futures_async_stream_macro/
lib.rs

1// SPDX-License-Identifier: Apache-2.0 OR MIT
2
3//! Implementation detail of the `futures-async-stream` crate. - **do not use directly**
4
5#![doc(test(
6    no_crate_inject,
7    attr(
8        deny(warnings, rust_2018_idioms, single_use_lifetimes),
9        allow(dead_code, unused_variables)
10    )
11))]
12#![forbid(unsafe_code)]
13#![feature(proc_macro_def_site)]
14#![allow(clippy::expl_impl_clone_on_copy)] // https://github.com/rust-lang/rust-clippy/issues/15842
15
16#[macro_use]
17mod error;
18
19#[macro_use]
20mod utils;
21
22mod elision;
23mod parse;
24mod stream;
25mod visitor;
26
27use proc_macro::{Delimiter, Group, TokenStream, TokenTree};
28use quote::ToTokens as _;
29use syn::{Error, Expr, ExprForLoop, parse_quote};
30
31use self::utils::{expr_async, parse_as_empty};
32
33/// Processes streams using a for loop.
34///
35/// See the crate-level documentation for details.
36#[proc_macro_attribute]
37pub fn for_await(args: TokenStream, input: TokenStream) -> TokenStream {
38    if let Err(e) = parse_as_empty(&args.into()) {
39        return e.to_compile_error().into();
40    }
41
42    let mut expr: ExprForLoop = syn::parse_macro_input!(input);
43    expr.attrs.insert(0, parse_quote!(#[for_await]));
44
45    let mut expr = Expr::ForLoop(expr);
46    visitor::Visitor::default().visit_for_loop(&mut expr);
47
48    expr.into_token_stream().into()
49}
50
51/// Creates streams via coroutines.
52///
53/// See the crate-level documentation for details.
54#[proc_macro_attribute]
55pub fn stream(args: TokenStream, input: TokenStream) -> TokenStream {
56    stream::attribute(args.into(), input.into(), parse::Context::Stream)
57        .unwrap_or_else(Error::into_compile_error)
58        .into()
59}
60
61/// Creates streams via coroutines. This is equivalent to `#[stream]` on async blocks.
62#[proc_macro]
63pub fn stream_block(input: TokenStream) -> TokenStream {
64    let input = TokenStream::from(TokenTree::Group(Group::new(Delimiter::Brace, input)));
65    let block = syn::parse_macro_input!(input);
66    let mut expr = expr_async(block);
67
68    stream::parse_async(&mut expr, parse::Context::Stream).into()
69}
70
71/// Creates streams via coroutines.
72///
73/// See the crate-level documentation for details.
74#[proc_macro_attribute]
75pub fn try_stream(args: TokenStream, input: TokenStream) -> TokenStream {
76    stream::attribute(args.into(), input.into(), parse::Context::TryStream)
77        .unwrap_or_else(Error::into_compile_error)
78        .into()
79}
80
81/// Creates streams via coroutines. This is equivalent to `#[try_stream]` on async blocks.
82#[proc_macro]
83pub fn try_stream_block(input: TokenStream) -> TokenStream {
84    let input = TokenStream::from(TokenTree::Group(Group::new(Delimiter::Brace, input)));
85    let block = syn::parse_macro_input!(input);
86    let mut expr = expr_async(block);
87
88    stream::parse_async(&mut expr, parse::Context::TryStream).into()
89}
futures_async_stream_macro/lib.rs

futures_async_stream_macro/
lib.rs
