1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74

//! [`Debug`](std::fmt::Debug) implementation.

use proc_macro2::TokenStream;
use quote::quote;

use crate::{Data, DeriveTrait, Item, SimpleType, TraitImpl};

/// Dummy-struct implement [`Trait`](crate::Trait) for
/// [`Debug`](std::fmt::Debug).
pub struct Debug;

impl TraitImpl for Debug {
	fn as_str(&self) -> &'static str {
		"Debug"
	}

	fn default_derive_trait(&self) -> DeriveTrait {
		DeriveTrait::Debug
	}

	fn supports_skip(&self) -> bool {
		true
	}

	fn build_signature(
		&self,
		_item: &Item,
		_trait_: &DeriveTrait,
		body: &TokenStream,
	) -> TokenStream {
		quote! {
			fn fmt(&self, __f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result {
				match self {
					#body
				}
			}
		}
	}

	fn build_body(&self, trait_: &DeriveTrait, data: &Data) -> TokenStream {
		let self_pattern = &data.self_pattern();
		let debug_name = data.ident.to_string();

		match data.simple_type() {
			SimpleType::Struct(_) => {
				let self_ident = data.iter_self_ident(trait_);
				let debug_fields = data.iter_field_ident(trait_).map(|field| field.to_string());

				quote! {
					#self_pattern => {
						let mut __builder = ::core::fmt::Formatter::debug_struct(__f, #debug_name);
						#(::core::fmt::DebugStruct::field(&mut __builder, #debug_fields, #self_ident);)*
						::core::fmt::DebugStruct::finish(&mut __builder)
					}
				}
			}
			SimpleType::Tuple(_) => {
				let self_ident = data.iter_self_ident(trait_);

				quote! {
					#self_pattern => {
						let mut __builder = ::core::fmt::Formatter::debug_tuple(__f, #debug_name);
						#(::core::fmt::DebugTuple::field(&mut __builder, #self_ident);)*
						::core::fmt::DebugTuple::finish(&mut __builder)
					}
				}
			}
			SimpleType::Unit(_) => {
				quote! { #self_pattern => ::core::fmt::Formatter::write_str(__f, #debug_name), }
			}
			SimpleType::Union(_) => unreachable!("unexpected trait for union"),
		}
	}
}