alloc support (for no_std environments)

Gates all allocator-dependent features on the 'alloc' cargo feature,
allowing use in no_std environments which have a heap and defined
allocator, but not full support for 'std'.

Author: tarcieri

.travis.yml

@@ -37,6 +37,10 @@ matrix:
     - env: EXTRA_ARGS="--no-default-features"
       script: cargo build $EXTRA_ARGS
 
+    # `alloc` crate-based implementation
+    - env: EXTRA_ARGS="--no-default-features --features=alloc --lib --tests"
+      rust: nightly # TODO: test 'alloc' on stable rust when it is fully stabilized
+
     # Serde implementation
     - env: EXTRA_ARGS="--features serde"
 

Cargo.toml

@@ -38,5 +38,6 @@ serde_test = "1.0"
 
 [features]
 default = ["std"]
+alloc = []
 i128 = ["byteorder/i128"]
-std = ["iovec"]
+std = ["alloc", "iovec"]

src/buf/buf.rs

@@ -2,7 +2,7 @@ use super::{IntoBuf, Take, Reader, Iter, FromBuf, Chain};
 use byteorder::{BigEndian, ByteOrder, LittleEndian};
 #[cfg(feature = "iovec")]
 use iovec::IoVec;
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 use prelude::*;
 
 use core::{cmp, ptr};
@@ -1077,7 +1077,7 @@ impl<'a, T: Buf + ?Sized> Buf for &'a mut T {
     }
 }
 
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 impl<T: Buf + ?Sized> Buf for Box<T> {
     fn remaining(&self) -> usize {
         (**self).remaining()

src/buf/buf_mut.rs

@@ -2,7 +2,7 @@ use super::{IntoBuf, Writer};
 use byteorder::{LittleEndian, ByteOrder, BigEndian};
 #[cfg(feature = "iovec")]
 use iovec::IoVec;
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 use prelude::*;
 
 use core::{cmp, ptr, usize};
@@ -1088,7 +1088,7 @@ impl<'a, T: BufMut + ?Sized> BufMut for &'a mut T {
     }
 }
 
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 impl<T: BufMut + ?Sized> BufMut for Box<T> {
     fn remaining_mut(&self) -> usize {
         (**self).remaining_mut()
@@ -1098,6 +1098,7 @@ impl<T: BufMut + ?Sized> BufMut for Box<T> {
         (**self).bytes_mut()
     }
 
+    #[cfg(feature = "iovec")]
     unsafe fn bytes_vec_mut<'b>(&'b mut self, dst: &mut [&'b mut IoVec]) -> usize {
         (**self).bytes_vec_mut(dst)
     }
@@ -1136,7 +1137,7 @@ impl<T: AsMut<[u8]> + AsRef<[u8]>> BufMut for io::Cursor<T> {
     }
 }
 
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 impl BufMut for Vec<u8> {
     #[inline]
     fn remaining_mut(&self) -> usize {

src/buf/from_buf.rs

@@ -1,7 +1,7 @@
 use {IntoBuf};
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 use prelude::*;
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 use {Buf, BufMut, Bytes, BytesMut};
 
 /// Conversion from a [`Buf`]
@@ -90,7 +90,7 @@ pub trait FromBuf {
     fn from_buf<T>(buf: T) -> Self where T: IntoBuf;
 }
 
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 impl FromBuf for Vec<u8> {
     fn from_buf<T>(buf: T) -> Self
         where T: IntoBuf
@@ -102,7 +102,7 @@ impl FromBuf for Vec<u8> {
     }
 }
 
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 impl FromBuf for Bytes {
     fn from_buf<T>(buf: T) -> Self
         where T: IntoBuf
@@ -111,7 +111,7 @@ impl FromBuf for Bytes {
     }
 }
 
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 impl FromBuf for BytesMut {
     fn from_buf<T>(buf: T) -> Self
         where T: IntoBuf

src/buf/mod.rs

@@ -24,7 +24,7 @@ mod into_buf;
 mod iter;
 mod reader;
 mod take;
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 mod vec_deque;
 mod writer;
 

src/buf/vec_deque.rs

@@ -1,3 +1,6 @@
+#[cfg(all(feature = "alloc", not(feature = "std")))]
+use alloc::collections::vec_deque::VecDeque;
+#[cfg(feature = "std")]
 use std::collections::VecDeque;
 
 use super::Buf;

src/bytes.rs

@@ -1,14 +1,19 @@
-use {IntoBuf, Buf, BufMut};
+use {BufMut};
+#[cfg(feature = "std")]
+use {Buf, IntoBuf};
+#[cfg(feature = "std")]
 use buf::Iter;
 use debug;
 use prelude::*;
 
-use std::{cmp, fmt, mem, hash, ops, slice, ptr, usize};
-use std::borrow::{Borrow, BorrowMut};
+use core::{cmp, fmt, mem, hash, ops, slice, ptr, usize};
+use core::borrow::{Borrow, BorrowMut};
+use core::sync::atomic::{self, AtomicUsize, AtomicPtr};
+use core::sync::atomic::Ordering::{Relaxed, Acquire, Release, AcqRel};
+use core::iter::{FromIterator, Iterator};
+
+#[cfg(feature = "std")]
 use std::io::Cursor;
-use std::sync::atomic::{self, AtomicUsize, AtomicPtr};
-use std::sync::atomic::Ordering::{Relaxed, Acquire, Release, AcqRel};
-use std::iter::{FromIterator, Iterator};
 
 /// A reference counted contiguous slice of memory.
 ///
@@ -835,6 +840,7 @@ impl Bytes {
     }
 }
 
+#[cfg(feature = "std")]
 impl IntoBuf for Bytes {
     type Buf = Cursor<Self>;
 
@@ -843,6 +849,7 @@ impl IntoBuf for Bytes {
     }
 }
 
+#[cfg(feature = "std")]
 impl<'a> IntoBuf for &'a Bytes {
     type Buf = Cursor<Self>;
 
@@ -986,6 +993,7 @@ impl Borrow<[u8]> for Bytes {
     }
 }
 
+#[cfg(feature = "std")]
 impl IntoIterator for Bytes {
     type Item = u8;
     type IntoIter = Iter<Cursor<Bytes>>;
@@ -995,6 +1003,7 @@ impl IntoIterator for Bytes {
     }
 }
 
+#[cfg(feature = "std")]
 impl<'a> IntoIterator for &'a Bytes {
     type Item = u8;
     type IntoIter = Iter<Cursor<&'a Bytes>>;
@@ -1563,6 +1572,7 @@ impl BufMut for BytesMut {
     }
 }
 
+#[cfg(feature = "std")]
 impl IntoBuf for BytesMut {
     type Buf = Cursor<Self>;
 
@@ -1571,6 +1581,7 @@ impl IntoBuf for BytesMut {
     }
 }
 
+#[cfg(feature = "std")]
 impl<'a> IntoBuf for &'a BytesMut {
     type Buf = Cursor<&'a BytesMut>;
 
@@ -1736,6 +1747,7 @@ impl Clone for BytesMut {
     }
 }
 
+#[cfg(feature = "std")]
 impl IntoIterator for BytesMut {
     type Item = u8;
     type IntoIter = Iter<Cursor<BytesMut>>;
@@ -1745,6 +1757,7 @@ impl IntoIterator for BytesMut {
     }
 }
 
+#[cfg(feature = "std")]
 impl<'a> IntoIterator for &'a BytesMut {
     type Item = u8;
     type IntoIter = Iter<Cursor<&'a BytesMut>>;

src/debug.rs

@@ -1,4 +1,4 @@
-use std::fmt;
+use core::fmt;
 
 /// Alternative implementation of `fmt::Debug` for byte slice.
 ///

src/lib.rs

@@ -72,6 +72,8 @@
 #![doc(html_root_url = "https://docs.rs/bytes/0.4.12")]
 #![no_std]
 
+#[cfg(all(feature = "alloc", not(feature = "std")))]
+extern crate alloc;
 extern crate byteorder;
 #[cfg(feature = "iovec")]
 extern crate iovec;
@@ -92,13 +94,13 @@ pub use buf::{
     Take,
 };
 
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 mod bytes;
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 mod debug;
-#[cfg(feature = "std")]
-pub use bytes::{Bytes, BytesMut};
 mod prelude;
+#[cfg(feature = "alloc")]
+pub use bytes::{Bytes, BytesMut};
 
 #[deprecated]
 pub use byteorder::{ByteOrder, BigEndian, LittleEndian};