1/// Define a type that supports parsing and printing a multi-character symbol
2/// as if it were a punctuation token.
3///
4/// # Usage
5///
6/// ```
7/// syn::custom_punctuation!(LeftRightArrow, <=>);
8/// ```
9///
10/// The generated syntax tree node supports the following operations just like
11/// any built-in punctuation token.
12///
13/// - [Peeking] — `input.peek(LeftRightArrow)`
14///
15/// - [Parsing] — `input.parse::<LeftRightArrow>()?`
16///
17/// - [Printing] — `quote!( ... #lrarrow ... )`
18///
19/// - Construction from a [`Span`] — `let lrarrow = LeftRightArrow(sp)`
20///
21/// - Construction from multiple [`Span`] — `let lrarrow = LeftRightArrow([sp, sp, sp])`
22///
23/// - Field access to its spans — `let spans = lrarrow.spans`
24///
25/// [Peeking]: crate::parse::ParseBuffer::peek
26/// [Parsing]: crate::parse::ParseBuffer::parse
27/// [Printing]: quote::ToTokens
28/// [`Span`]: proc_macro2::Span
29///
30/// # Example
31///
32/// ```
33/// use proc_macro2::{TokenStream, TokenTree};
34/// use syn::parse::{Parse, ParseStream, Peek, Result};
35/// use syn::punctuated::Punctuated;
36/// use syn::Expr;
37///
38/// syn::custom_punctuation!(PathSeparator, </>);
39///
40/// // expr </> expr </> expr ...
41/// struct PathSegments {
42/// segments: Punctuated<Expr, PathSeparator>,
43/// }
44///
45/// impl Parse for PathSegments {
46/// fn parse(input: ParseStream) -> Result<Self> {
47/// let mut segments = Punctuated::new();
48///
49/// let first = parse_until(input, PathSeparator)?;
50/// segments.push_value(syn::parse2(first)?);
51///
52/// while input.peek(PathSeparator) {
53/// segments.push_punct(input.parse()?);
54///
55/// let next = parse_until(input, PathSeparator)?;
56/// segments.push_value(syn::parse2(next)?);
57/// }
58///
59/// Ok(PathSegments { segments })
60/// }
61/// }
62///
63/// fn parse_until<E: Peek>(input: ParseStream, end: E) -> Result<TokenStream> {
64/// let mut tokens = TokenStream::new();
65/// while !input.is_empty() && !input.peek(end) {
66/// let next: TokenTree = input.parse()?;
67/// tokens.extend(Some(next));
68/// }
69/// Ok(tokens)
70/// }
71///
72/// fn main() {
73/// let input = r#" a::b </> c::d::e "#;
74/// let _: PathSegments = syn::parse_str(input).unwrap();
75/// }
76/// ```
77#[macro_export]
78macro_rules! custom_punctuation {
79 ($ident:ident, $($tt:tt)+) => {
80 pub struct $ident {
81 pub spans: $crate::custom_punctuation_repr!($($tt)+),
82 }
83
84 #[doc(hidden)]
85 #[allow(dead_code, non_snake_case)]
86 pub fn $ident<__S: $crate::__private::IntoSpans<$crate::custom_punctuation_repr!($($tt)+)>>(
87 spans: __S,
88 ) -> $ident {
89 let _validate_len = 0 $(+ $crate::custom_punctuation_len!(strict, $tt))*;
90 $ident {
91 spans: $crate::__private::IntoSpans::into_spans(spans)
92 }
93 }
94
95 impl $crate::__private::Default for $ident {
96 fn default() -> Self {
97 $ident($crate::__private::Span::call_site())
98 }
99 }
100
101 $crate::impl_parse_for_custom_punctuation!($ident, $($tt)+);
102 $crate::impl_to_tokens_for_custom_punctuation!($ident, $($tt)+);
103 $crate::impl_clone_for_custom_punctuation!($ident, $($tt)+);
104 $crate::impl_extra_traits_for_custom_punctuation!($ident, $($tt)+);
105 };
106}
107
108// Not public API.
109#[cfg(feature = "parsing")]
110#[doc(hidden)]
111#[macro_export]
112macro_rules! impl_parse_for_custom_punctuation {
113 ($ident:ident, $($tt:tt)+) => {
114 impl $crate::token::CustomToken for $ident {
115 fn peek(cursor: $crate::buffer::Cursor) -> bool {
116 $crate::token::parsing::peek_punct(cursor, $crate::stringify_punct!($($tt)+))
117 }
118
119 fn display() -> &'static $crate::__private::str {
120 concat!("`", $crate::stringify_punct!($($tt)+), "`")
121 }
122 }
123
124 impl $crate::parse::Parse for $ident {
125 fn parse(input: $crate::parse::ParseStream) -> $crate::parse::Result<$ident> {
126 let spans: $crate::custom_punctuation_repr!($($tt)+) =
127 $crate::token::parsing::punct(input, $crate::stringify_punct!($($tt)+))?;
128 Ok($ident(spans))
129 }
130 }
131 };
132}
133
134// Not public API.
135#[cfg(not(feature = "parsing"))]
136#[doc(hidden)]
137#[macro_export]
138macro_rules! impl_parse_for_custom_punctuation {
139 ($ident:ident, $($tt:tt)+) => {};
140}
141
142// Not public API.
143#[cfg(feature = "printing")]
144#[doc(hidden)]
145#[macro_export]
146macro_rules! impl_to_tokens_for_custom_punctuation {
147 ($ident:ident, $($tt:tt)+) => {
148 impl $crate::__private::ToTokens for $ident {
149 fn to_tokens(&self, tokens: &mut $crate::__private::TokenStream2) {
150 $crate::token::printing::punct($crate::stringify_punct!($($tt)+), &self.spans, tokens)
151 }
152 }
153 };
154}
155
156// Not public API.
157#[cfg(not(feature = "printing"))]
158#[doc(hidden)]
159#[macro_export]
160macro_rules! impl_to_tokens_for_custom_punctuation {
161 ($ident:ident, $($tt:tt)+) => {};
162}
163
164// Not public API.
165#[cfg(feature = "clone-impls")]
166#[doc(hidden)]
167#[macro_export]
168macro_rules! impl_clone_for_custom_punctuation {
169 ($ident:ident, $($tt:tt)+) => {
170 impl $crate::__private::Copy for $ident {}
171
172 #[allow(clippy::expl_impl_clone_on_copy)]
173 impl $crate::__private::Clone for $ident {
174 fn clone(&self) -> Self {
175 *self
176 }
177 }
178 };
179}
180
181// Not public API.
182#[cfg(not(feature = "clone-impls"))]
183#[doc(hidden)]
184#[macro_export]
185macro_rules! impl_clone_for_custom_punctuation {
186 ($ident:ident, $($tt:tt)+) => {};
187}
188
189// Not public API.
190#[cfg(feature = "extra-traits")]
191#[doc(hidden)]
192#[macro_export]
193macro_rules! impl_extra_traits_for_custom_punctuation {
194 ($ident:ident, $($tt:tt)+) => {
195 impl $crate::__private::Debug for $ident {
196 fn fmt(&self, f: &mut $crate::__private::Formatter) -> $crate::__private::fmt::Result {
197 $crate::__private::Formatter::write_str(f, stringify!($ident))
198 }
199 }
200
201 impl $crate::__private::Eq for $ident {}
202
203 impl $crate::__private::PartialEq for $ident {
204 fn eq(&self, _other: &Self) -> $crate::__private::bool {
205 true
206 }
207 }
208
209 impl $crate::__private::Hash for $ident {
210 fn hash<__H: $crate::__private::Hasher>(&self, _state: &mut __H) {}
211 }
212 };
213}
214
215// Not public API.
216#[cfg(not(feature = "extra-traits"))]
217#[doc(hidden)]
218#[macro_export]
219macro_rules! impl_extra_traits_for_custom_punctuation {
220 ($ident:ident, $($tt:tt)+) => {};
221}
222
223// Not public API.
224#[doc(hidden)]
225#[macro_export]
226macro_rules! custom_punctuation_repr {
227 ($($tt:tt)+) => {
228 [$crate::__private::Span; 0 $(+ $crate::custom_punctuation_len!(lenient, $tt))+]
229 };
230}
231
232// Not public API.
233#[doc(hidden)]
234#[macro_export]
235#[rustfmt::skip]
236macro_rules! custom_punctuation_len {
237 ($mode:ident, +) => { 1 };
238 ($mode:ident, +=) => { 2 };
239 ($mode:ident, &) => { 1 };
240 ($mode:ident, &&) => { 2 };
241 ($mode:ident, &=) => { 2 };
242 ($mode:ident, @) => { 1 };
243 ($mode:ident, !) => { 1 };
244 ($mode:ident, ^) => { 1 };
245 ($mode:ident, ^=) => { 2 };
246 ($mode:ident, :) => { 1 };
247 ($mode:ident, ::) => { 2 };
248 ($mode:ident, ,) => { 1 };
249 ($mode:ident, /) => { 1 };
250 ($mode:ident, /=) => { 2 };
251 ($mode:ident, .) => { 1 };
252 ($mode:ident, ..) => { 2 };
253 ($mode:ident, ...) => { 3 };
254 ($mode:ident, ..=) => { 3 };
255 ($mode:ident, =) => { 1 };
256 ($mode:ident, ==) => { 2 };
257 ($mode:ident, >=) => { 2 };
258 ($mode:ident, >) => { 1 };
259 ($mode:ident, <=) => { 2 };
260 ($mode:ident, <) => { 1 };
261 ($mode:ident, *=) => { 2 };
262 ($mode:ident, !=) => { 2 };
263 ($mode:ident, |) => { 1 };
264 ($mode:ident, |=) => { 2 };
265 ($mode:ident, ||) => { 2 };
266 ($mode:ident, #) => { 1 };
267 ($mode:ident, ?) => { 1 };
268 ($mode:ident, ->) => { 2 };
269 ($mode:ident, <-) => { 2 };
270 ($mode:ident, %) => { 1 };
271 ($mode:ident, %=) => { 2 };
272 ($mode:ident, =>) => { 2 };
273 ($mode:ident, ;) => { 1 };
274 ($mode:ident, <<) => { 2 };
275 ($mode:ident, <<=) => { 3 };
276 ($mode:ident, >>) => { 2 };
277 ($mode:ident, >>=) => { 3 };
278 ($mode:ident, *) => { 1 };
279 ($mode:ident, -) => { 1 };
280 ($mode:ident, -=) => { 2 };
281 ($mode:ident, ~) => { 1 };
282 (lenient, $tt:tt) => { 0 };
283 (strict, $tt:tt) => {{ $crate::custom_punctuation_unexpected!($tt); 0 }};
284}
285
286// Not public API.
287#[doc(hidden)]
288#[macro_export]
289macro_rules! custom_punctuation_unexpected {
290 () => {};
291}
292
293// Not public API.
294#[doc(hidden)]
295#[macro_export]
296macro_rules! stringify_punct {
297 ($($tt:tt)+) => {
298 concat!($(stringify!($tt)),+)
299 };
300}
301