1 files changed, 134 insertions, 0 deletions
diff --git a/third_party/rust/prost-derive/src/field/group.rs b/third_party/rust/prost-derive/src/field/group.rs
new file mode 100644
index 0000000000..6396128802
--- /dev/null
+++ b/third_party/rust/prost-derive/src/field/group.rs
@@ -0,0 +1,134 @@
+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 group = 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("group", attr) {
+                set_bool(&mut group, "duplicate group attributes")?;
+            } else if word_attr("boxed", attr) {
+                set_bool(&mut boxed, "duplicate boxed attributes")?;
+            } 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 !group {
+            return Ok(None);
+        }
+
+        match unknown_attrs.len() {
+            0 => (),
+            1 => bail!("unknown attribute for group field: {:?}", unknown_attrs[0]),
+            _ => bail!("unknown attributes for group field: {:?}", unknown_attrs),
+        }
+
+        let tag = match tag.or(inferred_tag) {
+            Some(tag) => tag,
+            None => bail!("group 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::group::encode(#tag, msg, buf);
+                }
+            },
+            Label::Required => quote! {
+                ::prost::encoding::group::encode(#tag, &#ident, buf);
+            },
+            Label::Repeated => quote! {
+                for msg in &#ident {
+                    ::prost::encoding::group::encode(#tag, msg, buf);
+                }
+            },
+        }
+    }
+
+    pub fn merge(&self, ident: TokenStream) -> TokenStream {
+        match self.label {
+            Label::Optional => quote! {
+                ::prost::encoding::group::merge(
+                    tag,
+                    wire_type,
+                    #ident.get_or_insert_with(Default::default),
+                    buf,
+                    ctx,
+                )
+            },
+            Label::Required => quote! {
+                ::prost::encoding::group::merge(tag, wire_type, #ident, buf, ctx)
+            },
+            Label::Repeated => quote! {
+                ::prost::encoding::group::merge_repeated(tag, 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::group::encoded_len(#tag, msg))
+            },
+            Label::Required => quote! {
+                ::prost::encoding::group::encoded_len(#tag, &#ident)
+            },
+            Label::Repeated => quote! {
+                ::prost::encoding::group::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()),
+        }
+    }
+}