variants-derive 0.0.1

derive macros enabling the variants crate
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46

/*
    Appellation: variants-derive <library>
    Contrib: FL03 <jo3mccain@icloud.com>
*/
//! The derive macros for the `variants` crate.
//! 
//! - [`VariantConstructors`]: generate functional constructors for all variants of an enum
#![allow(
    clippy::missing_safety_doc,
    clippy::module_inception,
    clippy::needless_doctest_main,
    clippy::upper_case_acronyms
)]
#![cfg_attr(not(feature = "std"), no_std)]

#[cfg(feature = "alloc")]
extern crate alloc;

#[cfg(not(any(feature = "std", feature = "alloc")))]
compile_error! {
    "Either feature `std` or `alloc` must be enabled"
}

extern crate proc_macro;
extern crate quote;
extern crate syn;

#[allow(dead_code)]
pub(crate) mod attrs;
pub(crate) mod impls;
pub(crate) mod utils;

use proc_macro::TokenStream;
use syn::{Data, DeriveInput};

/// This macro automatically generates functional constructors for all enclosed variants.
#[proc_macro_derive(VariantConstructors, attributes(variants))]
pub fn variant_constructors(input: TokenStream) -> TokenStream {
    let ast: DeriveInput = syn::parse(input).unwrap();

    match ast.data {
        Data::Enum(inner) => impls::impl_functional_constructors(&ast.ident, &inner.variants),
        _ => panic!("This derive macro only works with enums"),
    }
    .into()
}