1 | use super::*; |
2 | use crate::punctuated::Punctuated; |
3 | use proc_macro2::TokenStream; |
4 | use std::iter; |
5 | use std::slice; |
6 | |
7 | #[cfg (feature = "parsing" )] |
8 | use crate::parse::{Parse, ParseBuffer, ParseStream, Parser, Result}; |
9 | #[cfg (feature = "parsing" )] |
10 | use crate::punctuated::Pair; |
11 | |
12 | ast_struct! { |
13 | /// An attribute like `#[repr(transparent)]`. |
14 | /// |
15 | /// *This type is available only if Syn is built with the `"derive"` or `"full"` |
16 | /// feature.* |
17 | /// |
18 | /// <br> |
19 | /// |
20 | /// # Syntax |
21 | /// |
22 | /// Rust has six types of attributes. |
23 | /// |
24 | /// - Outer attributes like `#[repr(transparent)]`. These appear outside or |
25 | /// in front of the item they describe. |
26 | /// - Inner attributes like `#![feature(proc_macro)]`. These appear inside |
27 | /// of the item they describe, usually a module. |
28 | /// - Outer doc comments like `/// # Example`. |
29 | /// - Inner doc comments like `//! Please file an issue`. |
30 | /// - Outer block comments `/** # Example */`. |
31 | /// - Inner block comments `/*! Please file an issue */`. |
32 | /// |
33 | /// The `style` field of type `AttrStyle` distinguishes whether an attribute |
34 | /// is outer or inner. Doc comments and block comments are promoted to |
35 | /// attributes, as this is how they are processed by the compiler and by |
36 | /// `macro_rules!` macros. |
37 | /// |
38 | /// The `path` field gives the possibly colon-delimited path against which |
39 | /// the attribute is resolved. It is equal to `"doc"` for desugared doc |
40 | /// comments. The `tokens` field contains the rest of the attribute body as |
41 | /// tokens. |
42 | /// |
43 | /// ```text |
44 | /// #[derive(Copy)] #[crate::precondition x < 5] |
45 | /// ^^^^^^~~~~~~ ^^^^^^^^^^^^^^^^^^^ ~~~~~ |
46 | /// path tokens path tokens |
47 | /// ``` |
48 | /// |
49 | /// <br> |
50 | /// |
51 | /// # Parsing from tokens to Attribute |
52 | /// |
53 | /// This type does not implement the [`Parse`] trait and thus cannot be |
54 | /// parsed directly by [`ParseStream::parse`]. Instead use |
55 | /// [`ParseStream::call`] with one of the two parser functions |
56 | /// [`Attribute::parse_outer`] or [`Attribute::parse_inner`] depending on |
57 | /// which you intend to parse. |
58 | /// |
59 | /// [`Parse`]: parse::Parse |
60 | /// [`ParseStream::parse`]: parse::ParseBuffer::parse |
61 | /// [`ParseStream::call`]: parse::ParseBuffer::call |
62 | /// |
63 | /// ``` |
64 | /// use syn::{Attribute, Ident, Result, Token}; |
65 | /// use syn::parse::{Parse, ParseStream}; |
66 | /// |
67 | /// // Parses a unit struct with attributes. |
68 | /// // |
69 | /// // #[path = "s.tmpl"] |
70 | /// // struct S; |
71 | /// struct UnitStruct { |
72 | /// attrs: Vec<Attribute>, |
73 | /// struct_token: Token![struct], |
74 | /// name: Ident, |
75 | /// semi_token: Token![;], |
76 | /// } |
77 | /// |
78 | /// impl Parse for UnitStruct { |
79 | /// fn parse(input: ParseStream) -> Result<Self> { |
80 | /// Ok(UnitStruct { |
81 | /// attrs: input.call(Attribute::parse_outer)?, |
82 | /// struct_token: input.parse()?, |
83 | /// name: input.parse()?, |
84 | /// semi_token: input.parse()?, |
85 | /// }) |
86 | /// } |
87 | /// } |
88 | /// ``` |
89 | /// |
90 | /// <p><br></p> |
91 | /// |
92 | /// # Parsing from Attribute to structured arguments |
93 | /// |
94 | /// The grammar of attributes in Rust is very flexible, which makes the |
95 | /// syntax tree not that useful on its own. In particular, arguments of the |
96 | /// attribute are held in an arbitrary `tokens: TokenStream`. Macros are |
97 | /// expected to check the `path` of the attribute, decide whether they |
98 | /// recognize it, and then parse the remaining tokens according to whatever |
99 | /// grammar they wish to require for that kind of attribute. |
100 | /// |
101 | /// If the attribute you are parsing is expected to conform to the |
102 | /// conventional structured form of attribute, use [`parse_meta()`] to |
103 | /// obtain that structured representation. If the attribute follows some |
104 | /// other grammar of its own, use [`parse_args()`] to parse that into the |
105 | /// expected data structure. |
106 | /// |
107 | /// [`parse_meta()`]: Attribute::parse_meta |
108 | /// [`parse_args()`]: Attribute::parse_args |
109 | /// |
110 | /// <p><br></p> |
111 | /// |
112 | /// # Doc comments |
113 | /// |
114 | /// The compiler transforms doc comments, such as `/// comment` and `/*! |
115 | /// comment */`, into attributes before macros are expanded. Each comment is |
116 | /// expanded into an attribute of the form `#[doc = r"comment"]`. |
117 | /// |
118 | /// As an example, the following `mod` items are expanded identically: |
119 | /// |
120 | /// ``` |
121 | /// # use syn::{ItemMod, parse_quote}; |
122 | /// let doc: ItemMod = parse_quote! { |
123 | /// /// Single line doc comments |
124 | /// /// We write so many! |
125 | /// /** |
126 | /// * Multi-line comments... |
127 | /// * May span many lines |
128 | /// */ |
129 | /// mod example { |
130 | /// //! Of course, they can be inner too |
131 | /// /*! And fit in a single line */ |
132 | /// } |
133 | /// }; |
134 | /// let attr: ItemMod = parse_quote! { |
135 | /// #[doc = r" Single line doc comments"] |
136 | /// #[doc = r" We write so many!"] |
137 | /// #[doc = r" |
138 | /// * Multi-line comments... |
139 | /// * May span many lines |
140 | /// "] |
141 | /// mod example { |
142 | /// #![doc = r" Of course, they can be inner too"] |
143 | /// #![doc = r" And fit in a single line "] |
144 | /// } |
145 | /// }; |
146 | /// assert_eq!(doc, attr); |
147 | /// ``` |
148 | #[cfg_attr (doc_cfg, doc(cfg(any(feature = "full" , feature = "derive" ))))] |
149 | pub struct Attribute { |
150 | pub pound_token: Token![#], |
151 | pub style: AttrStyle, |
152 | pub bracket_token: token::Bracket, |
153 | pub path: Path, |
154 | pub tokens: TokenStream, |
155 | } |
156 | } |
157 | |
158 | impl Attribute { |
159 | /// Parses the content of the attribute, consisting of the path and tokens, |
160 | /// as a [`Meta`] if possible. |
161 | /// |
162 | /// *This function is available only if Syn is built with the `"parsing"` |
163 | /// feature.* |
164 | #[cfg (feature = "parsing" )] |
165 | #[cfg_attr (doc_cfg, doc(cfg(feature = "parsing" )))] |
166 | pub fn parse_meta(&self) -> Result<Meta> { |
167 | fn clone_ident_segment(segment: &PathSegment) -> PathSegment { |
168 | PathSegment { |
169 | ident: segment.ident.clone(), |
170 | arguments: PathArguments::None, |
171 | } |
172 | } |
173 | |
174 | let path = Path { |
175 | leading_colon: self |
176 | .path |
177 | .leading_colon |
178 | .as_ref() |
179 | .map(|colon| Token![::](colon.spans)), |
180 | segments: self |
181 | .path |
182 | .segments |
183 | .pairs() |
184 | .map(|pair| match pair { |
185 | Pair::Punctuated(seg, punct) => { |
186 | Pair::Punctuated(clone_ident_segment(seg), Token![::](punct.spans)) |
187 | } |
188 | Pair::End(seg) => Pair::End(clone_ident_segment(seg)), |
189 | }) |
190 | .collect(), |
191 | }; |
192 | |
193 | let parser = |input: ParseStream| parsing::parse_meta_after_path(path, input); |
194 | parse::Parser::parse2(parser, self.tokens.clone()) |
195 | } |
196 | |
197 | /// Parse the arguments to the attribute as a syntax tree. |
198 | /// |
199 | /// This is similar to `syn::parse2::<T>(attr.tokens)` except that: |
200 | /// |
201 | /// - the surrounding delimiters are *not* included in the input to the |
202 | /// parser; and |
203 | /// - the error message has a more useful span when `tokens` is empty. |
204 | /// |
205 | /// ```text |
206 | /// #[my_attr(value < 5)] |
207 | /// ^^^^^^^^^ what gets parsed |
208 | /// ``` |
209 | /// |
210 | /// *This function is available only if Syn is built with the `"parsing"` |
211 | /// feature.* |
212 | #[cfg (feature = "parsing" )] |
213 | #[cfg_attr (doc_cfg, doc(cfg(feature = "parsing" )))] |
214 | pub fn parse_args<T: Parse>(&self) -> Result<T> { |
215 | self.parse_args_with(T::parse) |
216 | } |
217 | |
218 | /// Parse the arguments to the attribute using the given parser. |
219 | /// |
220 | /// *This function is available only if Syn is built with the `"parsing"` |
221 | /// feature.* |
222 | #[cfg (feature = "parsing" )] |
223 | #[cfg_attr (doc_cfg, doc(cfg(feature = "parsing" )))] |
224 | pub fn parse_args_with<F: Parser>(&self, parser: F) -> Result<F::Output> { |
225 | let parser = |input: ParseStream| { |
226 | let args = enter_args(self, input)?; |
227 | parse::parse_stream(parser, &args) |
228 | }; |
229 | parser.parse2(self.tokens.clone()) |
230 | } |
231 | |
232 | /// Parses zero or more outer attributes from the stream. |
233 | /// |
234 | /// *This function is available only if Syn is built with the `"parsing"` |
235 | /// feature.* |
236 | #[cfg (feature = "parsing" )] |
237 | #[cfg_attr (doc_cfg, doc(cfg(feature = "parsing" )))] |
238 | pub fn parse_outer(input: ParseStream) -> Result<Vec<Self>> { |
239 | let mut attrs = Vec::new(); |
240 | while input.peek(Token![#]) { |
241 | attrs.push(input.call(parsing::single_parse_outer)?); |
242 | } |
243 | Ok(attrs) |
244 | } |
245 | |
246 | /// Parses zero or more inner attributes from the stream. |
247 | /// |
248 | /// *This function is available only if Syn is built with the `"parsing"` |
249 | /// feature.* |
250 | #[cfg (feature = "parsing" )] |
251 | #[cfg_attr (doc_cfg, doc(cfg(feature = "parsing" )))] |
252 | pub fn parse_inner(input: ParseStream) -> Result<Vec<Self>> { |
253 | let mut attrs = Vec::new(); |
254 | parsing::parse_inner(input, &mut attrs)?; |
255 | Ok(attrs) |
256 | } |
257 | } |
258 | |
259 | #[cfg (feature = "parsing" )] |
260 | fn expected_parentheses(attr: &Attribute) -> String { |
261 | let style: &str = match attr.style { |
262 | AttrStyle::Outer => "#" , |
263 | AttrStyle::Inner(_) => "#!" , |
264 | }; |
265 | |
266 | let mut path: String = String::new(); |
267 | for segment: &PathSegment in &attr.path.segments { |
268 | if !path.is_empty() || attr.path.leading_colon.is_some() { |
269 | path += "::" ; |
270 | } |
271 | path += &segment.ident.to_string(); |
272 | } |
273 | |
274 | format!(" {}[ {}(...)]" , style, path) |
275 | } |
276 | |
277 | #[cfg (feature = "parsing" )] |
278 | fn enter_args<'a>(attr: &Attribute, input: ParseStream<'a>) -> Result<ParseBuffer<'a>> { |
279 | if input.is_empty() { |
280 | let expected = expected_parentheses(attr); |
281 | let msg = format!("expected attribute arguments in parentheses: {}" , expected); |
282 | return Err(crate::error::new2( |
283 | attr.pound_token.span, |
284 | attr.bracket_token.span, |
285 | msg, |
286 | )); |
287 | } else if input.peek(Token![=]) { |
288 | let expected = expected_parentheses(attr); |
289 | let msg = format!("expected parentheses: {}" , expected); |
290 | return Err(input.error(msg)); |
291 | }; |
292 | |
293 | let content; |
294 | if input.peek(token::Paren) { |
295 | parenthesized!(content in input); |
296 | } else if input.peek(token::Bracket) { |
297 | bracketed!(content in input); |
298 | } else if input.peek(token::Brace) { |
299 | braced!(content in input); |
300 | } else { |
301 | return Err(input.error("unexpected token in attribute arguments" )); |
302 | } |
303 | |
304 | if input.is_empty() { |
305 | Ok(content) |
306 | } else { |
307 | Err(input.error("unexpected token in attribute arguments" )) |
308 | } |
309 | } |
310 | |
311 | ast_enum! { |
312 | /// Distinguishes between attributes that decorate an item and attributes |
313 | /// that are contained within an item. |
314 | /// |
315 | /// *This type is available only if Syn is built with the `"derive"` or `"full"` |
316 | /// feature.* |
317 | /// |
318 | /// # Outer attributes |
319 | /// |
320 | /// - `#[repr(transparent)]` |
321 | /// - `/// # Example` |
322 | /// - `/** Please file an issue */` |
323 | /// |
324 | /// # Inner attributes |
325 | /// |
326 | /// - `#![feature(proc_macro)]` |
327 | /// - `//! # Example` |
328 | /// - `/*! Please file an issue */` |
329 | #[cfg_attr (doc_cfg, doc(cfg(any(feature = "full" , feature = "derive" ))))] |
330 | pub enum AttrStyle { |
331 | Outer, |
332 | Inner(Token![!]), |
333 | } |
334 | } |
335 | |
336 | ast_enum_of_structs! { |
337 | /// Content of a compile-time structured attribute. |
338 | /// |
339 | /// *This type is available only if Syn is built with the `"derive"` or `"full"` |
340 | /// feature.* |
341 | /// |
342 | /// ## Path |
343 | /// |
344 | /// A meta path is like the `test` in `#[test]`. |
345 | /// |
346 | /// ## List |
347 | /// |
348 | /// A meta list is like the `derive(Copy)` in `#[derive(Copy)]`. |
349 | /// |
350 | /// ## NameValue |
351 | /// |
352 | /// A name-value meta is like the `path = "..."` in `#[path = |
353 | /// "sys/windows.rs"]`. |
354 | /// |
355 | /// # Syntax tree enum |
356 | /// |
357 | /// This type is a [syntax tree enum]. |
358 | /// |
359 | /// [syntax tree enum]: Expr#syntax-tree-enums |
360 | #[cfg_attr (doc_cfg, doc(cfg(any(feature = "full" , feature = "derive" ))))] |
361 | pub enum Meta { |
362 | Path(Path), |
363 | |
364 | /// A structured list within an attribute, like `derive(Copy, Clone)`. |
365 | List(MetaList), |
366 | |
367 | /// A name-value pair within an attribute, like `feature = "nightly"`. |
368 | NameValue(MetaNameValue), |
369 | } |
370 | } |
371 | |
372 | ast_struct! { |
373 | /// A structured list within an attribute, like `derive(Copy, Clone)`. |
374 | /// |
375 | /// *This type is available only if Syn is built with the `"derive"` or |
376 | /// `"full"` feature.* |
377 | #[cfg_attr (doc_cfg, doc(cfg(any(feature = "full" , feature = "derive" ))))] |
378 | pub struct MetaList { |
379 | pub path: Path, |
380 | pub paren_token: token::Paren, |
381 | pub nested: Punctuated<NestedMeta, Token![,]>, |
382 | } |
383 | } |
384 | |
385 | ast_struct! { |
386 | /// A name-value pair within an attribute, like `feature = "nightly"`. |
387 | /// |
388 | /// *This type is available only if Syn is built with the `"derive"` or |
389 | /// `"full"` feature.* |
390 | #[cfg_attr (doc_cfg, doc(cfg(any(feature = "full" , feature = "derive" ))))] |
391 | pub struct MetaNameValue { |
392 | pub path: Path, |
393 | pub eq_token: Token![=], |
394 | pub lit: Lit, |
395 | } |
396 | } |
397 | |
398 | impl Meta { |
399 | /// Returns the identifier that begins this structured meta item. |
400 | /// |
401 | /// For example this would return the `test` in `#[test]`, the `derive` in |
402 | /// `#[derive(Copy)]`, and the `path` in `#[path = "sys/windows.rs"]`. |
403 | pub fn path(&self) -> &Path { |
404 | match self { |
405 | Meta::Path(path: &Path) => path, |
406 | Meta::List(meta: &MetaList) => &meta.path, |
407 | Meta::NameValue(meta: &MetaNameValue) => &meta.path, |
408 | } |
409 | } |
410 | } |
411 | |
412 | ast_enum_of_structs! { |
413 | /// Element of a compile-time attribute list. |
414 | /// |
415 | /// *This type is available only if Syn is built with the `"derive"` or `"full"` |
416 | /// feature.* |
417 | #[cfg_attr (doc_cfg, doc(cfg(any(feature = "full" , feature = "derive" ))))] |
418 | pub enum NestedMeta { |
419 | /// A structured meta item, like the `Copy` in `#[derive(Copy)]` which |
420 | /// would be a nested `Meta::Path`. |
421 | Meta(Meta), |
422 | |
423 | /// A Rust literal, like the `"new_name"` in `#[rename("new_name")]`. |
424 | Lit(Lit), |
425 | } |
426 | } |
427 | |
428 | /// Conventional argument type associated with an invocation of an attribute |
429 | /// macro. |
430 | /// |
431 | /// For example if we are developing an attribute macro that is intended to be |
432 | /// invoked on function items as follows: |
433 | /// |
434 | /// ``` |
435 | /// # const IGNORE: &str = stringify! { |
436 | /// #[my_attribute(path = "/v1/refresh" )] |
437 | /// # }; |
438 | /// pub fn refresh() { |
439 | /// /* ... */ |
440 | /// } |
441 | /// ``` |
442 | /// |
443 | /// The implementation of this macro would want to parse its attribute arguments |
444 | /// as type `AttributeArgs`. |
445 | /// |
446 | /// ``` |
447 | /// # extern crate proc_macro; |
448 | /// # |
449 | /// use proc_macro::TokenStream; |
450 | /// use syn::{parse_macro_input, AttributeArgs, ItemFn}; |
451 | /// |
452 | /// # const IGNORE: &str = stringify! { |
453 | /// #[proc_macro_attribute] |
454 | /// # }; |
455 | /// pub fn my_attribute(args: TokenStream, input: TokenStream) -> TokenStream { |
456 | /// let args = parse_macro_input!(args as AttributeArgs); |
457 | /// let input = parse_macro_input!(input as ItemFn); |
458 | /// |
459 | /// /* ... */ |
460 | /// # "" .parse().unwrap() |
461 | /// } |
462 | /// ``` |
463 | #[cfg_attr (doc_cfg, doc(cfg(any(feature = "full" , feature = "derive" ))))] |
464 | pub type AttributeArgs = Vec<NestedMeta>; |
465 | |
466 | pub trait FilterAttrs<'a> { |
467 | type Ret: Iterator<Item = &'a Attribute>; |
468 | |
469 | fn outer(self) -> Self::Ret; |
470 | fn inner(self) -> Self::Ret; |
471 | } |
472 | |
473 | impl<'a> FilterAttrs<'a> for &'a [Attribute] { |
474 | type Ret = iter::Filter<slice::Iter<'a, Attribute>, fn(&&Attribute) -> bool>; |
475 | |
476 | fn outer(self) -> Self::Ret { |
477 | fn is_outer(attr: &&Attribute) -> bool { |
478 | match attr.style { |
479 | AttrStyle::Outer => true, |
480 | AttrStyle::Inner(_) => false, |
481 | } |
482 | } |
483 | self.iter().filter(is_outer) |
484 | } |
485 | |
486 | fn inner(self) -> Self::Ret { |
487 | fn is_inner(attr: &&Attribute) -> bool { |
488 | match attr.style { |
489 | AttrStyle::Inner(_) => true, |
490 | AttrStyle::Outer => false, |
491 | } |
492 | } |
493 | self.iter().filter(is_inner) |
494 | } |
495 | } |
496 | |
497 | #[cfg (feature = "parsing" )] |
498 | pub mod parsing { |
499 | use super::*; |
500 | use crate::ext::IdentExt; |
501 | use crate::parse::{Parse, ParseStream, Result}; |
502 | |
503 | pub fn parse_inner(input: ParseStream, attrs: &mut Vec<Attribute>) -> Result<()> { |
504 | while input.peek(Token![#]) && input.peek2(Token![!]) { |
505 | attrs.push(input.call(parsing::single_parse_inner)?); |
506 | } |
507 | Ok(()) |
508 | } |
509 | |
510 | pub fn single_parse_inner(input: ParseStream) -> Result<Attribute> { |
511 | let content; |
512 | Ok(Attribute { |
513 | pound_token: input.parse()?, |
514 | style: AttrStyle::Inner(input.parse()?), |
515 | bracket_token: bracketed!(content in input), |
516 | path: content.call(Path::parse_mod_style)?, |
517 | tokens: content.parse()?, |
518 | }) |
519 | } |
520 | |
521 | pub fn single_parse_outer(input: ParseStream) -> Result<Attribute> { |
522 | let content; |
523 | Ok(Attribute { |
524 | pound_token: input.parse()?, |
525 | style: AttrStyle::Outer, |
526 | bracket_token: bracketed!(content in input), |
527 | path: content.call(Path::parse_mod_style)?, |
528 | tokens: content.parse()?, |
529 | }) |
530 | } |
531 | |
532 | // Like Path::parse_mod_style but accepts keywords in the path. |
533 | fn parse_meta_path(input: ParseStream) -> Result<Path> { |
534 | Ok(Path { |
535 | leading_colon: input.parse()?, |
536 | segments: { |
537 | let mut segments = Punctuated::new(); |
538 | while input.peek(Ident::peek_any) { |
539 | let ident = Ident::parse_any(input)?; |
540 | segments.push_value(PathSegment::from(ident)); |
541 | if !input.peek(Token![::]) { |
542 | break; |
543 | } |
544 | let punct = input.parse()?; |
545 | segments.push_punct(punct); |
546 | } |
547 | if segments.is_empty() { |
548 | return Err(input.error("expected path" )); |
549 | } else if segments.trailing_punct() { |
550 | return Err(input.error("expected path segment" )); |
551 | } |
552 | segments |
553 | }, |
554 | }) |
555 | } |
556 | |
557 | #[cfg_attr (doc_cfg, doc(cfg(feature = "parsing" )))] |
558 | impl Parse for Meta { |
559 | fn parse(input: ParseStream) -> Result<Self> { |
560 | let path = input.call(parse_meta_path)?; |
561 | parse_meta_after_path(path, input) |
562 | } |
563 | } |
564 | |
565 | #[cfg_attr (doc_cfg, doc(cfg(feature = "parsing" )))] |
566 | impl Parse for MetaList { |
567 | fn parse(input: ParseStream) -> Result<Self> { |
568 | let path = input.call(parse_meta_path)?; |
569 | parse_meta_list_after_path(path, input) |
570 | } |
571 | } |
572 | |
573 | #[cfg_attr (doc_cfg, doc(cfg(feature = "parsing" )))] |
574 | impl Parse for MetaNameValue { |
575 | fn parse(input: ParseStream) -> Result<Self> { |
576 | let path = input.call(parse_meta_path)?; |
577 | parse_meta_name_value_after_path(path, input) |
578 | } |
579 | } |
580 | |
581 | #[cfg_attr (doc_cfg, doc(cfg(feature = "parsing" )))] |
582 | impl Parse for NestedMeta { |
583 | fn parse(input: ParseStream) -> Result<Self> { |
584 | if input.peek(Lit) && !(input.peek(LitBool) && input.peek2(Token![=])) { |
585 | input.parse().map(NestedMeta::Lit) |
586 | } else if input.peek(Ident::peek_any) |
587 | || input.peek(Token![::]) && input.peek3(Ident::peek_any) |
588 | { |
589 | input.parse().map(NestedMeta::Meta) |
590 | } else { |
591 | Err(input.error("expected identifier or literal" )) |
592 | } |
593 | } |
594 | } |
595 | |
596 | pub fn parse_meta_after_path(path: Path, input: ParseStream) -> Result<Meta> { |
597 | if input.peek(token::Paren) { |
598 | parse_meta_list_after_path(path, input).map(Meta::List) |
599 | } else if input.peek(Token![=]) { |
600 | parse_meta_name_value_after_path(path, input).map(Meta::NameValue) |
601 | } else { |
602 | Ok(Meta::Path(path)) |
603 | } |
604 | } |
605 | |
606 | fn parse_meta_list_after_path(path: Path, input: ParseStream) -> Result<MetaList> { |
607 | let content; |
608 | Ok(MetaList { |
609 | path, |
610 | paren_token: parenthesized!(content in input), |
611 | nested: content.parse_terminated(NestedMeta::parse)?, |
612 | }) |
613 | } |
614 | |
615 | fn parse_meta_name_value_after_path(path: Path, input: ParseStream) -> Result<MetaNameValue> { |
616 | Ok(MetaNameValue { |
617 | path, |
618 | eq_token: input.parse()?, |
619 | lit: input.parse()?, |
620 | }) |
621 | } |
622 | } |
623 | |
624 | #[cfg (feature = "printing" )] |
625 | mod printing { |
626 | use super::*; |
627 | use proc_macro2::TokenStream; |
628 | use quote::ToTokens; |
629 | |
630 | #[cfg_attr (doc_cfg, doc(cfg(feature = "printing" )))] |
631 | impl ToTokens for Attribute { |
632 | fn to_tokens(&self, tokens: &mut TokenStream) { |
633 | self.pound_token.to_tokens(tokens); |
634 | if let AttrStyle::Inner(b) = &self.style { |
635 | b.to_tokens(tokens); |
636 | } |
637 | self.bracket_token.surround(tokens, |tokens| { |
638 | self.path.to_tokens(tokens); |
639 | self.tokens.to_tokens(tokens); |
640 | }); |
641 | } |
642 | } |
643 | |
644 | #[cfg_attr (doc_cfg, doc(cfg(feature = "printing" )))] |
645 | impl ToTokens for MetaList { |
646 | fn to_tokens(&self, tokens: &mut TokenStream) { |
647 | self.path.to_tokens(tokens); |
648 | self.paren_token.surround(tokens, |tokens| { |
649 | self.nested.to_tokens(tokens); |
650 | }); |
651 | } |
652 | } |
653 | |
654 | #[cfg_attr (doc_cfg, doc(cfg(feature = "printing" )))] |
655 | impl ToTokens for MetaNameValue { |
656 | fn to_tokens(&self, tokens: &mut TokenStream) { |
657 | self.path.to_tokens(tokens); |
658 | self.eq_token.to_tokens(tokens); |
659 | self.lit.to_tokens(tokens); |
660 | } |
661 | } |
662 | } |
663 | |