1 //! A support library for macro authors when defining new macros.
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]`.
8 //! See [the book] for more.
10 //! [the book]: ../book/ch19-06-macros.html#procedural-macros-for-generating-code-from-attributes
12 #![stable(feature = "proc_macro_lib", since = "1.15.0")]
13 #![deny(missing_docs)]
15 html_root_url = "https://doc.rust-lang.org/nightly/",
16 html_playground_url = "https://play.rust-lang.org/",
17 issue_tracker_base_url = "https://github.com/rust-lang/rust/issues/",
18 test(no_crate_inject, attr(deny(warnings))),
19 test(attr(allow(dead_code, deprecated, unused_variables, unused_mut)))
21 #![feature(rustc_allow_const_fn_unstable)]
23 #![feature(staged_api)]
24 #![cfg_attr(bootstrap, feature(const_fn))]
25 #![cfg_attr(not(bootstrap), feature(const_fn_trait_bound))]
26 #![feature(const_fn_fn_ptr_basics)]
27 #![feature(allow_internal_unstable)]
28 #![feature(decl_macro)]
29 #![feature(extern_types)]
30 #![feature(in_band_lifetimes)]
31 #![feature(negative_impls)]
32 #![feature(auto_traits)]
33 #![feature(restricted_std)]
34 #![feature(rustc_attrs)]
35 #![feature(min_specialization)]
36 #![recursion_limit = "256"]
38 #[unstable(feature = "proc_macro_internals", issue = "27812")]
44 #[unstable(feature = "proc_macro_diagnostic", issue = "54140")]
45 pub use diagnostic::{Diagnostic, Level, MultiSpan};
47 use std::cmp::Ordering;
48 use std::ops::{Bound, RangeBounds};
49 use std::path::PathBuf;
50 use std::str::FromStr;
51 use std::{error, fmt, iter, mem};
53 /// Determines whether proc_macro has been made accessible to the currently
56 /// The proc_macro crate is only intended for use inside the implementation of
57 /// procedural macros. All the functions in this crate panic if invoked from
58 /// outside of a procedural macro, such as from a build script or unit test or
59 /// ordinary Rust binary.
61 /// With consideration for Rust libraries that are designed to support both
62 /// macro and non-macro use cases, `proc_macro::is_available()` provides a
63 /// non-panicking way to detect whether the infrastructure required to use the
64 /// API of proc_macro is presently available. Returns true if invoked from
65 /// inside of a procedural macro, false if invoked from any other binary.
66 #[unstable(feature = "proc_macro_is_available", issue = "71436")]
67 pub fn is_available() -> bool {
68 bridge::Bridge::is_available()
71 /// The main type provided by this crate, representing an abstract stream of
72 /// tokens, or, more specifically, a sequence of token trees.
73 /// The type provide interfaces for iterating over those token trees and, conversely,
74 /// collecting a number of token trees into one stream.
76 /// This is both the input and output of `#[proc_macro]`, `#[proc_macro_attribute]`
77 /// and `#[proc_macro_derive]` definitions.
78 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
80 pub struct TokenStream(bridge::client::TokenStream);
82 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
83 impl !Send for TokenStream {}
84 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
85 impl !Sync for TokenStream {}
87 /// Error returned from `TokenStream::from_str`.
88 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
94 #[stable(feature = "proc_macro_lexerror_impls", since = "1.44.0")]
95 impl fmt::Display for LexError {
96 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
97 f.write_str("cannot parse string into token stream")
101 #[stable(feature = "proc_macro_lexerror_impls", since = "1.44.0")]
102 impl error::Error for LexError {}
104 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
105 impl !Send for LexError {}
106 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
107 impl !Sync for LexError {}
110 /// Returns an empty `TokenStream` containing no token trees.
111 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
112 pub fn new() -> TokenStream {
113 TokenStream(bridge::client::TokenStream::new())
116 /// Checks if this `TokenStream` is empty.
117 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
118 pub fn is_empty(&self) -> bool {
123 /// Attempts to break the string into tokens and parse those tokens into a token stream.
124 /// May fail for a number of reasons, for example, if the string contains unbalanced delimiters
125 /// or characters not existing in the language.
126 /// All tokens in the parsed stream get `Span::call_site()` spans.
128 /// NOTE: some errors may cause panics instead of returning `LexError`. We reserve the right to
129 /// change these errors into `LexError`s later.
130 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
131 impl FromStr for TokenStream {
134 fn from_str(src: &str) -> Result<TokenStream, LexError> {
135 Ok(TokenStream(bridge::client::TokenStream::from_str(src)))
139 // N.B., the bridge only provides `to_string`, implement `fmt::Display`
140 // based on it (the reverse of the usual relationship between the two).
141 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
142 impl ToString for TokenStream {
143 fn to_string(&self) -> String {
148 /// Prints the token stream as a string that is supposed to be losslessly convertible back
149 /// into the same token stream (modulo spans), except for possibly `TokenTree::Group`s
150 /// with `Delimiter::None` delimiters and negative numeric literals.
151 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
152 impl fmt::Display for TokenStream {
153 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
154 f.write_str(&self.to_string())
158 /// Prints token in a form convenient for debugging.
159 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
160 impl fmt::Debug for TokenStream {
161 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
162 f.write_str("TokenStream ")?;
163 f.debug_list().entries(self.clone()).finish()
167 #[stable(feature = "proc_macro_token_stream_default", since = "1.45.0")]
168 impl Default for TokenStream {
169 fn default() -> Self {
174 #[unstable(feature = "proc_macro_quote", issue = "54722")]
175 pub use quote::{quote, quote_span};
177 /// Creates a token stream containing a single token tree.
178 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
179 impl From<TokenTree> for TokenStream {
180 fn from(tree: TokenTree) -> TokenStream {
181 TokenStream(bridge::client::TokenStream::from_token_tree(match tree {
182 TokenTree::Group(tt) => bridge::TokenTree::Group(tt.0),
183 TokenTree::Punct(tt) => bridge::TokenTree::Punct(tt.0),
184 TokenTree::Ident(tt) => bridge::TokenTree::Ident(tt.0),
185 TokenTree::Literal(tt) => bridge::TokenTree::Literal(tt.0),
190 /// Collects a number of token trees into a single stream.
191 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
192 impl iter::FromIterator<TokenTree> for TokenStream {
193 fn from_iter<I: IntoIterator<Item = TokenTree>>(trees: I) -> Self {
194 trees.into_iter().map(TokenStream::from).collect()
198 /// A "flattening" operation on token streams, collects token trees
199 /// from multiple token streams into a single stream.
200 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
201 impl iter::FromIterator<TokenStream> for TokenStream {
202 fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
203 let mut builder = bridge::client::TokenStreamBuilder::new();
204 streams.into_iter().for_each(|stream| builder.push(stream.0));
205 TokenStream(builder.build())
209 #[stable(feature = "token_stream_extend", since = "1.30.0")]
210 impl Extend<TokenTree> for TokenStream {
211 fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, trees: I) {
212 self.extend(trees.into_iter().map(TokenStream::from));
216 #[stable(feature = "token_stream_extend", since = "1.30.0")]
217 impl Extend<TokenStream> for TokenStream {
218 fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
219 // FIXME(eddyb) Use an optimized implementation if/when possible.
220 *self = iter::once(mem::replace(self, Self::new())).chain(streams).collect();
224 /// Public implementation details for the `TokenStream` type, such as iterators.
225 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
226 pub mod token_stream {
227 use crate::{bridge, Group, Ident, Literal, Punct, TokenStream, TokenTree};
229 /// An iterator over `TokenStream`'s `TokenTree`s.
230 /// The iteration is "shallow", e.g., the iterator doesn't recurse into delimited groups,
231 /// and returns whole groups as token trees.
233 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
234 pub struct IntoIter(bridge::client::TokenStreamIter);
236 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
237 impl Iterator for IntoIter {
238 type Item = TokenTree;
240 fn next(&mut self) -> Option<TokenTree> {
241 self.0.next().map(|tree| match tree {
242 bridge::TokenTree::Group(tt) => TokenTree::Group(Group(tt)),
243 bridge::TokenTree::Punct(tt) => TokenTree::Punct(Punct(tt)),
244 bridge::TokenTree::Ident(tt) => TokenTree::Ident(Ident(tt)),
245 bridge::TokenTree::Literal(tt) => TokenTree::Literal(Literal(tt)),
250 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
251 impl IntoIterator for TokenStream {
252 type Item = TokenTree;
253 type IntoIter = IntoIter;
255 fn into_iter(self) -> IntoIter {
256 IntoIter(self.0.into_iter())
261 /// `quote!(..)` accepts arbitrary tokens and expands into a `TokenStream` describing the input.
262 /// For example, `quote!(a + b)` will produce a expression, that, when evaluated, constructs
263 /// the `TokenStream` `[Ident("a"), Punct('+', Alone), Ident("b")]`.
265 /// Unquoting is done with `$`, and works by taking the single next ident as the unquoted term.
266 /// To quote `$` itself, use `$$`.
267 #[unstable(feature = "proc_macro_quote", issue = "54722")]
268 #[allow_internal_unstable(proc_macro_def_site)]
269 #[rustc_builtin_macro]
270 pub macro quote($($t:tt)*) {
271 /* compiler built-in */
274 #[unstable(feature = "proc_macro_internals", issue = "27812")]
278 /// A region of source code, along with macro expansion information.
279 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
280 #[derive(Copy, Clone)]
281 pub struct Span(bridge::client::Span);
283 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
284 impl !Send for Span {}
285 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
286 impl !Sync for Span {}
288 macro_rules! diagnostic_method {
289 ($name:ident, $level:expr) => {
290 /// Creates a new `Diagnostic` with the given `message` at the span
292 #[unstable(feature = "proc_macro_diagnostic", issue = "54140")]
293 pub fn $name<T: Into<String>>(self, message: T) -> Diagnostic {
294 Diagnostic::spanned(self, $level, message)
300 /// A span that resolves at the macro definition site.
301 #[unstable(feature = "proc_macro_def_site", issue = "54724")]
302 pub fn def_site() -> Span {
303 Span(bridge::client::Span::def_site())
306 /// The span of the invocation of the current procedural macro.
307 /// Identifiers created with this span will be resolved as if they were written
308 /// directly at the macro call location (call-site hygiene) and other code
309 /// at the macro call site will be able to refer to them as well.
310 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
311 pub fn call_site() -> Span {
312 Span(bridge::client::Span::call_site())
315 /// A span that represents `macro_rules` hygiene, and sometimes resolves at the macro
316 /// definition site (local variables, labels, `$crate`) and sometimes at the macro
317 /// call site (everything else).
318 /// The span location is taken from the call-site.
319 #[stable(feature = "proc_macro_mixed_site", since = "1.45.0")]
320 pub fn mixed_site() -> Span {
321 Span(bridge::client::Span::mixed_site())
324 /// The original source file into which this span points.
325 #[unstable(feature = "proc_macro_span", issue = "54725")]
326 pub fn source_file(&self) -> SourceFile {
327 SourceFile(self.0.source_file())
330 /// The `Span` for the tokens in the previous macro expansion from which
331 /// `self` was generated from, if any.
332 #[unstable(feature = "proc_macro_span", issue = "54725")]
333 pub fn parent(&self) -> Option<Span> {
334 self.0.parent().map(Span)
337 /// The span for the origin source code that `self` was generated from. If
338 /// this `Span` wasn't generated from other macro expansions then the return
339 /// value is the same as `*self`.
340 #[unstable(feature = "proc_macro_span", issue = "54725")]
341 pub fn source(&self) -> Span {
342 Span(self.0.source())
345 /// Gets the starting line/column in the source file for this span.
346 #[unstable(feature = "proc_macro_span", issue = "54725")]
347 pub fn start(&self) -> LineColumn {
351 /// Gets the ending line/column in the source file for this span.
352 #[unstable(feature = "proc_macro_span", issue = "54725")]
353 pub fn end(&self) -> LineColumn {
357 /// Creates a new span encompassing `self` and `other`.
359 /// Returns `None` if `self` and `other` are from different files.
360 #[unstable(feature = "proc_macro_span", issue = "54725")]
361 pub fn join(&self, other: Span) -> Option<Span> {
362 self.0.join(other.0).map(Span)
365 /// Creates a new span with the same line/column information as `self` but
366 /// that resolves symbols as though it were at `other`.
367 #[stable(feature = "proc_macro_span_resolved_at", since = "1.45.0")]
368 pub fn resolved_at(&self, other: Span) -> Span {
369 Span(self.0.resolved_at(other.0))
372 /// Creates a new span with the same name resolution behavior as `self` but
373 /// with the line/column information of `other`.
374 #[stable(feature = "proc_macro_span_located_at", since = "1.45.0")]
375 pub fn located_at(&self, other: Span) -> Span {
376 other.resolved_at(*self)
379 /// Compares to spans to see if they're equal.
380 #[unstable(feature = "proc_macro_span", issue = "54725")]
381 pub fn eq(&self, other: &Span) -> bool {
385 /// Returns the source text behind a span. This preserves the original source
386 /// code, including spaces and comments. It only returns a result if the span
387 /// corresponds to real source code.
389 /// Note: The observable result of a macro should only rely on the tokens and
390 /// not on this source text. The result of this function is a best effort to
391 /// be used for diagnostics only.
392 #[unstable(feature = "proc_macro_span", issue = "54725")]
393 pub fn source_text(&self) -> Option<String> {
397 diagnostic_method!(error, Level::Error);
398 diagnostic_method!(warning, Level::Warning);
399 diagnostic_method!(note, Level::Note);
400 diagnostic_method!(help, Level::Help);
403 /// Prints a span in a form convenient for debugging.
404 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
405 impl fmt::Debug for Span {
406 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
411 /// A line-column pair representing the start or end of a `Span`.
412 #[unstable(feature = "proc_macro_span", issue = "54725")]
413 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
414 pub struct LineColumn {
415 /// The 1-indexed line in the source file on which the span starts or ends (inclusive).
416 #[unstable(feature = "proc_macro_span", issue = "54725")]
418 /// The 0-indexed column (in UTF-8 characters) in the source file on which
419 /// the span starts or ends (inclusive).
420 #[unstable(feature = "proc_macro_span", issue = "54725")]
424 #[unstable(feature = "proc_macro_span", issue = "54725")]
425 impl !Send for LineColumn {}
426 #[unstable(feature = "proc_macro_span", issue = "54725")]
427 impl !Sync for LineColumn {}
429 #[unstable(feature = "proc_macro_span", issue = "54725")]
430 impl Ord for LineColumn {
431 fn cmp(&self, other: &Self) -> Ordering {
432 self.line.cmp(&other.line).then(self.column.cmp(&other.column))
436 #[unstable(feature = "proc_macro_span", issue = "54725")]
437 impl PartialOrd for LineColumn {
438 fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
439 Some(self.cmp(other))
443 /// The source file of a given `Span`.
444 #[unstable(feature = "proc_macro_span", issue = "54725")]
446 pub struct SourceFile(bridge::client::SourceFile);
449 /// Gets the path to this source file.
452 /// If the code span associated with this `SourceFile` was generated by an external macro, this
453 /// macro, this may not be an actual path on the filesystem. Use [`is_real`] to check.
455 /// Also note that even if `is_real` returns `true`, if `--remap-path-prefix` was passed on
456 /// the command line, the path as given may not actually be valid.
458 /// [`is_real`]: Self::is_real
459 #[unstable(feature = "proc_macro_span", issue = "54725")]
460 pub fn path(&self) -> PathBuf {
461 PathBuf::from(self.0.path())
464 /// Returns `true` if this source file is a real source file, and not generated by an external
465 /// macro's expansion.
466 #[unstable(feature = "proc_macro_span", issue = "54725")]
467 pub fn is_real(&self) -> bool {
468 // This is a hack until intercrate spans are implemented and we can have real source files
469 // for spans generated in external macros.
470 // https://github.com/rust-lang/rust/pull/43604#issuecomment-333334368
475 #[unstable(feature = "proc_macro_span", issue = "54725")]
476 impl fmt::Debug for SourceFile {
477 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
478 f.debug_struct("SourceFile")
479 .field("path", &self.path())
480 .field("is_real", &self.is_real())
485 #[unstable(feature = "proc_macro_span", issue = "54725")]
486 impl PartialEq for SourceFile {
487 fn eq(&self, other: &Self) -> bool {
492 #[unstable(feature = "proc_macro_span", issue = "54725")]
493 impl Eq for SourceFile {}
495 /// A single token or a delimited sequence of token trees (e.g., `[1, (), ..]`).
496 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
499 /// A token stream surrounded by bracket delimiters.
500 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
501 Group(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Group),
503 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
504 Ident(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Ident),
505 /// A single punctuation character (`+`, `,`, `$`, etc.).
506 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
507 Punct(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Punct),
508 /// A literal character (`'a'`), string (`"hello"`), number (`2.3`), etc.
509 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
510 Literal(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Literal),
513 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
514 impl !Send for TokenTree {}
515 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
516 impl !Sync for TokenTree {}
519 /// Returns the span of this tree, delegating to the `span` method of
520 /// the contained token or a delimited stream.
521 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
522 pub fn span(&self) -> Span {
524 TokenTree::Group(ref t) => t.span(),
525 TokenTree::Ident(ref t) => t.span(),
526 TokenTree::Punct(ref t) => t.span(),
527 TokenTree::Literal(ref t) => t.span(),
531 /// Configures the span for *only this token*.
533 /// Note that if this token is a `Group` then this method will not configure
534 /// the span of each of the internal tokens, this will simply delegate to
535 /// the `set_span` method of each variant.
536 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
537 pub fn set_span(&mut self, span: Span) {
539 TokenTree::Group(ref mut t) => t.set_span(span),
540 TokenTree::Ident(ref mut t) => t.set_span(span),
541 TokenTree::Punct(ref mut t) => t.set_span(span),
542 TokenTree::Literal(ref mut t) => t.set_span(span),
547 /// Prints token tree in a form convenient for debugging.
548 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
549 impl fmt::Debug for TokenTree {
550 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
551 // Each of these has the name in the struct type in the derived debug,
552 // so don't bother with an extra layer of indirection
554 TokenTree::Group(ref tt) => tt.fmt(f),
555 TokenTree::Ident(ref tt) => tt.fmt(f),
556 TokenTree::Punct(ref tt) => tt.fmt(f),
557 TokenTree::Literal(ref tt) => tt.fmt(f),
562 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
563 impl From<Group> for TokenTree {
564 fn from(g: Group) -> TokenTree {
569 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
570 impl From<Ident> for TokenTree {
571 fn from(g: Ident) -> TokenTree {
576 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
577 impl From<Punct> for TokenTree {
578 fn from(g: Punct) -> TokenTree {
583 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
584 impl From<Literal> for TokenTree {
585 fn from(g: Literal) -> TokenTree {
586 TokenTree::Literal(g)
590 // N.B., the bridge only provides `to_string`, implement `fmt::Display`
591 // based on it (the reverse of the usual relationship between the two).
592 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
593 impl ToString for TokenTree {
594 fn to_string(&self) -> String {
596 TokenTree::Group(ref t) => t.to_string(),
597 TokenTree::Ident(ref t) => t.to_string(),
598 TokenTree::Punct(ref t) => t.to_string(),
599 TokenTree::Literal(ref t) => t.to_string(),
604 /// Prints the token tree as a string that is supposed to be losslessly convertible back
605 /// into the same token tree (modulo spans), except for possibly `TokenTree::Group`s
606 /// with `Delimiter::None` delimiters and negative numeric literals.
607 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
608 impl fmt::Display for TokenTree {
609 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
610 f.write_str(&self.to_string())
614 /// A delimited token stream.
616 /// A `Group` internally contains a `TokenStream` which is surrounded by `Delimiter`s.
618 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
619 pub struct Group(bridge::client::Group);
621 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
622 impl !Send for Group {}
623 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
624 impl !Sync for Group {}
626 /// Describes how a sequence of token trees is delimited.
627 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
628 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
631 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
634 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
637 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
640 /// An implicit delimiter, that may, for example, appear around tokens coming from a
641 /// "macro variable" `$var`. It is important to preserve operator priorities in cases like
642 /// `$var * 3` where `$var` is `1 + 2`.
643 /// Implicit delimiters may not survive roundtrip of a token stream through a string.
644 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
649 /// Creates a new `Group` with the given delimiter and token stream.
651 /// This constructor will set the span for this group to
652 /// `Span::call_site()`. To change the span you can use the `set_span`
654 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
655 pub fn new(delimiter: Delimiter, stream: TokenStream) -> Group {
656 Group(bridge::client::Group::new(delimiter, stream.0))
659 /// Returns the delimiter of this `Group`
660 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
661 pub fn delimiter(&self) -> Delimiter {
665 /// Returns the `TokenStream` of tokens that are delimited in this `Group`.
667 /// Note that the returned token stream does not include the delimiter
669 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
670 pub fn stream(&self) -> TokenStream {
671 TokenStream(self.0.stream())
674 /// Returns the span for the delimiters of this token stream, spanning the
678 /// pub fn span(&self) -> Span {
681 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
682 pub fn span(&self) -> Span {
686 /// Returns the span pointing to the opening delimiter of this group.
689 /// pub fn span_open(&self) -> Span {
692 #[unstable(feature = "proc_macro_span", issue = "54725")]
693 pub fn span_open(&self) -> Span {
694 Span(self.0.span_open())
697 /// Returns the span pointing to the closing delimiter of this group.
700 /// pub fn span_close(&self) -> Span {
703 #[unstable(feature = "proc_macro_span", issue = "54725")]
704 pub fn span_close(&self) -> Span {
705 Span(self.0.span_close())
708 /// Configures the span for this `Group`'s delimiters, but not its internal
711 /// This method will **not** set the span of all the internal tokens spanned
712 /// by this group, but rather it will only set the span of the delimiter
713 /// tokens at the level of the `Group`.
714 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
715 pub fn set_span(&mut self, span: Span) {
716 self.0.set_span(span.0);
720 // N.B., the bridge only provides `to_string`, implement `fmt::Display`
721 // based on it (the reverse of the usual relationship between the two).
722 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
723 impl ToString for Group {
724 fn to_string(&self) -> String {
725 TokenStream::from(TokenTree::from(self.clone())).to_string()
729 /// Prints the group as a string that should be losslessly convertible back
730 /// into the same group (modulo spans), except for possibly `TokenTree::Group`s
731 /// with `Delimiter::None` delimiters.
732 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
733 impl fmt::Display for Group {
734 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
735 f.write_str(&self.to_string())
739 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
740 impl fmt::Debug for Group {
741 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
742 f.debug_struct("Group")
743 .field("delimiter", &self.delimiter())
744 .field("stream", &self.stream())
745 .field("span", &self.span())
750 /// An `Punct` is an single punctuation character like `+`, `-` or `#`.
752 /// Multi-character operators like `+=` are represented as two instances of `Punct` with different
753 /// forms of `Spacing` returned.
754 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
756 pub struct Punct(bridge::client::Punct);
758 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
759 impl !Send for Punct {}
760 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
761 impl !Sync for Punct {}
763 /// Whether an `Punct` is followed immediately by another `Punct` or
764 /// followed by another token or whitespace.
765 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
766 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
768 /// e.g., `+` is `Alone` in `+ =`, `+ident` or `+()`.
769 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
771 /// e.g., `+` is `Joint` in `+=` or `'#`.
772 /// Additionally, single quote `'` can join with identifiers to form lifetimes `'ident`.
773 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
778 /// Creates a new `Punct` from the given character and spacing.
779 /// The `ch` argument must be a valid punctuation character permitted by the language,
780 /// otherwise the function will panic.
782 /// The returned `Punct` will have the default span of `Span::call_site()`
783 /// which can be further configured with the `set_span` method below.
784 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
785 pub fn new(ch: char, spacing: Spacing) -> Punct {
786 Punct(bridge::client::Punct::new(ch, spacing))
789 /// Returns the value of this punctuation character as `char`.
790 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
791 pub fn as_char(&self) -> char {
795 /// Returns the spacing of this punctuation character, indicating whether it's immediately
796 /// followed by another `Punct` in the token stream, so they can potentially be combined into
797 /// a multi-character operator (`Joint`), or it's followed by some other token or whitespace
798 /// (`Alone`) so the operator has certainly ended.
799 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
800 pub fn spacing(&self) -> Spacing {
804 /// Returns the span for this punctuation character.
805 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
806 pub fn span(&self) -> Span {
810 /// Configure the span for this punctuation character.
811 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
812 pub fn set_span(&mut self, span: Span) {
813 self.0 = self.0.with_span(span.0);
817 // N.B., the bridge only provides `to_string`, implement `fmt::Display`
818 // based on it (the reverse of the usual relationship between the two).
819 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
820 impl ToString for Punct {
821 fn to_string(&self) -> String {
822 TokenStream::from(TokenTree::from(self.clone())).to_string()
826 /// Prints the punctuation character as a string that should be losslessly convertible
827 /// back into the same character.
828 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
829 impl fmt::Display for Punct {
830 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
831 f.write_str(&self.to_string())
835 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
836 impl fmt::Debug for Punct {
837 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
838 f.debug_struct("Punct")
839 .field("ch", &self.as_char())
840 .field("spacing", &self.spacing())
841 .field("span", &self.span())
846 #[stable(feature = "proc_macro_punct_eq", since = "1.50.0")]
847 impl PartialEq<char> for Punct {
848 fn eq(&self, rhs: &char) -> bool {
849 self.as_char() == *rhs
853 #[stable(feature = "proc_macro_punct_eq_flipped", since = "1.52.0")]
854 impl PartialEq<Punct> for char {
855 fn eq(&self, rhs: &Punct) -> bool {
856 *self == rhs.as_char()
860 /// An identifier (`ident`).
862 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
863 pub struct Ident(bridge::client::Ident);
866 /// Creates a new `Ident` with the given `string` as well as the specified
868 /// The `string` argument must be a valid identifier permitted by the
869 /// language (including keywords, e.g. `self` or `fn`). Otherwise, the function will panic.
871 /// Note that `span`, currently in rustc, configures the hygiene information
872 /// for this identifier.
874 /// As of this time `Span::call_site()` explicitly opts-in to "call-site" hygiene
875 /// meaning that identifiers created with this span will be resolved as if they were written
876 /// directly at the location of the macro call, and other code at the macro call site will be
877 /// able to refer to them as well.
879 /// Later spans like `Span::def_site()` will allow to opt-in to "definition-site" hygiene
880 /// meaning that identifiers created with this span will be resolved at the location of the
881 /// macro definition and other code at the macro call site will not be able to refer to them.
883 /// Due to the current importance of hygiene this constructor, unlike other
884 /// tokens, requires a `Span` to be specified at construction.
885 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
886 pub fn new(string: &str, span: Span) -> Ident {
887 Ident(bridge::client::Ident::new(string, span.0, false))
890 /// Same as `Ident::new`, but creates a raw identifier (`r#ident`).
891 /// The `string` argument be a valid identifier permitted by the language
892 /// (including keywords, e.g. `fn`). Keywords which are usable in path segments
893 /// (e.g. `self`, `super`) are not supported, and will cause a panic.
894 #[stable(feature = "proc_macro_raw_ident", since = "1.47.0")]
895 pub fn new_raw(string: &str, span: Span) -> Ident {
896 Ident(bridge::client::Ident::new(string, span.0, true))
899 /// Returns the span of this `Ident`, encompassing the entire string returned
900 /// by [`to_string`](Self::to_string).
901 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
902 pub fn span(&self) -> Span {
906 /// Configures the span of this `Ident`, possibly changing its hygiene context.
907 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
908 pub fn set_span(&mut self, span: Span) {
909 self.0 = self.0.with_span(span.0);
913 // N.B., the bridge only provides `to_string`, implement `fmt::Display`
914 // based on it (the reverse of the usual relationship between the two).
915 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
916 impl ToString for Ident {
917 fn to_string(&self) -> String {
918 TokenStream::from(TokenTree::from(self.clone())).to_string()
922 /// Prints the identifier as a string that should be losslessly convertible
923 /// back into the same identifier.
924 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
925 impl fmt::Display for Ident {
926 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
927 f.write_str(&self.to_string())
931 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
932 impl fmt::Debug for Ident {
933 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
934 f.debug_struct("Ident")
935 .field("ident", &self.to_string())
936 .field("span", &self.span())
941 /// A literal string (`"hello"`), byte string (`b"hello"`),
942 /// character (`'a'`), byte character (`b'a'`), an integer or floating point number
943 /// with or without a suffix (`1`, `1u8`, `2.3`, `2.3f32`).
944 /// Boolean literals like `true` and `false` do not belong here, they are `Ident`s.
946 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
947 pub struct Literal(bridge::client::Literal);
949 macro_rules! suffixed_int_literals {
950 ($($name:ident => $kind:ident,)*) => ($(
951 /// Creates a new suffixed integer literal with the specified value.
953 /// This function will create an integer like `1u32` where the integer
954 /// value specified is the first part of the token and the integral is
955 /// also suffixed at the end.
956 /// Literals created from negative numbers may not survive round-trips through
957 /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
959 /// Literals created through this method have the `Span::call_site()`
960 /// span by default, which can be configured with the `set_span` method
962 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
963 pub fn $name(n: $kind) -> Literal {
964 Literal(bridge::client::Literal::typed_integer(&n.to_string(), stringify!($kind)))
969 macro_rules! unsuffixed_int_literals {
970 ($($name:ident => $kind:ident,)*) => ($(
971 /// Creates a new unsuffixed integer literal with the specified value.
973 /// This function will create an integer like `1` where the integer
974 /// value specified is the first part of the token. No suffix is
975 /// specified on this token, meaning that invocations like
976 /// `Literal::i8_unsuffixed(1)` are equivalent to
977 /// `Literal::u32_unsuffixed(1)`.
978 /// Literals created from negative numbers may not survive rountrips through
979 /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
981 /// Literals created through this method have the `Span::call_site()`
982 /// span by default, which can be configured with the `set_span` method
984 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
985 pub fn $name(n: $kind) -> Literal {
986 Literal(bridge::client::Literal::integer(&n.to_string()))
992 suffixed_int_literals! {
997 u128_suffixed => u128,
998 usize_suffixed => usize,
1000 i16_suffixed => i16,
1001 i32_suffixed => i32,
1002 i64_suffixed => i64,
1003 i128_suffixed => i128,
1004 isize_suffixed => isize,
1007 unsuffixed_int_literals! {
1008 u8_unsuffixed => u8,
1009 u16_unsuffixed => u16,
1010 u32_unsuffixed => u32,
1011 u64_unsuffixed => u64,
1012 u128_unsuffixed => u128,
1013 usize_unsuffixed => usize,
1014 i8_unsuffixed => i8,
1015 i16_unsuffixed => i16,
1016 i32_unsuffixed => i32,
1017 i64_unsuffixed => i64,
1018 i128_unsuffixed => i128,
1019 isize_unsuffixed => isize,
1022 /// Creates a new unsuffixed floating-point literal.
1024 /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1025 /// the float's value is emitted directly into the token but no suffix is
1026 /// used, so it may be inferred to be a `f64` later in the compiler.
1027 /// Literals created from negative numbers may not survive rountrips through
1028 /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1032 /// This function requires that the specified float is finite, for
1033 /// example if it is infinity or NaN this function will panic.
1034 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1035 pub fn f32_unsuffixed(n: f32) -> Literal {
1037 panic!("Invalid float literal {}", n);
1039 Literal(bridge::client::Literal::float(&n.to_string()))
1042 /// Creates a new suffixed floating-point literal.
1044 /// This constructor will create a literal like `1.0f32` where the value
1045 /// specified is the preceding part of the token and `f32` is the suffix of
1046 /// the token. This token will always be inferred to be an `f32` in the
1048 /// Literals created from negative numbers may not survive rountrips through
1049 /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1053 /// This function requires that the specified float is finite, for
1054 /// example if it is infinity or NaN this function will panic.
1055 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1056 pub fn f32_suffixed(n: f32) -> Literal {
1058 panic!("Invalid float literal {}", n);
1060 Literal(bridge::client::Literal::f32(&n.to_string()))
1063 /// Creates a new unsuffixed floating-point literal.
1065 /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1066 /// the float's value is emitted directly into the token but no suffix is
1067 /// used, so it may be inferred to be a `f64` later in the compiler.
1068 /// Literals created from negative numbers may not survive rountrips through
1069 /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1073 /// This function requires that the specified float is finite, for
1074 /// example if it is infinity or NaN this function will panic.
1075 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1076 pub fn f64_unsuffixed(n: f64) -> Literal {
1078 panic!("Invalid float literal {}", n);
1080 Literal(bridge::client::Literal::float(&n.to_string()))
1083 /// Creates a new suffixed floating-point literal.
1085 /// This constructor will create a literal like `1.0f64` where the value
1086 /// specified is the preceding part of the token and `f64` is the suffix of
1087 /// the token. This token will always be inferred to be an `f64` in the
1089 /// Literals created from negative numbers may not survive rountrips through
1090 /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1094 /// This function requires that the specified float is finite, for
1095 /// example if it is infinity or NaN this function will panic.
1096 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1097 pub fn f64_suffixed(n: f64) -> Literal {
1099 panic!("Invalid float literal {}", n);
1101 Literal(bridge::client::Literal::f64(&n.to_string()))
1105 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1106 pub fn string(string: &str) -> Literal {
1107 Literal(bridge::client::Literal::string(string))
1110 /// Character literal.
1111 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1112 pub fn character(ch: char) -> Literal {
1113 Literal(bridge::client::Literal::character(ch))
1116 /// Byte string literal.
1117 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1118 pub fn byte_string(bytes: &[u8]) -> Literal {
1119 Literal(bridge::client::Literal::byte_string(bytes))
1122 /// Returns the span encompassing this literal.
1123 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1124 pub fn span(&self) -> Span {
1128 /// Configures the span associated for this literal.
1129 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1130 pub fn set_span(&mut self, span: Span) {
1131 self.0.set_span(span.0);
1134 /// Returns a `Span` that is a subset of `self.span()` containing only the
1135 /// source bytes in range `range`. Returns `None` if the would-be trimmed
1136 /// span is outside the bounds of `self`.
1137 // FIXME(SergioBenitez): check that the byte range starts and ends at a
1138 // UTF-8 boundary of the source. otherwise, it's likely that a panic will
1139 // occur elsewhere when the source text is printed.
1140 // FIXME(SergioBenitez): there is no way for the user to know what
1141 // `self.span()` actually maps to, so this method can currently only be
1142 // called blindly. For example, `to_string()` for the character 'c' returns
1143 // "'\u{63}'"; there is no way for the user to know whether the source text
1144 // was 'c' or whether it was '\u{63}'.
1145 #[unstable(feature = "proc_macro_span", issue = "54725")]
1146 pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
1147 // HACK(eddyb) something akin to `Option::cloned`, but for `Bound<&T>`.
1148 fn cloned_bound<T: Clone>(bound: Bound<&T>) -> Bound<T> {
1150 Bound::Included(x) => Bound::Included(x.clone()),
1151 Bound::Excluded(x) => Bound::Excluded(x.clone()),
1152 Bound::Unbounded => Bound::Unbounded,
1156 self.0.subspan(cloned_bound(range.start_bound()), cloned_bound(range.end_bound())).map(Span)
1160 // N.B., the bridge only provides `to_string`, implement `fmt::Display`
1161 // based on it (the reverse of the usual relationship between the two).
1162 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
1163 impl ToString for Literal {
1164 fn to_string(&self) -> String {
1165 TokenStream::from(TokenTree::from(self.clone())).to_string()
1169 /// Prints the literal as a string that should be losslessly convertible
1170 /// back into the same literal (except for possible rounding for floating point literals).
1171 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1172 impl fmt::Display for Literal {
1173 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1174 f.write_str(&self.to_string())
1178 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1179 impl fmt::Debug for Literal {
1180 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1185 /// Tracked access to environment variables.
1186 #[unstable(feature = "proc_macro_tracked_env", issue = "74690")]
1187 pub mod tracked_env {
1188 use std::env::{self, VarError};
1189 use std::ffi::OsStr;
1191 /// Retrieve an environment variable and add it to build dependency info.
1192 /// Build system executing the compiler will know that the variable was accessed during
1193 /// compilation, and will be able to rerun the build when the value of that variable changes.
1194 /// Besides the dependency tracking this function should be equivalent to `env::var` from the
1195 /// standard library, except that the argument must be UTF-8.
1196 #[unstable(feature = "proc_macro_tracked_env", issue = "74690")]
1197 pub fn var<K: AsRef<OsStr> + AsRef<str>>(key: K) -> Result<String, VarError> {
1198 let key: &str = key.as_ref();
1199 let value = env::var(key);
1200 crate::bridge::client::FreeFunctions::track_env_var(key, value.as_deref().ok());