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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
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//
// commit#ea76fa1b1b273e65e3b0b1046643715b49bec51f which is licensed under the
// MIT/Apache 2.0 license.
use proc_macro2::TokenStream;
use quote::quote;
use syn::Ident;
use syn::Variant;
use syn::{
self, punctuated::Punctuated, token::Comma, Data, DataStruct, DeriveInput, Field, Fields,
Generics,
};
use crate::derives::args::collect_args_fields;
use crate::derives::{args, into_app, subcommand};
use crate::item::Item;
use crate::item::Name;
pub(crate) fn derive_parser(input: &DeriveInput) -> Result<TokenStream, syn::Error> {
let ident = &input.ident;
let pkg_name = std::env::var("CARGO_PKG_NAME").ok().unwrap_or_default();
match input.data {
Data::Struct(DataStruct {
fields: Fields::Named(ref fields),
..
}) => {
let name = Name::Assigned(quote!(#pkg_name));
let item = Item::from_args_struct(input, name)?;
let fields = collect_args_fields(&item, fields)?;
gen_for_struct(&item, ident, &input.generics, &fields)
}
Data::Struct(DataStruct {
fields: Fields::Unit,
..
}) => {
let name = Name::Assigned(quote!(#pkg_name));
let item = Item::from_args_struct(input, name)?;
let fields = Punctuated::<Field, Comma>::new();
let fields = fields
.iter()
.map(|field| {
let item = Item::from_args_field(field, item.casing(), item.env_casing())?;
Ok((field, item))
})
.collect::<Result<Vec<_>, syn::Error>>()?;
gen_for_struct(&item, ident, &input.generics, &fields)
}
Data::Enum(ref e) => {
let name = Name::Assigned(quote!(#pkg_name));
let item = Item::from_subcommand_enum(input, name)?;
let variants = e
.variants
.iter()
.map(|variant| {
let item =
Item::from_subcommand_variant(variant, item.casing(), item.env_casing())?;
Ok((variant, item))
})
.collect::<Result<Vec<_>, syn::Error>>()?;
gen_for_enum(&item, ident, &input.generics, &variants)
}
_ => abort_call_site!("`#[derive(Parser)]` only supports non-tuple structs and enums"),
}
}
fn gen_for_struct(
item: &Item,
item_name: &Ident,
generics: &Generics,
fields: &[(&Field, Item)],
) -> Result<TokenStream, syn::Error> {
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let into_app = into_app::gen_for_struct(item, item_name, generics)?;
let args = args::gen_for_struct(item, item_name, generics, fields)?;
Ok(quote! {
#[automatically_derived]
#[allow(
unused_qualifications,
clippy::redundant_locals,
)]
impl #impl_generics clap::Parser for #item_name #ty_generics #where_clause {}
#into_app
#args
})
}
fn gen_for_enum(
item: &Item,
item_name: &Ident,
generics: &Generics,
variants: &[(&Variant, Item)],
) -> Result<TokenStream, syn::Error> {
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let into_app = into_app::gen_for_enum(item, item_name, generics)?;
let subcommand = subcommand::gen_for_enum(item, item_name, generics, variants)?;
Ok(quote! {
#[automatically_derived]
impl #impl_generics clap::Parser for #item_name #ty_generics #where_clause {}
#into_app
#subcommand
})
}