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use crate::{
attrs::{Attrs, Kind, Name, DEFAULT_CASING, DEFAULT_ENV_CASING},
dummies,
utils::Sp,
};
use proc_macro2::{Span, TokenStream};
use proc_macro_error::abort_call_site;
use quote::quote;
use syn::{
punctuated::Punctuated, token::Comma, Attribute, Data, DataEnum, DeriveInput, Fields, Ident,
Variant,
};
pub fn derive_arg_enum(input: &DeriveInput) -> TokenStream {
let ident = &input.ident;
dummies::arg_enum(ident);
match input.data {
Data::Enum(ref e) => gen_for_enum(ident, &input.attrs, e),
_ => abort_call_site!("`#[derive(ArgEnum)]` only supports enums"),
}
}
pub fn gen_for_enum(name: &Ident, attrs: &[Attribute], e: &DataEnum) -> TokenStream {
if !e.variants.iter().all(|v| matches!(v.fields, Fields::Unit)) {
return quote!();
};
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 variants = gen_variants(&lits);
let from_str = gen_from_str(&lits);
let as_arg = gen_as_arg(&lits);
quote! {
#[allow(dead_code, unreachable_code, unused_variables)]
#[allow(
clippy::style,
clippy::complexity,
clippy::pedantic,
clippy::restriction,
clippy::perf,
clippy::deprecated,
clippy::nursery,
clippy::cargo
)]
#[deny(clippy::correctness)]
impl clap::ArgEnum for #name {
#variants
#from_str
#as_arg
}
}
}
fn lits(
variants: &Punctuated<Variant, Comma>,
parent_attribute: &Attrs,
) -> Vec<(TokenStream, Ident)> {
variants
.iter()
.filter_map(|variant| {
let attrs = Attrs::from_arg_enum_variant(
variant,
parent_attribute.casing(),
parent_attribute.env_casing(),
);
if let Kind::Skip(_) = &*attrs.kind() {
None
} else {
Some((variant, attrs))
}
})
.flat_map(|(variant, attrs)| {
let mut ret = vec![(attrs.cased_name(), variant.ident.clone())];
attrs
.enum_aliases()
.into_iter()
.for_each(|x| ret.push((x, variant.ident.clone())));
ret
})
.collect::<Vec<_>>()
}
fn gen_variants(lits: &[(TokenStream, Ident)]) -> TokenStream {
let lit = lits.iter().map(|l| &l.0).collect::<Vec<_>>();
quote! {
const VARIANTS: &'static [&'static str] = &[#(#lit),*];
}
}
fn gen_from_str(lits: &[(TokenStream, Ident)]) -> TokenStream {
let (lit, variant): (Vec<TokenStream>, Vec<Ident>) = lits.iter().cloned().unzip();
quote! {
fn from_str(input: &str, case_insensitive: bool) -> ::std::result::Result<Self, String> {
let func = if case_insensitive {
::std::ascii::AsciiExt::eq_ignore_ascii_case
} else {
str::eq
};
match input {
#(val if func(val, #lit) => Ok(Self::#variant),)*
e => Err(format!("Invalid variant: {}", e)),
}
}
}
}
fn gen_as_arg(lits: &[(TokenStream, Ident)]) -> TokenStream {
let (lit, variant): (Vec<TokenStream>, Vec<Ident>) = lits.iter().cloned().unzip();
quote! {
fn as_arg(&self) -> Option<&'static str> {
match self {
#(Self::#variant => Some(#lit),)*
_ => None
}
}
}
}
