self.inner
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}
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/// Gets a mutable reference to the underlying `BufMut`.
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///
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/// It is inadvisable to directly write to the underlying `BufMut`.
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pub fn get_mut(&mut self) -> &mut T {
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&mut self.inner
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}
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/// Returns the maximum number of bytes that can be written
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///
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/// # Note
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///
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/// If the inner `BufMut` has fewer bytes than indicated by this method then
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/// that is the actual number of available bytes.
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pub fn limit(&self) -> usize {
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self.limit
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}
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/// Sets the maximum number of bytes that can be written.
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///
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/// # Note
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///
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/// If the inner `BufMut` has fewer bytes than `lim` then that is the actual
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/// number of available bytes.
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pub fn set_limit(&mut self, lim: usize) {
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self.limit = lim
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}
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}
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unsafe impl<T: BufMut> BufMut for Limit<T> {
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fn remaining_mut(&self) -> usize {
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cmp::min(self.inner.remaining_mut(), self.limit)
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}
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fn chunk_mut(&mut self) -> &mut UninitSlice {
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let bytes = self.inner.chunk_mut();
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let end = cmp::min(bytes.len(), self.limit);
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&mut bytes[..end]
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}
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unsafe fn advance_mut(&mut self, cnt: usize) {
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assert!(cnt <= self.limit);
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self.inner.advance_mut(cnt);
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self.limit -= cnt;
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}
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}
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