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use anyhow::{bail, Error}; use proc_macro2::TokenStream; use quote::{quote, ToTokens}; use syn::Meta; use crate::field::{set_bool, set_option, tag_attr, word_attr, Label}; #[derive(Clone)] pub struct Field { pub label: Label, pub tag: u32, } impl Field { pub fn new(attrs: &[Meta], inferred_tag: Option<u32>) -> Result<Option<Field>, Error> { let mut message = false; let mut label = None; let mut tag = None; let mut boxed = false; let mut unknown_attrs = Vec::new(); for attr in attrs { if word_attr("message", attr) { set_bool(&mut message, "duplicate message attribute")?; } else if word_attr("boxed", attr) { set_bool(&mut boxed, "duplicate boxed attribute")?; } else if let Some(t) = tag_attr(attr)? { set_option(&mut tag, t, "duplicate tag attributes")?; } else if let Some(l) = Label::from_attr(attr) { set_option(&mut label, l, "duplicate label attributes")?; } else { unknown_attrs.push(attr); } } if !message { return Ok(None); } match unknown_attrs.len() { 0 => (), 1 => bail!( "unknown attribute for message field: {:?}", unknown_attrs[0] ), _ => bail!("unknown attributes for message field: {:?}", unknown_attrs), } let tag = match tag.or(inferred_tag) { Some(tag) => tag, None => bail!("message field is missing a tag attribute"), }; Ok(Some(Field { label: label.unwrap_or(Label::Optional), tag: tag, })) } pub fn new_oneof(attrs: &[Meta]) -> Result<Option<Field>, Error> { if let Some(mut field) = Field::new(attrs, None)? { if let Some(attr) = attrs.iter().find(|attr| Label::from_attr(attr).is_some()) { bail!( "invalid attribute for oneof field: {}", attr.path().into_token_stream() ); } field.label = Label::Required; Ok(Some(field)) } else { Ok(None) } } pub fn encode(&self, ident: TokenStream) -> TokenStream { let tag = self.tag; match self.label { Label::Optional => quote! { if let Some(ref msg) = #ident { ::prost::encoding::message::encode(#tag, msg, buf); } }, Label::Required => quote! { ::prost::encoding::message::encode(#tag, &#ident, buf); }, Label::Repeated => quote! { for msg in &#ident { ::prost::encoding::message::encode(#tag, msg, buf); } }, } } pub fn merge(&self, ident: TokenStream) -> TokenStream { match self.label { Label::Optional => quote! { ::prost::encoding::message::merge(wire_type, #ident.get_or_insert_with(Default::default), buf, ctx) }, Label::Required => quote! { ::prost::encoding::message::merge(wire_type, #ident, buf, ctx) }, Label::Repeated => quote! { ::prost::encoding::message::merge_repeated(wire_type, #ident, buf, ctx) }, } } pub fn encoded_len(&self, ident: TokenStream) -> TokenStream { let tag = self.tag; match self.label { Label::Optional => quote! { #ident.as_ref().map_or(0, |msg| ::prost::encoding::message::encoded_len(#tag, msg)) }, Label::Required => quote! { ::prost::encoding::message::encoded_len(#tag, &#ident) }, Label::Repeated => quote! { ::prost::encoding::message::encoded_len_repeated(#tag, &#ident) }, } } pub fn clear(&self, ident: TokenStream) -> TokenStream { match self.label { Label::Optional => quote!(#ident = ::std::option::Option::None), Label::Required => quote!(#ident.clear()), Label::Repeated => quote!(#ident.clear()), } } }