#![doc(html_root_url = "https://docs.rs/prost-derive/0.12.6")]
// The `quote!` macro requires deep recursion.
#![recursion_limit = "4096"]
extern crate alloc;
extern crate proc_macro;
use anyhow::{bail, Error};
use itertools::Itertools;
use proc_macro::TokenStream;
use proc_macro2::Span;
use quote::quote;
use syn::{
punctuated::Punctuated, Data, DataEnum, DataStruct, DeriveInput, Expr, Fields, FieldsNamed,
FieldsUnnamed, Ident, Index, Variant,
};
mod field;
use crate::field::Field;
fn try_message(input: TokenStream) -> Result<TokenStream, Error> {
let input: DeriveInput = syn::parse(input)?;
let ident = input.ident;
syn::custom_keyword!(skip_debug);
let skip_debug = input
.attrs
.into_iter()
.any(|a| a.path().is_ident("prost") && a.parse_args::<skip_debug>().is_ok());
let variant_data = match input.data {
Data::Struct(variant_data) => variant_data,
Data::Enum(..) => bail!("Message can not be derived for an enum"),
Data::Union(..) => bail!("Message can not be derived for a union"),
};
let generics = &input.generics;
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let (is_struct, fields) = match variant_data {
DataStruct {
fields: Fields::Named(FieldsNamed { named: fields, .. }),
..
} => (true, fields.into_iter().collect()),
DataStruct {
fields:
Fields::Unnamed(FieldsUnnamed {
unnamed: fields, ..
}),
..
} => (false, fields.into_iter().collect()),
DataStruct {
fields: Fields::Unit,
..
} => (false, Vec::new()),
};
let mut next_tag: u32 = 1;
let mut fields = fields
.into_iter()
.enumerate()
.flat_map(|(i, field)| {
let field_ident = field.ident.map(|x| quote!(#x)).unwrap_or_else(|| {
let index = Index {
index: i as u32,
span: Span::call_site(),
};
quote!(#index)
});
match Field::new(field.attrs, Some(next_tag)) {
Ok(Some(field)) => {
next_tag = field.tags().iter().max().map(|t| t + 1).unwrap_or(next_tag);
Some(Ok((field_ident, field)))
}
Ok(None) => None,
Err(err) => Some(Err(
err.context(format!("invalid message field {}.{}", ident, field_ident))
)),
}
})
.collect::<Result<Vec<_>, _>>()?;
// We want Debug to be in declaration order
let unsorted_fields = fields.clone();
// Sort the fields by tag number so that fields will be encoded in tag order.
// TODO: This encodes oneof fields in the position of their lowest tag,
// regardless of the currently occupied variant, is that consequential?
// See: https://developers.google.com/protocol-buffers/docs/encoding#order
fields.sort_by_key(|(_, field)| field.tags().into_iter().min().unwrap());
let fields = fields;
let mut tags = fields
.iter()
.flat_map(|(_, field)| field.tags())
.collect::<Vec<_>>();
let num_tags = tags.len();
tags.sort_unstable();
tags.dedup();
if tags.len() != num_tags {
bail!("message {} has fields with duplicate tags", ident);
}
let encoded_len = fields
.iter()
.map(|(field_ident, field)| field.encoded_len(quote!(self.#field_ident)));
let encode = fields
.iter()
.map(|(field_ident, field)| field.encode(quote!(self.#field_ident)));
let merge = fields.iter().map(|(field_ident, field)| {
let merge = field.merge(quote!(value));
let tags = field.tags().into_iter().map(|tag| quote!(#tag));
let tags = Itertools::intersperse(tags, quote!(|));
quote! {
#(#tags)* => {
let mut value = &mut self.#field_ident;
#merge.map_err(|mut error| {
error.push(STRUCT_NAME, stringify!(#field_ident));
error
})
},
}
});
let struct_name = if fields.is_empty() {
quote!()
} else {
quote!(
const STRUCT_NAME: &'static str = stringify!(#ident);
)
};
let clear = fields
.iter()
.map(|(field_ident, field)| field.clear(quote!(self.#field_ident)));
let default = if is_struct {
let default = fields.iter().map(|(field_ident, field)| {
let value = field.default();
quote!(#field_ident: #value,)
});
quote! {#ident {
#(#default)*
}}
} else {
let default = fields.iter().map(|(_, field)| {
let value = field.default();
quote!(#value,)
});
quote! {#ident (
#(#default)*
)}
};
let methods = fields
.iter()
.flat_map(|(field_ident, field)| field.methods(field_ident))
.collect::<Vec<_>>();
let methods = if methods.is_empty() {
quote!()
} else {
quote! {
#[allow(dead_code)]
impl #impl_generics #ident #ty_generics #where_clause {
#(#methods)*
}
}
};
let expanded = quote! {
impl #impl_generics ::prost::Message for #ident #ty_generics #where_clause {
#[allow(unused_variables)]
fn encode_raw<B>(&self, buf: &mut B) where B: ::prost::bytes::BufMut {
#(#encode)*
}
#[allow(unused_variables)]
fn merge_field<B>(
&mut self,
tag: u32,
wire_type: ::prost::encoding::WireType,
buf: &mut B,
ctx: ::prost::encoding::DecodeContext,
) -> ::core::result::Result<(), ::prost::DecodeError>
where B: ::prost::bytes::Buf {
#struct_name
match tag {
#(#merge)*
_ => ::prost::encoding::skip_field(wire_type, tag, buf, ctx),
}
}
#[inline]
fn encoded_len(&self) -> usize {
0 #(+ #encoded_len)*
}
fn clear(&mut self) {
#(#clear;)*
}
}
impl #impl_generics ::core::default::Default for #ident #ty_generics #where_clause {
fn default() -> Self {
#default
}
}
};
let expanded = if skip_debug {
expanded
} else {
let debugs = unsorted_fields.iter().map(|(field_ident, field)| {
let wrapper = field.debug(quote!(self.#field_ident));
let call = if is_struct {
quote!(builder.field(stringify!(#field_ident), &wrapper))
} else {
quote!(builder.field(&wrapper))
};
quote! {
let builder = {
let wrapper = #wrapper;
#call
};
}
});
let debug_builder = if is_struct {
quote!(f.debug_struct(stringify!(#ident)))
} else {
quote!(f.debug_tuple(stringify!(#ident)))
};
quote! {
#expanded
impl #impl_generics ::core::fmt::Debug for #ident #ty_generics #where_clause {
fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
let mut builder = #debug_builder;
#(#debugs;)*
builder.finish()
}
}
}
};
let expanded = quote! {
#expanded
#methods
};
Ok(expanded.into())
}
#[proc_macro_derive(Message, attributes(prost))]
pub fn message(input: TokenStream) -> TokenStream {
try_message(input).unwrap()
}
fn try_enumeration(input: TokenStream) -> Result<TokenStream, Error> {
let input: DeriveInput = syn::parse(input)?;
let ident = input.ident;
let generics = &input.generics;
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let punctuated_variants = match input.data {
Data::Enum(DataEnum { variants, .. }) => variants,
Data::Struct(_) => bail!("Enumeration can not be derived for a struct"),
Data::Union(..) => bail!("Enumeration can not be derived for a union"),
};
// Map the variants into 'fields'.
let mut variants: Vec<(Ident, Expr)> = Vec::new();
for Variant {
ident,
fields,
discriminant,
..
} in punctuated_variants
{
match fields {
Fields::Unit => (),
Fields::Named(_) | Fields::Unnamed(_) => {
bail!("Enumeration variants may not have fields")
}
}
match discriminant {
Some((_, expr)) => variants.push((ident, expr)),
None => bail!("Enumeration variants must have a discriminant"),
}
}
if variants.is_empty() {
panic!("Enumeration must have at least one variant");
}
let default = variants[0].0.clone();
let is_valid = variants.iter().map(|(_, value)| quote!(#value => true));
let from = variants
.iter()
.map(|(variant, value)| quote!(#value => ::core::option::Option::Some(#ident::#variant)));
let try_from = variants
.iter()
.map(|(variant, value)| quote!(#value => ::core::result::Result::Ok(#ident::#variant)));
let is_valid_doc = format!("Returns `true` if `value` is a variant of `{}`.", ident);
let from_i32_doc = format!(
"Converts an `i32` to a `{}`, or `None` if `value` is not a valid variant.",
ident
);
let expanded = quote! {
impl #impl_generics #ident #ty_generics #where_clause {
#[doc=#is_valid_doc]
pub fn is_valid(value: i32) -> bool {
match value {
#(#is_valid,)*
_ => false,
}
}
#[deprecated = "Use the TryFrom<i32> implementation instead"]
#[doc=#from_i32_doc]
pub fn from_i32(value: i32) -> ::core::option::Option<#ident> {
match value {
#(#from,)*
_ => ::core::option::Option::None,
}
}
}
impl #impl_generics ::core::default::Default for #ident #ty_generics #where_clause {
fn default() -> #ident {
#ident::#default
}
}
impl #impl_generics ::core::convert::From::<#ident> for i32 #ty_generics #where_clause {
fn from(value: #ident) -> i32 {
value as i32
}
}
impl #impl_generics ::core::convert::TryFrom::<i32> for #ident #ty_generics #where_clause {
type Error = ::prost::DecodeError;
fn try_from(value: i32) -> ::core::result::Result<#ident, ::prost::DecodeError> {
match value {
#(#try_from,)*
_ => ::core::result::Result::Err(::prost::DecodeError::new("invalid enumeration value")),
}
}
}
};
Ok(expanded.into())
}
#[proc_macro_derive(Enumeration, attributes(prost))]
pub fn enumeration(input: TokenStream) -> TokenStream {
try_enumeration(input).unwrap()
}
fn try_oneof(input: TokenStream) -> Result<TokenStream, Error> {
let input: DeriveInput = syn::parse(input)?;
let ident = input.ident;
syn::custom_keyword!(skip_debug);
let skip_debug = input
.attrs
.into_iter()
.any(|a| a.path().is_ident("prost") && a.parse_args::<skip_debug>().is_ok());
let variants = match input.data {
Data::Enum(DataEnum { variants, .. }) => variants,
Data::Struct(..) => bail!("Oneof can not be derived for a struct"),
Data::Union(..) => bail!("Oneof can not be derived for a union"),
};
let generics = &input.generics;
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
// Map the variants into 'fields'.
let mut fields: Vec<(Ident, Field)> = Vec::new();
for Variant {
attrs,
ident: variant_ident,
fields: variant_fields,
..
} in variants
{
let variant_fields = match variant_fields {
Fields::Unit => Punctuated::new(),
Fields::Named(FieldsNamed { named: fields, .. })
| Fields::Unnamed(FieldsUnnamed {
unnamed: fields, ..
}) => fields,
};
if variant_fields.len() != 1 {
bail!("Oneof enum variants must have a single field");
}
match Field::new_oneof(attrs)? {
Some(field) => fields.push((variant_ident, field)),
None => bail!("invalid oneof variant: oneof variants may not be ignored"),
}
}
let mut tags = fields
.iter()
.flat_map(|(variant_ident, field)| -> Result<u32, Error> {
if field.tags().len() > 1 {
bail!(
"invalid oneof variant {}::{}: oneof variants may only have a single tag",
ident,
variant_ident
);
}
Ok(field.tags()[0])
})
.collect::<Vec<_>>();
tags.sort_unstable();
tags.dedup();
if tags.len() != fields.len() {
panic!("invalid oneof {}: variants have duplicate tags", ident);
}
let encode = fields.iter().map(|(variant_ident, field)| {
let encode = field.encode(quote!(*value));
quote!(#ident::#variant_ident(ref value) => { #encode })
});
let merge = fields.iter().map(|(variant_ident, field)| {
let tag = field.tags()[0];
let merge = field.merge(quote!(value));
quote! {
#tag => {
match field {
::core::option::Option::Some(#ident::#variant_ident(ref mut value)) => {
#merge
},
_ => {
let mut owned_value = ::core::default::Default::default();
let value = &mut owned_value;
#merge.map(|_| *field = ::core::option::Option::Some(#ident::#variant_ident(owned_value)))
},
}
}
}
});
let encoded_len = fields.iter().map(|(variant_ident, field)| {
let encoded_len = field.encoded_len(quote!(*value));
quote!(#ident::#variant_ident(ref value) => #encoded_len)
});
let expanded = quote! {
impl #impl_generics #ident #ty_generics #where_clause {
/// Encodes the message to a buffer.
pub fn encode<B>(&self, buf: &mut B) where B: ::prost::bytes::BufMut {
match *self {
#(#encode,)*
}
}
/// Decodes an instance of the message from a buffer, and merges it into self.
pub fn merge<B>(
field: &mut ::core::option::Option<#ident #ty_generics>,
tag: u32,
wire_type: ::prost::encoding::WireType,
buf: &mut B,
ctx: ::prost::encoding::DecodeContext,
) -> ::core::result::Result<(), ::prost::DecodeError>
where B: ::prost::bytes::Buf {
match tag {
#(#merge,)*
_ => unreachable!(concat!("invalid ", stringify!(#ident), " tag: {}"), tag),
}
}
/// Returns the encoded length of the message without a length delimiter.
#[inline]
pub fn encoded_len(&self) -> usize {
match *self {
#(#encoded_len,)*
}
}
}
};
let expanded = if skip_debug {
expanded
} else {
let debug = fields.iter().map(|(variant_ident, field)| {
let wrapper = field.debug(quote!(*value));
quote!(#ident::#variant_ident(ref value) => {
let wrapper = #wrapper;
f.debug_tuple(stringify!(#variant_ident))
.field(&wrapper)
.finish()
})
});
quote! {
#expanded
impl #impl_generics ::core::fmt::Debug for #ident #ty_generics #where_clause {
fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
match *self {
#(#debug,)*
}
}
}
}
};
Ok(expanded.into())
}
#[proc_macro_derive(Oneof, attributes(prost))]
pub fn oneof(input: TokenStream) -> TokenStream {
try_oneof(input).unwrap()
}
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