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// Copyright 2018 Guillaume Pinot (@TeXitoi) <texitoi@texitoi.eu>,
// Kevin Knapp (@kbknapp) <kbknapp@gmail.com>, and
// Ana Hobden (@hoverbear) <operator@hoverbear.org>
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use crate::{
attrs::{Attrs, Kind, Name, DEFAULT_CASING, DEFAULT_ENV_CASING},
dummies,
utils::Sp,
};
use proc_macro2::{Span, TokenStream};
use proc_macro_error::{abort, abort_call_site};
use quote::quote;
use quote::quote_spanned;
use syn::{
punctuated::Punctuated, spanned::Spanned, token::Comma, Attribute, Data, DataEnum, DeriveInput,
Fields, Ident, Variant,
};
pub fn derive_value_enum(input: &DeriveInput) -> TokenStream {
let ident = &input.ident;
dummies::value_enum(ident);
match input.data {
Data::Enum(ref e) => gen_for_enum(ident, &input.attrs, e),
_ => abort_call_site!("`#[derive(ValueEnum)]` only supports enums"),
}
}
pub fn gen_for_enum(name: &Ident, attrs: &[Attribute], e: &DataEnum) -> TokenStream {
let attrs = Attrs::from_struct(
Span::call_site(),
attrs,
Name::Derived(name.clone()),
Sp::call_site(DEFAULT_CASING),
Sp::call_site(DEFAULT_ENV_CASING),
);
let lits = lits(&e.variants, &attrs);
let value_variants = gen_value_variants(&lits);
let to_possible_value = gen_to_possible_value(&lits);
quote! {
#[allow(dead_code, unreachable_code, unused_variables, unused_braces)]
#[allow(
clippy::style,
clippy::complexity,
clippy::pedantic,
clippy::restriction,
clippy::perf,
clippy::deprecated,
clippy::nursery,
clippy::cargo,
clippy::suspicious_else_formatting,
)]
#[deny(clippy::correctness)]
impl clap::ValueEnum for #name {
#value_variants
#to_possible_value
}
}
}
fn lits(
variants: &Punctuated<Variant, Comma>,
parent_attribute: &Attrs,
) -> Vec<(TokenStream, Ident)> {
variants
.iter()
.filter_map(|variant| {
let attrs = Attrs::from_value_enum_variant(
variant,
parent_attribute.casing(),
parent_attribute.env_casing(),
);
if let Kind::Skip(_) = &*attrs.kind() {
None
} else {
if !matches!(variant.fields, Fields::Unit) {
abort!(variant.span(), "`#[derive(ValueEnum)]` only supports non-unit variants, unless they are skipped");
}
let fields = attrs.field_methods(false);
let name = attrs.cased_name();
Some((
quote_spanned! { variant.span()=>
clap::PossibleValue::new(#name)
#fields
},
variant.ident.clone(),
))
}
})
.collect::<Vec<_>>()
}
fn gen_value_variants(lits: &[(TokenStream, Ident)]) -> TokenStream {
let lit = lits.iter().map(|l| &l.1).collect::<Vec<_>>();
quote! {
fn value_variants<'a>() -> &'a [Self]{
&[#(Self::#lit),*]
}
}
}
fn gen_to_possible_value(lits: &[(TokenStream, Ident)]) -> TokenStream {
let (lit, variant): (Vec<TokenStream>, Vec<Ident>) = lits.iter().cloned().unzip();
quote! {
fn to_possible_value<'a>(&self) -> ::std::option::Option<clap::PossibleValue<'a>> {
match self {
#(Self::#variant => Some(#lit),)*
_ => None
}
}
}
}
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