vendor/clap_derive/src/derives/parser.rs

   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 crate::{
  16     derives::{args, into_app, subcommand},
  17     dummies,
  18 };
  19
  20 use proc_macro2::TokenStream;
  21 use proc_macro_error::abort_call_site;
  22 use quote::quote;
  23 use syn::{
  24     self, punctuated::Punctuated, token::Comma, Attribute, Data, DataEnum, DataStruct, DeriveInput,
  25     Field, Fields, Generics, Ident,
  26 };
  27
  28 pub fn derive_parser(input: &DeriveInput) -> TokenStream {
  29     let ident = &input.ident;
  30
  31     match input.data {
  32         Data::Struct(DataStruct {
  33             fields: Fields::Named(ref fields),
  34             ..
  35         }) => {
  36             dummies::parser_struct(ident);
  37             gen_for_struct(ident, &input.generics, &fields.named, &input.attrs)
  38         }
  39         Data::Struct(DataStruct {
  40             fields: Fields::Unit,
  41             ..
  42         }) => {
  43             dummies::parser_struct(ident);
  44             gen_for_struct(
  45                 ident,
  46                 &input.generics,
  47                 &Punctuated::<Field, Comma>::new(),
  48                 &input.attrs,
  49             )
  50         }
  51         Data::Enum(ref e) => {
  52             dummies::parser_enum(ident);
  53             gen_for_enum(ident, &input.generics, &input.attrs, e)
  54         }
  55         _ => abort_call_site!("`#[derive(Parser)]` only supports non-tuple structs and enums"),
  56     }
  57 }
  58
  59 fn gen_for_struct(
  60     name: &Ident,
  61     generics: &Generics,
  62     fields: &Punctuated<Field, Comma>,
  63     attrs: &[Attribute],
  64 ) -> TokenStream {
  65     let into_app = into_app::gen_for_struct(name, generics, attrs);
  66     let args = args::gen_for_struct(name, generics, fields, attrs);
  67
  68     let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
  69
  70     quote! {
  71         impl #impl_generics clap::Parser for #name #ty_generics #where_clause {}
  72
  73         #into_app
  74         #args
  75     }
  76 }
  77
  78 fn gen_for_enum(
  79     name: &Ident,
  80     generics: &Generics,
  81     attrs: &[Attribute],
  82     e: &DataEnum,
  83 ) -> TokenStream {
  84     let into_app = into_app::gen_for_enum(name, generics, attrs);
  85     let subcommand = subcommand::gen_for_enum(name, generics, attrs, e);
  86
  87     let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
  88
  89     quote! {
  90         impl #impl_generics clap::Parser for #name #ty_generics #where_clause {}
  91
  92         #into_app
  93         #subcommand
  94     }
  95 }