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