wgsl_to_wgpu 0.7.0

Generate typesafe Rust bindings for wgsl shaders in wgpu
Documentation 
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use proc_macro2::{Span, TokenStream};
use quote::quote;
use syn::Ident;

pub fn consts(module: &naga::Module) -> Vec<TokenStream> {
    // Create matching Rust constants for WGSl constants.
    module
        .constants
        .iter()
        .filter_map(|(_, t)| -> Option<TokenStream> {
            let name = Ident::new(t.name.as_ref()?, Span::call_site());

            // TODO: Add support for f64 and f16 once naga supports them.
            let type_and_value = match &module.const_expressions[t.init] {
                naga::Expression::Literal(literal) => match literal {
                    naga::Literal::F64(v) => Some(quote!(f32 = #v)),
                    naga::Literal::F32(v) => Some(quote!(f32 = #v)),
                    naga::Literal::U32(v) => Some(quote!(u32 = #v)),
                    naga::Literal::I32(v) => Some(quote!(i32 = #v)),
                    naga::Literal::Bool(v) => Some(quote!(bool = #v)),
                    naga::Literal::I64(v) => Some(quote!(i64 = #v)),
                    naga::Literal::AbstractInt(v) => Some(quote!(i64 = #v)),
                    naga::Literal::AbstractFloat(v) => Some(quote!(f64 = #v)),
                },
                _ => None,
            }?;

            Some(quote!( pub const #name: #type_and_value;))
        })
        .collect()
}

#[cfg(test)]
mod tests {
    use super::*;

    use crate::assert_tokens_eq;
    use indoc::indoc;

    #[test]
    fn write_global_consts() {
        let source = indoc! {r#"
            const INT_CONST = 12;
            const UNSIGNED_CONST = 34u;
            const FLOAT_CONST = 0.1;
            // TODO: Naga doesn't implement f16, even though it's in the WGSL spec
            // const SMALL_FLOAT_CONST:f16 = 0.1h;
            const BOOL_CONST = true;

            @fragment
            fn main() {
                // TODO: This is valid WGSL syntax, but naga doesn't support it apparently.
                // const C_INNER = 456;
            }
        "#};

        let module = naga::front::wgsl::parse_str(source).unwrap();

        let consts = consts(&module);
        let actual = quote!(#(#consts)*);
        eprintln!("{actual}");

        assert_tokens_eq!(
            quote! {
                pub const INT_CONST: i32 = 12i32;
                pub const UNSIGNED_CONST: u32 = 34u32;
                pub const FLOAT_CONST: f32 = 0.1f32;
                pub const BOOL_CONST: bool = true;
            },
            actual
        );
    }
}