verty 0.1.0

procedural macro to generate different versions of a type
Documentation 
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
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178

use proc_macro2::{Ident, TokenStream};
use quote::quote;
use syn::{Attribute, Expr, Field, GenericParam, Visibility, WherePredicate};

use crate::parse::FieldsFlavor;

pub struct OutputItemBase {
	pub attrs: Vec<Attribute>,
	pub vis: Visibility,
	pub ident: Ident,
	pub generic_params: Option<Vec<GenericParam>>,
	pub where_clause: Vec<WherePredicate>,
}

pub struct OutputFields {
	/// The fields. They must either all be named or all be unnamed.
	pub fields: Vec<Field>,
	/// The kind of fields to emit when `fields` is empty.
	pub flavor_bias: FieldsFlavor,
}

pub struct OutputVariant {
	pub attrs: Vec<Attribute>,
	pub ident: Ident,
	pub fields: OutputFields,
	pub discriminant: Option<Expr>,
}

// TODO(future): When `feature(adt_const_params)` stabilizes, make this a `const KIND: StructOrUnion` instead.
pub struct OutputStructOrUnion<const IS_UNION: bool> {
	pub base: OutputItemBase,
	pub fields: OutputFields,
}
pub type OutputStruct = OutputStructOrUnion<false>;
pub type OutputUnion = OutputStructOrUnion<true>;

pub struct OutputEnum {
	pub base: OutputItemBase,
	pub variants: Vec<OutputVariant>,
}

pub enum OutputItems {
	Structs(Vec<OutputStruct>),
	Enums(Vec<OutputEnum>),
	Unions(Vec<OutputUnion>),
}

impl OutputFields {
	fn is_unit(&self) -> bool {
		self.fields.is_empty() && self.flavor_bias == FieldsFlavor::Unit
	}

	pub fn print(self) -> TokenStream {
		let Self {
			fields,
			flavor_bias,
		} = self;

		let flavor = match fields.first() {
			Some(f) => {
				if f.ident.is_some() {
					FieldsFlavor::Struct
				} else {
					FieldsFlavor::Tuple
				}
			}
			None => flavor_bias,
		};

		let fields_inner = quote! { #(#fields),* };

		match flavor {
			FieldsFlavor::Unit => TokenStream::new(),
			FieldsFlavor::Tuple => quote! { (#fields_inner) },
			FieldsFlavor::Struct => quote! { {#fields_inner} },
		}
	}
}

impl OutputVariant {
	pub fn print(self) -> TokenStream {
		let OutputVariant {
			attrs,
			ident,
			fields,
			discriminant,
		} = self;

		let fields = fields.print();

		let discriminant = discriminant.map(|d| quote! { = #d });

		quote! {
			#(#attrs)*
			#ident #fields #discriminant
		}
	}
}

impl<const IS_UNION: bool> OutputStructOrUnion<IS_UNION> {
	pub fn print(self) -> TokenStream {
		let Self {
			base:
				OutputItemBase {
					attrs,
					vis,
					ident,
					generic_params,
					where_clause,
				},
			fields,
		} = self;

		let generic_params = generic_params.map(|param| {
			quote! { <#(#param),*> }
		});

		let where_clause = (!where_clause.is_empty()).then(|| quote! { where #(#where_clause),* });

		let fields = if fields.is_unit() {
			quote! { ; }
		} else {
			fields.print()
		};

		let kw = if IS_UNION {
			quote!(union)
		} else {
			quote!(struct)
		};

		quote! {
			#(#attrs)*
			#vis #kw #ident #generic_params #where_clause #fields
		}
	}
}

impl OutputEnum {
	pub fn print(self) -> TokenStream {
		let Self {
			base:
				OutputItemBase {
					attrs,
					vis,
					ident,
					generic_params,
					where_clause,
				},
			variants,
		} = self;

		let generic_params = generic_params.map(|param| {
			quote! { <#(#param),*> }
		});

		let where_clause = (!where_clause.is_empty()).then(|| quote! { where #(#where_clause),* });

		let variants = variants.into_iter().map(|v| v.print());

		quote! {
			#(#attrs)*
			#vis enum #ident #generic_params #where_clause {
				#(#variants),*
			}
		}
	}
}

impl OutputItems {
	pub fn print(self) -> TokenStream {
		match self {
			Self::Structs(v) => v.into_iter().map(|s| s.print()).collect(),
			Self::Enums(v) => v.into_iter().map(|s| s.print()).collect(),
			Self::Unions(v) => v.into_iter().map(|s| s.print()).collect(),
		}
	}
}