1use super::TokenStreamExt;
2use alloc::borrow::Cow;
3use alloc::rc::Rc;
4use core::iter;
5use proc_macro2::{Group, Ident, Literal, Punct, Span, TokenStream, TokenTree};
6use std::ffi::{CStr, CString};
7
8/// Types that can be interpolated inside a `quote!` invocation.
9///
10/// [`quote!`]: macro.quote.html
11pub trait ToTokens {
12 /// Write `self` to the given `TokenStream`.
13 ///
14 /// The token append methods provided by the [`TokenStreamExt`] extension
15 /// trait may be useful for implementing `ToTokens`.
16 ///
17 /// [`TokenStreamExt`]: trait.TokenStreamExt.html
18 ///
19 /// # Example
20 ///
21 /// Example implementation for a struct representing Rust paths like
22 /// `std::cmp::PartialEq`:
23 ///
24 /// ```
25 /// use proc_macro2::{TokenTree, Spacing, Span, Punct, TokenStream};
26 /// use quote::{TokenStreamExt, ToTokens};
27 ///
28 /// pub struct Path {
29 /// pub global: bool,
30 /// pub segments: Vec<PathSegment>,
31 /// }
32 ///
33 /// impl ToTokens for Path {
34 /// fn to_tokens(&self, tokens: &mut TokenStream) {
35 /// for (i, segment) in self.segments.iter().enumerate() {
36 /// if i > 0 || self.global {
37 /// // Double colon `::`
38 /// tokens.append(Punct::new(':', Spacing::Joint));
39 /// tokens.append(Punct::new(':', Spacing::Alone));
40 /// }
41 /// segment.to_tokens(tokens);
42 /// }
43 /// }
44 /// }
45 /// #
46 /// # pub struct PathSegment;
47 /// #
48 /// # impl ToTokens for PathSegment {
49 /// # fn to_tokens(&self, tokens: &mut TokenStream) {
50 /// # unimplemented!()
51 /// # }
52 /// # }
53 /// ```
54 fn to_tokens(&self, tokens: &mut TokenStream);
55
56 /// Convert `self` directly into a `TokenStream` object.
57 ///
58 /// This method is implicitly implemented using `to_tokens`, and acts as a
59 /// convenience method for consumers of the `ToTokens` trait.
60 fn to_token_stream(&self) -> TokenStream {
61 let mut tokens = TokenStream::new();
62 self.to_tokens(&mut tokens);
63 tokens
64 }
65
66 /// Convert `self` directly into a `TokenStream` object.
67 ///
68 /// This method is implicitly implemented using `to_tokens`, and acts as a
69 /// convenience method for consumers of the `ToTokens` trait.
70 fn into_token_stream(self) -> TokenStream
71 where
72 Self: Sized,
73 {
74 self.to_token_stream()
75 }
76}
77
78impl<T: ?Sized + ToTokens> ToTokens for &T {
79 fn to_tokens(&self, tokens: &mut TokenStream) {
80 (**self).to_tokens(tokens);
81 }
82}
83
84impl<T: ?Sized + ToTokens> ToTokens for &mut T {
85 fn to_tokens(&self, tokens: &mut TokenStream) {
86 (**self).to_tokens(tokens);
87 }
88}
89
90impl<'a, T: ?Sized + ToOwned + ToTokens> ToTokens for Cow<'a, T> {
91 fn to_tokens(&self, tokens: &mut TokenStream) {
92 (**self).to_tokens(tokens);
93 }
94}
95
96impl<T: ?Sized + ToTokens> ToTokens for Box<T> {
97 fn to_tokens(&self, tokens: &mut TokenStream) {
98 (**self).to_tokens(tokens);
99 }
100}
101
102impl<T: ?Sized + ToTokens> ToTokens for Rc<T> {
103 fn to_tokens(&self, tokens: &mut TokenStream) {
104 (**self).to_tokens(tokens);
105 }
106}
107
108impl<T: ToTokens> ToTokens for Option<T> {
109 fn to_tokens(&self, tokens: &mut TokenStream) {
110 if let Some(t: &T) = self {
111 t.to_tokens(tokens);
112 }
113 }
114}
115
116impl ToTokens for str {
117 fn to_tokens(&self, tokens: &mut TokenStream) {
118 tokens.append(token:Literal::string(self));
119 }
120}
121
122impl ToTokens for String {
123 fn to_tokens(&self, tokens: &mut TokenStream) {
124 self.as_str().to_tokens(tokens);
125 }
126}
127
128impl ToTokens for i8 {
129 fn to_tokens(&self, tokens: &mut TokenStream) {
130 tokens.append(token:Literal::i8_suffixed(*self));
131 }
132}
133
134impl ToTokens for i16 {
135 fn to_tokens(&self, tokens: &mut TokenStream) {
136 tokens.append(token:Literal::i16_suffixed(*self));
137 }
138}
139
140impl ToTokens for i32 {
141 fn to_tokens(&self, tokens: &mut TokenStream) {
142 tokens.append(token:Literal::i32_suffixed(*self));
143 }
144}
145
146impl ToTokens for i64 {
147 fn to_tokens(&self, tokens: &mut TokenStream) {
148 tokens.append(token:Literal::i64_suffixed(*self));
149 }
150}
151
152impl ToTokens for i128 {
153 fn to_tokens(&self, tokens: &mut TokenStream) {
154 tokens.append(token:Literal::i128_suffixed(*self));
155 }
156}
157
158impl ToTokens for isize {
159 fn to_tokens(&self, tokens: &mut TokenStream) {
160 tokens.append(token:Literal::isize_suffixed(*self));
161 }
162}
163
164impl ToTokens for u8 {
165 fn to_tokens(&self, tokens: &mut TokenStream) {
166 tokens.append(token:Literal::u8_suffixed(*self));
167 }
168}
169
170impl ToTokens for u16 {
171 fn to_tokens(&self, tokens: &mut TokenStream) {
172 tokens.append(token:Literal::u16_suffixed(*self));
173 }
174}
175
176impl ToTokens for u32 {
177 fn to_tokens(&self, tokens: &mut TokenStream) {
178 tokens.append(token:Literal::u32_suffixed(*self));
179 }
180}
181
182impl ToTokens for u64 {
183 fn to_tokens(&self, tokens: &mut TokenStream) {
184 tokens.append(token:Literal::u64_suffixed(*self));
185 }
186}
187
188impl ToTokens for u128 {
189 fn to_tokens(&self, tokens: &mut TokenStream) {
190 tokens.append(token:Literal::u128_suffixed(*self));
191 }
192}
193
194impl ToTokens for usize {
195 fn to_tokens(&self, tokens: &mut TokenStream) {
196 tokens.append(token:Literal::usize_suffixed(*self));
197 }
198}
199
200impl ToTokens for f32 {
201 fn to_tokens(&self, tokens: &mut TokenStream) {
202 tokens.append(token:Literal::f32_suffixed(*self));
203 }
204}
205
206impl ToTokens for f64 {
207 fn to_tokens(&self, tokens: &mut TokenStream) {
208 tokens.append(token:Literal::f64_suffixed(*self));
209 }
210}
211
212impl ToTokens for char {
213 fn to_tokens(&self, tokens: &mut TokenStream) {
214 tokens.append(token:Literal::character(*self));
215 }
216}
217
218impl ToTokens for bool {
219 fn to_tokens(&self, tokens: &mut TokenStream) {
220 let word: &'static str = if *self { "true" } else { "false" };
221 tokens.append(token:Ident::new(string:word, Span::call_site()));
222 }
223}
224
225impl ToTokens for CStr {
226 fn to_tokens(&self, tokens: &mut TokenStream) {
227 tokens.append(token:Literal::c_string(self));
228 }
229}
230
231impl ToTokens for CString {
232 fn to_tokens(&self, tokens: &mut TokenStream) {
233 tokens.append(token:Literal::c_string(self));
234 }
235}
236
237impl ToTokens for Group {
238 fn to_tokens(&self, tokens: &mut TokenStream) {
239 tokens.append(self.clone());
240 }
241}
242
243impl ToTokens for Ident {
244 fn to_tokens(&self, tokens: &mut TokenStream) {
245 tokens.append(self.clone());
246 }
247}
248
249impl ToTokens for Punct {
250 fn to_tokens(&self, tokens: &mut TokenStream) {
251 tokens.append(self.clone());
252 }
253}
254
255impl ToTokens for Literal {
256 fn to_tokens(&self, tokens: &mut TokenStream) {
257 tokens.append(self.clone());
258 }
259}
260
261impl ToTokens for TokenTree {
262 fn to_tokens(&self, tokens: &mut TokenStream) {
263 tokens.append(self.clone());
264 }
265}
266
267impl ToTokens for TokenStream {
268 fn to_tokens(&self, tokens: &mut TokenStream) {
269 tokens.extend(iter:iter::once(self.clone()));
270 }
271
272 fn into_token_stream(self) -> TokenStream {
273 self
274 }
275}
276