1use std::borrow::Cow;
2use std::ffi::{CStr, CString};
3use std::rc::Rc;
4
5use crate::{ConcatTreesHelper, Group, Ident, Literal, Punct, Span, TokenStream, TokenTree};
6
7/// Types that can be interpolated inside a [`quote!`] invocation.
8///
9/// [`quote!`]: crate::quote!
10#[unstable(feature = "proc_macro_totokens", issue = "130977")]
11pub trait ToTokens {
12 /// Write `self` to the given `TokenStream`.
13 ///
14 /// # Example
15 ///
16 /// Example implementation for a struct representing Rust paths like
17 /// `std::cmp::PartialEq`:
18 ///
19 /// ```
20 /// #![feature(proc_macro_totokens)]
21 ///
22 /// use std::iter;
23 /// use proc_macro::{Spacing, Punct, TokenStream, TokenTree, ToTokens};
24 ///
25 /// pub struct Path {
26 /// pub global: bool,
27 /// pub segments: Vec<PathSegment>,
28 /// }
29 ///
30 /// impl ToTokens for Path {
31 /// fn to_tokens(&self, tokens: &mut TokenStream) {
32 /// for (i, segment) in self.segments.iter().enumerate() {
33 /// if i > 0 || self.global {
34 /// // Double colon `::`
35 /// tokens.extend(iter::once(TokenTree::from(Punct::new(':', Spacing::Joint))));
36 /// tokens.extend(iter::once(TokenTree::from(Punct::new(':', Spacing::Alone))));
37 /// }
38 /// segment.to_tokens(tokens);
39 /// }
40 /// }
41 /// }
42 /// #
43 /// # pub struct PathSegment;
44 /// #
45 /// # impl ToTokens for PathSegment {
46 /// # fn to_tokens(&self, tokens: &mut TokenStream) {
47 /// # unimplemented!()
48 /// # }
49 /// # }
50 /// ```
51 fn to_tokens(&self, tokens: &mut TokenStream);
52
53 /// Convert `self` directly into a `TokenStream` object.
54 ///
55 /// This method is implicitly implemented using `to_tokens`, and acts as a
56 /// convenience method for consumers of the `ToTokens` trait.
57 fn to_token_stream(&self) -> TokenStream {
58 let mut tokens = TokenStream::new();
59 self.to_tokens(&mut tokens);
60 tokens
61 }
62
63 /// Convert `self` directly into a `TokenStream` object.
64 ///
65 /// This method is implicitly implemented using `to_tokens`, and acts as a
66 /// convenience method for consumers of the `ToTokens` trait.
67 fn into_token_stream(self) -> TokenStream
68 where
69 Self: Sized,
70 {
71 self.to_token_stream()
72 }
73}
74
75#[unstable(feature = "proc_macro_totokens", issue = "130977")]
76impl ToTokens for TokenTree {
77 fn to_tokens(&self, tokens: &mut TokenStream) {
78 tokens.extend_one(self.clone());
79 }
80
81 fn into_token_stream(self) -> TokenStream {
82 let mut builder: ConcatTreesHelper = ConcatTreesHelper::new(capacity:1);
83 builder.push(self);
84 builder.build()
85 }
86}
87
88#[unstable(feature = "proc_macro_totokens", issue = "130977")]
89impl ToTokens for TokenStream {
90 fn to_tokens(&self, tokens: &mut TokenStream) {
91 tokens.extend(self.clone());
92 }
93
94 fn into_token_stream(self) -> TokenStream {
95 self
96 }
97}
98
99#[unstable(feature = "proc_macro_totokens", issue = "130977")]
100impl ToTokens for Literal {
101 fn to_tokens(&self, tokens: &mut TokenStream) {
102 tokens.extend_one(item:TokenTree::from(self.clone()));
103 }
104}
105
106#[unstable(feature = "proc_macro_totokens", issue = "130977")]
107impl ToTokens for Ident {
108 fn to_tokens(&self, tokens: &mut TokenStream) {
109 tokens.extend_one(item:TokenTree::from(self.clone()));
110 }
111}
112
113#[unstable(feature = "proc_macro_totokens", issue = "130977")]
114impl ToTokens for Punct {
115 fn to_tokens(&self, tokens: &mut TokenStream) {
116 tokens.extend_one(item:TokenTree::from(self.clone()));
117 }
118}
119
120#[unstable(feature = "proc_macro_totokens", issue = "130977")]
121impl ToTokens for Group {
122 fn to_tokens(&self, tokens: &mut TokenStream) {
123 tokens.extend_one(item:TokenTree::from(self.clone()));
124 }
125}
126
127#[unstable(feature = "proc_macro_totokens", issue = "130977")]
128impl<T: ToTokens + ?Sized> ToTokens for &T {
129 fn to_tokens(&self, tokens: &mut TokenStream) {
130 (**self).to_tokens(tokens)
131 }
132}
133
134#[unstable(feature = "proc_macro_totokens", issue = "130977")]
135impl<T: ToTokens + ?Sized> ToTokens for &mut T {
136 fn to_tokens(&self, tokens: &mut TokenStream) {
137 (**self).to_tokens(tokens)
138 }
139}
140
141#[unstable(feature = "proc_macro_totokens", issue = "130977")]
142impl<T: ToTokens + ?Sized> ToTokens for Box<T> {
143 fn to_tokens(&self, tokens: &mut TokenStream) {
144 (**self).to_tokens(tokens)
145 }
146}
147
148#[unstable(feature = "proc_macro_totokens", issue = "130977")]
149impl<T: ToTokens + ?Sized> ToTokens for Rc<T> {
150 fn to_tokens(&self, tokens: &mut TokenStream) {
151 (**self).to_tokens(tokens)
152 }
153}
154
155#[unstable(feature = "proc_macro_totokens", issue = "130977")]
156impl<T: ToTokens + ToOwned + ?Sized> ToTokens for Cow<'_, T> {
157 fn to_tokens(&self, tokens: &mut TokenStream) {
158 (**self).to_tokens(tokens)
159 }
160}
161
162#[unstable(feature = "proc_macro_totokens", issue = "130977")]
163impl<T: ToTokens> ToTokens for Option<T> {
164 fn to_tokens(&self, tokens: &mut TokenStream) {
165 if let Some(t: &T) = self {
166 t.to_tokens(tokens);
167 }
168 }
169}
170
171#[unstable(feature = "proc_macro_totokens", issue = "130977")]
172impl ToTokens for u8 {
173 fn to_tokens(&self, tokens: &mut TokenStream) {
174 Literal::u8_suffixed(*self).to_tokens(tokens)
175 }
176}
177
178#[unstable(feature = "proc_macro_totokens", issue = "130977")]
179impl ToTokens for u16 {
180 fn to_tokens(&self, tokens: &mut TokenStream) {
181 Literal::u16_suffixed(*self).to_tokens(tokens)
182 }
183}
184
185#[unstable(feature = "proc_macro_totokens", issue = "130977")]
186impl ToTokens for u32 {
187 fn to_tokens(&self, tokens: &mut TokenStream) {
188 Literal::u32_suffixed(*self).to_tokens(tokens)
189 }
190}
191
192#[unstable(feature = "proc_macro_totokens", issue = "130977")]
193impl ToTokens for u64 {
194 fn to_tokens(&self, tokens: &mut TokenStream) {
195 Literal::u64_suffixed(*self).to_tokens(tokens)
196 }
197}
198
199#[unstable(feature = "proc_macro_totokens", issue = "130977")]
200impl ToTokens for u128 {
201 fn to_tokens(&self, tokens: &mut TokenStream) {
202 Literal::u128_suffixed(*self).to_tokens(tokens)
203 }
204}
205
206#[unstable(feature = "proc_macro_totokens", issue = "130977")]
207impl ToTokens for i8 {
208 fn to_tokens(&self, tokens: &mut TokenStream) {
209 Literal::i8_suffixed(*self).to_tokens(tokens)
210 }
211}
212
213#[unstable(feature = "proc_macro_totokens", issue = "130977")]
214impl ToTokens for i16 {
215 fn to_tokens(&self, tokens: &mut TokenStream) {
216 Literal::i16_suffixed(*self).to_tokens(tokens)
217 }
218}
219
220#[unstable(feature = "proc_macro_totokens", issue = "130977")]
221impl ToTokens for i32 {
222 fn to_tokens(&self, tokens: &mut TokenStream) {
223 Literal::i32_suffixed(*self).to_tokens(tokens)
224 }
225}
226
227#[unstable(feature = "proc_macro_totokens", issue = "130977")]
228impl ToTokens for i64 {
229 fn to_tokens(&self, tokens: &mut TokenStream) {
230 Literal::i64_suffixed(*self).to_tokens(tokens)
231 }
232}
233
234#[unstable(feature = "proc_macro_totokens", issue = "130977")]
235impl ToTokens for i128 {
236 fn to_tokens(&self, tokens: &mut TokenStream) {
237 Literal::i128_suffixed(*self).to_tokens(tokens)
238 }
239}
240
241#[unstable(feature = "proc_macro_totokens", issue = "130977")]
242impl ToTokens for f32 {
243 fn to_tokens(&self, tokens: &mut TokenStream) {
244 Literal::f32_suffixed(*self).to_tokens(tokens)
245 }
246}
247
248#[unstable(feature = "proc_macro_totokens", issue = "130977")]
249impl ToTokens for f64 {
250 fn to_tokens(&self, tokens: &mut TokenStream) {
251 Literal::f64_suffixed(*self).to_tokens(tokens)
252 }
253}
254
255#[unstable(feature = "proc_macro_totokens", issue = "130977")]
256impl ToTokens for usize {
257 fn to_tokens(&self, tokens: &mut TokenStream) {
258 Literal::usize_suffixed(*self).to_tokens(tokens)
259 }
260}
261
262#[unstable(feature = "proc_macro_totokens", issue = "130977")]
263impl ToTokens for isize {
264 fn to_tokens(&self, tokens: &mut TokenStream) {
265 Literal::isize_suffixed(*self).to_tokens(tokens)
266 }
267}
268
269#[unstable(feature = "proc_macro_totokens", issue = "130977")]
270impl ToTokens for bool {
271 fn to_tokens(&self, tokens: &mut TokenStream) {
272 let word: &'static str = if *self { "true" } else { "false" };
273 Ident::new(string:word, Span::call_site()).to_tokens(tokens)
274 }
275}
276
277#[unstable(feature = "proc_macro_totokens", issue = "130977")]
278impl ToTokens for char {
279 fn to_tokens(&self, tokens: &mut TokenStream) {
280 Literal::character(*self).to_tokens(tokens)
281 }
282}
283
284#[unstable(feature = "proc_macro_totokens", issue = "130977")]
285impl ToTokens for str {
286 fn to_tokens(&self, tokens: &mut TokenStream) {
287 Literal::string(self).to_tokens(tokens)
288 }
289}
290
291#[unstable(feature = "proc_macro_totokens", issue = "130977")]
292impl ToTokens for String {
293 fn to_tokens(&self, tokens: &mut TokenStream) {
294 Literal::string(self).to_tokens(tokens)
295 }
296}
297
298#[unstable(feature = "proc_macro_totokens", issue = "130977")]
299impl ToTokens for CStr {
300 fn to_tokens(&self, tokens: &mut TokenStream) {
301 Literal::c_string(self).to_tokens(tokens)
302 }
303}
304
305#[unstable(feature = "proc_macro_totokens", issue = "130977")]
306impl ToTokens for CString {
307 fn to_tokens(&self, tokens: &mut TokenStream) {
308 Literal::c_string(self).to_tokens(tokens)
309 }
310}
311