prost_derive/field/
message.rs

1use anyhow::{bail, Error};
2use proc_macro2::TokenStream;
3use quote::{quote, ToTokens};
4use syn::Meta;
5
6use crate::field::{set_bool, set_option, tag_attr, word_attr, Label};
7
8#[derive(Clone)]
9pub struct Field {
10    pub label: Label,
11    pub tag: u32,
12}
13
14impl Field {
15    pub fn new(attrs: &[Meta], inferred_tag: Option<u32>) -> Result<Option<Field>, Error> {
16        let mut message = false;
17        let mut label = None;
18        let mut tag = None;
19        let mut boxed = false;
20
21        let mut unknown_attrs = Vec::new();
22
23        for attr in attrs {
24            if word_attr("message", attr) {
25                set_bool(&mut message, "duplicate message attribute")?;
26            } else if word_attr("boxed", attr) {
27                set_bool(&mut boxed, "duplicate boxed attribute")?;
28            } else if let Some(t) = tag_attr(attr)? {
29                set_option(&mut tag, t, "duplicate tag attributes")?;
30            } else if let Some(l) = Label::from_attr(attr) {
31                set_option(&mut label, l, "duplicate label attributes")?;
32            } else {
33                unknown_attrs.push(attr);
34            }
35        }
36
37        if !message {
38            return Ok(None);
39        }
40
41        match unknown_attrs.len() {
42            0 => (),
43            1 => bail!(
44                "unknown attribute for message field: {:?}",
45                unknown_attrs[0]
46            ),
47            _ => bail!("unknown attributes for message field: {:?}", unknown_attrs),
48        }
49
50        let tag = match tag.or(inferred_tag) {
51            Some(tag) => tag,
52            None => bail!("message field is missing a tag attribute"),
53        };
54
55        Ok(Some(Field {
56            label: label.unwrap_or(Label::Optional),
57            tag,
58        }))
59    }
60
61    pub fn new_oneof(attrs: &[Meta]) -> Result<Option<Field>, Error> {
62        if let Some(mut field) = Field::new(attrs, None)? {
63            if let Some(attr) = attrs.iter().find(|attr| Label::from_attr(attr).is_some()) {
64                bail!(
65                    "invalid attribute for oneof field: {}",
66                    attr.path().into_token_stream()
67                );
68            }
69            field.label = Label::Required;
70            Ok(Some(field))
71        } else {
72            Ok(None)
73        }
74    }
75
76    pub fn encode(&self, ident: TokenStream) -> TokenStream {
77        let tag = self.tag;
78        match self.label {
79            Label::Optional => quote! {
80                if let Some(ref msg) = #ident {
81                    ::prost::encoding::message::encode(#tag, msg, buf);
82                }
83            },
84            Label::Required => quote! {
85                ::prost::encoding::message::encode(#tag, &#ident, buf);
86            },
87            Label::Repeated => quote! {
88                for msg in &#ident {
89                    ::prost::encoding::message::encode(#tag, msg, buf);
90                }
91            },
92        }
93    }
94
95    pub fn merge(&self, ident: TokenStream) -> TokenStream {
96        match self.label {
97            Label::Optional => quote! {
98                ::prost::encoding::message::merge(wire_type,
99                                                 #ident.get_or_insert_with(::core::default::Default::default),
100                                                 buf,
101                                                 ctx)
102            },
103            Label::Required => quote! {
104                ::prost::encoding::message::merge(wire_type, #ident, buf, ctx)
105            },
106            Label::Repeated => quote! {
107                ::prost::encoding::message::merge_repeated(wire_type, #ident, buf, ctx)
108            },
109        }
110    }
111
112    pub fn encoded_len(&self, ident: TokenStream) -> TokenStream {
113        let tag = self.tag;
114        match self.label {
115            Label::Optional => quote! {
116                #ident.as_ref().map_or(0, |msg| ::prost::encoding::message::encoded_len(#tag, msg))
117            },
118            Label::Required => quote! {
119                ::prost::encoding::message::encoded_len(#tag, &#ident)
120            },
121            Label::Repeated => quote! {
122                ::prost::encoding::message::encoded_len_repeated(#tag, &#ident)
123            },
124        }
125    }
126
127    pub fn clear(&self, ident: TokenStream) -> TokenStream {
128        match self.label {
129            Label::Optional => quote!(#ident = ::core::option::Option::None),
130            Label::Required => quote!(#ident.clear()),
131            Label::Repeated => quote!(#ident.clear()),
132        }
133    }
134}
prost_derive/field/message.rs

prost_derive/field/
message.rs
