ZIm/crates/gpui3_macros/src/derive_element.rs
2023-09-20 22:26:46 -06:00

93 lines
2.9 KiB
Rust

use proc_macro::TokenStream;
use proc_macro2::Ident;
use quote::quote;
use syn::{parse_macro_input, parse_quote, DeriveInput, GenericParam, Generics};
use crate::derive_into_element::impl_into_element;
pub fn derive_element(input: TokenStream) -> TokenStream {
let ast = parse_macro_input!(input as DeriveInput);
let type_name = ast.ident;
let placeholder_view_generics: Generics = parse_quote! { <V: 'static> };
let (impl_generics, type_generics, where_clause, view_type_name, lifetimes) =
if let Some(first_type_param) = ast.generics.params.iter().find_map(|param| {
if let GenericParam::Type(type_param) = param {
Some(type_param.ident.clone())
} else {
None
}
}) {
let mut lifetimes = vec![];
for param in ast.generics.params.iter() {
if let GenericParam::Lifetime(lifetime_def) = param {
lifetimes.push(lifetime_def.lifetime.clone());
}
}
let generics = ast.generics.split_for_impl();
(
generics.0,
Some(generics.1),
generics.2,
first_type_param,
lifetimes,
)
} else {
let generics = placeholder_view_generics.split_for_impl();
let placeholder_view_type_name: Ident = parse_quote! { V };
(
generics.0,
None,
generics.2,
placeholder_view_type_name,
vec![],
)
};
let lifetimes = if !lifetimes.is_empty() {
quote! { <#(#lifetimes),*> }
} else {
quote! {}
};
let impl_into_element = impl_into_element(
&impl_generics,
&view_type_name,
&type_name,
&type_generics,
&where_clause,
);
let gen = quote! {
impl #impl_generics gpui2::element::Element<#view_type_name> for #type_name #type_generics
#where_clause
{
type PaintState = gpui2::element::AnyElement<#view_type_name #lifetimes>;
fn layout(
&mut self,
view: &mut V,
cx: &mut gpui2::ViewContext<V>,
) -> anyhow::Result<(gpui2::element::LayoutId, Self::PaintState)> {
let mut rendered_element = self.render(view, cx).into_element().into_any();
let layout_id = rendered_element.layout(view, cx)?;
Ok((layout_id, rendered_element))
}
fn paint(
&mut self,
view: &mut V,
parent_origin: gpui2::Vector2F,
_: &gpui2::element::Layout,
rendered_element: &mut Self::PaintState,
cx: &mut gpui2::ViewContext<V>,
) {
rendered_element.paint(view, parent_origin, cx);
}
}
#impl_into_element
};
gen.into()
}