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// Rust language amplification derive library providing multiple generic trait
// implementations, type wrappers, derive macros and other language enhancements
//
// Written in 2019-2020 by
//     Elichai Turkel <elichai.turkel@gmail.com>
//     Dr. Maxim Orlovsky <orlovsky@pandoracore.com>
//
// To the extent possible under law, the author(s) have dedicated all
// copyright and related and neighboring rights to this software to
// the public domain worldwide. This software is distributed without
// any warranty.
//
// You should have received a copy of the MIT License
// along with this software.
// If not, see <https://opensource.org/licenses/MIT>.

#![recursion_limit = "256"]
#![feature(try_find)]
#![allow(unused)]
#![cfg_attr(test, deny(warnings))]

#[macro_use]
extern crate quote;
#[macro_use]
extern crate syn;

use syn::export::{Span, ToTokens, TokenStream, TokenStream2};
use syn::spanned::Spanned;
use syn::{
    Attribute, Data, DataStruct, DeriveInput, Error, Field, Fields, Ident, Index, Lit, Member,
    Meta, MetaList, NestedMeta, Path, Result, Type, TypeSlice,
};

#[proc_macro_derive(Getters)]
pub fn derive_getters(input: TokenStream) -> TokenStream {
    let derive_input = parse_macro_input!(input as DeriveInput);
    getters_inner(derive_input)
        .unwrap_or_else(|e| e.to_compile_error())
        .into()
}

#[proc_macro_derive(AsAny)]
pub fn derive_as_any(input: TokenStream) -> TokenStream {
    let derive_input = parse_macro_input!(input as DeriveInput);
    as_any_inner(derive_input)
        .unwrap_or_else(|e| e.to_compile_error())
        .into()
}

fn getters_inner(input: DeriveInput) -> Result<TokenStream2> {
    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
    let ident_name = &input.ident;

    let data = match input.data {
        Data::Struct(ref data) => data,
        Data::Enum(ref data) => Err(Error::new_spanned(
            &input,
            "Deriving getters is not supported in enums",
        ))?,
        //strict_encode_inner_enum(&input, &data),
        Data::Union(_) => Err(Error::new_spanned(
            &input,
            "Deriving getters is not supported in unions",
        ))?,
    };

    let recurse = match data.fields {
        Fields::Named(ref fields) => fields.named.iter().map(|f| {
            let name = &f.ident;
            let ty = &f.ty;
            quote_spanned! { f.span() =>
                #[inline]
                pub fn #name(&self) -> &#ty {
                    &self.#name
                }
            }
        }),
        Fields::Unnamed(ref fields) => Err(Error::new_spanned(
            &input,
            "Deriving getters is not supported for tuple-bases structs",
        ))?,
        Fields::Unit => Err(Error::new_spanned(
            &input,
            "Deriving getters is meaningless for unit structs",
        ))?,
    };

    Ok(quote! {
        impl #impl_generics #ident_name #ty_generics #where_clause {
            #( #recurse )*
        }
    })
}

fn as_any_inner(input: DeriveInput) -> Result<TokenStream2> {
    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
    let ident_name = &input.ident;

    Ok(quote! {
        impl #impl_generics ::amplify::AsAny for #ident_name #ty_generics #where_clause {
           fn as_any(&self) -> &dyn ::core::any::Any {
                self as &dyn ::core::any::Any
            }
        }
    })
}