//! Procedural macros for Feldera tuple types and `IsNone`.

//!

//! The `declare_tuple!` macro decides which layout to use based on tuple size

//! and the active storage format rules.

use proc_macro::TokenStream;

use quote::quote;

use syn::{parse_macro_input, DeriveInput};

mod tuples;

/// Parses input of the form: `declare_tuple!(Tup1<T0>);`

/// and generates dbsp tuple structs.

#[proc_macro]

pub fn declare_tuple(input: TokenStream) -> TokenStream {

let tuple = parse_macro_input!(input as tuples::TupleDef);

let expanded = tuples::declare_tuple_impl(tuple);

if std::env::var_os("FELDERA_DEV_MACROS_DUMP").is_some() {

let parsed_file: syn::File = syn::parse2(expanded.clone()).expect("Failed to parse output");

let formatted = prettyplease::unparse(&parsed_file);

eprintln!("{}", formatted);

}

expanded.into()

}

#[proc_macro_derive(IsNone)]

pub fn derive_not_none(item: TokenStream) -> TokenStream {

let input = parse_macro_input!(item as DeriveInput);

let ident = input.ident;

let generics = input.generics;

let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();

let expanded = quote! {

impl #impl_generics ::dbsp::utils::IsNone for #ident #ty_generics #where_clause {

type Inner = Self;

#[inline]

fn is_none(&self) -> bool {

false

}

#[inline]

fn unwrap_or_self(&self) -> &Self::Inner {

self

}

#[inline]

fn from_inner(inner: Self::Inner) -> Self {

inner

}

}

};

TokenStream::from(expanded)

}