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use darling::FromMeta;
use proc_macro::TokenStream;
use quote::{format_ident, quote};
use syn::{
parse_macro_input, punctuated::Punctuated, token::Comma, AttributeArgs, ExprArray, FnArg,
ItemFn, Path, Type,
};
#[derive(FromMeta)]
struct Arguments {
name: String,
description: String,
examples: ExprArray,
categories: ExprArray,
}
#[proc_macro_attribute]
pub fn function(attr: TokenStream, item: TokenStream) -> TokenStream {
let arguments = match Arguments::from_list(&parse_macro_input!(attr as AttributeArgs)) {
Ok(arguments) => arguments,
Err(error) => return TokenStream::from(error.write_errors()),
};
let name_argument = arguments.name;
let description_argument = arguments.description;
let examples_argument = arguments.examples;
let categories_argument = arguments.categories;
let item_fn = parse_macro_input!(item as ItemFn);
let name = &item_fn.sig.ident;
let metadata_name = format_ident!("{}_METADATA", name.to_string().to_uppercase());
let proxy_name = format_ident!("{}_proxy", name);
let parameters = item_fn.sig.inputs.iter().map(|fn_arg| {
if let FnArg::Typed(pat_type) = fn_arg {
if let Type::Path(type_path) = &*pat_type.ty {
match type_path.path.get_ident().unwrap().to_string().as_str() {
"Expression" => quote! { crate::functions::Parameter::Expression },
"Integer" => quote! { crate::functions::Parameter::Integer },
"NonNegativeInteger" => {
quote! { crate::functions::Parameter::NonNegativeInteger }
}
"PositiveInteger" => {
quote! { crate::functions::Parameter::PositiveInteger }
}
"Rational" => quote! { crate::functions::Parameter::Rational },
"Complex" => quote! { crate::functions::Parameter::Complex },
"Vector" => quote! { crate::functions::Parameter::Vector },
"Matrix" => quote! { crate::functions::Parameter::Matrix },
"SquareMatrix" => quote! { crate::functions::Parameter::SquareMatrix },
"bool" => quote! { crate::functions::Parameter::Boolean },
_ => unimplemented!(),
}
} else {
unreachable!();
}
} else {
unreachable!();
}
});
let arguments =
(0..item_fn.sig.inputs.len()).map(|i| quote! { arguments[#i].clone().try_into()? });
let tokens = quote! {
#item_fn
pub(crate) const #metadata_name: crate::functions::Metadata = crate::functions::Metadata {
name: #name_argument,
description: #description_argument,
parameters: &[#(#parameters),*],
examples: &#examples_argument,
categories: &#categories_argument,
};
pub(crate) fn #proxy_name(arguments: &[crate::expression::Expression]) ->
::std::result::Result<crate::expression::Expression, crate::expression::Expression> {
::std::result::Result::Ok(#name(#(#arguments),*).into())
}
};
tokens.into()
}
#[proc_macro]
pub fn functions(input: TokenStream) -> TokenStream {
let mut statements = Vec::new();
for path in parse_macro_input!(input with Punctuated::<Path, Comma>::parse_terminated) {
let name = &path.segments.last().unwrap().ident;
let mut metadata_path = path.clone();
metadata_path.segments.last_mut().unwrap().ident =
format_ident!("{}_METADATA", name.to_string().to_uppercase());
let mut proxy_path = path.clone();
proxy_path.segments.last_mut().unwrap().ident = format_ident!("{}_proxy", name);
statements.push(quote! {
functions.push(Function {
metadata: #metadata_path,
implementation: wrap_proxy(#metadata_path.parameters, #proxy_path),
});
});
}
let tokens = quote! {{
let mut functions = Vec::new();
#(#statements)*
functions
}};
tokens.into()
}