mirror of
https://github.com/bevyengine/bevy
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bevy_reflect: enum_utility cleanup (#13424)
# Objective The `enum_utility` module contains the `get_variant_constructors` function, which is used to generate token streams for constructing enums. It's used for the `FromReflect::from_reflect` implementation and the `Reflect::try_apply` implementation. Due to the complexity of enums, this function is understandably a little messy and difficult to extend. ## Solution Clean up the `enum_utility` module. Now "clean" is a bit subjective. I believe my solution is "cleaner" in that the logic to generate the tokens are strictly coupled with the intended usage. Because of this, `try_apply` is also no longer strictly coupled with `from_reflect`. This makes it easier to extend with new functionality, which is something I'm doing in a future unrelated PR that I have based off this one. ## Testing There shouldn't be any testing required other than ensuring that the project still builds and that CI passes.
This commit is contained in:
Gino Valente
GitHub
parent
c4cedb12c8
commit
faf003fc9d
3 changed files with 256 additions and 109 deletions
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@ -1,122 +1,266 @@
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use crate::derive_data::StructField;
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use crate::field_attributes::DefaultBehavior;
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use crate::{
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derive_data::{EnumVariantFields, ReflectEnum},
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utility::ident_or_index,
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};
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use crate::{derive_data::ReflectEnum, utility::ident_or_index};
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use bevy_macro_utils::fq_std::{FQDefault, FQOption};
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use proc_macro2::Ident;
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use quote::{quote, ToTokens};
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use syn::Member;
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use proc_macro2::{Ident, TokenStream};
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use quote::{format_ident, quote};
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/// Contains all data needed to construct all variants within an enum.
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pub(crate) struct EnumVariantConstructors {
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pub(crate) struct EnumVariantOutputData {
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/// The names of each variant as a string.
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///
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/// For example, `Some` and `None` for the `Option` enum.
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pub variant_names: Vec<String>,
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/// The stream of tokens that will construct each variant.
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pub variant_constructors: Vec<proc_macro2::TokenStream>,
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/// The constructor portion of each variant.
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///
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/// For example, `Option::Some { 0: value }` and `Option::None {}` for the `Option` enum.
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pub variant_constructors: Vec<TokenStream>,
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}
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/// Gets the constructors for all variants in the given enum.
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pub(crate) fn get_variant_constructors(
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reflect_enum: &ReflectEnum,
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ref_value: &Ident,
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return_apply_error: bool,
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) -> EnumVariantConstructors {
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let bevy_reflect_path = reflect_enum.meta().bevy_reflect_path();
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let variant_count = reflect_enum.variants().len();
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let mut variant_names = Vec::with_capacity(variant_count);
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let mut variant_constructors = Vec::with_capacity(variant_count);
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#[derive(Copy, Clone)]
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pub(crate) struct VariantField<'a, 'b> {
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/// The alias for the field.
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///
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/// This should be used whenever the field needs to be referenced in a token stream.
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pub alias: &'a Ident,
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/// The name of the variant that contains the field.
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pub variant_name: &'a str,
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/// The field data.
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pub field: &'a StructField<'b>,
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}
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for variant in reflect_enum.variants() {
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let ident = &variant.data.ident;
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let name = ident.to_string();
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let variant_constructor = reflect_enum.get_unit(ident);
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/// Trait used to control how enum variants are built.
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pub(crate) trait VariantBuilder: Sized {
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/// Returns the enum data.
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fn reflect_enum(&self) -> &ReflectEnum;
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let fields: &[StructField] = match &variant.fields {
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EnumVariantFields::Unit => &[],
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EnumVariantFields::Named(fields) | EnumVariantFields::Unnamed(fields) => {
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fields.as_slice()
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/// Returns a token stream that accesses a field of a variant as an `Option<dyn Reflect>`.
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///
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/// The default implementation of this method will return a token stream
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/// which gets the field dynamically so as to support `dyn Enum`.
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///
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/// # Parameters
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/// * `this`: The identifier of the enum
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/// * `field`: The field to access
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fn access_field(&self, this: &Ident, field: VariantField) -> TokenStream {
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match &field.field.data.ident {
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Some(field_ident) => {
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let name = field_ident.to_string();
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quote!(#this.field(#name))
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}
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};
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let mut reflect_index: usize = 0;
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let constructor_fields = fields.iter().enumerate().map(|(declare_index, field)| {
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let field_ident = ident_or_index(field.data.ident.as_ref(), declare_index);
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let field_ty = &field.data.ty;
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let field_value = if field.attrs.ignore.is_ignored() {
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match &field.attrs.default {
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DefaultBehavior::Func(path) => quote! { #path() },
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_ => quote! { #FQDefault::default() }
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}
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} else {
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let field_accessor = match &field.data.ident {
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Some(ident) => {
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let name = ident.to_string();
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quote!(#ref_value.field(#name))
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}
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None => quote!(#ref_value.field_at(#reflect_index)),
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};
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reflect_index += 1;
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let (resolve_error, resolve_missing) = if return_apply_error {
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let field_ref_str = match &field_ident {
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Member::Named(ident) => format!("{ident}"),
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Member::Unnamed(index) => format!(".{}", index.index)
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};
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let ty = field.data.ty.to_token_stream();
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(
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quote!(.ok_or(#bevy_reflect_path::ApplyError::MismatchedTypes {
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// The unwrap won't panic. By this point the #field_accessor would have been invoked once and any failure to
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// access the given field handled by the `resolve_missing` code bellow.
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from_type: ::core::convert::Into::into(
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#bevy_reflect_path::DynamicTypePath::reflect_type_path(#FQOption::unwrap(#field_accessor))
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),
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to_type: ::core::convert::Into::into(<#ty as #bevy_reflect_path::TypePath>::type_path())
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})?),
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quote!(.ok_or(#bevy_reflect_path::ApplyError::MissingEnumField {
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variant_name: ::core::convert::Into::into(#name),
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field_name: ::core::convert::Into::into(#field_ref_str)
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})?)
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)
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None => {
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if let Some(field_index) = field.field.reflection_index {
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quote!(#this.field_at(#field_index))
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} else {
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(quote!(?), quote!(?))
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quote!(::core::compile_error!(
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"internal bevy_reflect error: field should be active"
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))
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}
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}
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}
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}
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/// Returns a token stream that unwraps a field of a variant as a `&dyn Reflect`
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/// (from an `Option<dyn Reflect>`).
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///
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/// # Parameters
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/// * `field`: The field to access
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fn unwrap_field(&self, field: VariantField) -> TokenStream;
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/// Returns a token stream that constructs a field of a variant as a concrete type
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/// (from a `&dyn Reflect`).
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///
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/// # Parameters
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/// * `field`: The field to access
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fn construct_field(&self, field: VariantField) -> TokenStream;
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/// Returns a token stream that constructs an instance of an active field.
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///
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/// # Parameters
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/// * `this`: The identifier of the enum
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/// * `field`: The field to access
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fn on_active_field(&self, this: &Ident, field: VariantField) -> TokenStream {
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let field_accessor = self.access_field(this, field);
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let alias = field.alias;
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let field_constructor = self.construct_field(field);
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match &field.field.attrs.default {
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DefaultBehavior::Func(path) => quote! {
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if let #FQOption::Some(#alias) = #field_accessor {
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#field_constructor
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} else {
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#path()
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}
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},
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DefaultBehavior::Default => quote! {
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if let #FQOption::Some(#alias) = #field_accessor {
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#field_constructor
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} else {
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#FQDefault::default()
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}
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},
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DefaultBehavior::Required => {
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let field_unwrapper = self.unwrap_field(field);
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quote! {{
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// `#alias` is used by both the unwrapper and constructor
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let #alias = #field_accessor;
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let #alias = #field_unwrapper;
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#field_constructor
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}}
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}
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}
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}
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/// Returns a token stream that constructs an instance of an ignored field.
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///
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/// # Parameters
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/// * `field`: The field to access
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fn on_ignored_field(&self, field: VariantField) -> TokenStream {
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match &field.field.attrs.default {
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DefaultBehavior::Func(path) => quote! { #path() },
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_ => quote! { #FQDefault::default() },
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}
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}
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/// Builds the enum variant output data.
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fn build(&self, this: &Ident) -> EnumVariantOutputData {
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let variants = self.reflect_enum().variants();
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let mut variant_names = Vec::with_capacity(variants.len());
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let mut variant_constructors = Vec::with_capacity(variants.len());
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for variant in variants {
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let variant_ident = &variant.data.ident;
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let variant_name = variant_ident.to_string();
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let variant_path = self.reflect_enum().get_unit(variant_ident);
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let fields = variant.fields();
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let field_constructors = fields.iter().map(|field| {
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let member = ident_or_index(field.data.ident.as_ref(), field.declaration_index);
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let alias = format_ident!("_{}", member);
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let variant_field = VariantField {
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alias: &alias,
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variant_name: &variant_name,
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field,
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};
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match &field.attrs.default {
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DefaultBehavior::Func(path) => quote! {
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if let #FQOption::Some(field) = #field_accessor {
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<#field_ty as #bevy_reflect_path::FromReflect>::from_reflect(field)
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#resolve_error
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} else {
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#path()
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}
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},
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DefaultBehavior::Default => quote! {
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if let #FQOption::Some(field) = #field_accessor {
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<#field_ty as #bevy_reflect_path::FromReflect>::from_reflect(field)
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#resolve_error
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} else {
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#FQDefault::default()
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}
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},
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DefaultBehavior::Required => quote! {
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<#field_ty as #bevy_reflect_path::FromReflect>::from_reflect(#field_accessor #resolve_missing)
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#resolve_error
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},
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let value = if field.attrs.ignore.is_ignored() {
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self.on_ignored_field(variant_field)
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} else {
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self.on_active_field(this, variant_field)
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};
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let constructor = quote! {
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#member: #value
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};
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constructor
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});
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let constructor = quote! {
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#variant_path {
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#( #field_constructors ),*
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}
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};
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quote! { #field_ident : #field_value }
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});
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variant_constructors.push(quote! {
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#variant_constructor { #( #constructor_fields ),* }
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});
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variant_names.push(name);
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}
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EnumVariantConstructors {
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variant_names,
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variant_constructors,
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variant_names.push(variant_name);
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variant_constructors.push(constructor);
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}
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EnumVariantOutputData {
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variant_names,
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variant_constructors,
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}
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}
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}
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/// Generates the enum variant output data needed to build the `FromReflect::from_reflect` implementation.
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pub(crate) struct FromReflectVariantBuilder<'a> {
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reflect_enum: &'a ReflectEnum<'a>,
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}
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impl<'a> FromReflectVariantBuilder<'a> {
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pub fn new(reflect_enum: &'a ReflectEnum) -> Self {
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Self { reflect_enum }
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}
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}
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impl<'a> VariantBuilder for FromReflectVariantBuilder<'a> {
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fn reflect_enum(&self) -> &ReflectEnum {
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self.reflect_enum
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}
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fn unwrap_field(&self, field: VariantField) -> TokenStream {
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let alias = field.alias;
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quote!(#alias?)
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}
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fn construct_field(&self, field: VariantField) -> TokenStream {
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let bevy_reflect_path = self.reflect_enum.meta().bevy_reflect_path();
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let field_ty = &field.field.data.ty;
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let alias = field.alias;
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quote! {
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<#field_ty as #bevy_reflect_path::FromReflect>::from_reflect(#alias)?
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}
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}
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}
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/// Generates the enum variant output data needed to build the `Reflect::try_apply` implementation.
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pub(crate) struct TryApplyVariantBuilder<'a> {
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reflect_enum: &'a ReflectEnum<'a>,
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}
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impl<'a> TryApplyVariantBuilder<'a> {
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pub fn new(reflect_enum: &'a ReflectEnum) -> Self {
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Self { reflect_enum }
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}
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}
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impl<'a> VariantBuilder for TryApplyVariantBuilder<'a> {
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fn reflect_enum(&self) -> &ReflectEnum {
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self.reflect_enum
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}
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fn unwrap_field(&self, field: VariantField) -> TokenStream {
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let VariantField {
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alias,
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variant_name,
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field,
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..
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} = field;
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let bevy_reflect_path = self.reflect_enum.meta().bevy_reflect_path();
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let field_name = match &field.data.ident {
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Some(ident) => format!("{ident}"),
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None => format!(".{}", field.declaration_index),
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};
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quote! {
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#alias.ok_or(#bevy_reflect_path::ApplyError::MissingEnumField {
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variant_name: ::core::convert::Into::into(#variant_name),
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field_name: ::core::convert::Into::into(#field_name)
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})?
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}
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}
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fn construct_field(&self, field: VariantField) -> TokenStream {
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let bevy_reflect_path = self.reflect_enum.meta().bevy_reflect_path();
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let alias = field.alias;
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let field_ty = &field.field.data.ty;
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quote! {
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<#field_ty as #bevy_reflect_path::FromReflect>::from_reflect(#alias)
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.ok_or(#bevy_reflect_path::ApplyError::MismatchedTypes {
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from_type: ::core::convert::Into::into(
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#bevy_reflect_path::DynamicTypePath::reflect_type_path(#alias)
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),
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to_type: ::core::convert::Into::into(<#field_ty as #bevy_reflect_path::TypePath>::type_path())
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})?
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}
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}
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}
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@ -1,6 +1,6 @@
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use crate::container_attributes::REFLECT_DEFAULT;
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use crate::derive_data::ReflectEnum;
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use crate::enum_utility::{get_variant_constructors, EnumVariantConstructors};
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use crate::enum_utility::{EnumVariantOutputData, FromReflectVariantBuilder, VariantBuilder};
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use crate::field_attributes::DefaultBehavior;
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use crate::utility::{ident_or_index, WhereClauseOptions};
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use crate::{ReflectMeta, ReflectStruct};
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@ -41,10 +41,12 @@ pub(crate) fn impl_enum(reflect_enum: &ReflectEnum) -> proc_macro2::TokenStream
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let bevy_reflect_path = reflect_enum.meta().bevy_reflect_path();
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let ref_value = Ident::new("__param0", Span::call_site());
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let EnumVariantConstructors {
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let EnumVariantOutputData {
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variant_names,
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variant_constructors,
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} = get_variant_constructors(reflect_enum, &ref_value, false);
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..
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} = FromReflectVariantBuilder::new(reflect_enum).build(&ref_value);
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let (impl_generics, ty_generics, where_clause) = enum_path.generics().split_for_impl();
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@ -1,5 +1,5 @@
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use crate::derive_data::{EnumVariantFields, ReflectEnum, StructField};
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use crate::enum_utility::{get_variant_constructors, EnumVariantConstructors};
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use crate::enum_utility::{EnumVariantOutputData, TryApplyVariantBuilder, VariantBuilder};
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use crate::impls::{impl_type_path, impl_typed};
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use bevy_macro_utils::fq_std::{FQAny, FQBox, FQOption, FQResult};
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use proc_macro2::{Ident, Span};
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@ -27,10 +27,11 @@ pub(crate) fn impl_enum(reflect_enum: &ReflectEnum) -> proc_macro2::TokenStream
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enum_variant_type,
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} = generate_impls(reflect_enum, &ref_index, &ref_name);
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let EnumVariantConstructors {
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let EnumVariantOutputData {
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variant_names,
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variant_constructors,
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} = get_variant_constructors(reflect_enum, &ref_value, true);
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..
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} = TryApplyVariantBuilder::new(reflect_enum).build(&ref_value);
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let hash_fn = reflect_enum
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.meta()
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