mirror of
https://github.com/fluencelabs/rust-libp2p
synced 2025-06-12 01:21:21 +00:00
Add a custom derive for NetworkBehaviour (#619)
* Add ProtocolsHandlerSelect * Add a custom derive for NetworkBehaviour * Remove 2018 edition * More work * Update the tests and work * Allow ignored fields * More fixes * Give access to everything in the poll method
This commit is contained in:
Pierre Krieger
GitHub
394
misc/core-derive/src/lib.rs
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394
misc/core-derive/src/lib.rs
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@ -0,0 +1,394 @@
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// Copyright 2018 Parity Technologies (UK) Ltd.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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// copy of this software and associated documentation files (the "Software"),
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// to deal in the Software without restriction, including without limitation
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// the rights to use, copy, modify, merge, publish, distribute, sublicense,
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// and/or sell copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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#![recursion_limit = "256"]
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extern crate proc_macro;
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#[macro_use]
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extern crate syn;
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#[macro_use]
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extern crate quote;
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use self::proc_macro::TokenStream;
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use syn::{DeriveInput, Data, DataStruct, Ident};
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/// The interface that satisfies Rust.
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#[proc_macro_derive(NetworkBehaviour, attributes(behaviour))]
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pub fn hello_macro_derive(input: TokenStream) -> TokenStream {
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let ast = parse_macro_input!(input as DeriveInput);
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build(&ast)
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}
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/// The actual implementation.
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fn build(ast: &DeriveInput) -> TokenStream {
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match ast.data {
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Data::Struct(ref s) => build_struct(ast, s),
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Data::Enum(_) => unimplemented!("Deriving NetworkBehavior is not implemented for enums"),
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Data::Union(_) => unimplemented!("Deriving NetworkBehavior is not implemented for unions"),
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}
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}
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/// The version for structs
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fn build_struct(ast: &DeriveInput, data_struct: &DataStruct) -> TokenStream {
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let name = &ast.ident;
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let (_, ty_generics, where_clause) = ast.generics.split_for_impl();
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let trait_to_impl = quote!{::libp2p::core::nodes::swarm::NetworkBehavior};
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let either_ident = quote!{::libp2p::core::either::EitherOutput};
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let network_behaviour_action = quote!{::libp2p::core::nodes::swarm::NetworkBehaviorAction};
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let protocols_handler = quote!{::libp2p::core::nodes::protocols_handler::ProtocolsHandler};
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let proto_select_ident = quote!{::libp2p::core::nodes::protocols_handler::ProtocolsHandlerSelect};
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let peer_id = quote!{::libp2p::core::PeerId};
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let connected_point = quote!{::libp2p::core::nodes::ConnectedPoint};
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// Name of the type parameter that represents the substream.
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let substream_generic = {
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let mut n = "TSubstream".to_string();
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// Avoid collisions.
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while ast.generics.type_params().any(|tp| tp.ident.to_string() == n) {
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n.push('1');
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}
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let n = Ident::new(&n, name.span());
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quote!{#n}
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};
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// Build the generics.
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let impl_generics = {
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let tp = ast.generics.type_params();
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let lf = ast.generics.lifetimes();
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let cst = ast.generics.const_params();
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quote!{<#(#lf,)* #(#tp,)* #(#cst,)* #substream_generic>}
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};
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// Build the `where ...` clause of the trait implementation.
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let where_clause = {
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let mut additional = data_struct.fields.iter().flat_map(|field| {
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if is_ignored(&field) {
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return vec![];
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}
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let ty = &field.ty;
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vec![
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quote!{#ty: #trait_to_impl},
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quote!{<#ty as #trait_to_impl>::ProtocolsHandler: #protocols_handler<Substream = #substream_generic>},
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// Note: this bound is required because of https://github.com/rust-lang/rust/issues/55697
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quote!{<<#ty as #trait_to_impl>::ProtocolsHandler as #protocols_handler>::Protocol: ::libp2p::core::ConnectionUpgrade<#substream_generic>},
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]
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}).collect::<Vec<_>>();
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additional.push(quote!{#substream_generic: ::libp2p::tokio_io::AsyncRead});
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additional.push(quote!{#substream_generic: ::libp2p::tokio_io::AsyncWrite});
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if let Some(where_clause) = where_clause {
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Some(quote!{#where_clause, #(#additional),*})
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} else {
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Some(quote!{where #(#additional),*})
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}
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};
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// The final out event.
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// If we find a `#[behaviour(out_event = "Foo")]` attribute on the struct, we set `Foo` as
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// the out event. Otherwise we use `()`.
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let out_event = {
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let mut out = quote!{()};
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for meta_items in ast.attrs.iter().filter_map(get_meta_items) {
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for meta_item in meta_items {
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match meta_item {
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syn::NestedMeta::Meta(syn::Meta::NameValue(ref m)) if m.ident == "out_event" => {
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if let syn::Lit::Str(ref s) = m.lit {
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let ident: Ident = syn::parse_str(&s.value()).unwrap();
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out = quote!{#ident};
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}
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}
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_ => ()
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}
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}
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}
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out
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};
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// Build the list of statements to put in the body of `inject_connected()`.
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let inject_connected_stmts = {
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let num_fields = data_struct.fields.iter().filter(|f| !is_ignored(f)).count();
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data_struct.fields.iter().enumerate().filter_map(move |(field_n, field)| {
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if is_ignored(&field) {
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return None;
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}
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Some(if field_n == num_fields - 1 {
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match field.ident {
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Some(ref i) => quote!{ self.#i.inject_connected(peer_id, endpoint); },
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None => quote!{ self.#field_n.inject_connected(peer_id, endpoint); },
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}
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} else {
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match field.ident {
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Some(ref i) => quote!{ self.#i.inject_connected(peer_id.clone(), endpoint.clone()); },
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None => quote!{ self.#field_n.inject_connected(peer_id.clone(), endpoint.clone()); },
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}
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})
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})
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};
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// Build the list of statements to put in the body of `inject_disconnected()`.
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let inject_disconnected_stmts = {
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let num_fields = data_struct.fields.iter().filter(|f| !is_ignored(f)).count();
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data_struct.fields.iter().enumerate().filter_map(move |(field_n, field)| {
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if is_ignored(&field) {
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return None;
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}
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Some(if field_n == num_fields - 1 {
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match field.ident {
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Some(ref i) => quote!{ self.#i.inject_disconnected(peer_id, endpoint); },
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None => quote!{ self.#field_n.inject_disconnected(peer_id, endpoint); },
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}
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} else {
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match field.ident {
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Some(ref i) => quote!{ self.#i.inject_disconnected(peer_id, endpoint.clone()); },
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None => quote!{ self.#field_n.inject_disconnected(peer_id, endpoint.clone()); },
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}
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})
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})
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};
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// Build the list of variants to put in the body of `inject_node_event()`.
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//
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// The event type is a construction of nested `#either_ident`s of the events of the children.
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// We call `inject_node_event` on the corresponding child.
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let inject_node_event_stmts = data_struct.fields.iter().enumerate().filter(|f| !is_ignored(&f.1)).enumerate().map(|(enum_n, (field_n, field))| {
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let mut elem = if enum_n != 0 {
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quote!{ #either_ident::Second(ev) }
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} else {
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quote!{ ev }
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};
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for _ in 0 .. data_struct.fields.iter().filter(|f| !is_ignored(f)).count() - 1 - field_n {
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elem = quote!{ #either_ident::First(#elem) };
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}
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Some(match field.ident {
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Some(ref i) => quote!{ #elem => self.#i.inject_node_event(peer_id, ev) },
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None => quote!{ #elem => self.#field_n.inject_node_event(peer_id, ev) },
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})
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});
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// The `ProtocolsHandler` associated type.
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let protocols_handler_ty = {
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let mut ph_ty = None;
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for field in data_struct.fields.iter() {
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if is_ignored(&field) {
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continue;
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}
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let ty = &field.ty;
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let field_info = quote!{ <#ty as #trait_to_impl>::ProtocolsHandler };
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match ph_ty {
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Some(ev) => ph_ty = Some(quote!{ #proto_select_ident<#ev, #field_info> }),
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ref mut ev @ None => *ev = Some(field_info),
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}
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}
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ph_ty.unwrap_or(quote!{()}) // TODO: `!` instead
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};
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// The content of `new_handler()`.
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// Example output: `self.field1.select(self.field2.select(self.field3))`.
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let new_handler = {
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let mut out_handler = None;
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for (field_n, field) in data_struct.fields.iter().enumerate() {
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if is_ignored(&field) {
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continue;
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}
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let field_name = match field.ident {
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Some(ref i) => quote!{ self.#i },
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None => quote!{ self.#field_n },
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};
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let builder = quote! {
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#field_name.new_handler()
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};
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match out_handler {
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Some(h) => out_handler = Some(quote!{ #h.select(#builder) }),
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ref mut h @ None => *h = Some(builder),
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}
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}
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out_handler.unwrap_or(quote!{()}) // TODO: incorrect
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};
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// The method to use to poll.
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// If we find a `#[behaviour(poll_method = "poll")]` attribute on the struct, we call
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// `self.poll()` at the end of the polling.
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let poll_method = {
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let mut poll_method = quote!{Async::NotReady};
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for meta_items in ast.attrs.iter().filter_map(get_meta_items) {
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for meta_item in meta_items {
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match meta_item {
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syn::NestedMeta::Meta(syn::Meta::NameValue(ref m)) if m.ident == "poll_method" => {
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if let syn::Lit::Str(ref s) = m.lit {
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let ident: Ident = syn::parse_str(&s.value()).unwrap();
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poll_method = quote!{#name::#ident(self)};
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}
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}
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_ => ()
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}
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}
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}
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poll_method
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};
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// List of statements to put in `poll()`.
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//
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// We poll each child one by one and wrap around the output.
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let poll_stmts = data_struct.fields.iter().enumerate().filter(|f| !is_ignored(&f.1)).enumerate().map(|(enum_n, (field_n, field))| {
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let field_name = match field.ident {
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Some(ref i) => quote!{ self.#i },
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None => quote!{ self.#field_n },
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};
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let mut handler_fn: Option<Ident> = None;
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for meta_items in field.attrs.iter().filter_map(get_meta_items) {
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for meta_item in meta_items {
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match meta_item {
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// Parse `#[behaviour(handler = "foo")]`
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syn::NestedMeta::Meta(syn::Meta::NameValue(ref m)) if m.ident == "handler" => {
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if let syn::Lit::Str(ref s) = m.lit {
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handler_fn = Some(syn::parse_str(&s.value()).unwrap());
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}
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}
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_ => ()
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}
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}
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}
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let handling = if let Some(handler_fn) = handler_fn {
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quote!{self.#handler_fn(event)}
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} else {
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quote!{}
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};
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let mut wrapped_event = if enum_n != 0 {
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quote!{ #either_ident::Second(event) }
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} else {
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quote!{ event }
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};
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for _ in 0 .. data_struct.fields.iter().filter(|f| !is_ignored(f)).count() - 1 - field_n {
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wrapped_event = quote!{ #either_ident::First(#wrapped_event) };
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}
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Some(quote!{
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loop {
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match #field_name.poll() {
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Async::Ready(#network_behaviour_action::GenerateEvent(event)) => {
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#handling
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}
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Async::Ready(#network_behaviour_action::DialAddress { address }) => {
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return Async::Ready(#network_behaviour_action::DialAddress { address });
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}
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Async::Ready(#network_behaviour_action::DialPeer { peer_id }) => {
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return Async::Ready(#network_behaviour_action::DialPeer { peer_id });
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}
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Async::Ready(#network_behaviour_action::SendEvent { peer_id, event }) => {
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return Async::Ready(#network_behaviour_action::SendEvent {
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peer_id,
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event: #wrapped_event,
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});
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}
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Async::NotReady => break,
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}
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}
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})
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});
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// Now the magic happens.
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let final_quote = quote!{
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impl #impl_generics #trait_to_impl for #name #ty_generics
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#where_clause
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{
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type ProtocolsHandler = #protocols_handler_ty;
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type OutEvent = #out_event;
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#[inline]
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fn new_handler(&mut self) -> Self::ProtocolsHandler {
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use #protocols_handler;
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#new_handler
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}
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#[inline]
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fn inject_connected(&mut self, peer_id: #peer_id, endpoint: #connected_point) {
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#(#inject_connected_stmts);*
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}
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#[inline]
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fn inject_disconnected(&mut self, peer_id: &#peer_id, endpoint: #connected_point) {
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#(#inject_disconnected_stmts);*
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}
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#[inline]
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fn inject_node_event(
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&mut self,
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peer_id: #peer_id,
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event: <Self::ProtocolsHandler as #protocols_handler>::OutEvent
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) {
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match event {
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#(#inject_node_event_stmts),*
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}
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}
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fn poll(&mut self) -> ::libp2p::futures::Async<#network_behaviour_action<<Self::ProtocolsHandler as #protocols_handler>::InEvent, Self::OutEvent>> {
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use libp2p::futures::prelude::*;
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#(#poll_stmts)*
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let f: ::libp2p::futures::Async<#network_behaviour_action<<Self::ProtocolsHandler as #protocols_handler>::InEvent, Self::OutEvent>> = #poll_method;
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f
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}
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}
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};
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final_quote.into()
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}
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fn get_meta_items(attr: &syn::Attribute) -> Option<Vec<syn::NestedMeta>> {
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if attr.path.segments.len() == 1 && attr.path.segments[0].ident == "behaviour" {
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match attr.interpret_meta() {
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Some(syn::Meta::List(ref meta)) => Some(meta.nested.iter().cloned().collect()),
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_ => {
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None
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}
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}
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} else {
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None
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}
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}
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/// Returns true if a field is marked as ignored by the user.
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fn is_ignored(field: &syn::Field) -> bool {
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for meta_items in field.attrs.iter().filter_map(get_meta_items) {
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for meta_item in meta_items {
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match meta_item {
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syn::NestedMeta::Meta(syn::Meta::Word(ref m)) if m == "ignore" => {
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return true;
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}
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_ => ()
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}
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}
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}
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false
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}
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