Some modules support no_std

.github/workflows/ci.yml

@@ -40,6 +40,7 @@ jobs:
       with:
         command:  check
         args: --features unstable --all --bins --examples --tests
+
     - name: check bench
       uses: actions-rs/cargo@v1
       if: matrix.rust == 'nightly'
@@ -71,6 +72,24 @@ jobs:
         command: test
         args: --doc --features "unstable attributes"
 
+  build__with_no_std:
+    name: Build with no-std
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@master
+
+    - name: setup
+      run: |
+        rustup default nightly
+        rustup target add thumbv7m-none-eabi
+
+    - name: check no_std
+      uses: actions-rs/cargo@v1
+      with:
+        command:  check
+        args: --no-default-features --features alloc --target thumbv7m-none-eabi -Z avoid-dev-deps
+
   check_fmt_and_docs:
     name: Checking fmt and docs
     runs-on: ubuntu-latest

Cargo.toml

@@ -38,15 +38,19 @@ docs = ["attributes", "unstable", "default"]
 unstable = ["std", "broadcaster", "futures-timer"]
 attributes = ["async-attributes"]
 std = [
+  "alloc",
   "crossbeam-utils",
-  "futures-core",
+  "futures-core/std",
   "futures-io",
   "memchr",
   "once_cell",
-  "pin-project-lite",
   "pin-utils",
   "slab",
 ]
+alloc = [
+  "futures-core/alloc",
+  "pin-project-lite",
+]
 
 [dependencies]
 async-attributes = { version = "1.1.1", optional = true }
@@ -55,7 +59,7 @@ broadcaster = { version = "1.0.0", optional = true }
 crossbeam-channel = { version = "0.4.0", optional = true }
 crossbeam-deque = { version = "0.7.2", optional = true }
 crossbeam-utils = { version = "0.7.0", optional = true }
-futures-core = { version = "0.3.1", optional = true }
+futures-core = { version = "0.3.1", optional = true, default-features = false }
 futures-io = { version = "0.3.1", optional = true }
 futures-timer = { version = "2.0.2", optional = true }
 kv-log-macro = { version = "1.0.4", optional = true }

src/future/future/mod.rs

@@ -21,8 +21,8 @@ cfg_unstable_default! {
 }
 
 extension_trait! {
-    use std::pin::Pin;
-    use std::ops::{Deref, DerefMut};
+    use core::pin::Pin;
+    use core::ops::{Deref, DerefMut};
 
     use crate::task::{Context, Poll};
 
@@ -136,7 +136,7 @@ extension_trait! {
 
         [`Future`]: ../future/trait.Future.html
     "#]
-    pub trait FutureExt: std::future::Future {
+    pub trait FutureExt: core::future::Future {
         /// Returns a Future that delays execution for a specified time.
         ///
         /// # Examples

src/future/mod.rs

@@ -46,15 +46,20 @@
 //! [`Future::race`]: trait.Future.html#method.race
 //! [`Future::try_race`]: trait.Future.html#method.try_race
 
-pub use future::Future;
-pub use pending::pending;
-pub use poll_fn::poll_fn;
-pub use ready::ready;
+cfg_alloc! {
+    pub use future::Future;
+    pub(crate) mod future;
+}
+
+cfg_std! {
+    pub use pending::pending;
+    pub use poll_fn::poll_fn;
+    pub use ready::ready;
 
-pub(crate) mod future;
-mod pending;
-mod poll_fn;
-mod ready;
+    mod pending;
+    mod poll_fn;
+    mod ready;
+}
 
 cfg_default! {
     pub use timeout::{timeout, TimeoutError};

src/lib.rs

@@ -221,6 +221,7 @@
 //! features = ["std"]
 //! ```
 
+#![cfg_attr(not(feature = "std"), no_std)]
 #![cfg_attr(feature = "docs", feature(doc_cfg))]
 #![warn(missing_docs, missing_debug_implementations, rust_2018_idioms)]
 #![allow(clippy::mutex_atomic, clippy::module_inception)]
@@ -229,6 +230,8 @@
 #![doc(html_logo_url = "https://async.rs/images/logo--hero.svg")]
 #![recursion_limit = "2048"]
 
+extern crate alloc;
+
 #[macro_use]
 mod utils;
 
@@ -240,14 +243,17 @@ pub use async_attributes::{main, test};
 #[cfg(feature = "std")]
 mod macros;
 
-cfg_std! {
+cfg_alloc! {
+    pub mod task;
     pub mod future;
+    pub mod stream;
+}
+
+cfg_std! {
     pub mod io;
     pub mod os;
     pub mod prelude;
-    pub mod stream;
     pub mod sync;
-    pub mod task;
 }
 
 cfg_default! {

src/stream/double_ended_stream/next_back.rs

@@ -1,5 +1,5 @@
-use std::pin::Pin;
-use std::future::Future;
+use core::pin::Pin;
+use core::future::Future;
 
 use crate::stream::DoubleEndedStream;
 use crate::task::{Context, Poll};

src/stream/double_ended_stream/nth_back.rs

@@ -1,6 +1,6 @@
-use std::future::Future;
-use std::pin::Pin;
-use std::task::{Context, Poll};
+use core::future::Future;
+use core::pin::Pin;
+use core::task::{Context, Poll};
 
 use crate::stream::DoubleEndedStream;
 

src/stream/double_ended_stream/rfind.rs

@@ -1,6 +1,6 @@
-use std::task::{Context, Poll};
-use std::future::Future;
-use std::pin::Pin;
+use core::task::{Context, Poll};
+use core::future::Future;
+use core::pin::Pin;
 
 use crate::stream::DoubleEndedStream;
 

src/stream/double_ended_stream/rfold.rs

@@ -1,6 +1,6 @@
-use std::future::Future;
-use std::pin::Pin;
-use std::task::{Context, Poll};
+use core::future::Future;
+use core::pin::Pin;
+use core::task::{Context, Poll};
 
 use pin_project_lite::pin_project;
 

src/stream/double_ended_stream/try_rfold.rs

@@ -1,5 +1,5 @@
 use crate::future::Future;
-use std::pin::Pin;
+use core::pin::Pin;
 use crate::task::{Context, Poll};
 
 use pin_project_lite::pin_project;

src/stream/empty.rs

@@ -1,5 +1,5 @@
-use std::marker::PhantomData;
-use std::pin::Pin;
+use core::marker::PhantomData;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};

src/stream/extend.rs

@@ -1,6 +1,6 @@
-use std::pin::Pin;
+use core::pin::Pin;
+use core::future::Future;
 
-use crate::prelude::*;
 use crate::stream::IntoStream;
 
 /// Extends a collection with the contents of a stream.

src/stream/from_fn.rs

@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};

src/stream/from_iter.rs

@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 

src/stream/from_stream.rs

@@ -1,5 +1,5 @@
-use std::future::Future;
-use std::pin::Pin;
+use core::future::Future;
+use core::pin::Pin;
 
 use crate::stream::IntoStream;
 

src/stream/interval.rs

@@ -2,10 +2,10 @@ use std::pin::Pin;
 use std::task::{Context, Poll};
 use std::time::{Duration, Instant};
 
+use crate::future::Future;
+use crate::stream::Stream;
 use futures_timer::Delay;
 
-use crate::prelude::*;
-
 /// Creates a new stream that yields at a set interval.
 ///
 /// The stream first yields after `dur`, and continues to yield every

src/stream/once.rs

@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 

src/stream/pending.rs

@@ -1,6 +1,6 @@
-use std::marker::PhantomData;
-use std::pin::Pin;
-use std::task::{Context, Poll};
+use core::marker::PhantomData;
+use core::pin::Pin;
+use core::task::{Context, Poll};
 
 use crate::stream::{DoubleEndedStream, ExactSizeStream, FusedStream, Stream};
 

src/stream/product.rs

@@ -1,5 +1,5 @@
-use std::pin::Pin;
-use std::future::Future;
+use core::pin::Pin;
+use core::future::Future;
 
 use crate::stream::Stream;
 

src/stream/repeat.rs

@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};

src/stream/repeat_with.rs

@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};

src/stream/stream/all.rs

@@ -1,6 +1,6 @@
-use std::marker::PhantomData;
-use std::pin::Pin;
-use std::future::Future;
+use core::marker::PhantomData;
+use core::pin::Pin;
+use core::future::Future;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};

src/stream/stream/any.rs

@@ -1,6 +1,6 @@
-use std::marker::PhantomData;
-use std::pin::Pin;
-use std::future::Future;
+use core::marker::PhantomData;
+use core::pin::Pin;
+use core::future::Future;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};

src/stream/stream/chain.rs

@@ -1,9 +1,10 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
 use super::fuse::Fuse;
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
+use crate::stream::Stream;
 use crate::task::{Context, Poll};
 
 pin_project! {

src/stream/stream/cloned.rs

@@ -1,7 +1,7 @@
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 use pin_project_lite::pin_project;
-use std::pin::Pin;
+use core::pin::Pin;
 
 pin_project! {
     /// A stream that clones the elements of an underlying stream.

src/stream/stream/cmp.rs

@@ -1,11 +1,11 @@
-use std::cmp::Ordering;
-use std::pin::Pin;
-use std::future::Future;
+use core::cmp::Ordering;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
 use super::fuse::Fuse;
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 

src/stream/stream/copied.rs

@@ -1,7 +1,7 @@
 use crate::stream::Stream;
 use crate::task::{Context, Poll};
 use pin_project_lite::pin_project;
-use std::pin::Pin;
+use core::pin::Pin;
 
 pin_project! {
     /// A stream that copies the elements of an underlying stream.

src/stream/stream/count.rs

@@ -1,5 +1,5 @@
-use std::future::Future;
-use std::pin::Pin;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 

src/stream/stream/cycle.rs

@@ -1,5 +1,5 @@
-use std::mem::ManuallyDrop;
-use std::pin::Pin;
+use core::mem::ManuallyDrop;
+use core::pin::Pin;
 
 use crate::stream::Stream;
 use crate::task::{Context, Poll};

src/stream/stream/delay.rs

@@ -1,6 +1,6 @@
-use std::future::Future;
-use std::pin::Pin;
-use std::time::Duration;
+use core::future::Future;
+use core::pin::Pin;
+use core::time::Duration;
 
 use pin_project_lite::pin_project;
 

src/stream/stream/enumerate.rs

@@ -1,4 +1,4 @@
-use std::pin::Pin;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 

src/stream/stream/eq.rs

@@ -1,10 +1,10 @@
-use std::pin::Pin;
-use std::future::Future;
+use core::future::Future;
+use core::pin::Pin;
 
 use pin_project_lite::pin_project;
 
 use super::fuse::Fuse;
-use crate::prelude::*;
+use crate::stream::stream::StreamExt;
 use crate::stream::Stream;
 use crate::task::{Context, Poll};