1 // Copyright 2018 Guillaume Pinot (@TeXitoi) <texitoi@texitoi.eu>,
2 // Kevin Knapp (@kbknapp) <kbknapp@gmail.com>, and
3 // Ana Hobden (@hoverbear) <operator@hoverbear.org>
4 //
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
10 //
11 // This work was derived from Structopt (https://github.com/TeXitoi/structopt)
12 // commit#ea76fa1b1b273e65e3b0b1046643715b49bec51f which is licensed under the
13 // MIT/Apache 2.0 license.
14
15 use proc_macro2::TokenStream;
16 use quote::quote;
17 use syn::Ident;
18 use syn::Variant;
19 use syn::{
20 self, punctuated::Punctuated, token::Comma, Data, DataStruct, DeriveInput, Field, Fields,
21 Generics,
22 };
23
24 use crate::derives::{args, into_app, subcommand};
25 use crate::item::Item;
26 use crate::item::Name;
27
derive_parser(input: &DeriveInput) -> Result<TokenStream, syn::Error>28 pub fn derive_parser(input: &DeriveInput) -> Result<TokenStream, syn::Error> {
29 let ident = &input.ident;
30 let pkg_name = std::env::var("CARGO_PKG_NAME").ok().unwrap_or_default();
31
32 match input.data {
33 Data::Struct(DataStruct {
34 fields: Fields::Named(ref fields),
35 ..
36 }) => {
37 let name = Name::Assigned(quote!(#pkg_name));
38 let item = Item::from_args_struct(input, name)?;
39 let fields = fields
40 .named
41 .iter()
42 .map(|field| {
43 let item = Item::from_args_field(field, item.casing(), item.env_casing())?;
44 Ok((field, item))
45 })
46 .collect::<Result<Vec<_>, syn::Error>>()?;
47 gen_for_struct(&item, ident, &input.generics, &fields)
48 }
49 Data::Struct(DataStruct {
50 fields: Fields::Unit,
51 ..
52 }) => {
53 let name = Name::Assigned(quote!(#pkg_name));
54 let item = Item::from_args_struct(input, name)?;
55 let fields = Punctuated::<Field, Comma>::new();
56 let fields = fields
57 .iter()
58 .map(|field| {
59 let item = Item::from_args_field(field, item.casing(), item.env_casing())?;
60 Ok((field, item))
61 })
62 .collect::<Result<Vec<_>, syn::Error>>()?;
63 gen_for_struct(&item, ident, &input.generics, &fields)
64 }
65 Data::Enum(ref e) => {
66 let name = Name::Assigned(quote!(#pkg_name));
67 let item = Item::from_subcommand_enum(input, name)?;
68 let variants = e
69 .variants
70 .iter()
71 .map(|variant| {
72 let item =
73 Item::from_subcommand_variant(variant, item.casing(), item.env_casing())?;
74 Ok((variant, item))
75 })
76 .collect::<Result<Vec<_>, syn::Error>>()?;
77 gen_for_enum(&item, ident, &input.generics, &variants)
78 }
79 _ => abort_call_site!("`#[derive(Parser)]` only supports non-tuple structs and enums"),
80 }
81 }
82
gen_for_struct( item: &Item, item_name: &Ident, generics: &Generics, fields: &[(&Field, Item)], ) -> Result<TokenStream, syn::Error>83 fn gen_for_struct(
84 item: &Item,
85 item_name: &Ident,
86 generics: &Generics,
87 fields: &[(&Field, Item)],
88 ) -> Result<TokenStream, syn::Error> {
89 let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
90
91 let into_app = into_app::gen_for_struct(item, item_name, generics)?;
92 let args = args::gen_for_struct(item, item_name, generics, fields)?;
93
94 Ok(quote! {
95 impl #impl_generics clap::Parser for #item_name #ty_generics #where_clause {}
96
97 #into_app
98 #args
99 })
100 }
101
gen_for_enum( item: &Item, item_name: &Ident, generics: &Generics, variants: &[(&Variant, Item)], ) -> Result<TokenStream, syn::Error>102 fn gen_for_enum(
103 item: &Item,
104 item_name: &Ident,
105 generics: &Generics,
106 variants: &[(&Variant, Item)],
107 ) -> Result<TokenStream, syn::Error> {
108 let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
109
110 let into_app = into_app::gen_for_enum(item, item_name, generics)?;
111 let subcommand = subcommand::gen_for_enum(item, item_name, generics, variants)?;
112
113 Ok(quote! {
114 impl #impl_generics clap::Parser for #item_name #ty_generics #where_clause {}
115
116 #into_app
117 #subcommand
118 })
119 }
120