452 lines
16 KiB
Rust
452 lines
16 KiB
Rust
//! Implementation of the top level `*Event` derive macro.
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use proc_macro2::{Span, TokenStream};
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use quote::quote;
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use syn::{
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Data, DataStruct, DeriveInput, Field, Fields, FieldsNamed, Ident, Meta, MetaList, NestedMeta,
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};
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use crate::{
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event_parse::{to_kind_variation, EventKind, EventKindVariation},
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import_ruma_events,
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};
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/// Derive `Event` macro code generation.
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pub fn expand_event(input: DeriveInput) -> syn::Result<TokenStream> {
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let ruma_events = import_ruma_events();
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let ident = &input.ident;
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let (kind, var) = to_kind_variation(ident).ok_or_else(|| {
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syn::Error::new(Span::call_site(), "not a valid ruma event struct identifier")
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})?;
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let fields: Vec<_> = if let Data::Struct(DataStruct { fields, .. }) = input.data.clone() {
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if let Fields::Named(FieldsNamed { named, .. }) = fields {
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if !named.iter().any(|f| f.ident.as_ref().unwrap() == "content") {
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return Err(syn::Error::new(
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Span::call_site(),
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"struct must contain a `content` field",
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));
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}
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named.into_iter().collect()
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} else {
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return Err(syn::Error::new_spanned(
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fields,
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"the `Event` derive only supports named fields",
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));
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}
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} else {
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return Err(syn::Error::new_spanned(
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input.ident,
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"the `Event` derive only supports structs with named fields",
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));
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};
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let serialize_impl = expand_serialize_event(&input, &var, &fields, &ruma_events);
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let deserialize_impl = expand_deserialize_event(&input, &var, &fields, &ruma_events)?;
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let conversion_impl = expand_from_into(&input, &kind, &var, &fields, &ruma_events);
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let eq_impl = expand_eq_ord_event(&input, &fields);
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Ok(quote! {
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#conversion_impl
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#serialize_impl
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#deserialize_impl
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#eq_impl
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})
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}
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fn expand_serialize_event(
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input: &DeriveInput,
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var: &EventKindVariation,
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fields: &[Field],
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ruma_events: &TokenStream,
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) -> TokenStream {
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let serde = quote! { #ruma_events::exports::serde };
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let ident = &input.ident;
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let (impl_gen, ty_gen, where_clause) = input.generics.split_for_impl();
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let serialize_fields: Vec<_> = fields
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.iter()
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.map(|field| {
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let name = field.ident.as_ref().unwrap();
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if name == "content" && var.is_redacted() {
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quote! {
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if #ruma_events::RedactedEventContent::has_serialize_fields(&self.content) {
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state.serialize_field("content", &self.content)?;
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}
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}
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} else if name == "prev_content" {
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quote! {
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if let Some(content) = self.prev_content.as_ref() {
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state.serialize_field("prev_content", content)?;
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}
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}
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} else if name == "unsigned" {
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quote! {
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if !self.unsigned.is_empty() {
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state.serialize_field("unsigned", &self.unsigned)?;
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}
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}
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} else {
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quote! {
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state.serialize_field(stringify!(#name), &self.#name)?;
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}
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}
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})
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.collect();
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quote! {
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#[automatically_derived]
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impl #impl_gen #serde::ser::Serialize for #ident #ty_gen #where_clause {
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fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
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where
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S: #serde::ser::Serializer,
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{
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use #serde::ser::{SerializeStruct as _, Error as _};
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let event_type = #ruma_events::EventContent::event_type(&self.content);
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let mut state = serializer.serialize_struct(stringify!(#ident), 7)?;
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state.serialize_field("type", event_type)?;
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#( #serialize_fields )*
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state.end()
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}
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}
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}
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}
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fn expand_deserialize_event(
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input: &DeriveInput,
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var: &EventKindVariation,
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fields: &[Field],
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ruma_events: &TokenStream,
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) -> syn::Result<TokenStream> {
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let serde = quote! { #ruma_events::exports::serde };
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let serde_json = quote! { #ruma_events::exports::serde_json };
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let ident = &input.ident;
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// we know there is a content field already
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let content_type = fields
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.iter()
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// we also know that the fields are named and have an ident
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.find(|f| f.ident.as_ref().unwrap() == "content")
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.map(|f| f.ty.clone())
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.unwrap();
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let (impl_generics, ty_gen, where_clause) = input.generics.split_for_impl();
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let is_generic = !input.generics.params.is_empty();
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let enum_variants: Vec<_> = fields
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.iter()
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.map(|field| {
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let name = field.ident.as_ref().unwrap();
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to_camel_case(name)
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})
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.collect();
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let deserialize_var_types: Vec<_> = fields
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.iter()
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.map(|field| {
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let name = field.ident.as_ref().unwrap();
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let ty = &field.ty;
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if name == "content" || name == "prev_content" {
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if is_generic {
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quote! { Box<#serde_json::value::RawValue> }
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} else {
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quote! { #content_type }
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}
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} else {
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quote! { #ty }
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}
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})
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.collect();
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let ok_or_else_fields: Vec<_> = fields
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.iter()
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.map(|field| {
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let name = field.ident.as_ref().unwrap();
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Ok(if name == "content" {
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if is_generic && var.is_redacted() {
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quote! {
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let content = match C::has_deserialize_fields() {
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#ruma_events::HasDeserializeFields::False => {
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C::empty(&event_type).map_err(A::Error::custom)?
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},
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#ruma_events::HasDeserializeFields::True => {
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let json = content.ok_or_else(
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|| #serde::de::Error::missing_field("content"),
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)?;
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C::from_parts(&event_type, &json).map_err(A::Error::custom)?
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},
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#ruma_events::HasDeserializeFields::Optional => {
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let json = content.unwrap_or(
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#serde_json::value::RawValue::from_string("{}".to_owned())
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.unwrap()
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);
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C::from_parts(&event_type, &json).map_err(A::Error::custom)?
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},
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};
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}
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} else if is_generic {
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quote! {
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let json =
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content.ok_or_else(|| #serde::de::Error::missing_field("content"))?;
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let content = C::from_parts(&event_type, &json).map_err(A::Error::custom)?;
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}
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} else {
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quote! {
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let content = content.ok_or_else(
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|| #serde::de::Error::missing_field("content"),
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)?;
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}
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}
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} else if name == "prev_content" {
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if is_generic {
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quote! {
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let prev_content = if let Some(json) = prev_content {
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Some(C::from_parts(&event_type, &json).map_err(A::Error::custom)?)
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} else {
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None
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};
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}
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} else {
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quote! {
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let prev_content = if let Some(content) = prev_content {
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Some(content)
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} else {
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None
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};
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}
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}
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} else if name == "unsigned" {
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quote! { let unsigned = unsigned.unwrap_or_default(); }
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} else {
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let attrs: Vec<_> = field
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.attrs
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.iter()
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.filter(|a| a.path.is_ident("ruma_event"))
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.map(|a| a.parse_meta())
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.collect::<syn::Result<_>>()?;
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let has_default_attr = attrs.iter().any(|a| {
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matches!(
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a,
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Meta::List(MetaList { nested, .. })
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if nested.iter().any(|n| {
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matches!(n, NestedMeta::Meta(Meta::Path(p)) if p.is_ident("default"))
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})
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)
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});
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if has_default_attr {
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quote! {
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let #name = #name.unwrap_or_default();
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}
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} else {
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quote! {
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let #name = #name.ok_or_else(|| {
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#serde::de::Error::missing_field(stringify!(#name))
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})?;
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}
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}
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})
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})
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.collect::<syn::Result<_>>()?;
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let field_names: Vec<_> = fields.iter().flat_map(|f| &f.ident).collect();
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let deserialize_impl_gen = if is_generic {
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let gen = &input.generics.params;
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quote! { <'de, #gen> }
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} else {
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quote! { <'de> }
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};
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let deserialize_phantom_type = if is_generic {
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quote! { ::std::marker::PhantomData }
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} else {
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quote! {}
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};
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Ok(quote! {
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#[automatically_derived]
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impl #deserialize_impl_gen #serde::de::Deserialize<'de> for #ident #ty_gen #where_clause {
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fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
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where
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D: #serde::de::Deserializer<'de>,
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{
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#[derive(#serde::Deserialize)]
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#[serde(field_identifier, rename_all = "snake_case")]
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enum Field {
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// since this is represented as an enum we have to add it so the JSON picks it
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// up
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Type,
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#( #enum_variants, )*
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#[serde(other)]
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Unknown,
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}
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/// Visits the fields of an event struct to handle deserialization of
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/// the `content` and `prev_content` fields.
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struct EventVisitor #impl_generics (#deserialize_phantom_type #ty_gen);
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#[automatically_derived]
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impl #deserialize_impl_gen #serde::de::Visitor<'de>
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for EventVisitor #ty_gen #where_clause
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{
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type Value = #ident #ty_gen;
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fn expecting(
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&self,
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formatter: &mut ::std::fmt::Formatter<'_>,
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) -> ::std::fmt::Result {
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write!(formatter, "struct implementing {}", stringify!(#content_type))
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}
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fn visit_map<A>(self, mut map: A) -> Result<Self::Value, A::Error>
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where
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A: #serde::de::MapAccess<'de>,
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{
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use #serde::de::Error as _;
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let mut event_type: Option<String> = None;
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#( let mut #field_names: Option<#deserialize_var_types> = None; )*
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while let Some(key) = map.next_key()? {
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match key {
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Field::Unknown => {
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let _: #serde::de::IgnoredAny = map.next_value()?;
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},
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Field::Type => {
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if event_type.is_some() {
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return Err(#serde::de::Error::duplicate_field("type"));
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}
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event_type = Some(map.next_value()?);
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}
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#(
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Field::#enum_variants => {
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if #field_names.is_some() {
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return Err(#serde::de::Error::duplicate_field(
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stringify!(#field_names),
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));
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}
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#field_names = Some(map.next_value()?);
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}
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)*
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}
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}
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let event_type =
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event_type.ok_or_else(|| #serde::de::Error::missing_field("type"))?;
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#( #ok_or_else_fields )*
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Ok(#ident {
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#( #field_names ),*
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})
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}
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}
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deserializer.deserialize_map(EventVisitor(#deserialize_phantom_type))
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}
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}
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})
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}
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fn expand_from_into(
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input: &DeriveInput,
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kind: &EventKind,
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var: &EventKindVariation,
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fields: &[Field],
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ruma_events: &TokenStream,
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) -> Option<TokenStream> {
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let ruma_identifiers = quote! { #ruma_events::exports::ruma_identifiers };
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let ident = &input.ident;
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let (impl_generics, ty_gen, where_clause) = input.generics.split_for_impl();
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let fields: Vec<_> = fields.iter().flat_map(|f| &f.ident).collect();
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if let EventKindVariation::Sync | EventKindVariation::RedactedSync = var {
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let full_struct = kind.to_event_ident(&var.to_full_variation());
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Some(quote! {
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#[automatically_derived]
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impl #impl_generics From<#full_struct #ty_gen> for #ident #ty_gen #where_clause {
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fn from(event: #full_struct #ty_gen) -> Self {
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let #full_struct { #( #fields, )* .. } = event;
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Self { #( #fields, )* }
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}
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}
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#[automatically_derived]
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impl #impl_generics #ident #ty_gen #where_clause {
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/// Convert this sync event into a full event, one with a room_id field.
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pub fn into_full_event(
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self,
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room_id: #ruma_identifiers::RoomId,
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) -> #full_struct #ty_gen {
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let Self { #( #fields, )* } = self;
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#full_struct {
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#( #fields, )*
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room_id,
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}
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}
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}
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})
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} else {
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None
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}
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}
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fn expand_eq_ord_event(input: &DeriveInput, fields: &[Field]) -> Option<TokenStream> {
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if fields.iter().flat_map(|f| f.ident.as_ref()).any(|f| f == "event_id") {
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let ident = &input.ident;
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let (impl_gen, ty_gen, where_clause) = input.generics.split_for_impl();
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Some(quote! {
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#[automatically_derived]
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impl #impl_gen ::std::cmp::PartialEq for #ident #ty_gen #where_clause {
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/// This checks if two `EventId`s are equal.
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fn eq(&self, other: &Self) -> ::std::primitive::bool {
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self.event_id == other.event_id
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}
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}
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#[automatically_derived]
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impl #impl_gen ::std::cmp::Eq for #ident #ty_gen #where_clause {}
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#[automatically_derived]
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impl #impl_gen ::std::cmp::PartialOrd for #ident #ty_gen #where_clause {
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/// This compares `EventId`s and orders them lexicographically.
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fn partial_cmp(&self, other: &Self) -> ::std::option::Option<::std::cmp::Ordering> {
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self.event_id.partial_cmp(&other.event_id)
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}
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}
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#[automatically_derived]
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impl #impl_gen ::std::cmp::Ord for #ident #ty_gen #where_clause {
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/// This compares `EventId`s and orders them lexicographically.
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fn cmp(&self, other: &Self) -> ::std::cmp::Ordering {
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self.event_id.cmp(&other.event_id)
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}
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}
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})
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} else {
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None
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}
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}
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/// CamelCase's a field ident like "foo_bar" to "FooBar".
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fn to_camel_case(name: &Ident) -> Ident {
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let span = name.span();
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let name = name.to_string();
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let s: String = name
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.split('_')
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.map(|s| s.chars().next().unwrap().to_uppercase().to_string() + &s[1..])
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.collect();
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Ident::new(&s, span)
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}
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