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 proc_macro_error::abort_call_site;
17 use quote::quote;
18 use syn::Ident;
19 use syn::Variant;
20 use syn::{
21 self, punctuated::Punctuated, token::Comma, Data, DataStruct, DeriveInput, Field, Fields,
22 Generics,
23 };
24
25 use crate::derives::{args, into_app, subcommand};
26 use crate::dummies;
27 use crate::item::Item;
28 use crate::item::Name;
29
derive_parser(input: &DeriveInput) -> TokenStream30 pub fn derive_parser(input: &DeriveInput) -> TokenStream {
31 let ident = &input.ident;
32 let pkg_name = std::env::var("CARGO_PKG_NAME").ok().unwrap_or_default();
33
34 match input.data {
35 Data::Struct(DataStruct {
36 fields: Fields::Named(ref fields),
37 ..
38 }) => {
39 dummies::parser_struct(ident);
40
41 let name = Name::Assigned(quote!(#pkg_name));
42 let item = Item::from_args_struct(input, name);
43 let fields = fields
44 .named
45 .iter()
46 .map(|field| {
47 let item = Item::from_args_field(field, item.casing(), item.env_casing());
48 (field, item)
49 })
50 .collect::<Vec<_>>();
51 gen_for_struct(&item, ident, &input.generics, &fields)
52 }
53 Data::Struct(DataStruct {
54 fields: Fields::Unit,
55 ..
56 }) => {
57 dummies::parser_struct(ident);
58
59 let name = Name::Assigned(quote!(#pkg_name));
60 let item = Item::from_args_struct(input, name);
61 let fields = Punctuated::<Field, Comma>::new();
62 let fields = fields
63 .iter()
64 .map(|field| {
65 let item = Item::from_args_field(field, item.casing(), item.env_casing());
66 (field, item)
67 })
68 .collect::<Vec<_>>();
69 gen_for_struct(&item, ident, &input.generics, &fields)
70 }
71 Data::Enum(ref e) => {
72 dummies::parser_enum(ident);
73
74 let name = Name::Assigned(quote!(#pkg_name));
75 let item = Item::from_subcommand_enum(input, name);
76 let variants = e
77 .variants
78 .iter()
79 .map(|variant| {
80 let item =
81 Item::from_subcommand_variant(variant, item.casing(), item.env_casing());
82 (variant, item)
83 })
84 .collect::<Vec<_>>();
85 gen_for_enum(&item, ident, &input.generics, &variants)
86 }
87 _ => abort_call_site!("`#[derive(Parser)]` only supports non-tuple structs and enums"),
88 }
89 }
90
gen_for_struct( item: &Item, item_name: &Ident, generics: &Generics, fields: &[(&Field, Item)], ) -> TokenStream91 fn gen_for_struct(
92 item: &Item,
93 item_name: &Ident,
94 generics: &Generics,
95 fields: &[(&Field, Item)],
96 ) -> TokenStream {
97 let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
98
99 let into_app = into_app::gen_for_struct(item, item_name, generics);
100 let args = args::gen_for_struct(item, item_name, generics, fields);
101
102 quote! {
103 impl #impl_generics clap::Parser for #item_name #ty_generics #where_clause {}
104
105 #into_app
106 #args
107 }
108 }
109
gen_for_enum( item: &Item, item_name: &Ident, generics: &Generics, variants: &[(&Variant, Item)], ) -> TokenStream110 fn gen_for_enum(
111 item: &Item,
112 item_name: &Ident,
113 generics: &Generics,
114 variants: &[(&Variant, Item)],
115 ) -> TokenStream {
116 let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
117
118 let into_app = into_app::gen_for_enum(item, item_name, generics);
119 let subcommand = subcommand::gen_for_enum(item, item_name, generics, variants);
120
121 quote! {
122 impl #impl_generics clap::Parser for #item_name #ty_generics #where_clause {}
123
124 #into_app
125 #subcommand
126 }
127 }
128