`impl<T> Write for UniquePtr<T> where ... Pin<&a mut T> : Write`.
This commit implements forwarding of `Write` trait implementation from
`UniquePtr<T>` to the pointee type. This is quite similar to how
`Box<T>` also forwards - see
https://doc.rust-lang.org/std/boxed/struct.Box.html#impl-Write-for-Box%3CW%3E
This commit has quite similar, orphan-rule-related motivation as the
earlier https://github.com/dtolnay/cxx/pull/1368 which covered the
`Read` trait. For a more specific motivating example, please see
http://review.skia.org/skia/+/923337/3/experimental/rust_png/ffi/FFI.rs#254
diff --git a/src/unique_ptr.rs b/src/unique_ptr.rs
index b56dbe8..ac38729 100644
--- a/src/unique_ptr.rs
+++ b/src/unique_ptr.rs
@@ -14,7 +14,7 @@
use core::ops::{Deref, DerefMut};
use core::pin::Pin;
#[cfg(feature = "std")]
-use std::io::{self, Read};
+use std::io::{self, Read, Write};
/// Binding to C++ `std::unique_ptr<T, std::default_delete<T>>`.
#[repr(C)]
@@ -220,6 +220,44 @@
// `read_buf` and/or `is_read_vectored`).
}
+/// Forwarding `Write` trait implementation in a manner similar to `Box<T>`.
+///
+/// Note that the implementation will panic for null `UniquePtr<T>`.
+#[cfg(feature = "std")]
+impl<T> Write for UniquePtr<T>
+where
+ for<'a> Pin<&'a mut T>: Write,
+ T: UniquePtrTarget,
+{
+ #[inline]
+ fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+ self.pin_mut().write(buf)
+ }
+
+ #[inline]
+ fn write_vectored(&mut self, bufs: &[io::IoSlice<'_>]) -> io::Result<usize> {
+ self.pin_mut().write_vectored(bufs)
+ }
+
+ #[inline]
+ fn flush(&mut self) -> io::Result<()> {
+ self.pin_mut().flush()
+ }
+
+ #[inline]
+ fn write_all(&mut self, buf: &[u8]) -> io::Result<()> {
+ self.pin_mut().write_all(buf)
+ }
+
+ #[inline]
+ fn write_fmt(&mut self, fmt: fmt::Arguments<'_>) -> io::Result<()> {
+ self.pin_mut().write_fmt(fmt)
+ }
+
+ // TODO: Foward other `Write` trait methods when they get stabilized (e.g.
+ // `write_all_vectored` and/or `is_write_vectored`).
+}
+
/// Trait bound for types which may be used as the `T` inside of a
/// `UniquePtr<T>` in generic code.
///
