use proc_macro::TokenStream;
use quote::quote;
use std::num::NonZeroUsize;
#[derive(Clone, Copy, PartialEq)]
enum Runtime {
Basic,
Threaded,
}
fn parse_knobs(
mut input: syn::ItemFn,
args: syn::AttributeArgs,
is_test: bool,
rt_threaded: bool,
) -> Result<TokenStream, syn::Error> {
let sig = &mut input.sig;
let body = &input.block;
let attrs = &input.attrs;
let vis = input.vis;
if sig.asyncness.is_none() {
let msg = "the async keyword is missing from the function declaration";
return Err(syn::Error::new_spanned(sig.fn_token, msg));
}
sig.asyncness = None;
let mut runtime = None;
let mut core_threads = None;
let mut max_threads = None;
for arg in args {
match arg {
syn::NestedMeta::Meta(syn::Meta::NameValue(namevalue)) => {
let ident = namevalue.path.get_ident();
if ident.is_none() {
let msg = "Must have specified ident";
return Err(syn::Error::new_spanned(namevalue, msg));
}
match ident.unwrap().to_string().to_lowercase().as_str() {
"core_threads" => {
if rt_threaded {
match &namevalue.lit {
syn::Lit::Int(expr) => {
let num = expr.base10_parse::<NonZeroUsize>().unwrap();
if num.get() > 1 {
runtime = Some(Runtime::Threaded);
} else {
runtime = Some(Runtime::Basic);
}
if let Some(v) = max_threads {
if v < num {
return Err(syn::Error::new_spanned(
namevalue,
"max_threads cannot be less than core_threads",
));
}
}
core_threads = Some(num);
}
_ => {
return Err(syn::Error::new_spanned(
namevalue,
"core_threads argument must be an int",
))
}
}
} else {
return Err(syn::Error::new_spanned(
namevalue,
"core_threads can only be set with rt-threaded feature flag enabled",
));
}
}
"max_threads" => match &namevalue.lit {
syn::Lit::Int(expr) => {
let num = expr.base10_parse::<NonZeroUsize>().unwrap();
if let Some(v) = core_threads {
if num < v {
return Err(syn::Error::new_spanned(
namevalue,
"max_threads cannot be less than core_threads",
));
}
}
max_threads = Some(num);
}
_ => {
return Err(syn::Error::new_spanned(
namevalue,
"max_threads argument must be an int",
))
}
},
name => {
let msg = format!("Unknown attribute pair {} is specified; expected one of: `core_threads`, `max_threads`", name);
return Err(syn::Error::new_spanned(namevalue, msg));
}
}
}
syn::NestedMeta::Meta(syn::Meta::Path(path)) => {
let ident = path.get_ident();
if ident.is_none() {
let msg = "Must have specified ident";
return Err(syn::Error::new_spanned(path, msg));
}
match ident.unwrap().to_string().to_lowercase().as_str() {
"threaded_scheduler" => {
runtime = Some(runtime.unwrap_or_else(|| Runtime::Threaded))
}
"basic_scheduler" => runtime = Some(runtime.unwrap_or_else(|| Runtime::Basic)),
name => {
let msg = format!("Unknown attribute {} is specified; expected `basic_scheduler` or `threaded_scheduler`", name);
return Err(syn::Error::new_spanned(path, msg));
}
}
}
other => {
return Err(syn::Error::new_spanned(
other,
"Unknown attribute inside the macro",
));
}
}
}
let mut rt = quote! { async_std::runtime::Builder::new().basic_scheduler() };
if rt_threaded && (runtime == Some(Runtime::Threaded) || (runtime.is_none() && !is_test)) {
rt = quote! { #rt.threaded_scheduler() };
}
if let Some(v) = core_threads.map(|v| v.get()) {
rt = quote! { #rt.core_threads(#v) };
}
if let Some(v) = max_threads.map(|v| v.get()) {
rt = quote! { #rt.max_threads(#v) };
}
let header = {
if is_test {
quote! {
#[test]
}
} else {
quote! {}
}
};
let result = quote! {
#header
#(#attrs)*
#vis #sig {
#rt
.enable_all()
.build()
.unwrap()
.block_on(async { #body })
}
};
Ok(result.into())
}
#[cfg(not(test))] pub(crate) fn main(args: TokenStream, item: TokenStream, rt_threaded: bool) -> TokenStream {
let input = syn::parse_macro_input!(item as syn::ItemFn);
let args = syn::parse_macro_input!(args as syn::AttributeArgs);
if input.sig.ident == "main" && !input.sig.inputs.is_empty() {
let msg = "the main function cannot accept arguments";
return syn::Error::new_spanned(&input.sig.inputs, msg)
.to_compile_error()
.into();
}
parse_knobs(input, args, false, rt_threaded).unwrap_or_else(|e| e.to_compile_error().into())
}
pub(crate) fn test(args: TokenStream, item: TokenStream, rt_threaded: bool) -> TokenStream {
let input = syn::parse_macro_input!(item as syn::ItemFn);
let args = syn::parse_macro_input!(args as syn::AttributeArgs);
for attr in &input.attrs {
if attr.path.is_ident("test") {
let msg = "second test attribute is supplied";
return syn::Error::new_spanned(&attr, msg)
.to_compile_error()
.into();
}
}
if !input.sig.inputs.is_empty() {
let msg = "the test function cannot accept arguments";
return syn::Error::new_spanned(&input.sig.inputs, msg)
.to_compile_error()
.into();
}
parse_knobs(input, args, true, rt_threaded).unwrap_or_else(|e| e.to_compile_error().into())
}
pub(crate) mod old {
use proc_macro::TokenStream;
use quote::quote;
enum Runtime {
Basic,
Threaded,
Auto,
}
#[cfg(not(test))] pub(crate) fn main(args: TokenStream, item: TokenStream) -> TokenStream {
let mut input = syn::parse_macro_input!(item as syn::ItemFn);
let args = syn::parse_macro_input!(args as syn::AttributeArgs);
let sig = &mut input.sig;
let name = &sig.ident;
let inputs = &sig.inputs;
let body = &input.block;
let attrs = &input.attrs;
let vis = input.vis;
if sig.asyncness.is_none() {
let msg = "the async keyword is missing from the function declaration";
return syn::Error::new_spanned(sig.fn_token, msg)
.to_compile_error()
.into();
} else if name == "main" && !inputs.is_empty() {
let msg = "the main function cannot accept arguments";
return syn::Error::new_spanned(&sig.inputs, msg)
.to_compile_error()
.into();
}
sig.asyncness = None;
let mut runtime = Runtime::Auto;
for arg in args {
if let syn::NestedMeta::Meta(syn::Meta::Path(path)) = arg {
let ident = path.get_ident();
if ident.is_none() {
let msg = "Must have specified ident";
return syn::Error::new_spanned(path, msg).to_compile_error().into();
}
match ident.unwrap().to_string().to_lowercase().as_str() {
"threaded_scheduler" => runtime = Runtime::Threaded,
"basic_scheduler" => runtime = Runtime::Basic,
name => {
let msg = format!("Unknown attribute {} is specified; expected `basic_scheduler` or `threaded_scheduler`", name);
return syn::Error::new_spanned(path, msg).to_compile_error().into();
}
}
}
}
let result = match runtime {
Runtime::Threaded | Runtime::Auto => quote! {
#(#attrs)*
#vis #sig {
async_std::runtime::Runtime::new().unwrap().block_on(async { #body })
}
},
Runtime::Basic => quote! {
#(#attrs)*
#vis #sig {
async_std::runtime::Builder::new()
.basic_scheduler()
.enable_all()
.build()
.unwrap()
.block_on(async { #body })
}
},
};
result.into()
}
pub(crate) fn test(args: TokenStream, item: TokenStream) -> TokenStream {
let input = syn::parse_macro_input!(item as syn::ItemFn);
let args = syn::parse_macro_input!(args as syn::AttributeArgs);
let ret = &input.sig.output;
let name = &input.sig.ident;
let body = &input.block;
let attrs = &input.attrs;
let vis = input.vis;
for attr in attrs {
if attr.path.is_ident("test") {
let msg = "second test attribute is supplied";
return syn::Error::new_spanned(&attr, msg)
.to_compile_error()
.into();
}
}
if input.sig.asyncness.is_none() {
let msg = "the async keyword is missing from the function declaration";
return syn::Error::new_spanned(&input.sig.fn_token, msg)
.to_compile_error()
.into();
} else if !input.sig.inputs.is_empty() {
let msg = "the test function cannot accept arguments";
return syn::Error::new_spanned(&input.sig.inputs, msg)
.to_compile_error()
.into();
}
let mut runtime = Runtime::Auto;
for arg in args {
if let syn::NestedMeta::Meta(syn::Meta::Path(path)) = arg {
let ident = path.get_ident();
if ident.is_none() {
let msg = "Must have specified ident";
return syn::Error::new_spanned(path, msg).to_compile_error().into();
}
match ident.unwrap().to_string().to_lowercase().as_str() {
"threaded_scheduler" => runtime = Runtime::Threaded,
"basic_scheduler" => runtime = Runtime::Basic,
name => {
let msg = format!("Unknown attribute {} is specified; expected `basic_scheduler` or `threaded_scheduler`", name);
return syn::Error::new_spanned(path, msg).to_compile_error().into();
}
}
}
}
let result = match runtime {
Runtime::Threaded => quote! {
#[test]
#(#attrs)*
#vis fn #name() #ret {
async_std::runtime::Runtime::new().unwrap().block_on(async { #body })
}
},
Runtime::Basic | Runtime::Auto => quote! {
#[test]
#(#attrs)*
#vis fn #name() #ret {
async_std::runtime::Builder::new()
.basic_scheduler()
.enable_all()
.build()
.unwrap()
.block_on(async { #body })
}
},
};
result.into()
}
}