79 lines
2.5 KiB
Rust
79 lines
2.5 KiB
Rust
// Copyright (c) 2019 Rodolphe Bréard
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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extern crate proc_macro;
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use proc_macro::TokenStream;
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use quote::quote;
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use syn::{parse_macro_input, ItemFn};
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fn get_type(
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params: &syn::punctuated::Punctuated<syn::FnArg, syn::token::Comma>,
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) -> Result<(Box<syn::Type>, syn::Type), ()> {
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match params.iter().count() {
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1 => {
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let ctx = Box::new(syn::Type::Verbatim(syn::TypeVerbatim {
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tts: quote! {
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opensmtpd::NoContext
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},
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}));
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let cb = syn::Type::Verbatim(syn::TypeVerbatim {
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tts: quote! { opensmtpd::Callback::NoCtx },
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});
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Ok((ctx, cb))
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}
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2 => match params.iter().next().unwrap() {
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syn::FnArg::Captured(ref a) => match &a.ty {
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syn::Type::Reference(r) => {
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let cb = match r.mutability {
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Some(_) => syn::Type::Verbatim(syn::TypeVerbatim {
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tts: quote! { opensmtpd::Callback::CtxMut },
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}),
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None => syn::Type::Verbatim(syn::TypeVerbatim {
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tts: quote! { opensmtpd::Callback::Ctx },
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}),
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};
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Ok((r.elem.clone(), cb))
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}
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_ => Err(()),
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},
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_ => Err(()),
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},
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_ => Err(()),
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}
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}
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#[proc_macro_attribute]
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pub fn event(attr: TokenStream, input: TokenStream) -> TokenStream {
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let attr = attr.to_string();
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let item = parse_macro_input!(input as ItemFn);
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let fn_name = &item.ident;
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let fn_params = &item.decl.inputs;
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let (ctx_type, callback_type) = match get_type(fn_params) {
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Ok(t) => t,
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Err(_e) => {
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panic!();
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}
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};
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let fn_body = &item.block;
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let fn_output = &item.decl.output;
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let output = quote! {
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fn #fn_name() -> opensmtpd::EventHandler<#ctx_type> {
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opensmtpd::EventHandler::new(
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#attr,
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#callback_type(|#fn_params| #fn_output #fn_body)
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)
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}
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};
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output.into()
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}
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#[proc_macro_attribute]
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pub fn report(attr: TokenStream, input: TokenStream) -> TokenStream {
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event(attr, input)
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}
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