proc_macro/
lib.rs

1//! A support library for macro authors when defining new macros.
2//!
3//! This library, provided by the standard distribution, provides the types
4//! consumed in the interfaces of procedurally defined macro definitions such as
5//! function-like macros `#[proc_macro]`, macro attributes `#[proc_macro_attribute]` and
6//! custom derive attributes`#[proc_macro_derive]`.
7//!
8//! See [the book] for more.
9//!
10//! [the book]: ../book/ch19-06-macros.html#procedural-macros-for-generating-code-from-attributes
11
12#![stable(feature = "proc_macro_lib", since = "1.15.0")]
13#![deny(missing_docs)]
14#![doc(
15    html_playground_url = "https://play.rust-lang.org/",
16    issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
17    test(no_crate_inject, attr(deny(warnings))),
18    test(attr(allow(dead_code, deprecated, unused_variables, unused_mut)))
19)]
20#![doc(rust_logo)]
21#![feature(rustdoc_internals)]
22#![feature(staged_api)]
23#![feature(allow_internal_unstable)]
24#![feature(decl_macro)]
25#![feature(maybe_uninit_write_slice)]
26#![feature(negative_impls)]
27#![feature(panic_can_unwind)]
28#![feature(restricted_std)]
29#![feature(rustc_attrs)]
30#![feature(extend_one)]
31#![recursion_limit = "256"]
32#![allow(internal_features)]
33#![deny(ffi_unwind_calls)]
34#![warn(rustdoc::unescaped_backticks)]
35#![warn(unreachable_pub)]
36
37#[unstable(feature = "proc_macro_internals", issue = "27812")]
38#[doc(hidden)]
39pub mod bridge;
40
41mod diagnostic;
42mod escape;
43mod to_tokens;
44
45use std::ffi::CStr;
46use std::ops::{Range, RangeBounds};
47use std::path::PathBuf;
48use std::str::FromStr;
49use std::{error, fmt};
50
51#[unstable(feature = "proc_macro_diagnostic", issue = "54140")]
52pub use diagnostic::{Diagnostic, Level, MultiSpan};
53#[unstable(feature = "proc_macro_totokens", issue = "130977")]
54pub use to_tokens::ToTokens;
55
56use crate::escape::{EscapeOptions, escape_bytes};
57
58/// Determines whether proc_macro has been made accessible to the currently
59/// running program.
60///
61/// The proc_macro crate is only intended for use inside the implementation of
62/// procedural macros. All the functions in this crate panic if invoked from
63/// outside of a procedural macro, such as from a build script or unit test or
64/// ordinary Rust binary.
65///
66/// With consideration for Rust libraries that are designed to support both
67/// macro and non-macro use cases, `proc_macro::is_available()` provides a
68/// non-panicking way to detect whether the infrastructure required to use the
69/// API of proc_macro is presently available. Returns true if invoked from
70/// inside of a procedural macro, false if invoked from any other binary.
71#[stable(feature = "proc_macro_is_available", since = "1.57.0")]
72pub fn is_available() -> bool {
73    bridge::client::is_available()
74}
75
76/// The main type provided by this crate, representing an abstract stream of
77/// tokens, or, more specifically, a sequence of token trees.
78/// The type provides interfaces for iterating over those token trees and, conversely,
79/// collecting a number of token trees into one stream.
80///
81/// This is both the input and output of `#[proc_macro]`, `#[proc_macro_attribute]`
82/// and `#[proc_macro_derive]` definitions.
83#[rustc_diagnostic_item = "TokenStream"]
84#[stable(feature = "proc_macro_lib", since = "1.15.0")]
85#[derive(Clone)]
86pub struct TokenStream(Option<bridge::client::TokenStream>);
87
88#[stable(feature = "proc_macro_lib", since = "1.15.0")]
89impl !Send for TokenStream {}
90#[stable(feature = "proc_macro_lib", since = "1.15.0")]
91impl !Sync for TokenStream {}
92
93/// Error returned from `TokenStream::from_str`.
94#[stable(feature = "proc_macro_lib", since = "1.15.0")]
95#[non_exhaustive]
96#[derive(Debug)]
97pub struct LexError;
98
99#[stable(feature = "proc_macro_lexerror_impls", since = "1.44.0")]
100impl fmt::Display for LexError {
101    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
102        f.write_str("cannot parse string into token stream")
103    }
104}
105
106#[stable(feature = "proc_macro_lexerror_impls", since = "1.44.0")]
107impl error::Error for LexError {}
108
109#[stable(feature = "proc_macro_lib", since = "1.15.0")]
110impl !Send for LexError {}
111#[stable(feature = "proc_macro_lib", since = "1.15.0")]
112impl !Sync for LexError {}
113
114/// Error returned from `TokenStream::expand_expr`.
115#[unstable(feature = "proc_macro_expand", issue = "90765")]
116#[non_exhaustive]
117#[derive(Debug)]
118pub struct ExpandError;
119
120#[unstable(feature = "proc_macro_expand", issue = "90765")]
121impl fmt::Display for ExpandError {
122    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
123        f.write_str("macro expansion failed")
124    }
125}
126
127#[unstable(feature = "proc_macro_expand", issue = "90765")]
128impl error::Error for ExpandError {}
129
130#[unstable(feature = "proc_macro_expand", issue = "90765")]
131impl !Send for ExpandError {}
132
133#[unstable(feature = "proc_macro_expand", issue = "90765")]
134impl !Sync for ExpandError {}
135
136impl TokenStream {
137    /// Returns an empty `TokenStream` containing no token trees.
138    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
139    pub fn new() -> TokenStream {
140        TokenStream(None)
141    }
142
143    /// Checks if this `TokenStream` is empty.
144    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
145    pub fn is_empty(&self) -> bool {
146        self.0.as_ref().map(|h| h.is_empty()).unwrap_or(true)
147    }
148
149    /// Parses this `TokenStream` as an expression and attempts to expand any
150    /// macros within it. Returns the expanded `TokenStream`.
151    ///
152    /// Currently only expressions expanding to literals will succeed, although
153    /// this may be relaxed in the future.
154    ///
155    /// NOTE: In error conditions, `expand_expr` may leave macros unexpanded,
156    /// report an error, failing compilation, and/or return an `Err(..)`. The
157    /// specific behavior for any error condition, and what conditions are
158    /// considered errors, is unspecified and may change in the future.
159    #[unstable(feature = "proc_macro_expand", issue = "90765")]
160    pub fn expand_expr(&self) -> Result<TokenStream, ExpandError> {
161        let stream = self.0.as_ref().ok_or(ExpandError)?;
162        match bridge::client::TokenStream::expand_expr(stream) {
163            Ok(stream) => Ok(TokenStream(Some(stream))),
164            Err(_) => Err(ExpandError),
165        }
166    }
167}
168
169/// Attempts to break the string into tokens and parse those tokens into a token stream.
170/// May fail for a number of reasons, for example, if the string contains unbalanced delimiters
171/// or characters not existing in the language.
172/// All tokens in the parsed stream get `Span::call_site()` spans.
173///
174/// NOTE: some errors may cause panics instead of returning `LexError`. We reserve the right to
175/// change these errors into `LexError`s later.
176#[stable(feature = "proc_macro_lib", since = "1.15.0")]
177impl FromStr for TokenStream {
178    type Err = LexError;
179
180    fn from_str(src: &str) -> Result<TokenStream, LexError> {
181        Ok(TokenStream(Some(bridge::client::TokenStream::from_str(src))))
182    }
183}
184
185/// Prints the token stream as a string that is supposed to be losslessly convertible back
186/// into the same token stream (modulo spans), except for possibly `TokenTree::Group`s
187/// with `Delimiter::None` delimiters and negative numeric literals.
188///
189/// Note: the exact form of the output is subject to change, e.g. there might
190/// be changes in the whitespace used between tokens. Therefore, you should
191/// *not* do any kind of simple substring matching on the output string (as
192/// produced by `to_string`) to implement a proc macro, because that matching
193/// might stop working if such changes happen. Instead, you should work at the
194/// `TokenTree` level, e.g. matching against `TokenTree::Ident`,
195/// `TokenTree::Punct`, or `TokenTree::Literal`.
196#[stable(feature = "proc_macro_lib", since = "1.15.0")]
197impl fmt::Display for TokenStream {
198    #[allow(clippy::recursive_format_impl)] // clippy doesn't see the specialization
199    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
200        match &self.0 {
201            Some(ts) => write!(f, "{}", ts.to_string()),
202            None => Ok(()),
203        }
204    }
205}
206
207/// Prints token in a form convenient for debugging.
208#[stable(feature = "proc_macro_lib", since = "1.15.0")]
209impl fmt::Debug for TokenStream {
210    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
211        f.write_str("TokenStream ")?;
212        f.debug_list().entries(self.clone()).finish()
213    }
214}
215
216#[stable(feature = "proc_macro_token_stream_default", since = "1.45.0")]
217impl Default for TokenStream {
218    fn default() -> Self {
219        TokenStream::new()
220    }
221}
222
223#[unstable(feature = "proc_macro_quote", issue = "54722")]
224pub use quote::{quote, quote_span};
225
226fn tree_to_bridge_tree(
227    tree: TokenTree,
228) -> bridge::TokenTree<bridge::client::TokenStream, bridge::client::Span, bridge::client::Symbol> {
229    match tree {
230        TokenTree::Group(tt) => bridge::TokenTree::Group(tt.0),
231        TokenTree::Punct(tt) => bridge::TokenTree::Punct(tt.0),
232        TokenTree::Ident(tt) => bridge::TokenTree::Ident(tt.0),
233        TokenTree::Literal(tt) => bridge::TokenTree::Literal(tt.0),
234    }
235}
236
237/// Creates a token stream containing a single token tree.
238#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
239impl From<TokenTree> for TokenStream {
240    fn from(tree: TokenTree) -> TokenStream {
241        TokenStream(Some(bridge::client::TokenStream::from_token_tree(tree_to_bridge_tree(tree))))
242    }
243}
244
245/// Non-generic helper for implementing `FromIterator<TokenTree>` and
246/// `Extend<TokenTree>` with less monomorphization in calling crates.
247struct ConcatTreesHelper {
248    trees: Vec<
249        bridge::TokenTree<
250            bridge::client::TokenStream,
251            bridge::client::Span,
252            bridge::client::Symbol,
253        >,
254    >,
255}
256
257impl ConcatTreesHelper {
258    fn new(capacity: usize) -> Self {
259        ConcatTreesHelper { trees: Vec::with_capacity(capacity) }
260    }
261
262    fn push(&mut self, tree: TokenTree) {
263        self.trees.push(tree_to_bridge_tree(tree));
264    }
265
266    fn build(self) -> TokenStream {
267        if self.trees.is_empty() {
268            TokenStream(None)
269        } else {
270            TokenStream(Some(bridge::client::TokenStream::concat_trees(None, self.trees)))
271        }
272    }
273
274    fn append_to(self, stream: &mut TokenStream) {
275        if self.trees.is_empty() {
276            return;
277        }
278        stream.0 = Some(bridge::client::TokenStream::concat_trees(stream.0.take(), self.trees))
279    }
280}
281
282/// Non-generic helper for implementing `FromIterator<TokenStream>` and
283/// `Extend<TokenStream>` with less monomorphization in calling crates.
284struct ConcatStreamsHelper {
285    streams: Vec<bridge::client::TokenStream>,
286}
287
288impl ConcatStreamsHelper {
289    fn new(capacity: usize) -> Self {
290        ConcatStreamsHelper { streams: Vec::with_capacity(capacity) }
291    }
292
293    fn push(&mut self, stream: TokenStream) {
294        if let Some(stream) = stream.0 {
295            self.streams.push(stream);
296        }
297    }
298
299    fn build(mut self) -> TokenStream {
300        if self.streams.len() <= 1 {
301            TokenStream(self.streams.pop())
302        } else {
303            TokenStream(Some(bridge::client::TokenStream::concat_streams(None, self.streams)))
304        }
305    }
306
307    fn append_to(mut self, stream: &mut TokenStream) {
308        if self.streams.is_empty() {
309            return;
310        }
311        let base = stream.0.take();
312        if base.is_none() && self.streams.len() == 1 {
313            stream.0 = self.streams.pop();
314        } else {
315            stream.0 = Some(bridge::client::TokenStream::concat_streams(base, self.streams));
316        }
317    }
318}
319
320/// Collects a number of token trees into a single stream.
321#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
322impl FromIterator<TokenTree> for TokenStream {
323    fn from_iter<I: IntoIterator<Item = TokenTree>>(trees: I) -> Self {
324        let iter = trees.into_iter();
325        let mut builder = ConcatTreesHelper::new(iter.size_hint().0);
326        iter.for_each(|tree| builder.push(tree));
327        builder.build()
328    }
329}
330
331/// A "flattening" operation on token streams, collects token trees
332/// from multiple token streams into a single stream.
333#[stable(feature = "proc_macro_lib", since = "1.15.0")]
334impl FromIterator<TokenStream> for TokenStream {
335    fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
336        let iter = streams.into_iter();
337        let mut builder = ConcatStreamsHelper::new(iter.size_hint().0);
338        iter.for_each(|stream| builder.push(stream));
339        builder.build()
340    }
341}
342
343#[stable(feature = "token_stream_extend", since = "1.30.0")]
344impl Extend<TokenTree> for TokenStream {
345    fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, trees: I) {
346        let iter = trees.into_iter();
347        let mut builder = ConcatTreesHelper::new(iter.size_hint().0);
348        iter.for_each(|tree| builder.push(tree));
349        builder.append_to(self);
350    }
351}
352
353#[stable(feature = "token_stream_extend", since = "1.30.0")]
354impl Extend<TokenStream> for TokenStream {
355    fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
356        let iter = streams.into_iter();
357        let mut builder = ConcatStreamsHelper::new(iter.size_hint().0);
358        iter.for_each(|stream| builder.push(stream));
359        builder.append_to(self);
360    }
361}
362
363/// Public implementation details for the `TokenStream` type, such as iterators.
364#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
365pub mod token_stream {
366    use crate::{Group, Ident, Literal, Punct, TokenStream, TokenTree, bridge};
367
368    /// An iterator over `TokenStream`'s `TokenTree`s.
369    /// The iteration is "shallow", e.g., the iterator doesn't recurse into delimited groups,
370    /// and returns whole groups as token trees.
371    #[derive(Clone)]
372    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
373    pub struct IntoIter(
374        std::vec::IntoIter<
375            bridge::TokenTree<
376                bridge::client::TokenStream,
377                bridge::client::Span,
378                bridge::client::Symbol,
379            >,
380        >,
381    );
382
383    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
384    impl Iterator for IntoIter {
385        type Item = TokenTree;
386
387        fn next(&mut self) -> Option<TokenTree> {
388            self.0.next().map(|tree| match tree {
389                bridge::TokenTree::Group(tt) => TokenTree::Group(Group(tt)),
390                bridge::TokenTree::Punct(tt) => TokenTree::Punct(Punct(tt)),
391                bridge::TokenTree::Ident(tt) => TokenTree::Ident(Ident(tt)),
392                bridge::TokenTree::Literal(tt) => TokenTree::Literal(Literal(tt)),
393            })
394        }
395
396        fn size_hint(&self) -> (usize, Option<usize>) {
397            self.0.size_hint()
398        }
399
400        fn count(self) -> usize {
401            self.0.count()
402        }
403    }
404
405    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
406    impl IntoIterator for TokenStream {
407        type Item = TokenTree;
408        type IntoIter = IntoIter;
409
410        fn into_iter(self) -> IntoIter {
411            IntoIter(self.0.map(|v| v.into_trees()).unwrap_or_default().into_iter())
412        }
413    }
414}
415
416/// `quote!(..)` accepts arbitrary tokens and expands into a `TokenStream` describing the input.
417/// For example, `quote!(a + b)` will produce an expression, that, when evaluated, constructs
418/// the `TokenStream` `[Ident("a"), Punct('+', Alone), Ident("b")]`.
419///
420/// Unquoting is done with `$`, and works by taking the single next ident as the unquoted term.
421/// To quote `$` itself, use `$$`.
422#[unstable(feature = "proc_macro_quote", issue = "54722")]
423#[allow_internal_unstable(proc_macro_def_site, proc_macro_internals, proc_macro_totokens)]
424#[rustc_builtin_macro]
425pub macro quote($($t:tt)*) {
426    /* compiler built-in */
427}
428
429#[unstable(feature = "proc_macro_internals", issue = "27812")]
430#[doc(hidden)]
431mod quote;
432
433/// A region of source code, along with macro expansion information.
434#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
435#[derive(Copy, Clone)]
436pub struct Span(bridge::client::Span);
437
438#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
439impl !Send for Span {}
440#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
441impl !Sync for Span {}
442
443macro_rules! diagnostic_method {
444    ($name:ident, $level:expr) => {
445        /// Creates a new `Diagnostic` with the given `message` at the span
446        /// `self`.
447        #[unstable(feature = "proc_macro_diagnostic", issue = "54140")]
448        pub fn $name<T: Into<String>>(self, message: T) -> Diagnostic {
449            Diagnostic::spanned(self, $level, message)
450        }
451    };
452}
453
454impl Span {
455    /// A span that resolves at the macro definition site.
456    #[unstable(feature = "proc_macro_def_site", issue = "54724")]
457    pub fn def_site() -> Span {
458        Span(bridge::client::Span::def_site())
459    }
460
461    /// The span of the invocation of the current procedural macro.
462    /// Identifiers created with this span will be resolved as if they were written
463    /// directly at the macro call location (call-site hygiene) and other code
464    /// at the macro call site will be able to refer to them as well.
465    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
466    pub fn call_site() -> Span {
467        Span(bridge::client::Span::call_site())
468    }
469
470    /// A span that represents `macro_rules` hygiene, and sometimes resolves at the macro
471    /// definition site (local variables, labels, `$crate`) and sometimes at the macro
472    /// call site (everything else).
473    /// The span location is taken from the call-site.
474    #[stable(feature = "proc_macro_mixed_site", since = "1.45.0")]
475    pub fn mixed_site() -> Span {
476        Span(bridge::client::Span::mixed_site())
477    }
478
479    /// The original source file into which this span points.
480    #[unstable(feature = "proc_macro_span", issue = "54725")]
481    pub fn source_file(&self) -> SourceFile {
482        SourceFile(self.0.source_file())
483    }
484
485    /// The `Span` for the tokens in the previous macro expansion from which
486    /// `self` was generated from, if any.
487    #[unstable(feature = "proc_macro_span", issue = "54725")]
488    pub fn parent(&self) -> Option<Span> {
489        self.0.parent().map(Span)
490    }
491
492    /// The span for the origin source code that `self` was generated from. If
493    /// this `Span` wasn't generated from other macro expansions then the return
494    /// value is the same as `*self`.
495    #[unstable(feature = "proc_macro_span", issue = "54725")]
496    pub fn source(&self) -> Span {
497        Span(self.0.source())
498    }
499
500    /// Returns the span's byte position range in the source file.
501    #[unstable(feature = "proc_macro_span", issue = "54725")]
502    pub fn byte_range(&self) -> Range<usize> {
503        self.0.byte_range()
504    }
505
506    /// Creates an empty span pointing to directly before this span.
507    #[unstable(feature = "proc_macro_span", issue = "54725")]
508    pub fn start(&self) -> Span {
509        Span(self.0.start())
510    }
511
512    /// Creates an empty span pointing to directly after this span.
513    #[unstable(feature = "proc_macro_span", issue = "54725")]
514    pub fn end(&self) -> Span {
515        Span(self.0.end())
516    }
517
518    /// The one-indexed line of the source file where the span starts.
519    ///
520    /// To obtain the line of the span's end, use `span.end().line()`.
521    #[unstable(feature = "proc_macro_span", issue = "54725")]
522    pub fn line(&self) -> usize {
523        self.0.line()
524    }
525
526    /// The one-indexed column of the source file where the span starts.
527    ///
528    /// To obtain the column of the span's end, use `span.end().column()`.
529    #[unstable(feature = "proc_macro_span", issue = "54725")]
530    pub fn column(&self) -> usize {
531        self.0.column()
532    }
533
534    /// Creates a new span encompassing `self` and `other`.
535    ///
536    /// Returns `None` if `self` and `other` are from different files.
537    #[unstable(feature = "proc_macro_span", issue = "54725")]
538    pub fn join(&self, other: Span) -> Option<Span> {
539        self.0.join(other.0).map(Span)
540    }
541
542    /// Creates a new span with the same line/column information as `self` but
543    /// that resolves symbols as though it were at `other`.
544    #[stable(feature = "proc_macro_span_resolved_at", since = "1.45.0")]
545    pub fn resolved_at(&self, other: Span) -> Span {
546        Span(self.0.resolved_at(other.0))
547    }
548
549    /// Creates a new span with the same name resolution behavior as `self` but
550    /// with the line/column information of `other`.
551    #[stable(feature = "proc_macro_span_located_at", since = "1.45.0")]
552    pub fn located_at(&self, other: Span) -> Span {
553        other.resolved_at(*self)
554    }
555
556    /// Compares two spans to see if they're equal.
557    #[unstable(feature = "proc_macro_span", issue = "54725")]
558    pub fn eq(&self, other: &Span) -> bool {
559        self.0 == other.0
560    }
561
562    /// Returns the source text behind a span. This preserves the original source
563    /// code, including spaces and comments. It only returns a result if the span
564    /// corresponds to real source code.
565    ///
566    /// Note: The observable result of a macro should only rely on the tokens and
567    /// not on this source text. The result of this function is a best effort to
568    /// be used for diagnostics only.
569    #[stable(feature = "proc_macro_source_text", since = "1.66.0")]
570    pub fn source_text(&self) -> Option<String> {
571        self.0.source_text()
572    }
573
574    // Used by the implementation of `Span::quote`
575    #[doc(hidden)]
576    #[unstable(feature = "proc_macro_internals", issue = "27812")]
577    pub fn save_span(&self) -> usize {
578        self.0.save_span()
579    }
580
581    // Used by the implementation of `Span::quote`
582    #[doc(hidden)]
583    #[unstable(feature = "proc_macro_internals", issue = "27812")]
584    pub fn recover_proc_macro_span(id: usize) -> Span {
585        Span(bridge::client::Span::recover_proc_macro_span(id))
586    }
587
588    diagnostic_method!(error, Level::Error);
589    diagnostic_method!(warning, Level::Warning);
590    diagnostic_method!(note, Level::Note);
591    diagnostic_method!(help, Level::Help);
592}
593
594/// Prints a span in a form convenient for debugging.
595#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
596impl fmt::Debug for Span {
597    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
598        self.0.fmt(f)
599    }
600}
601
602/// The source file of a given `Span`.
603#[unstable(feature = "proc_macro_span", issue = "54725")]
604#[derive(Clone)]
605pub struct SourceFile(bridge::client::SourceFile);
606
607impl SourceFile {
608    /// Gets the path to this source file.
609    ///
610    /// ### Note
611    /// If the code span associated with this `SourceFile` was generated by an external macro, this
612    /// macro, this might not be an actual path on the filesystem. Use [`is_real`] to check.
613    ///
614    /// Also note that even if `is_real` returns `true`, if `--remap-path-prefix` was passed on
615    /// the command line, the path as given might not actually be valid.
616    ///
617    /// [`is_real`]: Self::is_real
618    #[unstable(feature = "proc_macro_span", issue = "54725")]
619    pub fn path(&self) -> PathBuf {
620        PathBuf::from(self.0.path())
621    }
622
623    /// Returns `true` if this source file is a real source file, and not generated by an external
624    /// macro's expansion.
625    #[unstable(feature = "proc_macro_span", issue = "54725")]
626    pub fn is_real(&self) -> bool {
627        // This is a hack until intercrate spans are implemented and we can have real source files
628        // for spans generated in external macros.
629        // https://github.com/rust-lang/rust/pull/43604#issuecomment-333334368
630        self.0.is_real()
631    }
632}
633
634#[unstable(feature = "proc_macro_span", issue = "54725")]
635impl fmt::Debug for SourceFile {
636    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
637        f.debug_struct("SourceFile")
638            .field("path", &self.path())
639            .field("is_real", &self.is_real())
640            .finish()
641    }
642}
643
644#[unstable(feature = "proc_macro_span", issue = "54725")]
645impl PartialEq for SourceFile {
646    fn eq(&self, other: &Self) -> bool {
647        self.0.eq(&other.0)
648    }
649}
650
651#[unstable(feature = "proc_macro_span", issue = "54725")]
652impl Eq for SourceFile {}
653
654/// A single token or a delimited sequence of token trees (e.g., `[1, (), ..]`).
655#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
656#[derive(Clone)]
657pub enum TokenTree {
658    /// A token stream surrounded by bracket delimiters.
659    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
660    Group(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Group),
661    /// An identifier.
662    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
663    Ident(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Ident),
664    /// A single punctuation character (`+`, `,`, `$`, etc.).
665    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
666    Punct(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Punct),
667    /// A literal character (`'a'`), string (`"hello"`), number (`2.3`), etc.
668    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
669    Literal(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Literal),
670}
671
672#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
673impl !Send for TokenTree {}
674#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
675impl !Sync for TokenTree {}
676
677impl TokenTree {
678    /// Returns the span of this tree, delegating to the `span` method of
679    /// the contained token or a delimited stream.
680    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
681    pub fn span(&self) -> Span {
682        match *self {
683            TokenTree::Group(ref t) => t.span(),
684            TokenTree::Ident(ref t) => t.span(),
685            TokenTree::Punct(ref t) => t.span(),
686            TokenTree::Literal(ref t) => t.span(),
687        }
688    }
689
690    /// Configures the span for *only this token*.
691    ///
692    /// Note that if this token is a `Group` then this method will not configure
693    /// the span of each of the internal tokens, this will simply delegate to
694    /// the `set_span` method of each variant.
695    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
696    pub fn set_span(&mut self, span: Span) {
697        match *self {
698            TokenTree::Group(ref mut t) => t.set_span(span),
699            TokenTree::Ident(ref mut t) => t.set_span(span),
700            TokenTree::Punct(ref mut t) => t.set_span(span),
701            TokenTree::Literal(ref mut t) => t.set_span(span),
702        }
703    }
704}
705
706/// Prints token tree in a form convenient for debugging.
707#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
708impl fmt::Debug for TokenTree {
709    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
710        // Each of these has the name in the struct type in the derived debug,
711        // so don't bother with an extra layer of indirection
712        match *self {
713            TokenTree::Group(ref tt) => tt.fmt(f),
714            TokenTree::Ident(ref tt) => tt.fmt(f),
715            TokenTree::Punct(ref tt) => tt.fmt(f),
716            TokenTree::Literal(ref tt) => tt.fmt(f),
717        }
718    }
719}
720
721#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
722impl From<Group> for TokenTree {
723    fn from(g: Group) -> TokenTree {
724        TokenTree::Group(g)
725    }
726}
727
728#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
729impl From<Ident> for TokenTree {
730    fn from(g: Ident) -> TokenTree {
731        TokenTree::Ident(g)
732    }
733}
734
735#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
736impl From<Punct> for TokenTree {
737    fn from(g: Punct) -> TokenTree {
738        TokenTree::Punct(g)
739    }
740}
741
742#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
743impl From<Literal> for TokenTree {
744    fn from(g: Literal) -> TokenTree {
745        TokenTree::Literal(g)
746    }
747}
748
749/// Prints the token tree as a string that is supposed to be losslessly convertible back
750/// into the same token tree (modulo spans), except for possibly `TokenTree::Group`s
751/// with `Delimiter::None` delimiters and negative numeric literals.
752///
753/// Note: the exact form of the output is subject to change, e.g. there might
754/// be changes in the whitespace used between tokens. Therefore, you should
755/// *not* do any kind of simple substring matching on the output string (as
756/// produced by `to_string`) to implement a proc macro, because that matching
757/// might stop working if such changes happen. Instead, you should work at the
758/// `TokenTree` level, e.g. matching against `TokenTree::Ident`,
759/// `TokenTree::Punct`, or `TokenTree::Literal`.
760#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
761impl fmt::Display for TokenTree {
762    #[allow(clippy::recursive_format_impl)] // clippy doesn't see the specialization
763    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
764        match self {
765            TokenTree::Group(t) => write!(f, "{t}"),
766            TokenTree::Ident(t) => write!(f, "{t}"),
767            TokenTree::Punct(t) => write!(f, "{t}"),
768            TokenTree::Literal(t) => write!(f, "{t}"),
769        }
770    }
771}
772
773/// A delimited token stream.
774///
775/// A `Group` internally contains a `TokenStream` which is surrounded by `Delimiter`s.
776#[derive(Clone)]
777#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
778pub struct Group(bridge::Group<bridge::client::TokenStream, bridge::client::Span>);
779
780#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
781impl !Send for Group {}
782#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
783impl !Sync for Group {}
784
785/// Describes how a sequence of token trees is delimited.
786#[derive(Copy, Clone, Debug, PartialEq, Eq)]
787#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
788pub enum Delimiter {
789    /// `( ... )`
790    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
791    Parenthesis,
792    /// `{ ... }`
793    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
794    Brace,
795    /// `[ ... ]`
796    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
797    Bracket,
798    /// `∅ ... ∅`
799    /// An invisible delimiter, that may, for example, appear around tokens coming from a
800    /// "macro variable" `$var`. It is important to preserve operator priorities in cases like
801    /// `$var * 3` where `$var` is `1 + 2`.
802    /// Invisible delimiters might not survive roundtrip of a token stream through a string.
803    ///
804    /// <div class="warning">
805    ///
806    /// Note: rustc currently can ignore the grouping of tokens delimited by `None` in the output
807    /// of a proc_macro. Only `None`-delimited groups created by a macro_rules macro in the input
808    /// of a proc_macro macro are preserved, and only in very specific circumstances.
809    /// Any `None`-delimited groups (re)created by a proc_macro will therefore not preserve
810    /// operator priorities as indicated above. The other `Delimiter` variants should be used
811    /// instead in this context. This is a rustc bug. For details, see
812    /// [rust-lang/rust#67062](https://github.com/rust-lang/rust/issues/67062).
813    ///
814    /// </div>
815    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
816    None,
817}
818
819impl Group {
820    /// Creates a new `Group` with the given delimiter and token stream.
821    ///
822    /// This constructor will set the span for this group to
823    /// `Span::call_site()`. To change the span you can use the `set_span`
824    /// method below.
825    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
826    pub fn new(delimiter: Delimiter, stream: TokenStream) -> Group {
827        Group(bridge::Group {
828            delimiter,
829            stream: stream.0,
830            span: bridge::DelimSpan::from_single(Span::call_site().0),
831        })
832    }
833
834    /// Returns the delimiter of this `Group`
835    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
836    pub fn delimiter(&self) -> Delimiter {
837        self.0.delimiter
838    }
839
840    /// Returns the `TokenStream` of tokens that are delimited in this `Group`.
841    ///
842    /// Note that the returned token stream does not include the delimiter
843    /// returned above.
844    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
845    pub fn stream(&self) -> TokenStream {
846        TokenStream(self.0.stream.clone())
847    }
848
849    /// Returns the span for the delimiters of this token stream, spanning the
850    /// entire `Group`.
851    ///
852    /// ```text
853    /// pub fn span(&self) -> Span {
854    ///            ^^^^^^^
855    /// ```
856    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
857    pub fn span(&self) -> Span {
858        Span(self.0.span.entire)
859    }
860
861    /// Returns the span pointing to the opening delimiter of this group.
862    ///
863    /// ```text
864    /// pub fn span_open(&self) -> Span {
865    ///                 ^
866    /// ```
867    #[stable(feature = "proc_macro_group_span", since = "1.55.0")]
868    pub fn span_open(&self) -> Span {
869        Span(self.0.span.open)
870    }
871
872    /// Returns the span pointing to the closing delimiter of this group.
873    ///
874    /// ```text
875    /// pub fn span_close(&self) -> Span {
876    ///                        ^
877    /// ```
878    #[stable(feature = "proc_macro_group_span", since = "1.55.0")]
879    pub fn span_close(&self) -> Span {
880        Span(self.0.span.close)
881    }
882
883    /// Configures the span for this `Group`'s delimiters, but not its internal
884    /// tokens.
885    ///
886    /// This method will **not** set the span of all the internal tokens spanned
887    /// by this group, but rather it will only set the span of the delimiter
888    /// tokens at the level of the `Group`.
889    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
890    pub fn set_span(&mut self, span: Span) {
891        self.0.span = bridge::DelimSpan::from_single(span.0);
892    }
893}
894
895/// Prints the group as a string that should be losslessly convertible back
896/// into the same group (modulo spans), except for possibly `TokenTree::Group`s
897/// with `Delimiter::None` delimiters.
898#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
899impl fmt::Display for Group {
900    #[allow(clippy::recursive_format_impl)] // clippy doesn't see the specialization
901    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
902        write!(f, "{}", TokenStream::from(TokenTree::from(self.clone())))
903    }
904}
905
906#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
907impl fmt::Debug for Group {
908    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
909        f.debug_struct("Group")
910            .field("delimiter", &self.delimiter())
911            .field("stream", &self.stream())
912            .field("span", &self.span())
913            .finish()
914    }
915}
916
917/// A `Punct` is a single punctuation character such as `+`, `-` or `#`.
918///
919/// Multi-character operators like `+=` are represented as two instances of `Punct` with different
920/// forms of `Spacing` returned.
921#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
922#[derive(Clone)]
923pub struct Punct(bridge::Punct<bridge::client::Span>);
924
925#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
926impl !Send for Punct {}
927#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
928impl !Sync for Punct {}
929
930/// Indicates whether a `Punct` token can join with the following token
931/// to form a multi-character operator.
932#[derive(Copy, Clone, Debug, PartialEq, Eq)]
933#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
934pub enum Spacing {
935    /// A `Punct` token can join with the following token to form a multi-character operator.
936    ///
937    /// In token streams constructed using proc macro interfaces, `Joint` punctuation tokens can be
938    /// followed by any other tokens. However, in token streams parsed from source code, the
939    /// compiler will only set spacing to `Joint` in the following cases.
940    /// - When a `Punct` is immediately followed by another `Punct` without a whitespace. E.g. `+`
941    ///   is `Joint` in `+=` and `++`.
942    /// - When a single quote `'` is immediately followed by an identifier without a whitespace.
943    ///   E.g. `'` is `Joint` in `'lifetime`.
944    ///
945    /// This list may be extended in the future to enable more token combinations.
946    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
947    Joint,
948    /// A `Punct` token cannot join with the following token to form a multi-character operator.
949    ///
950    /// `Alone` punctuation tokens can be followed by any other tokens. In token streams parsed
951    /// from source code, the compiler will set spacing to `Alone` in all cases not covered by the
952    /// conditions for `Joint` above. E.g. `+` is `Alone` in `+ =`, `+ident` and `+()`. In
953    /// particular, tokens not followed by anything will be marked as `Alone`.
954    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
955    Alone,
956}
957
958impl Punct {
959    /// Creates a new `Punct` from the given character and spacing.
960    /// The `ch` argument must be a valid punctuation character permitted by the language,
961    /// otherwise the function will panic.
962    ///
963    /// The returned `Punct` will have the default span of `Span::call_site()`
964    /// which can be further configured with the `set_span` method below.
965    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
966    pub fn new(ch: char, spacing: Spacing) -> Punct {
967        const LEGAL_CHARS: &[char] = &[
968            '=', '<', '>', '!', '~', '+', '-', '*', '/', '%', '^', '&', '|', '@', '.', ',', ';',
969            ':', '#', '$', '?', '\'',
970        ];
971        if !LEGAL_CHARS.contains(&ch) {
972            panic!("unsupported character `{:?}`", ch);
973        }
974        Punct(bridge::Punct {
975            ch: ch as u8,
976            joint: spacing == Spacing::Joint,
977            span: Span::call_site().0,
978        })
979    }
980
981    /// Returns the value of this punctuation character as `char`.
982    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
983    pub fn as_char(&self) -> char {
984        self.0.ch as char
985    }
986
987    /// Returns the spacing of this punctuation character, indicating whether it can be potentially
988    /// combined into a multi-character operator with the following token (`Joint`), or whether the
989    /// operator has definitely ended (`Alone`).
990    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
991    pub fn spacing(&self) -> Spacing {
992        if self.0.joint { Spacing::Joint } else { Spacing::Alone }
993    }
994
995    /// Returns the span for this punctuation character.
996    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
997    pub fn span(&self) -> Span {
998        Span(self.0.span)
999    }
1000
1001    /// Configure the span for this punctuation character.
1002    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1003    pub fn set_span(&mut self, span: Span) {
1004        self.0.span = span.0;
1005    }
1006}
1007
1008/// Prints the punctuation character as a string that should be losslessly convertible
1009/// back into the same character.
1010#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1011impl fmt::Display for Punct {
1012    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1013        write!(f, "{}", self.as_char())
1014    }
1015}
1016
1017#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1018impl fmt::Debug for Punct {
1019    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1020        f.debug_struct("Punct")
1021            .field("ch", &self.as_char())
1022            .field("spacing", &self.spacing())
1023            .field("span", &self.span())
1024            .finish()
1025    }
1026}
1027
1028#[stable(feature = "proc_macro_punct_eq", since = "1.50.0")]
1029impl PartialEq<char> for Punct {
1030    fn eq(&self, rhs: &char) -> bool {
1031        self.as_char() == *rhs
1032    }
1033}
1034
1035#[stable(feature = "proc_macro_punct_eq_flipped", since = "1.52.0")]
1036impl PartialEq<Punct> for char {
1037    fn eq(&self, rhs: &Punct) -> bool {
1038        *self == rhs.as_char()
1039    }
1040}
1041
1042/// An identifier (`ident`).
1043#[derive(Clone)]
1044#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1045pub struct Ident(bridge::Ident<bridge::client::Span, bridge::client::Symbol>);
1046
1047impl Ident {
1048    /// Creates a new `Ident` with the given `string` as well as the specified
1049    /// `span`.
1050    /// The `string` argument must be a valid identifier permitted by the
1051    /// language (including keywords, e.g. `self` or `fn`). Otherwise, the function will panic.
1052    ///
1053    /// Note that `span`, currently in rustc, configures the hygiene information
1054    /// for this identifier.
1055    ///
1056    /// As of this time `Span::call_site()` explicitly opts-in to "call-site" hygiene
1057    /// meaning that identifiers created with this span will be resolved as if they were written
1058    /// directly at the location of the macro call, and other code at the macro call site will be
1059    /// able to refer to them as well.
1060    ///
1061    /// Later spans like `Span::def_site()` will allow to opt-in to "definition-site" hygiene
1062    /// meaning that identifiers created with this span will be resolved at the location of the
1063    /// macro definition and other code at the macro call site will not be able to refer to them.
1064    ///
1065    /// Due to the current importance of hygiene this constructor, unlike other
1066    /// tokens, requires a `Span` to be specified at construction.
1067    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1068    pub fn new(string: &str, span: Span) -> Ident {
1069        Ident(bridge::Ident {
1070            sym: bridge::client::Symbol::new_ident(string, false),
1071            is_raw: false,
1072            span: span.0,
1073        })
1074    }
1075
1076    /// Same as `Ident::new`, but creates a raw identifier (`r#ident`).
1077    /// The `string` argument be a valid identifier permitted by the language
1078    /// (including keywords, e.g. `fn`). Keywords which are usable in path segments
1079    /// (e.g. `self`, `super`) are not supported, and will cause a panic.
1080    #[stable(feature = "proc_macro_raw_ident", since = "1.47.0")]
1081    pub fn new_raw(string: &str, span: Span) -> Ident {
1082        Ident(bridge::Ident {
1083            sym: bridge::client::Symbol::new_ident(string, true),
1084            is_raw: true,
1085            span: span.0,
1086        })
1087    }
1088
1089    /// Returns the span of this `Ident`, encompassing the entire string returned
1090    /// by [`to_string`](ToString::to_string).
1091    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1092    pub fn span(&self) -> Span {
1093        Span(self.0.span)
1094    }
1095
1096    /// Configures the span of this `Ident`, possibly changing its hygiene context.
1097    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1098    pub fn set_span(&mut self, span: Span) {
1099        self.0.span = span.0;
1100    }
1101}
1102
1103/// Prints the identifier as a string that should be losslessly convertible back
1104/// into the same identifier.
1105#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1106impl fmt::Display for Ident {
1107    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1108        if self.0.is_raw {
1109            f.write_str("r#")?;
1110        }
1111        fmt::Display::fmt(&self.0.sym, f)
1112    }
1113}
1114
1115#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1116impl fmt::Debug for Ident {
1117    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1118        f.debug_struct("Ident")
1119            .field("ident", &self.to_string())
1120            .field("span", &self.span())
1121            .finish()
1122    }
1123}
1124
1125/// A literal string (`"hello"`), byte string (`b"hello"`), C string (`c"hello"`),
1126/// character (`'a'`), byte character (`b'a'`), an integer or floating point number
1127/// with or without a suffix (`1`, `1u8`, `2.3`, `2.3f32`).
1128/// Boolean literals like `true` and `false` do not belong here, they are `Ident`s.
1129#[derive(Clone)]
1130#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1131pub struct Literal(bridge::Literal<bridge::client::Span, bridge::client::Symbol>);
1132
1133macro_rules! suffixed_int_literals {
1134    ($($name:ident => $kind:ident,)*) => ($(
1135        /// Creates a new suffixed integer literal with the specified value.
1136        ///
1137        /// This function will create an integer like `1u32` where the integer
1138        /// value specified is the first part of the token and the integral is
1139        /// also suffixed at the end.
1140        /// Literals created from negative numbers might not survive round-trips through
1141        /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1142        ///
1143        /// Literals created through this method have the `Span::call_site()`
1144        /// span by default, which can be configured with the `set_span` method
1145        /// below.
1146        #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1147        pub fn $name(n: $kind) -> Literal {
1148            Literal(bridge::Literal {
1149                kind: bridge::LitKind::Integer,
1150                symbol: bridge::client::Symbol::new(&n.to_string()),
1151                suffix: Some(bridge::client::Symbol::new(stringify!($kind))),
1152                span: Span::call_site().0,
1153            })
1154        }
1155    )*)
1156}
1157
1158macro_rules! unsuffixed_int_literals {
1159    ($($name:ident => $kind:ident,)*) => ($(
1160        /// Creates a new unsuffixed integer literal with the specified value.
1161        ///
1162        /// This function will create an integer like `1` where the integer
1163        /// value specified is the first part of the token. No suffix is
1164        /// specified on this token, meaning that invocations like
1165        /// `Literal::i8_unsuffixed(1)` are equivalent to
1166        /// `Literal::u32_unsuffixed(1)`.
1167        /// Literals created from negative numbers might not survive rountrips through
1168        /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1169        ///
1170        /// Literals created through this method have the `Span::call_site()`
1171        /// span by default, which can be configured with the `set_span` method
1172        /// below.
1173        #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1174        pub fn $name(n: $kind) -> Literal {
1175            Literal(bridge::Literal {
1176                kind: bridge::LitKind::Integer,
1177                symbol: bridge::client::Symbol::new(&n.to_string()),
1178                suffix: None,
1179                span: Span::call_site().0,
1180            })
1181        }
1182    )*)
1183}
1184
1185impl Literal {
1186    fn new(kind: bridge::LitKind, value: &str, suffix: Option<&str>) -> Self {
1187        Literal(bridge::Literal {
1188            kind,
1189            symbol: bridge::client::Symbol::new(value),
1190            suffix: suffix.map(bridge::client::Symbol::new),
1191            span: Span::call_site().0,
1192        })
1193    }
1194
1195    suffixed_int_literals! {
1196        u8_suffixed => u8,
1197        u16_suffixed => u16,
1198        u32_suffixed => u32,
1199        u64_suffixed => u64,
1200        u128_suffixed => u128,
1201        usize_suffixed => usize,
1202        i8_suffixed => i8,
1203        i16_suffixed => i16,
1204        i32_suffixed => i32,
1205        i64_suffixed => i64,
1206        i128_suffixed => i128,
1207        isize_suffixed => isize,
1208    }
1209
1210    unsuffixed_int_literals! {
1211        u8_unsuffixed => u8,
1212        u16_unsuffixed => u16,
1213        u32_unsuffixed => u32,
1214        u64_unsuffixed => u64,
1215        u128_unsuffixed => u128,
1216        usize_unsuffixed => usize,
1217        i8_unsuffixed => i8,
1218        i16_unsuffixed => i16,
1219        i32_unsuffixed => i32,
1220        i64_unsuffixed => i64,
1221        i128_unsuffixed => i128,
1222        isize_unsuffixed => isize,
1223    }
1224
1225    /// Creates a new unsuffixed floating-point literal.
1226    ///
1227    /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1228    /// the float's value is emitted directly into the token but no suffix is
1229    /// used, so it may be inferred to be a `f64` later in the compiler.
1230    /// Literals created from negative numbers might not survive rountrips through
1231    /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1232    ///
1233    /// # Panics
1234    ///
1235    /// This function requires that the specified float is finite, for
1236    /// example if it is infinity or NaN this function will panic.
1237    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1238    pub fn f32_unsuffixed(n: f32) -> Literal {
1239        if !n.is_finite() {
1240            panic!("Invalid float literal {n}");
1241        }
1242        let mut repr = n.to_string();
1243        if !repr.contains('.') {
1244            repr.push_str(".0");
1245        }
1246        Literal::new(bridge::LitKind::Float, &repr, None)
1247    }
1248
1249    /// Creates a new suffixed floating-point literal.
1250    ///
1251    /// This constructor will create a literal like `1.0f32` where the value
1252    /// specified is the preceding part of the token and `f32` is the suffix of
1253    /// the token. This token will always be inferred to be an `f32` in the
1254    /// compiler.
1255    /// Literals created from negative numbers might not survive rountrips through
1256    /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1257    ///
1258    /// # Panics
1259    ///
1260    /// This function requires that the specified float is finite, for
1261    /// example if it is infinity or NaN this function will panic.
1262    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1263    pub fn f32_suffixed(n: f32) -> Literal {
1264        if !n.is_finite() {
1265            panic!("Invalid float literal {n}");
1266        }
1267        Literal::new(bridge::LitKind::Float, &n.to_string(), Some("f32"))
1268    }
1269
1270    /// Creates a new unsuffixed floating-point literal.
1271    ///
1272    /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1273    /// the float's value is emitted directly into the token but no suffix is
1274    /// used, so it may be inferred to be a `f64` later in the compiler.
1275    /// Literals created from negative numbers might not survive rountrips through
1276    /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1277    ///
1278    /// # Panics
1279    ///
1280    /// This function requires that the specified float is finite, for
1281    /// example if it is infinity or NaN this function will panic.
1282    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1283    pub fn f64_unsuffixed(n: f64) -> Literal {
1284        if !n.is_finite() {
1285            panic!("Invalid float literal {n}");
1286        }
1287        let mut repr = n.to_string();
1288        if !repr.contains('.') {
1289            repr.push_str(".0");
1290        }
1291        Literal::new(bridge::LitKind::Float, &repr, None)
1292    }
1293
1294    /// Creates a new suffixed floating-point literal.
1295    ///
1296    /// This constructor will create a literal like `1.0f64` where the value
1297    /// specified is the preceding part of the token and `f64` is the suffix of
1298    /// the token. This token will always be inferred to be an `f64` in the
1299    /// compiler.
1300    /// Literals created from negative numbers might not survive rountrips through
1301    /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1302    ///
1303    /// # Panics
1304    ///
1305    /// This function requires that the specified float is finite, for
1306    /// example if it is infinity or NaN this function will panic.
1307    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1308    pub fn f64_suffixed(n: f64) -> Literal {
1309        if !n.is_finite() {
1310            panic!("Invalid float literal {n}");
1311        }
1312        Literal::new(bridge::LitKind::Float, &n.to_string(), Some("f64"))
1313    }
1314
1315    /// String literal.
1316    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1317    pub fn string(string: &str) -> Literal {
1318        let escape = EscapeOptions {
1319            escape_single_quote: false,
1320            escape_double_quote: true,
1321            escape_nonascii: false,
1322        };
1323        let repr = escape_bytes(string.as_bytes(), escape);
1324        Literal::new(bridge::LitKind::Str, &repr, None)
1325    }
1326
1327    /// Character literal.
1328    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1329    pub fn character(ch: char) -> Literal {
1330        let escape = EscapeOptions {
1331            escape_single_quote: true,
1332            escape_double_quote: false,
1333            escape_nonascii: false,
1334        };
1335        let repr = escape_bytes(ch.encode_utf8(&mut [0u8; 4]).as_bytes(), escape);
1336        Literal::new(bridge::LitKind::Char, &repr, None)
1337    }
1338
1339    /// Byte character literal.
1340    #[stable(feature = "proc_macro_byte_character", since = "1.79.0")]
1341    pub fn byte_character(byte: u8) -> Literal {
1342        let escape = EscapeOptions {
1343            escape_single_quote: true,
1344            escape_double_quote: false,
1345            escape_nonascii: true,
1346        };
1347        let repr = escape_bytes(&[byte], escape);
1348        Literal::new(bridge::LitKind::Byte, &repr, None)
1349    }
1350
1351    /// Byte string literal.
1352    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1353    pub fn byte_string(bytes: &[u8]) -> Literal {
1354        let escape = EscapeOptions {
1355            escape_single_quote: false,
1356            escape_double_quote: true,
1357            escape_nonascii: true,
1358        };
1359        let repr = escape_bytes(bytes, escape);
1360        Literal::new(bridge::LitKind::ByteStr, &repr, None)
1361    }
1362
1363    /// C string literal.
1364    #[stable(feature = "proc_macro_c_str_literals", since = "1.79.0")]
1365    pub fn c_string(string: &CStr) -> Literal {
1366        let escape = EscapeOptions {
1367            escape_single_quote: false,
1368            escape_double_quote: true,
1369            escape_nonascii: false,
1370        };
1371        let repr = escape_bytes(string.to_bytes(), escape);
1372        Literal::new(bridge::LitKind::CStr, &repr, None)
1373    }
1374
1375    /// Returns the span encompassing this literal.
1376    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1377    pub fn span(&self) -> Span {
1378        Span(self.0.span)
1379    }
1380
1381    /// Configures the span associated for this literal.
1382    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1383    pub fn set_span(&mut self, span: Span) {
1384        self.0.span = span.0;
1385    }
1386
1387    /// Returns a `Span` that is a subset of `self.span()` containing only the
1388    /// source bytes in range `range`. Returns `None` if the would-be trimmed
1389    /// span is outside the bounds of `self`.
1390    // FIXME(SergioBenitez): check that the byte range starts and ends at a
1391    // UTF-8 boundary of the source. otherwise, it's likely that a panic will
1392    // occur elsewhere when the source text is printed.
1393    // FIXME(SergioBenitez): there is no way for the user to know what
1394    // `self.span()` actually maps to, so this method can currently only be
1395    // called blindly. For example, `to_string()` for the character 'c' returns
1396    // "'\u{63}'"; there is no way for the user to know whether the source text
1397    // was 'c' or whether it was '\u{63}'.
1398    #[unstable(feature = "proc_macro_span", issue = "54725")]
1399    pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
1400        self.0.span.subspan(range.start_bound().cloned(), range.end_bound().cloned()).map(Span)
1401    }
1402
1403    fn with_symbol_and_suffix<R>(&self, f: impl FnOnce(&str, &str) -> R) -> R {
1404        self.0.symbol.with(|symbol| match self.0.suffix {
1405            Some(suffix) => suffix.with(|suffix| f(symbol, suffix)),
1406            None => f(symbol, ""),
1407        })
1408    }
1409
1410    /// Invokes the callback with a `&[&str]` consisting of each part of the
1411    /// literal's representation. This is done to allow the `ToString` and
1412    /// `Display` implementations to borrow references to symbol values, and
1413    /// both be optimized to reduce overhead.
1414    fn with_stringify_parts<R>(&self, f: impl FnOnce(&[&str]) -> R) -> R {
1415        /// Returns a string containing exactly `num` '#' characters.
1416        /// Uses a 256-character source string literal which is always safe to
1417        /// index with a `u8` index.
1418        fn get_hashes_str(num: u8) -> &'static str {
1419            const HASHES: &str = "\
1420            ################################################################\
1421            ################################################################\
1422            ################################################################\
1423            ################################################################\
1424            ";
1425            const _: () = assert!(HASHES.len() == 256);
1426            &HASHES[..num as usize]
1427        }
1428
1429        self.with_symbol_and_suffix(|symbol, suffix| match self.0.kind {
1430            bridge::LitKind::Byte => f(&["b'", symbol, "'", suffix]),
1431            bridge::LitKind::Char => f(&["'", symbol, "'", suffix]),
1432            bridge::LitKind::Str => f(&["\"", symbol, "\"", suffix]),
1433            bridge::LitKind::StrRaw(n) => {
1434                let hashes = get_hashes_str(n);
1435                f(&["r", hashes, "\"", symbol, "\"", hashes, suffix])
1436            }
1437            bridge::LitKind::ByteStr => f(&["b\"", symbol, "\"", suffix]),
1438            bridge::LitKind::ByteStrRaw(n) => {
1439                let hashes = get_hashes_str(n);
1440                f(&["br", hashes, "\"", symbol, "\"", hashes, suffix])
1441            }
1442            bridge::LitKind::CStr => f(&["c\"", symbol, "\"", suffix]),
1443            bridge::LitKind::CStrRaw(n) => {
1444                let hashes = get_hashes_str(n);
1445                f(&["cr", hashes, "\"", symbol, "\"", hashes, suffix])
1446            }
1447
1448            bridge::LitKind::Integer | bridge::LitKind::Float | bridge::LitKind::ErrWithGuar => {
1449                f(&[symbol, suffix])
1450            }
1451        })
1452    }
1453}
1454
1455/// Parse a single literal from its stringified representation.
1456///
1457/// In order to parse successfully, the input string must not contain anything
1458/// but the literal token. Specifically, it must not contain whitespace or
1459/// comments in addition to the literal.
1460///
1461/// The resulting literal token will have a `Span::call_site()` span.
1462///
1463/// NOTE: some errors may cause panics instead of returning `LexError`. We
1464/// reserve the right to change these errors into `LexError`s later.
1465#[stable(feature = "proc_macro_literal_parse", since = "1.54.0")]
1466impl FromStr for Literal {
1467    type Err = LexError;
1468
1469    fn from_str(src: &str) -> Result<Self, LexError> {
1470        match bridge::client::FreeFunctions::literal_from_str(src) {
1471            Ok(literal) => Ok(Literal(literal)),
1472            Err(()) => Err(LexError),
1473        }
1474    }
1475}
1476
1477/// Prints the literal as a string that should be losslessly convertible
1478/// back into the same literal (except for possible rounding for floating point literals).
1479#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1480impl fmt::Display for Literal {
1481    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1482        self.with_stringify_parts(|parts| {
1483            for part in parts {
1484                fmt::Display::fmt(part, f)?;
1485            }
1486            Ok(())
1487        })
1488    }
1489}
1490
1491#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1492impl fmt::Debug for Literal {
1493    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1494        f.debug_struct("Literal")
1495            // format the kind on one line even in {:#?} mode
1496            .field("kind", &format_args!("{:?}", self.0.kind))
1497            .field("symbol", &self.0.symbol)
1498            // format `Some("...")` on one line even in {:#?} mode
1499            .field("suffix", &format_args!("{:?}", self.0.suffix))
1500            .field("span", &self.0.span)
1501            .finish()
1502    }
1503}
1504
1505/// Tracked access to environment variables.
1506#[unstable(feature = "proc_macro_tracked_env", issue = "99515")]
1507pub mod tracked_env {
1508    use std::env::{self, VarError};
1509    use std::ffi::OsStr;
1510
1511    /// Retrieve an environment variable and add it to build dependency info.
1512    /// The build system executing the compiler will know that the variable was accessed during
1513    /// compilation, and will be able to rerun the build when the value of that variable changes.
1514    /// Besides the dependency tracking this function should be equivalent to `env::var` from the
1515    /// standard library, except that the argument must be UTF-8.
1516    #[unstable(feature = "proc_macro_tracked_env", issue = "99515")]
1517    pub fn var<K: AsRef<OsStr> + AsRef<str>>(key: K) -> Result<String, VarError> {
1518        let key: &str = key.as_ref();
1519        let value = crate::bridge::client::FreeFunctions::injected_env_var(key)
1520            .map_or_else(|| env::var(key), Ok);
1521        crate::bridge::client::FreeFunctions::track_env_var(key, value.as_deref().ok());
1522        value
1523    }
1524}
1525
1526/// Tracked access to additional files.
1527#[unstable(feature = "track_path", issue = "99515")]
1528pub mod tracked_path {
1529
1530    /// Track a file explicitly.
1531    ///
1532    /// Commonly used for tracking asset preprocessing.
1533    #[unstable(feature = "track_path", issue = "99515")]
1534    pub fn path<P: AsRef<str>>(path: P) {
1535        let path: &str = path.as_ref();
1536        crate::bridge::client::FreeFunctions::track_path(path);
1537    }
1538}