core/lua_macros/src/lib.rs

mod mark_as_ci_command;
mod struct_to_ci_enum;

use mark_as_ci_command::generate_final_function;
use proc_macro::TokenStream;
use proc_macro2::{Span, TokenStream as TokenStream2};
use quote::{format_ident, quote};
use struct_to_ci_enum::{generate_command_enum, generate_generate_ci_function, generate_help_function};
use syn::{self, parse_quote, parse_str, DeriveInput, FieldMutability, ItemFn, Token, Visibility};

#[proc_macro_attribute]
pub fn turn_struct_to_ci_command_enum(_attrs: TokenStream, input: TokenStream) -> TokenStream {
    // Construct a representation of Rust code as a syntax tree
    // that we can manipulate
    let mut input: DeriveInput = syn::parse(input).expect("This should always be valid rust code, as it's extracted from direct code");

    let mut named_fields = match &input.data {
        syn::Data::Struct(input) => match &input.fields {
            syn::Fields::Named(named_fields) => named_fields,
            _ => unimplemented!("The macro only works for named fields (e.g.: `Name: Type`)"),
        },
        _ => unimplemented!("The macro only works for structs"),
    }
    .to_owned();

    let attr_parsed = parse_quote! {
        /// This is a help function
    };

    named_fields.named.push(syn::Field {
        attrs: vec![attr_parsed],
        // attrs: attr_parser
        //     .parse("#[doc = r\"This is a help function\"]".to_token_stream().into())
        //     .expect("See reason for other one"),
        vis: Visibility::Inherited,
        mutability: FieldMutability::None,
        ident: Some(format_ident!("help")),
        colon_token: Some(Token![:](Span::call_site())),
        ty: parse_str("fn(Option<String>) -> String").expect("This is static and valid rust code"),
    });

    match &mut input.data {
        syn::Data::Struct(input) => input.fields = syn::Fields::Named(named_fields.clone()),
        _ => unreachable!("This was a DataStruct before"),
    };

    // Build the trait implementation
    let generate_ci_function: TokenStream2 = generate_generate_ci_function(&input);

    let command_enum = generate_command_enum(&named_fields);

    let help_function = generate_help_function(&named_fields);

    quote! {
        #command_enum

        #generate_ci_function

        //#help_function
    }
    .into()
}

#[proc_macro_attribute]
pub fn ci_command(_attrs: TokenStream, input: TokenStream) -> TokenStream {
    let mut input: ItemFn = syn::parse(input).expect("This should always be valid rust code, as it's extracted from direct code");
    let output_function = generate_final_function(&mut input);
    output_function.into()
}