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(stmt_expr_attributes)]
31#![feature(extend_one)]
32#![recursion_limit = "256"]
33#![allow(internal_features)]
34#![deny(ffi_unwind_calls)]
35#![warn(rustdoc::unescaped_backticks)]
36#![warn(unreachable_pub)]
37#![deny(unsafe_op_in_unsafe_fn)]
38
39#[unstable(feature = "proc_macro_internals", issue = "27812")]
40#[doc(hidden)]
41pub mod bridge;
42
43mod diagnostic;
44mod escape;
45mod to_tokens;
46
47use std::ffi::CStr;
48use std::ops::{Range, RangeBounds};
49use std::path::PathBuf;
50use std::str::FromStr;
51use std::{error, fmt};
52
53#[unstable(feature = "proc_macro_diagnostic", issue = "54140")]
54pub use diagnostic::{Diagnostic, Level, MultiSpan};
55#[unstable(feature = "proc_macro_value", issue = "136652")]
56pub use rustc_literal_escaper::EscapeError;
57use rustc_literal_escaper::{MixedUnit, Mode, byte_from_char, unescape_mixed, unescape_unicode};
58#[unstable(feature = "proc_macro_totokens", issue = "130977")]
59pub use to_tokens::ToTokens;
60
61use crate::escape::{EscapeOptions, escape_bytes};
62
63/// Errors returned when trying to retrieve a literal unescaped value.
64#[unstable(feature = "proc_macro_value", issue = "136652")]
65#[derive(Debug, PartialEq, Eq)]
66pub enum ConversionErrorKind {
67    /// The literal failed to be escaped, take a look at [`EscapeError`] for more information.
68    FailedToUnescape(EscapeError),
69    /// Trying to convert a literal with the wrong type.
70    InvalidLiteralKind,
71}
72
73/// Determines whether proc_macro has been made accessible to the currently
74/// running program.
75///
76/// The proc_macro crate is only intended for use inside the implementation of
77/// procedural macros. All the functions in this crate panic if invoked from
78/// outside of a procedural macro, such as from a build script or unit test or
79/// ordinary Rust binary.
80///
81/// With consideration for Rust libraries that are designed to support both
82/// macro and non-macro use cases, `proc_macro::is_available()` provides a
83/// non-panicking way to detect whether the infrastructure required to use the
84/// API of proc_macro is presently available. Returns true if invoked from
85/// inside of a procedural macro, false if invoked from any other binary.
86#[stable(feature = "proc_macro_is_available", since = "1.57.0")]
87pub fn is_available() -> bool {
88    bridge::client::is_available()
89}
90
91/// The main type provided by this crate, representing an abstract stream of
92/// tokens, or, more specifically, a sequence of token trees.
93/// The type provides interfaces for iterating over those token trees and, conversely,
94/// collecting a number of token trees into one stream.
95///
96/// This is both the input and output of `#[proc_macro]`, `#[proc_macro_attribute]`
97/// and `#[proc_macro_derive]` definitions.
98#[rustc_diagnostic_item = "TokenStream"]
99#[stable(feature = "proc_macro_lib", since = "1.15.0")]
100#[derive(Clone)]
101pub struct TokenStream(Option<bridge::client::TokenStream>);
102
103#[stable(feature = "proc_macro_lib", since = "1.15.0")]
104impl !Send for TokenStream {}
105#[stable(feature = "proc_macro_lib", since = "1.15.0")]
106impl !Sync for TokenStream {}
107
108/// Error returned from `TokenStream::from_str`.
109#[stable(feature = "proc_macro_lib", since = "1.15.0")]
110#[non_exhaustive]
111#[derive(Debug)]
112pub struct LexError;
113
114#[stable(feature = "proc_macro_lexerror_impls", since = "1.44.0")]
115impl fmt::Display for LexError {
116    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
117        f.write_str("cannot parse string into token stream")
118    }
119}
120
121#[stable(feature = "proc_macro_lexerror_impls", since = "1.44.0")]
122impl error::Error for LexError {}
123
124#[stable(feature = "proc_macro_lib", since = "1.15.0")]
125impl !Send for LexError {}
126#[stable(feature = "proc_macro_lib", since = "1.15.0")]
127impl !Sync for LexError {}
128
129/// Error returned from `TokenStream::expand_expr`.
130#[unstable(feature = "proc_macro_expand", issue = "90765")]
131#[non_exhaustive]
132#[derive(Debug)]
133pub struct ExpandError;
134
135#[unstable(feature = "proc_macro_expand", issue = "90765")]
136impl fmt::Display for ExpandError {
137    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
138        f.write_str("macro expansion failed")
139    }
140}
141
142#[unstable(feature = "proc_macro_expand", issue = "90765")]
143impl error::Error for ExpandError {}
144
145#[unstable(feature = "proc_macro_expand", issue = "90765")]
146impl !Send for ExpandError {}
147
148#[unstable(feature = "proc_macro_expand", issue = "90765")]
149impl !Sync for ExpandError {}
150
151impl TokenStream {
152    /// Returns an empty `TokenStream` containing no token trees.
153    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
154    pub fn new() -> TokenStream {
155        TokenStream(None)
156    }
157
158    /// Checks if this `TokenStream` is empty.
159    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
160    pub fn is_empty(&self) -> bool {
161        self.0.as_ref().map(|h| h.is_empty()).unwrap_or(true)
162    }
163
164    /// Parses this `TokenStream` as an expression and attempts to expand any
165    /// macros within it. Returns the expanded `TokenStream`.
166    ///
167    /// Currently only expressions expanding to literals will succeed, although
168    /// this may be relaxed in the future.
169    ///
170    /// NOTE: In error conditions, `expand_expr` may leave macros unexpanded,
171    /// report an error, failing compilation, and/or return an `Err(..)`. The
172    /// specific behavior for any error condition, and what conditions are
173    /// considered errors, is unspecified and may change in the future.
174    #[unstable(feature = "proc_macro_expand", issue = "90765")]
175    pub fn expand_expr(&self) -> Result<TokenStream, ExpandError> {
176        let stream = self.0.as_ref().ok_or(ExpandError)?;
177        match bridge::client::TokenStream::expand_expr(stream) {
178            Ok(stream) => Ok(TokenStream(Some(stream))),
179            Err(_) => Err(ExpandError),
180        }
181    }
182}
183
184/// Attempts to break the string into tokens and parse those tokens into a token stream.
185/// May fail for a number of reasons, for example, if the string contains unbalanced delimiters
186/// or characters not existing in the language.
187/// All tokens in the parsed stream get `Span::call_site()` spans.
188///
189/// NOTE: some errors may cause panics instead of returning `LexError`. We reserve the right to
190/// change these errors into `LexError`s later.
191#[stable(feature = "proc_macro_lib", since = "1.15.0")]
192impl FromStr for TokenStream {
193    type Err = LexError;
194
195    fn from_str(src: &str) -> Result<TokenStream, LexError> {
196        Ok(TokenStream(Some(bridge::client::TokenStream::from_str(src))))
197    }
198}
199
200/// Prints the token stream as a string that is supposed to be losslessly convertible back
201/// into the same token stream (modulo spans), except for possibly `TokenTree::Group`s
202/// with `Delimiter::None` delimiters and negative numeric literals.
203///
204/// Note: the exact form of the output is subject to change, e.g. there might
205/// be changes in the whitespace used between tokens. Therefore, you should
206/// *not* do any kind of simple substring matching on the output string (as
207/// produced by `to_string`) to implement a proc macro, because that matching
208/// might stop working if such changes happen. Instead, you should work at the
209/// `TokenTree` level, e.g. matching against `TokenTree::Ident`,
210/// `TokenTree::Punct`, or `TokenTree::Literal`.
211#[stable(feature = "proc_macro_lib", since = "1.15.0")]
212impl fmt::Display for TokenStream {
213    #[allow(clippy::recursive_format_impl)] // clippy doesn't see the specialization
214    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
215        match &self.0 {
216            Some(ts) => write!(f, "{}", ts.to_string()),
217            None => Ok(()),
218        }
219    }
220}
221
222/// Prints token in a form convenient for debugging.
223#[stable(feature = "proc_macro_lib", since = "1.15.0")]
224impl fmt::Debug for TokenStream {
225    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
226        f.write_str("TokenStream ")?;
227        f.debug_list().entries(self.clone()).finish()
228    }
229}
230
231#[stable(feature = "proc_macro_token_stream_default", since = "1.45.0")]
232impl Default for TokenStream {
233    fn default() -> Self {
234        TokenStream::new()
235    }
236}
237
238#[unstable(feature = "proc_macro_quote", issue = "54722")]
239pub use quote::{quote, quote_span};
240
241fn tree_to_bridge_tree(
242    tree: TokenTree,
243) -> bridge::TokenTree<bridge::client::TokenStream, bridge::client::Span, bridge::client::Symbol> {
244    match tree {
245        TokenTree::Group(tt) => bridge::TokenTree::Group(tt.0),
246        TokenTree::Punct(tt) => bridge::TokenTree::Punct(tt.0),
247        TokenTree::Ident(tt) => bridge::TokenTree::Ident(tt.0),
248        TokenTree::Literal(tt) => bridge::TokenTree::Literal(tt.0),
249    }
250}
251
252/// Creates a token stream containing a single token tree.
253#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
254impl From<TokenTree> for TokenStream {
255    fn from(tree: TokenTree) -> TokenStream {
256        TokenStream(Some(bridge::client::TokenStream::from_token_tree(tree_to_bridge_tree(tree))))
257    }
258}
259
260/// Non-generic helper for implementing `FromIterator<TokenTree>` and
261/// `Extend<TokenTree>` with less monomorphization in calling crates.
262struct ConcatTreesHelper {
263    trees: Vec<
264        bridge::TokenTree<
265            bridge::client::TokenStream,
266            bridge::client::Span,
267            bridge::client::Symbol,
268        >,
269    >,
270}
271
272impl ConcatTreesHelper {
273    fn new(capacity: usize) -> Self {
274        ConcatTreesHelper { trees: Vec::with_capacity(capacity) }
275    }
276
277    fn push(&mut self, tree: TokenTree) {
278        self.trees.push(tree_to_bridge_tree(tree));
279    }
280
281    fn build(self) -> TokenStream {
282        if self.trees.is_empty() {
283            TokenStream(None)
284        } else {
285            TokenStream(Some(bridge::client::TokenStream::concat_trees(None, self.trees)))
286        }
287    }
288
289    fn append_to(self, stream: &mut TokenStream) {
290        if self.trees.is_empty() {
291            return;
292        }
293        stream.0 = Some(bridge::client::TokenStream::concat_trees(stream.0.take(), self.trees))
294    }
295}
296
297/// Non-generic helper for implementing `FromIterator<TokenStream>` and
298/// `Extend<TokenStream>` with less monomorphization in calling crates.
299struct ConcatStreamsHelper {
300    streams: Vec<bridge::client::TokenStream>,
301}
302
303impl ConcatStreamsHelper {
304    fn new(capacity: usize) -> Self {
305        ConcatStreamsHelper { streams: Vec::with_capacity(capacity) }
306    }
307
308    fn push(&mut self, stream: TokenStream) {
309        if let Some(stream) = stream.0 {
310            self.streams.push(stream);
311        }
312    }
313
314    fn build(mut self) -> TokenStream {
315        if self.streams.len() <= 1 {
316            TokenStream(self.streams.pop())
317        } else {
318            TokenStream(Some(bridge::client::TokenStream::concat_streams(None, self.streams)))
319        }
320    }
321
322    fn append_to(mut self, stream: &mut TokenStream) {
323        if self.streams.is_empty() {
324            return;
325        }
326        let base = stream.0.take();
327        if base.is_none() && self.streams.len() == 1 {
328            stream.0 = self.streams.pop();
329        } else {
330            stream.0 = Some(bridge::client::TokenStream::concat_streams(base, self.streams));
331        }
332    }
333}
334
335/// Collects a number of token trees into a single stream.
336#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
337impl FromIterator<TokenTree> for TokenStream {
338    fn from_iter<I: IntoIterator<Item = TokenTree>>(trees: I) -> Self {
339        let iter = trees.into_iter();
340        let mut builder = ConcatTreesHelper::new(iter.size_hint().0);
341        iter.for_each(|tree| builder.push(tree));
342        builder.build()
343    }
344}
345
346/// A "flattening" operation on token streams, collects token trees
347/// from multiple token streams into a single stream.
348#[stable(feature = "proc_macro_lib", since = "1.15.0")]
349impl FromIterator<TokenStream> for TokenStream {
350    fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
351        let iter = streams.into_iter();
352        let mut builder = ConcatStreamsHelper::new(iter.size_hint().0);
353        iter.for_each(|stream| builder.push(stream));
354        builder.build()
355    }
356}
357
358#[stable(feature = "token_stream_extend", since = "1.30.0")]
359impl Extend<TokenTree> for TokenStream {
360    fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, trees: I) {
361        let iter = trees.into_iter();
362        let mut builder = ConcatTreesHelper::new(iter.size_hint().0);
363        iter.for_each(|tree| builder.push(tree));
364        builder.append_to(self);
365    }
366}
367
368#[stable(feature = "token_stream_extend", since = "1.30.0")]
369impl Extend<TokenStream> for TokenStream {
370    fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
371        let iter = streams.into_iter();
372        let mut builder = ConcatStreamsHelper::new(iter.size_hint().0);
373        iter.for_each(|stream| builder.push(stream));
374        builder.append_to(self);
375    }
376}
377
378/// Public implementation details for the `TokenStream` type, such as iterators.
379#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
380pub mod token_stream {
381    use crate::{Group, Ident, Literal, Punct, TokenStream, TokenTree, bridge};
382
383    /// An iterator over `TokenStream`'s `TokenTree`s.
384    /// The iteration is "shallow", e.g., the iterator doesn't recurse into delimited groups,
385    /// and returns whole groups as token trees.
386    #[derive(Clone)]
387    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
388    pub struct IntoIter(
389        std::vec::IntoIter<
390            bridge::TokenTree<
391                bridge::client::TokenStream,
392                bridge::client::Span,
393                bridge::client::Symbol,
394            >,
395        >,
396    );
397
398    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
399    impl Iterator for IntoIter {
400        type Item = TokenTree;
401
402        fn next(&mut self) -> Option<TokenTree> {
403            self.0.next().map(|tree| match tree {
404                bridge::TokenTree::Group(tt) => TokenTree::Group(Group(tt)),
405                bridge::TokenTree::Punct(tt) => TokenTree::Punct(Punct(tt)),
406                bridge::TokenTree::Ident(tt) => TokenTree::Ident(Ident(tt)),
407                bridge::TokenTree::Literal(tt) => TokenTree::Literal(Literal(tt)),
408            })
409        }
410
411        fn size_hint(&self) -> (usize, Option<usize>) {
412            self.0.size_hint()
413        }
414
415        fn count(self) -> usize {
416            self.0.count()
417        }
418    }
419
420    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
421    impl IntoIterator for TokenStream {
422        type Item = TokenTree;
423        type IntoIter = IntoIter;
424
425        fn into_iter(self) -> IntoIter {
426            IntoIter(self.0.map(|v| v.into_trees()).unwrap_or_default().into_iter())
427        }
428    }
429}
430
431/// `quote!(..)` accepts arbitrary tokens and expands into a `TokenStream` describing the input.
432/// For example, `quote!(a + b)` will produce an expression, that, when evaluated, constructs
433/// the `TokenStream` `[Ident("a"), Punct('+', Alone), Ident("b")]`.
434///
435/// Unquoting is done with `$`, and works by taking the single next ident as the unquoted term.
436/// To quote `$` itself, use `$$`.
437#[unstable(feature = "proc_macro_quote", issue = "54722")]
438#[allow_internal_unstable(proc_macro_def_site, proc_macro_internals, proc_macro_totokens)]
439#[rustc_builtin_macro]
440pub macro quote($($t:tt)*) {
441    /* compiler built-in */
442}
443
444#[unstable(feature = "proc_macro_internals", issue = "27812")]
445#[doc(hidden)]
446mod quote;
447
448/// A region of source code, along with macro expansion information.
449#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
450#[derive(Copy, Clone)]
451pub struct Span(bridge::client::Span);
452
453#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
454impl !Send for Span {}
455#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
456impl !Sync for Span {}
457
458macro_rules! diagnostic_method {
459    ($name:ident, $level:expr) => {
460        /// Creates a new `Diagnostic` with the given `message` at the span
461        /// `self`.
462        #[unstable(feature = "proc_macro_diagnostic", issue = "54140")]
463        pub fn $name<T: Into<String>>(self, message: T) -> Diagnostic {
464            Diagnostic::spanned(self, $level, message)
465        }
466    };
467}
468
469impl Span {
470    /// A span that resolves at the macro definition site.
471    #[unstable(feature = "proc_macro_def_site", issue = "54724")]
472    pub fn def_site() -> Span {
473        Span(bridge::client::Span::def_site())
474    }
475
476    /// The span of the invocation of the current procedural macro.
477    /// Identifiers created with this span will be resolved as if they were written
478    /// directly at the macro call location (call-site hygiene) and other code
479    /// at the macro call site will be able to refer to them as well.
480    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
481    pub fn call_site() -> Span {
482        Span(bridge::client::Span::call_site())
483    }
484
485    /// A span that represents `macro_rules` hygiene, and sometimes resolves at the macro
486    /// definition site (local variables, labels, `$crate`) and sometimes at the macro
487    /// call site (everything else).
488    /// The span location is taken from the call-site.
489    #[stable(feature = "proc_macro_mixed_site", since = "1.45.0")]
490    pub fn mixed_site() -> Span {
491        Span(bridge::client::Span::mixed_site())
492    }
493
494    /// The `Span` for the tokens in the previous macro expansion from which
495    /// `self` was generated from, if any.
496    #[unstable(feature = "proc_macro_span", issue = "54725")]
497    pub fn parent(&self) -> Option<Span> {
498        self.0.parent().map(Span)
499    }
500
501    /// The span for the origin source code that `self` was generated from. If
502    /// this `Span` wasn't generated from other macro expansions then the return
503    /// value is the same as `*self`.
504    #[unstable(feature = "proc_macro_span", issue = "54725")]
505    pub fn source(&self) -> Span {
506        Span(self.0.source())
507    }
508
509    /// Returns the span's byte position range in the source file.
510    #[unstable(feature = "proc_macro_span", issue = "54725")]
511    pub fn byte_range(&self) -> Range<usize> {
512        self.0.byte_range()
513    }
514
515    /// Creates an empty span pointing to directly before this span.
516    #[unstable(feature = "proc_macro_span", issue = "54725")]
517    pub fn start(&self) -> Span {
518        Span(self.0.start())
519    }
520
521    /// Creates an empty span pointing to directly after this span.
522    #[unstable(feature = "proc_macro_span", issue = "54725")]
523    pub fn end(&self) -> Span {
524        Span(self.0.end())
525    }
526
527    /// The one-indexed line of the source file where the span starts.
528    ///
529    /// To obtain the line of the span's end, use `span.end().line()`.
530    #[unstable(feature = "proc_macro_span", issue = "54725")]
531    pub fn line(&self) -> usize {
532        self.0.line()
533    }
534
535    /// The one-indexed column of the source file where the span starts.
536    ///
537    /// To obtain the column of the span's end, use `span.end().column()`.
538    #[unstable(feature = "proc_macro_span", issue = "54725")]
539    pub fn column(&self) -> usize {
540        self.0.column()
541    }
542
543    /// The path to the source file in which this span occurs, for display purposes.
544    ///
545    /// This might not correspond to a valid file system path.
546    /// It might be remapped, or might be an artificial path such as `"<macro expansion>"`.
547    #[unstable(feature = "proc_macro_span", issue = "54725")]
548    pub fn file(&self) -> String {
549        self.0.file()
550    }
551
552    /// The path to the source file in which this span occurs on disk.
553    ///
554    /// This is the actual path on disk. It is unaffected by path remapping.
555    ///
556    /// This path should not be embedded in the output of the macro; prefer `file()` instead.
557    #[unstable(feature = "proc_macro_span", issue = "54725")]
558    pub fn local_file(&self) -> Option<PathBuf> {
559        self.0.local_file().map(|s| PathBuf::from(s))
560    }
561
562    /// Creates a new span encompassing `self` and `other`.
563    ///
564    /// Returns `None` if `self` and `other` are from different files.
565    #[unstable(feature = "proc_macro_span", issue = "54725")]
566    pub fn join(&self, other: Span) -> Option<Span> {
567        self.0.join(other.0).map(Span)
568    }
569
570    /// Creates a new span with the same line/column information as `self` but
571    /// that resolves symbols as though it were at `other`.
572    #[stable(feature = "proc_macro_span_resolved_at", since = "1.45.0")]
573    pub fn resolved_at(&self, other: Span) -> Span {
574        Span(self.0.resolved_at(other.0))
575    }
576
577    /// Creates a new span with the same name resolution behavior as `self` but
578    /// with the line/column information of `other`.
579    #[stable(feature = "proc_macro_span_located_at", since = "1.45.0")]
580    pub fn located_at(&self, other: Span) -> Span {
581        other.resolved_at(*self)
582    }
583
584    /// Compares two spans to see if they're equal.
585    #[unstable(feature = "proc_macro_span", issue = "54725")]
586    pub fn eq(&self, other: &Span) -> bool {
587        self.0 == other.0
588    }
589
590    /// Returns the source text behind a span. This preserves the original source
591    /// code, including spaces and comments. It only returns a result if the span
592    /// corresponds to real source code.
593    ///
594    /// Note: The observable result of a macro should only rely on the tokens and
595    /// not on this source text. The result of this function is a best effort to
596    /// be used for diagnostics only.
597    #[stable(feature = "proc_macro_source_text", since = "1.66.0")]
598    pub fn source_text(&self) -> Option<String> {
599        self.0.source_text()
600    }
601
602    // Used by the implementation of `Span::quote`
603    #[doc(hidden)]
604    #[unstable(feature = "proc_macro_internals", issue = "27812")]
605    pub fn save_span(&self) -> usize {
606        self.0.save_span()
607    }
608
609    // Used by the implementation of `Span::quote`
610    #[doc(hidden)]
611    #[unstable(feature = "proc_macro_internals", issue = "27812")]
612    pub fn recover_proc_macro_span(id: usize) -> Span {
613        Span(bridge::client::Span::recover_proc_macro_span(id))
614    }
615
616    diagnostic_method!(error, Level::Error);
617    diagnostic_method!(warning, Level::Warning);
618    diagnostic_method!(note, Level::Note);
619    diagnostic_method!(help, Level::Help);
620}
621
622/// Prints a span in a form convenient for debugging.
623#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
624impl fmt::Debug for Span {
625    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
626        self.0.fmt(f)
627    }
628}
629
630/// A single token or a delimited sequence of token trees (e.g., `[1, (), ..]`).
631#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
632#[derive(Clone)]
633pub enum TokenTree {
634    /// A token stream surrounded by bracket delimiters.
635    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
636    Group(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Group),
637    /// An identifier.
638    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
639    Ident(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Ident),
640    /// A single punctuation character (`+`, `,`, `$`, etc.).
641    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
642    Punct(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Punct),
643    /// A literal character (`'a'`), string (`"hello"`), number (`2.3`), etc.
644    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
645    Literal(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Literal),
646}
647
648#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
649impl !Send for TokenTree {}
650#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
651impl !Sync for TokenTree {}
652
653impl TokenTree {
654    /// Returns the span of this tree, delegating to the `span` method of
655    /// the contained token or a delimited stream.
656    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
657    pub fn span(&self) -> Span {
658        match *self {
659            TokenTree::Group(ref t) => t.span(),
660            TokenTree::Ident(ref t) => t.span(),
661            TokenTree::Punct(ref t) => t.span(),
662            TokenTree::Literal(ref t) => t.span(),
663        }
664    }
665
666    /// Configures the span for *only this token*.
667    ///
668    /// Note that if this token is a `Group` then this method will not configure
669    /// the span of each of the internal tokens, this will simply delegate to
670    /// the `set_span` method of each variant.
671    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
672    pub fn set_span(&mut self, span: Span) {
673        match *self {
674            TokenTree::Group(ref mut t) => t.set_span(span),
675            TokenTree::Ident(ref mut t) => t.set_span(span),
676            TokenTree::Punct(ref mut t) => t.set_span(span),
677            TokenTree::Literal(ref mut t) => t.set_span(span),
678        }
679    }
680}
681
682/// Prints token tree in a form convenient for debugging.
683#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
684impl fmt::Debug for TokenTree {
685    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
686        // Each of these has the name in the struct type in the derived debug,
687        // so don't bother with an extra layer of indirection
688        match *self {
689            TokenTree::Group(ref tt) => tt.fmt(f),
690            TokenTree::Ident(ref tt) => tt.fmt(f),
691            TokenTree::Punct(ref tt) => tt.fmt(f),
692            TokenTree::Literal(ref tt) => tt.fmt(f),
693        }
694    }
695}
696
697#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
698impl From<Group> for TokenTree {
699    fn from(g: Group) -> TokenTree {
700        TokenTree::Group(g)
701    }
702}
703
704#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
705impl From<Ident> for TokenTree {
706    fn from(g: Ident) -> TokenTree {
707        TokenTree::Ident(g)
708    }
709}
710
711#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
712impl From<Punct> for TokenTree {
713    fn from(g: Punct) -> TokenTree {
714        TokenTree::Punct(g)
715    }
716}
717
718#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
719impl From<Literal> for TokenTree {
720    fn from(g: Literal) -> TokenTree {
721        TokenTree::Literal(g)
722    }
723}
724
725/// Prints the token tree as a string that is supposed to be losslessly convertible back
726/// into the same token tree (modulo spans), except for possibly `TokenTree::Group`s
727/// with `Delimiter::None` delimiters and negative numeric literals.
728///
729/// Note: the exact form of the output is subject to change, e.g. there might
730/// be changes in the whitespace used between tokens. Therefore, you should
731/// *not* do any kind of simple substring matching on the output string (as
732/// produced by `to_string`) to implement a proc macro, because that matching
733/// might stop working if such changes happen. Instead, you should work at the
734/// `TokenTree` level, e.g. matching against `TokenTree::Ident`,
735/// `TokenTree::Punct`, or `TokenTree::Literal`.
736#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
737impl fmt::Display for TokenTree {
738    #[allow(clippy::recursive_format_impl)] // clippy doesn't see the specialization
739    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
740        match self {
741            TokenTree::Group(t) => write!(f, "{t}"),
742            TokenTree::Ident(t) => write!(f, "{t}"),
743            TokenTree::Punct(t) => write!(f, "{t}"),
744            TokenTree::Literal(t) => write!(f, "{t}"),
745        }
746    }
747}
748
749/// A delimited token stream.
750///
751/// A `Group` internally contains a `TokenStream` which is surrounded by `Delimiter`s.
752#[derive(Clone)]
753#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
754pub struct Group(bridge::Group<bridge::client::TokenStream, bridge::client::Span>);
755
756#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
757impl !Send for Group {}
758#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
759impl !Sync for Group {}
760
761/// Describes how a sequence of token trees is delimited.
762#[derive(Copy, Clone, Debug, PartialEq, Eq)]
763#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
764pub enum Delimiter {
765    /// `( ... )`
766    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
767    Parenthesis,
768    /// `{ ... }`
769    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
770    Brace,
771    /// `[ ... ]`
772    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
773    Bracket,
774    /// `∅ ... ∅`
775    /// An invisible delimiter, that may, for example, appear around tokens coming from a
776    /// "macro variable" `$var`. It is important to preserve operator priorities in cases like
777    /// `$var * 3` where `$var` is `1 + 2`.
778    /// Invisible delimiters might not survive roundtrip of a token stream through a string.
779    ///
780    /// <div class="warning">
781    ///
782    /// Note: rustc currently can ignore the grouping of tokens delimited by `None` in the output
783    /// of a proc_macro. Only `None`-delimited groups created by a macro_rules macro in the input
784    /// of a proc_macro macro are preserved, and only in very specific circumstances.
785    /// Any `None`-delimited groups (re)created by a proc_macro will therefore not preserve
786    /// operator priorities as indicated above. The other `Delimiter` variants should be used
787    /// instead in this context. This is a rustc bug. For details, see
788    /// [rust-lang/rust#67062](https://github.com/rust-lang/rust/issues/67062).
789    ///
790    /// </div>
791    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
792    None,
793}
794
795impl Group {
796    /// Creates a new `Group` with the given delimiter and token stream.
797    ///
798    /// This constructor will set the span for this group to
799    /// `Span::call_site()`. To change the span you can use the `set_span`
800    /// method below.
801    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
802    pub fn new(delimiter: Delimiter, stream: TokenStream) -> Group {
803        Group(bridge::Group {
804            delimiter,
805            stream: stream.0,
806            span: bridge::DelimSpan::from_single(Span::call_site().0),
807        })
808    }
809
810    /// Returns the delimiter of this `Group`
811    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
812    pub fn delimiter(&self) -> Delimiter {
813        self.0.delimiter
814    }
815
816    /// Returns the `TokenStream` of tokens that are delimited in this `Group`.
817    ///
818    /// Note that the returned token stream does not include the delimiter
819    /// returned above.
820    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
821    pub fn stream(&self) -> TokenStream {
822        TokenStream(self.0.stream.clone())
823    }
824
825    /// Returns the span for the delimiters of this token stream, spanning the
826    /// entire `Group`.
827    ///
828    /// ```text
829    /// pub fn span(&self) -> Span {
830    ///            ^^^^^^^
831    /// ```
832    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
833    pub fn span(&self) -> Span {
834        Span(self.0.span.entire)
835    }
836
837    /// Returns the span pointing to the opening delimiter of this group.
838    ///
839    /// ```text
840    /// pub fn span_open(&self) -> Span {
841    ///                 ^
842    /// ```
843    #[stable(feature = "proc_macro_group_span", since = "1.55.0")]
844    pub fn span_open(&self) -> Span {
845        Span(self.0.span.open)
846    }
847
848    /// Returns the span pointing to the closing delimiter of this group.
849    ///
850    /// ```text
851    /// pub fn span_close(&self) -> Span {
852    ///                        ^
853    /// ```
854    #[stable(feature = "proc_macro_group_span", since = "1.55.0")]
855    pub fn span_close(&self) -> Span {
856        Span(self.0.span.close)
857    }
858
859    /// Configures the span for this `Group`'s delimiters, but not its internal
860    /// tokens.
861    ///
862    /// This method will **not** set the span of all the internal tokens spanned
863    /// by this group, but rather it will only set the span of the delimiter
864    /// tokens at the level of the `Group`.
865    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
866    pub fn set_span(&mut self, span: Span) {
867        self.0.span = bridge::DelimSpan::from_single(span.0);
868    }
869}
870
871/// Prints the group as a string that should be losslessly convertible back
872/// into the same group (modulo spans), except for possibly `TokenTree::Group`s
873/// with `Delimiter::None` delimiters.
874#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
875impl fmt::Display for Group {
876    #[allow(clippy::recursive_format_impl)] // clippy doesn't see the specialization
877    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
878        write!(f, "{}", TokenStream::from(TokenTree::from(self.clone())))
879    }
880}
881
882#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
883impl fmt::Debug for Group {
884    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
885        f.debug_struct("Group")
886            .field("delimiter", &self.delimiter())
887            .field("stream", &self.stream())
888            .field("span", &self.span())
889            .finish()
890    }
891}
892
893/// A `Punct` is a single punctuation character such as `+`, `-` or `#`.
894///
895/// Multi-character operators like `+=` are represented as two instances of `Punct` with different
896/// forms of `Spacing` returned.
897#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
898#[derive(Clone)]
899pub struct Punct(bridge::Punct<bridge::client::Span>);
900
901#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
902impl !Send for Punct {}
903#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
904impl !Sync for Punct {}
905
906/// Indicates whether a `Punct` token can join with the following token
907/// to form a multi-character operator.
908#[derive(Copy, Clone, Debug, PartialEq, Eq)]
909#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
910pub enum Spacing {
911    /// A `Punct` token can join with the following token to form a multi-character operator.
912    ///
913    /// In token streams constructed using proc macro interfaces, `Joint` punctuation tokens can be
914    /// followed by any other tokens. However, in token streams parsed from source code, the
915    /// compiler will only set spacing to `Joint` in the following cases.
916    /// - When a `Punct` is immediately followed by another `Punct` without a whitespace. E.g. `+`
917    ///   is `Joint` in `+=` and `++`.
918    /// - When a single quote `'` is immediately followed by an identifier without a whitespace.
919    ///   E.g. `'` is `Joint` in `'lifetime`.
920    ///
921    /// This list may be extended in the future to enable more token combinations.
922    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
923    Joint,
924    /// A `Punct` token cannot join with the following token to form a multi-character operator.
925    ///
926    /// `Alone` punctuation tokens can be followed by any other tokens. In token streams parsed
927    /// from source code, the compiler will set spacing to `Alone` in all cases not covered by the
928    /// conditions for `Joint` above. E.g. `+` is `Alone` in `+ =`, `+ident` and `+()`. In
929    /// particular, tokens not followed by anything will be marked as `Alone`.
930    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
931    Alone,
932}
933
934impl Punct {
935    /// Creates a new `Punct` from the given character and spacing.
936    /// The `ch` argument must be a valid punctuation character permitted by the language,
937    /// otherwise the function will panic.
938    ///
939    /// The returned `Punct` will have the default span of `Span::call_site()`
940    /// which can be further configured with the `set_span` method below.
941    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
942    pub fn new(ch: char, spacing: Spacing) -> Punct {
943        const LEGAL_CHARS: &[char] = &[
944            '=', '<', '>', '!', '~', '+', '-', '*', '/', '%', '^', '&', '|', '@', '.', ',', ';',
945            ':', '#', '$', '?', '\'',
946        ];
947        if !LEGAL_CHARS.contains(&ch) {
948            panic!("unsupported character `{:?}`", ch);
949        }
950        Punct(bridge::Punct {
951            ch: ch as u8,
952            joint: spacing == Spacing::Joint,
953            span: Span::call_site().0,
954        })
955    }
956
957    /// Returns the value of this punctuation character as `char`.
958    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
959    pub fn as_char(&self) -> char {
960        self.0.ch as char
961    }
962
963    /// Returns the spacing of this punctuation character, indicating whether it can be potentially
964    /// combined into a multi-character operator with the following token (`Joint`), or whether the
965    /// operator has definitely ended (`Alone`).
966    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
967    pub fn spacing(&self) -> Spacing {
968        if self.0.joint { Spacing::Joint } else { Spacing::Alone }
969    }
970
971    /// Returns the span for this punctuation character.
972    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
973    pub fn span(&self) -> Span {
974        Span(self.0.span)
975    }
976
977    /// Configure the span for this punctuation character.
978    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
979    pub fn set_span(&mut self, span: Span) {
980        self.0.span = span.0;
981    }
982}
983
984/// Prints the punctuation character as a string that should be losslessly convertible
985/// back into the same character.
986#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
987impl fmt::Display for Punct {
988    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
989        write!(f, "{}", self.as_char())
990    }
991}
992
993#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
994impl fmt::Debug for Punct {
995    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
996        f.debug_struct("Punct")
997            .field("ch", &self.as_char())
998            .field("spacing", &self.spacing())
999            .field("span", &self.span())
1000            .finish()
1001    }
1002}
1003
1004#[stable(feature = "proc_macro_punct_eq", since = "1.50.0")]
1005impl PartialEq<char> for Punct {
1006    fn eq(&self, rhs: &char) -> bool {
1007        self.as_char() == *rhs
1008    }
1009}
1010
1011#[stable(feature = "proc_macro_punct_eq_flipped", since = "1.52.0")]
1012impl PartialEq<Punct> for char {
1013    fn eq(&self, rhs: &Punct) -> bool {
1014        *self == rhs.as_char()
1015    }
1016}
1017
1018/// An identifier (`ident`).
1019#[derive(Clone)]
1020#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1021pub struct Ident(bridge::Ident<bridge::client::Span, bridge::client::Symbol>);
1022
1023impl Ident {
1024    /// Creates a new `Ident` with the given `string` as well as the specified
1025    /// `span`.
1026    /// The `string` argument must be a valid identifier permitted by the
1027    /// language (including keywords, e.g. `self` or `fn`). Otherwise, the function will panic.
1028    ///
1029    /// Note that `span`, currently in rustc, configures the hygiene information
1030    /// for this identifier.
1031    ///
1032    /// As of this time `Span::call_site()` explicitly opts-in to "call-site" hygiene
1033    /// meaning that identifiers created with this span will be resolved as if they were written
1034    /// directly at the location of the macro call, and other code at the macro call site will be
1035    /// able to refer to them as well.
1036    ///
1037    /// Later spans like `Span::def_site()` will allow to opt-in to "definition-site" hygiene
1038    /// meaning that identifiers created with this span will be resolved at the location of the
1039    /// macro definition and other code at the macro call site will not be able to refer to them.
1040    ///
1041    /// Due to the current importance of hygiene this constructor, unlike other
1042    /// tokens, requires a `Span` to be specified at construction.
1043    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1044    pub fn new(string: &str, span: Span) -> Ident {
1045        Ident(bridge::Ident {
1046            sym: bridge::client::Symbol::new_ident(string, false),
1047            is_raw: false,
1048            span: span.0,
1049        })
1050    }
1051
1052    /// Same as `Ident::new`, but creates a raw identifier (`r#ident`).
1053    /// The `string` argument be a valid identifier permitted by the language
1054    /// (including keywords, e.g. `fn`). Keywords which are usable in path segments
1055    /// (e.g. `self`, `super`) are not supported, and will cause a panic.
1056    #[stable(feature = "proc_macro_raw_ident", since = "1.47.0")]
1057    pub fn new_raw(string: &str, span: Span) -> Ident {
1058        Ident(bridge::Ident {
1059            sym: bridge::client::Symbol::new_ident(string, true),
1060            is_raw: true,
1061            span: span.0,
1062        })
1063    }
1064
1065    /// Returns the span of this `Ident`, encompassing the entire string returned
1066    /// by [`to_string`](ToString::to_string).
1067    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1068    pub fn span(&self) -> Span {
1069        Span(self.0.span)
1070    }
1071
1072    /// Configures the span of this `Ident`, possibly changing its hygiene context.
1073    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1074    pub fn set_span(&mut self, span: Span) {
1075        self.0.span = span.0;
1076    }
1077}
1078
1079/// Prints the identifier as a string that should be losslessly convertible back
1080/// into the same identifier.
1081#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1082impl fmt::Display for Ident {
1083    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1084        if self.0.is_raw {
1085            f.write_str("r#")?;
1086        }
1087        fmt::Display::fmt(&self.0.sym, f)
1088    }
1089}
1090
1091#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1092impl fmt::Debug for Ident {
1093    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1094        f.debug_struct("Ident")
1095            .field("ident", &self.to_string())
1096            .field("span", &self.span())
1097            .finish()
1098    }
1099}
1100
1101/// A literal string (`"hello"`), byte string (`b"hello"`), C string (`c"hello"`),
1102/// character (`'a'`), byte character (`b'a'`), an integer or floating point number
1103/// with or without a suffix (`1`, `1u8`, `2.3`, `2.3f32`).
1104/// Boolean literals like `true` and `false` do not belong here, they are `Ident`s.
1105#[derive(Clone)]
1106#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1107pub struct Literal(bridge::Literal<bridge::client::Span, bridge::client::Symbol>);
1108
1109macro_rules! suffixed_int_literals {
1110    ($($name:ident => $kind:ident,)*) => ($(
1111        /// Creates a new suffixed integer literal with the specified value.
1112        ///
1113        /// This function will create an integer like `1u32` where the integer
1114        /// value specified is the first part of the token and the integral is
1115        /// also suffixed at the end.
1116        /// Literals created from negative numbers might not survive round-trips through
1117        /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1118        ///
1119        /// Literals created through this method have the `Span::call_site()`
1120        /// span by default, which can be configured with the `set_span` method
1121        /// below.
1122        #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1123        pub fn $name(n: $kind) -> Literal {
1124            Literal(bridge::Literal {
1125                kind: bridge::LitKind::Integer,
1126                symbol: bridge::client::Symbol::new(&n.to_string()),
1127                suffix: Some(bridge::client::Symbol::new(stringify!($kind))),
1128                span: Span::call_site().0,
1129            })
1130        }
1131    )*)
1132}
1133
1134macro_rules! unsuffixed_int_literals {
1135    ($($name:ident => $kind:ident,)*) => ($(
1136        /// Creates a new unsuffixed integer literal with the specified value.
1137        ///
1138        /// This function will create an integer like `1` where the integer
1139        /// value specified is the first part of the token. No suffix is
1140        /// specified on this token, meaning that invocations like
1141        /// `Literal::i8_unsuffixed(1)` are equivalent to
1142        /// `Literal::u32_unsuffixed(1)`.
1143        /// Literals created from negative numbers might not survive rountrips through
1144        /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1145        ///
1146        /// Literals created through this method have the `Span::call_site()`
1147        /// span by default, which can be configured with the `set_span` method
1148        /// below.
1149        #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1150        pub fn $name(n: $kind) -> Literal {
1151            Literal(bridge::Literal {
1152                kind: bridge::LitKind::Integer,
1153                symbol: bridge::client::Symbol::new(&n.to_string()),
1154                suffix: None,
1155                span: Span::call_site().0,
1156            })
1157        }
1158    )*)
1159}
1160
1161impl Literal {
1162    fn new(kind: bridge::LitKind, value: &str, suffix: Option<&str>) -> Self {
1163        Literal(bridge::Literal {
1164            kind,
1165            symbol: bridge::client::Symbol::new(value),
1166            suffix: suffix.map(bridge::client::Symbol::new),
1167            span: Span::call_site().0,
1168        })
1169    }
1170
1171    suffixed_int_literals! {
1172        u8_suffixed => u8,
1173        u16_suffixed => u16,
1174        u32_suffixed => u32,
1175        u64_suffixed => u64,
1176        u128_suffixed => u128,
1177        usize_suffixed => usize,
1178        i8_suffixed => i8,
1179        i16_suffixed => i16,
1180        i32_suffixed => i32,
1181        i64_suffixed => i64,
1182        i128_suffixed => i128,
1183        isize_suffixed => isize,
1184    }
1185
1186    unsuffixed_int_literals! {
1187        u8_unsuffixed => u8,
1188        u16_unsuffixed => u16,
1189        u32_unsuffixed => u32,
1190        u64_unsuffixed => u64,
1191        u128_unsuffixed => u128,
1192        usize_unsuffixed => usize,
1193        i8_unsuffixed => i8,
1194        i16_unsuffixed => i16,
1195        i32_unsuffixed => i32,
1196        i64_unsuffixed => i64,
1197        i128_unsuffixed => i128,
1198        isize_unsuffixed => isize,
1199    }
1200
1201    /// Creates a new unsuffixed floating-point literal.
1202    ///
1203    /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1204    /// the float's value is emitted directly into the token but no suffix is
1205    /// used, so it may be inferred to be a `f64` later in the compiler.
1206    /// Literals created from negative numbers might not survive rountrips through
1207    /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1208    ///
1209    /// # Panics
1210    ///
1211    /// This function requires that the specified float is finite, for
1212    /// example if it is infinity or NaN this function will panic.
1213    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1214    pub fn f32_unsuffixed(n: f32) -> Literal {
1215        if !n.is_finite() {
1216            panic!("Invalid float literal {n}");
1217        }
1218        let mut repr = n.to_string();
1219        if !repr.contains('.') {
1220            repr.push_str(".0");
1221        }
1222        Literal::new(bridge::LitKind::Float, &repr, None)
1223    }
1224
1225    /// Creates a new suffixed floating-point literal.
1226    ///
1227    /// This constructor will create a literal like `1.0f32` where the value
1228    /// specified is the preceding part of the token and `f32` is the suffix of
1229    /// the token. This token will always be inferred to be an `f32` in the
1230    /// compiler.
1231    /// Literals created from negative numbers might not survive rountrips through
1232    /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1233    ///
1234    /// # Panics
1235    ///
1236    /// This function requires that the specified float is finite, for
1237    /// example if it is infinity or NaN this function will panic.
1238    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1239    pub fn f32_suffixed(n: f32) -> Literal {
1240        if !n.is_finite() {
1241            panic!("Invalid float literal {n}");
1242        }
1243        Literal::new(bridge::LitKind::Float, &n.to_string(), Some("f32"))
1244    }
1245
1246    /// Creates a new unsuffixed floating-point literal.
1247    ///
1248    /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1249    /// the float's value is emitted directly into the token but no suffix is
1250    /// used, so it may be inferred to be a `f64` later in the compiler.
1251    /// Literals created from negative numbers might not survive rountrips through
1252    /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1253    ///
1254    /// # Panics
1255    ///
1256    /// This function requires that the specified float is finite, for
1257    /// example if it is infinity or NaN this function will panic.
1258    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1259    pub fn f64_unsuffixed(n: f64) -> Literal {
1260        if !n.is_finite() {
1261            panic!("Invalid float literal {n}");
1262        }
1263        let mut repr = n.to_string();
1264        if !repr.contains('.') {
1265            repr.push_str(".0");
1266        }
1267        Literal::new(bridge::LitKind::Float, &repr, None)
1268    }
1269
1270    /// Creates a new suffixed floating-point literal.
1271    ///
1272    /// This constructor will create a literal like `1.0f64` where the value
1273    /// specified is the preceding part of the token and `f64` is the suffix of
1274    /// the token. This token will always be inferred to be an `f64` in the
1275    /// compiler.
1276    /// Literals created from negative numbers might not survive rountrips through
1277    /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1278    ///
1279    /// # Panics
1280    ///
1281    /// This function requires that the specified float is finite, for
1282    /// example if it is infinity or NaN this function will panic.
1283    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1284    pub fn f64_suffixed(n: f64) -> Literal {
1285        if !n.is_finite() {
1286            panic!("Invalid float literal {n}");
1287        }
1288        Literal::new(bridge::LitKind::Float, &n.to_string(), Some("f64"))
1289    }
1290
1291    /// String literal.
1292    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1293    pub fn string(string: &str) -> Literal {
1294        let escape = EscapeOptions {
1295            escape_single_quote: false,
1296            escape_double_quote: true,
1297            escape_nonascii: false,
1298        };
1299        let repr = escape_bytes(string.as_bytes(), escape);
1300        Literal::new(bridge::LitKind::Str, &repr, None)
1301    }
1302
1303    /// Character literal.
1304    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1305    pub fn character(ch: char) -> Literal {
1306        let escape = EscapeOptions {
1307            escape_single_quote: true,
1308            escape_double_quote: false,
1309            escape_nonascii: false,
1310        };
1311        let repr = escape_bytes(ch.encode_utf8(&mut [0u8; 4]).as_bytes(), escape);
1312        Literal::new(bridge::LitKind::Char, &repr, None)
1313    }
1314
1315    /// Byte character literal.
1316    #[stable(feature = "proc_macro_byte_character", since = "1.79.0")]
1317    pub fn byte_character(byte: u8) -> Literal {
1318        let escape = EscapeOptions {
1319            escape_single_quote: true,
1320            escape_double_quote: false,
1321            escape_nonascii: true,
1322        };
1323        let repr = escape_bytes(&[byte], escape);
1324        Literal::new(bridge::LitKind::Byte, &repr, None)
1325    }
1326
1327    /// Byte string literal.
1328    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1329    pub fn byte_string(bytes: &[u8]) -> Literal {
1330        let escape = EscapeOptions {
1331            escape_single_quote: false,
1332            escape_double_quote: true,
1333            escape_nonascii: true,
1334        };
1335        let repr = escape_bytes(bytes, escape);
1336        Literal::new(bridge::LitKind::ByteStr, &repr, None)
1337    }
1338
1339    /// C string literal.
1340    #[stable(feature = "proc_macro_c_str_literals", since = "1.79.0")]
1341    pub fn c_string(string: &CStr) -> Literal {
1342        let escape = EscapeOptions {
1343            escape_single_quote: false,
1344            escape_double_quote: true,
1345            escape_nonascii: false,
1346        };
1347        let repr = escape_bytes(string.to_bytes(), escape);
1348        Literal::new(bridge::LitKind::CStr, &repr, None)
1349    }
1350
1351    /// Returns the span encompassing this literal.
1352    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1353    pub fn span(&self) -> Span {
1354        Span(self.0.span)
1355    }
1356
1357    /// Configures the span associated for this literal.
1358    #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1359    pub fn set_span(&mut self, span: Span) {
1360        self.0.span = span.0;
1361    }
1362
1363    /// Returns a `Span` that is a subset of `self.span()` containing only the
1364    /// source bytes in range `range`. Returns `None` if the would-be trimmed
1365    /// span is outside the bounds of `self`.
1366    // FIXME(SergioBenitez): check that the byte range starts and ends at a
1367    // UTF-8 boundary of the source. otherwise, it's likely that a panic will
1368    // occur elsewhere when the source text is printed.
1369    // FIXME(SergioBenitez): there is no way for the user to know what
1370    // `self.span()` actually maps to, so this method can currently only be
1371    // called blindly. For example, `to_string()` for the character 'c' returns
1372    // "'\u{63}'"; there is no way for the user to know whether the source text
1373    // was 'c' or whether it was '\u{63}'.
1374    #[unstable(feature = "proc_macro_span", issue = "54725")]
1375    pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
1376        self.0.span.subspan(range.start_bound().cloned(), range.end_bound().cloned()).map(Span)
1377    }
1378
1379    fn with_symbol_and_suffix<R>(&self, f: impl FnOnce(&str, &str) -> R) -> R {
1380        self.0.symbol.with(|symbol| match self.0.suffix {
1381            Some(suffix) => suffix.with(|suffix| f(symbol, suffix)),
1382            None => f(symbol, ""),
1383        })
1384    }
1385
1386    /// Invokes the callback with a `&[&str]` consisting of each part of the
1387    /// literal's representation. This is done to allow the `ToString` and
1388    /// `Display` implementations to borrow references to symbol values, and
1389    /// both be optimized to reduce overhead.
1390    fn with_stringify_parts<R>(&self, f: impl FnOnce(&[&str]) -> R) -> R {
1391        /// Returns a string containing exactly `num` '#' characters.
1392        /// Uses a 256-character source string literal which is always safe to
1393        /// index with a `u8` index.
1394        fn get_hashes_str(num: u8) -> &'static str {
1395            const HASHES: &str = "\
1396            ################################################################\
1397            ################################################################\
1398            ################################################################\
1399            ################################################################\
1400            ";
1401            const _: () = assert!(HASHES.len() == 256);
1402            &HASHES[..num as usize]
1403        }
1404
1405        self.with_symbol_and_suffix(|symbol, suffix| match self.0.kind {
1406            bridge::LitKind::Byte => f(&["b'", symbol, "'", suffix]),
1407            bridge::LitKind::Char => f(&["'", symbol, "'", suffix]),
1408            bridge::LitKind::Str => f(&["\"", symbol, "\"", suffix]),
1409            bridge::LitKind::StrRaw(n) => {
1410                let hashes = get_hashes_str(n);
1411                f(&["r", hashes, "\"", symbol, "\"", hashes, suffix])
1412            }
1413            bridge::LitKind::ByteStr => f(&["b\"", symbol, "\"", suffix]),
1414            bridge::LitKind::ByteStrRaw(n) => {
1415                let hashes = get_hashes_str(n);
1416                f(&["br", hashes, "\"", symbol, "\"", hashes, suffix])
1417            }
1418            bridge::LitKind::CStr => f(&["c\"", symbol, "\"", suffix]),
1419            bridge::LitKind::CStrRaw(n) => {
1420                let hashes = get_hashes_str(n);
1421                f(&["cr", hashes, "\"", symbol, "\"", hashes, suffix])
1422            }
1423
1424            bridge::LitKind::Integer | bridge::LitKind::Float | bridge::LitKind::ErrWithGuar => {
1425                f(&[symbol, suffix])
1426            }
1427        })
1428    }
1429
1430    /// Returns the unescaped string value if the current literal is a string or a string literal.
1431    #[unstable(feature = "proc_macro_value", issue = "136652")]
1432    pub fn str_value(&self) -> Result<String, ConversionErrorKind> {
1433        self.0.symbol.with(|symbol| match self.0.kind {
1434            bridge::LitKind::Str => {
1435                if symbol.contains('\\') {
1436                    let mut buf = String::with_capacity(symbol.len());
1437                    let mut error = None;
1438                    // Force-inlining here is aggressive but the closure is
1439                    // called on every char in the string, so it can be hot in
1440                    // programs with many long strings containing escapes.
1441                    unescape_unicode(
1442                        symbol,
1443                        Mode::Str,
1444                        &mut #[inline(always)]
1445                        |_, c| match c {
1446                            Ok(c) => buf.push(c),
1447                            Err(err) => {
1448                                if err.is_fatal() {
1449                                    error = Some(ConversionErrorKind::FailedToUnescape(err));
1450                                }
1451                            }
1452                        },
1453                    );
1454                    if let Some(error) = error { Err(error) } else { Ok(buf) }
1455                } else {
1456                    Ok(symbol.to_string())
1457                }
1458            }
1459            bridge::LitKind::StrRaw(_) => Ok(symbol.to_string()),
1460            _ => Err(ConversionErrorKind::InvalidLiteralKind),
1461        })
1462    }
1463
1464    /// Returns the unescaped string value if the current literal is a c-string or a c-string
1465    /// literal.
1466    #[unstable(feature = "proc_macro_value", issue = "136652")]
1467    pub fn cstr_value(&self) -> Result<Vec<u8>, ConversionErrorKind> {
1468        self.0.symbol.with(|symbol| match self.0.kind {
1469            bridge::LitKind::CStr => {
1470                let mut error = None;
1471                let mut buf = Vec::with_capacity(symbol.len());
1472
1473                unescape_mixed(symbol, Mode::CStr, &mut |_span, c| match c {
1474                    Ok(MixedUnit::Char(c)) => {
1475                        buf.extend_from_slice(c.encode_utf8(&mut [0; 4]).as_bytes())
1476                    }
1477                    Ok(MixedUnit::HighByte(b)) => buf.push(b),
1478                    Err(err) => {
1479                        if err.is_fatal() {
1480                            error = Some(ConversionErrorKind::FailedToUnescape(err));
1481                        }
1482                    }
1483                });
1484                if let Some(error) = error {
1485                    Err(error)
1486                } else {
1487                    buf.push(0);
1488                    Ok(buf)
1489                }
1490            }
1491            bridge::LitKind::CStrRaw(_) => {
1492                // Raw strings have no escapes so we can convert the symbol
1493                // directly to a `Lrc<u8>` after appending the terminating NUL
1494                // char.
1495                let mut buf = symbol.to_owned().into_bytes();
1496                buf.push(0);
1497                Ok(buf)
1498            }
1499            _ => Err(ConversionErrorKind::InvalidLiteralKind),
1500        })
1501    }
1502
1503    /// Returns the unescaped string value if the current literal is a byte string or a byte string
1504    /// literal.
1505    #[unstable(feature = "proc_macro_value", issue = "136652")]
1506    pub fn byte_str_value(&self) -> Result<Vec<u8>, ConversionErrorKind> {
1507        self.0.symbol.with(|symbol| match self.0.kind {
1508            bridge::LitKind::ByteStr => {
1509                let mut buf = Vec::with_capacity(symbol.len());
1510                let mut error = None;
1511
1512                unescape_unicode(symbol, Mode::ByteStr, &mut |_, c| match c {
1513                    Ok(c) => buf.push(byte_from_char(c)),
1514                    Err(err) => {
1515                        if err.is_fatal() {
1516                            error = Some(ConversionErrorKind::FailedToUnescape(err));
1517                        }
1518                    }
1519                });
1520                if let Some(error) = error { Err(error) } else { Ok(buf) }
1521            }
1522            bridge::LitKind::ByteStrRaw(_) => {
1523                // Raw strings have no escapes so we can convert the symbol
1524                // directly to a `Lrc<u8>`.
1525                Ok(symbol.to_owned().into_bytes())
1526            }
1527            _ => Err(ConversionErrorKind::InvalidLiteralKind),
1528        })
1529    }
1530}
1531
1532/// Parse a single literal from its stringified representation.
1533///
1534/// In order to parse successfully, the input string must not contain anything
1535/// but the literal token. Specifically, it must not contain whitespace or
1536/// comments in addition to the literal.
1537///
1538/// The resulting literal token will have a `Span::call_site()` span.
1539///
1540/// NOTE: some errors may cause panics instead of returning `LexError`. We
1541/// reserve the right to change these errors into `LexError`s later.
1542#[stable(feature = "proc_macro_literal_parse", since = "1.54.0")]
1543impl FromStr for Literal {
1544    type Err = LexError;
1545
1546    fn from_str(src: &str) -> Result<Self, LexError> {
1547        match bridge::client::FreeFunctions::literal_from_str(src) {
1548            Ok(literal) => Ok(Literal(literal)),
1549            Err(()) => Err(LexError),
1550        }
1551    }
1552}
1553
1554/// Prints the literal as a string that should be losslessly convertible
1555/// back into the same literal (except for possible rounding for floating point literals).
1556#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1557impl fmt::Display for Literal {
1558    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1559        self.with_stringify_parts(|parts| {
1560            for part in parts {
1561                fmt::Display::fmt(part, f)?;
1562            }
1563            Ok(())
1564        })
1565    }
1566}
1567
1568#[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1569impl fmt::Debug for Literal {
1570    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1571        f.debug_struct("Literal")
1572            // format the kind on one line even in {:#?} mode
1573            .field("kind", &format_args!("{:?}", self.0.kind))
1574            .field("symbol", &self.0.symbol)
1575            // format `Some("...")` on one line even in {:#?} mode
1576            .field("suffix", &format_args!("{:?}", self.0.suffix))
1577            .field("span", &self.0.span)
1578            .finish()
1579    }
1580}
1581
1582/// Tracked access to environment variables.
1583#[unstable(feature = "proc_macro_tracked_env", issue = "99515")]
1584pub mod tracked_env {
1585    use std::env::{self, VarError};
1586    use std::ffi::OsStr;
1587
1588    /// Retrieve an environment variable and add it to build dependency info.
1589    /// The build system executing the compiler will know that the variable was accessed during
1590    /// compilation, and will be able to rerun the build when the value of that variable changes.
1591    /// Besides the dependency tracking this function should be equivalent to `env::var` from the
1592    /// standard library, except that the argument must be UTF-8.
1593    #[unstable(feature = "proc_macro_tracked_env", issue = "99515")]
1594    pub fn var<K: AsRef<OsStr> + AsRef<str>>(key: K) -> Result<String, VarError> {
1595        let key: &str = key.as_ref();
1596        let value = crate::bridge::client::FreeFunctions::injected_env_var(key)
1597            .map_or_else(|| env::var(key), Ok);
1598        crate::bridge::client::FreeFunctions::track_env_var(key, value.as_deref().ok());
1599        value
1600    }
1601}
1602
1603/// Tracked access to additional files.
1604#[unstable(feature = "track_path", issue = "99515")]
1605pub mod tracked_path {
1606
1607    /// Track a file explicitly.
1608    ///
1609    /// Commonly used for tracking asset preprocessing.
1610    #[unstable(feature = "track_path", issue = "99515")]
1611    pub fn path<P: AsRef<str>>(path: P) {
1612        let path: &str = path.as_ref();
1613        crate::bridge::client::FreeFunctions::track_path(path);
1614    }
1615}