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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,
}))
}
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(::core::default::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 = ::core::option::Option::None),
Label::Required => quote!(#ident.clear()),
Label::Repeated => quote!(#ident.clear()),
}
}
}