RUST-2103 Update the rest of actions to document options (#1272)

Author: abr-egn

macros/src/action_impl.rs

@@ -0,0 +1,185 @@
+extern crate proc_macro;
+
+use quote::quote;
+use syn::{
+    braced,
+    parenthesized,
+    parse::{Parse, ParseStream},
+    parse_macro_input,
+    parse_quote_spanned,
+    spanned::Spanned,
+    Block,
+    Generics,
+    Ident,
+    Lifetime,
+    Token,
+    Type,
+};
+
+use crate::parse_name;
+
+pub(crate) fn action_impl(
+    attrs: proc_macro::TokenStream,
+    input: proc_macro::TokenStream,
+) -> proc_macro::TokenStream {
+    let ActionImplAttrs { sync_type } = parse_macro_input!(attrs as ActionImplAttrs);
+    let ActionImpl {
+        generics,
+        lifetime,
+        action,
+        future_name,
+        exec_self_mut,
+        exec_output,
+        exec_body,
+    } = parse_macro_input!(input as ActionImpl);
+
+    let mut unbounded_generics = generics.clone();
+    for lt in unbounded_generics.lifetimes_mut() {
+        lt.bounds.clear();
+    }
+    for ty in unbounded_generics.type_params_mut() {
+        ty.bounds.clear();
+    }
+
+    let sync_run = if let Some(sync_type) = sync_type {
+        quote! {
+            /// Synchronously execute this action.
+            pub fn run(self) -> Result<#sync_type> {
+                crate::sync::TOKIO_RUNTIME.block_on(std::future::IntoFuture::into_future(self)).map(<#sync_type>::new)
+            }
+        }
+    } else {
+        quote! {
+            /// Synchronously execute this action.
+            pub fn run(self) -> #exec_output {
+                crate::sync::TOKIO_RUNTIME.block_on(std::future::IntoFuture::into_future(self))
+            }
+        }
+    };
+
+    quote! {
+        impl #generics crate::action::private::Sealed for #action { }
+
+        impl #generics crate::action::Action for #action { }
+
+        impl #generics std::future::IntoFuture for #action {
+            type Output = #exec_output;
+            type IntoFuture = #future_name #unbounded_generics;
+
+            fn into_future(#exec_self_mut self) -> Self::IntoFuture {
+                #future_name (Box::pin(async move {
+                    #exec_body
+                }))
+            }
+        }
+
+        pub struct #future_name #generics (crate::BoxFuture<#lifetime, #exec_output>);
+
+        impl #generics std::future::Future for #future_name #unbounded_generics {
+            type Output = #exec_output;
+
+            fn poll(mut self: std::pin::Pin<&mut Self>, cx: &mut std::task::Context<'_>) -> std::task::Poll<Self::Output> {
+                self.0.as_mut().poll(cx)
+            }
+        }
+
+        #[cfg(feature = "sync")]
+        impl #generics #action {
+            #sync_run
+        }
+    }.into()
+}
+
+// impl<generics> Action for ActionType {
+// type Future = FutureName;
+// async fn execute([mut] self) -> OutType { <exec body> }
+// [SyncWrap]
+// }
+struct ActionImpl {
+    generics: Generics,
+    lifetime: Lifetime,
+    action: Type,
+    future_name: Ident,
+    exec_self_mut: Option<Token![mut]>,
+    exec_output: Type,
+    exec_body: Block,
+}
+
+impl Parse for ActionImpl {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        // impl<generics> Action for ActionType
+        input.parse::<Token![impl]>()?;
+        let generics: Generics = input.parse()?;
+        let mut lifetime = None;
+        for lt in generics.lifetimes() {
+            if lifetime.is_some() {
+                return Err(input.error("only one lifetime argument permitted"));
+            }
+            lifetime = Some(lt);
+        }
+        let lifetime = match lifetime {
+            Some(lt) => lt.lifetime.clone(),
+            None => parse_quote_spanned! { generics.span() => 'static },
+        };
+        parse_name(input, "Action")?;
+        input.parse::<Token![for]>()?;
+        let action = input.parse()?;
+
+        let impl_body;
+        braced!(impl_body in input);
+
+        // type Future = FutureName;
+        impl_body.parse::<Token![type]>()?;
+        parse_name(&impl_body, "Future")?;
+        impl_body.parse::<Token![=]>()?;
+        let future_name = impl_body.parse()?;
+        impl_body.parse::<Token![;]>()?;
+
+        // async fn execute([mut] self) -> OutType { <exec body> }
+        impl_body.parse::<Token![async]>()?;
+        impl_body.parse::<Token![fn]>()?;
+        parse_name(&impl_body, "execute")?;
+        let exec_args;
+        parenthesized!(exec_args in impl_body);
+        let exec_self_mut = exec_args.parse()?;
+        exec_args.parse::<Token![self]>()?;
+        if !exec_args.is_empty() {
+            return Err(exec_args.error("unexpected token"));
+        }
+        impl_body.parse::<Token![->]>()?;
+        let exec_output = impl_body.parse()?;
+        let exec_body = impl_body.parse()?;
+
+        if !impl_body.is_empty() {
+            return Err(exec_args.error("unexpected token"));
+        }
+
+        Ok(ActionImpl {
+            generics,
+            lifetime,
+            action,
+            future_name,
+            exec_self_mut,
+            exec_output,
+            exec_body,
+        })
+    }
+}
+
+struct ActionImplAttrs {
+    sync_type: Option<Type>,
+}
+
+impl Parse for ActionImplAttrs {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        let mut out = Self { sync_type: None };
+        if input.is_empty() {
+            return Ok(out);
+        }
+
+        parse_name(input, "sync")?;
+        input.parse::<Token![=]>()?;
+        out.sync_type = Some(input.parse()?);
+        Ok(out)
+    }
+}