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Diffstat (limited to 'wire_format_derive/wire_format_derive.rs')
| -rw-r--r-- | wire_format_derive/wire_format_derive.rs | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/wire_format_derive/wire_format_derive.rs b/wire_format_derive/wire_format_derive.rs new file mode 100644 index 0000000..290ffc5 --- /dev/null +++ b/wire_format_derive/wire_format_derive.rs @@ -0,0 +1,303 @@ +// Copyright 2018 The Chromium OS Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +//! Derives a 9P wire format encoding for a struct by recursively calling +//! `WireFormat::encode` or `WireFormat::decode` on the fields of the struct. +//! This is only intended to be used from within the `p9` crate. + +#![recursion_limit = "256"] + +extern crate proc_macro; +extern crate proc_macro2; + +#[macro_use] +extern crate quote; + +#[macro_use] +extern crate syn; + +use proc_macro2::{Span, TokenStream}; +use syn::spanned::Spanned; +use syn::{Data, DeriveInput, Fields, Ident}; + +/// The function that derives the actual implementation. +#[proc_macro_derive(P9WireFormat)] +pub fn p9_wire_format(input: proc_macro::TokenStream) -> proc_macro::TokenStream { + let input = parse_macro_input!(input as DeriveInput); + p9_wire_format_inner(input).into() +} + +fn p9_wire_format_inner(input: DeriveInput) -> TokenStream { + if !input.generics.params.is_empty() { + return quote! { + compile_error!("derive(P9WireFormat) does not support generic parameters"); + }; + } + + let container = input.ident; + + let byte_size_impl = byte_size_sum(&input.data); + let encode_impl = encode_wire_format(&input.data); + let decode_impl = decode_wire_format(&input.data, &container); + + let scope = format!("wire_format_{}", container).to_lowercase(); + let scope = Ident::new(&scope, Span::call_site()); + quote! { + mod #scope { + extern crate std; + use self::std::io; + use self::std::result::Result::Ok; + + use super::#container; + + use protocol::WireFormat; + + impl WireFormat for #container { + fn byte_size(&self) -> u32 { + #byte_size_impl + } + + fn encode<W: io::Write>(&self, _writer: &mut W) -> io::Result<()> { + #encode_impl + } + + fn decode<R: io::Read>(_reader: &mut R) -> io::Result<Self> { + #decode_impl + } + } + } + } +} + +// Generate code that recursively calls byte_size on every field in the struct. +fn byte_size_sum(data: &Data) -> TokenStream { + if let Data::Struct(ref data) = *data { + if let Fields::Named(ref fields) = data.fields { + let fields = fields.named.iter().map(|f| { + let field = &f.ident; + let span = field.span(); + quote_spanned! {span=> + WireFormat::byte_size(&self.#field) + } + }); + + quote! { + 0 #(+ #fields)* + } + } else { + unimplemented!(); + } + } else { + unimplemented!(); + } +} + +// Generate code that recursively calls encode on every field in the struct. +fn encode_wire_format(data: &Data) -> TokenStream { + if let Data::Struct(ref data) = *data { + if let Fields::Named(ref fields) = data.fields { + let fields = fields.named.iter().map(|f| { + let field = &f.ident; + let span = field.span(); + quote_spanned! {span=> + WireFormat::encode(&self.#field, _writer)?; + } + }); + + quote! { + #(#fields)* + + Ok(()) + } + } else { + unimplemented!(); + } + } else { + unimplemented!(); + } +} + +// Generate code that recursively calls decode on every field in the struct. +fn decode_wire_format(data: &Data, container: &Ident) -> TokenStream { + if let Data::Struct(ref data) = *data { + if let Fields::Named(ref fields) = data.fields { + let values = fields.named.iter().map(|f| { + let field = &f.ident; + let span = field.span(); + quote_spanned! {span=> + let #field = WireFormat::decode(_reader)?; + } + }); + + let members = fields.named.iter().map(|f| { + let field = &f.ident; + quote! { + #field: #field, + } + }); + + quote! { + #(#values)* + + Ok(#container { + #(#members)* + }) + } + } else { + unimplemented!(); + } + } else { + unimplemented!(); + } +} + +#[cfg(test)] +mod tests { + use super::*; + + #[test] + fn byte_size() { + let input: DeriveInput = parse_quote! { + struct Item { + ident: u32, + with_underscores: String, + other: u8, + } + }; + + let expected = quote! { + 0 + + WireFormat::byte_size(&self.ident) + + WireFormat::byte_size(&self.with_underscores) + + WireFormat::byte_size(&self.other) + }; + + assert_eq!(byte_size_sum(&input.data).to_string(), expected.to_string()); + } + + #[test] + fn encode() { + let input: DeriveInput = parse_quote! { + struct Item { + ident: u32, + with_underscores: String, + other: u8, + } + }; + + let expected = quote! { + WireFormat::encode(&self.ident, _writer)?; + WireFormat::encode(&self.with_underscores, _writer)?; + WireFormat::encode(&self.other, _writer)?; + Ok(()) + }; + + assert_eq!( + encode_wire_format(&input.data).to_string(), + expected.to_string(), + ); + } + + #[test] + fn decode() { + let input: DeriveInput = parse_quote! { + struct Item { + ident: u32, + with_underscores: String, + other: u8, + } + }; + + let container = Ident::new("Item", Span::call_site()); + let expected = quote! { + let ident = WireFormat::decode(_reader)?; + let with_underscores = WireFormat::decode(_reader)?; + let other = WireFormat::decode(_reader)?; + Ok(Item { + ident: ident, + with_underscores: with_underscores, + other: other, + }) + }; + + assert_eq!( + decode_wire_format(&input.data, &container).to_string(), + expected.to_string(), + ); + } + + #[test] + fn end_to_end() { + let input: DeriveInput = parse_quote! { + struct Niijima_先輩 { + a: u8, + b: u16, + c: u32, + d: u64, + e: String, + f: Vec<String>, + g: Nested, + } + }; + + let expected = quote! { + mod wire_format_niijima_先輩 { + extern crate std; + use self::std::io; + use self::std::result::Result::Ok; + + use super::Niijima_先輩; + + use protocol::WireFormat; + + impl WireFormat for Niijima_先輩 { + fn byte_size(&self) -> u32 { + 0 + + WireFormat::byte_size(&self.a) + + WireFormat::byte_size(&self.b) + + WireFormat::byte_size(&self.c) + + WireFormat::byte_size(&self.d) + + WireFormat::byte_size(&self.e) + + WireFormat::byte_size(&self.f) + + WireFormat::byte_size(&self.g) + } + + fn encode<W: io::Write>(&self, _writer: &mut W) -> io::Result<()> { + WireFormat::encode(&self.a, _writer)?; + WireFormat::encode(&self.b, _writer)?; + WireFormat::encode(&self.c, _writer)?; + WireFormat::encode(&self.d, _writer)?; + WireFormat::encode(&self.e, _writer)?; + WireFormat::encode(&self.f, _writer)?; + WireFormat::encode(&self.g, _writer)?; + Ok(()) + } + fn decode<R: io::Read>(_reader: &mut R) -> io::Result<Self> { + let a = WireFormat::decode(_reader)?; + let b = WireFormat::decode(_reader)?; + let c = WireFormat::decode(_reader)?; + let d = WireFormat::decode(_reader)?; + let e = WireFormat::decode(_reader)?; + let f = WireFormat::decode(_reader)?; + let g = WireFormat::decode(_reader)?; + Ok(Niijima_先輩 { + a: a, + b: b, + c: c, + d: d, + e: e, + f: f, + g: g, + }) + } + } + } + }; + + assert_eq!( + p9_wire_format_inner(input).to_string(), + expected.to_string(), + ); + } +} |