io: add std/alloc features, add Box/Vec impls.

Author: Dirbaio

embedded-io/Cargo.toml

@@ -10,3 +10,11 @@ categories = [
     "embedded",
     "no-std",
 ]
+
+[features]
+std = ["alloc"]
+alloc = []
+
+[package.metadata.docs.rs]
+features = ["std"]
+rustdoc-args = ["--cfg", "docsrs"]

embedded-io/src/impls/boxx.rs

@@ -0,0 +1,47 @@
+use crate::{BufRead, Io, Read, Seek, Write};
+use alloc::boxed::Box;
+
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
+impl<T: ?Sized + Io> Io for Box<T> {
+    type Error = T::Error;
+}
+
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
+impl<T: ?Sized + Read> Read for Box<T> {
+    #[inline]
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
+        T::read(self, buf)
+    }
+}
+
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
+impl<T: ?Sized + BufRead> BufRead for Box<T> {
+    fn fill_buf(&mut self) -> Result<&[u8], Self::Error> {
+        T::fill_buf(self)
+    }
+
+    fn consume(&mut self, amt: usize) {
+        T::consume(self, amt)
+    }
+}
+
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
+impl<T: ?Sized + Write> Write for Box<T> {
+    #[inline]
+    fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        T::write(self, buf)
+    }
+
+    #[inline]
+    fn flush(&mut self) -> Result<(), Self::Error> {
+        T::flush(self)
+    }
+}
+
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
+impl<T: ?Sized + Seek> Seek for Box<T> {
+    #[inline]
+    fn seek(&mut self, pos: crate::SeekFrom) -> Result<u64, Self::Error> {
+        T::seek(self, pos)
+    }
+}

embedded-io/src/impls/mod.rs

@@ -1,2 +1,7 @@
 mod slice_mut;
 mod slice_ref;
+
+#[cfg(feature = "alloc")]
+mod boxx;
+#[cfg(feature = "alloc")]
+mod vec;

embedded-io/src/impls/vec.rs

@@ -0,0 +1,21 @@
+use crate::{Io, Write};
+use alloc::vec::Vec;
+
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
+impl Io for Vec<u8> {
+    type Error = core::convert::Infallible;
+}
+
+#[cfg_attr(docsrs, doc(cfg(any(feature = "std", feature = "alloc"))))]
+impl Write for Vec<u8> {
+    #[inline]
+    fn write(&mut self, buf: &[u8]) -> Result<usize, Self::Error> {
+        self.extend_from_slice(buf);
+        Ok(buf.len())
+    }
+
+    #[inline]
+    fn flush(&mut self) -> Result<(), Self::Error> {
+        Ok(())
+    }
+}

embedded-io/src/lib.rs

@@ -1,9 +1,13 @@
-#![no_std]
+#![cfg_attr(not(feature = "std"), no_std)]
+#![cfg_attr(docsrs, feature(doc_cfg))]
 #![warn(missing_docs)]
 #![doc = include_str!("../README.md")]
 
 use core::fmt;
 
+#[cfg(feature = "alloc")]
+extern crate alloc;
+
 mod impls;
 
 /// Enumeration of possible methods to seek within an I/O object.
@@ -87,6 +91,9 @@ impl<E: fmt::Debug> fmt::Display for ReadExactError<E> {
     }
 }
 
+#[cfg(feature = "std")]
+impl<E: fmt::Debug> std::error::Error for ReadExactError<E> {}
+
 /// Error returned by [`Write::write_fmt`]
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub enum WriteFmtError<E> {
@@ -110,6 +117,9 @@ impl<E: fmt::Debug> fmt::Display for WriteFmtError<E> {
     }
 }
 
+#[cfg(feature = "std")]
+impl<E: fmt::Debug> std::error::Error for WriteFmtError<E> {}
+
 /// Error returned by [`Write::write_all`]
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub enum WriteAllError<E> {
@@ -131,6 +141,9 @@ impl<E: fmt::Debug> fmt::Display for WriteAllError<E> {
     }
 }
 
+#[cfg(feature = "std")]
+impl<E: fmt::Debug> std::error::Error for WriteAllError<E> {}
+
 /// Blocking reader.
 ///
 /// Semantics are the same as [`std::io::Read`], check its documentation for details.