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)]
25 #![feature(const_fn_fn_ptr_basics)]
26 #![feature(allow_internal_unstable)]
27 #![feature(decl_macro)]
28 #![feature(extern_types)]
29 #![feature(in_band_lifetimes)]
30 #![feature(negative_impls)]
31 #![feature(auto_traits)]
32 #![feature(restricted_std)]
33 #![feature(rustc_attrs)]
34 #![feature(min_specialization)]
35 #![recursion_limit = "256"]
37 #[unstable(feature = "proc_macro_internals", issue = "27812")]
43 #[unstable(feature = "proc_macro_diagnostic", issue = "54140")]
44 pub use diagnostic::{Diagnostic, Level, MultiSpan};
46 use std::cmp::Ordering;
47 use std::ops::{Bound, RangeBounds};
48 use std::path::PathBuf;
49 use std::str::FromStr;
50 use std::{error, fmt, iter, mem};
52 /// Determines whether proc_macro has been made accessible to the currently
55 /// The proc_macro crate is only intended for use inside the implementation of
56 /// procedural macros. All the functions in this crate panic if invoked from
57 /// outside of a procedural macro, such as from a build script or unit test or
58 /// ordinary Rust binary.
60 /// With consideration for Rust libraries that are designed to support both
61 /// macro and non-macro use cases, `proc_macro::is_available()` provides a
62 /// non-panicking way to detect whether the infrastructure required to use the
63 /// API of proc_macro is presently available. Returns true if invoked from
64 /// inside of a procedural macro, false if invoked from any other binary.
65 #[unstable(feature = "proc_macro_is_available", issue = "71436")]
66 pub fn is_available() -> bool {
67 bridge::Bridge::is_available()
70 /// The main type provided by this crate, representing an abstract stream of
71 /// tokens, or, more specifically, a sequence of token trees.
72 /// The type provide interfaces for iterating over those token trees and, conversely,
73 /// collecting a number of token trees into one stream.
75 /// This is both the input and output of `#[proc_macro]`, `#[proc_macro_attribute]`
76 /// and `#[proc_macro_derive]` definitions.
77 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
79 pub struct TokenStream(bridge::client::TokenStream);
81 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
82 impl !Send for TokenStream {}
83 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
84 impl !Sync for TokenStream {}
86 /// Error returned from `TokenStream::from_str`.
87 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
93 #[stable(feature = "proc_macro_lexerror_impls", since = "1.44.0")]
94 impl fmt::Display for LexError {
95 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
96 f.write_str("cannot parse string into token stream")
100 #[stable(feature = "proc_macro_lexerror_impls", since = "1.44.0")]
101 impl error::Error for LexError {}
103 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
104 impl !Send for LexError {}
105 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
106 impl !Sync for LexError {}
109 /// Returns an empty `TokenStream` containing no token trees.
110 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
111 pub fn new() -> TokenStream {
112 TokenStream(bridge::client::TokenStream::new())
115 /// Checks if this `TokenStream` is empty.
116 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
117 pub fn is_empty(&self) -> bool {
122 /// Attempts to break the string into tokens and parse those tokens into a token stream.
123 /// May fail for a number of reasons, for example, if the string contains unbalanced delimiters
124 /// or characters not existing in the language.
125 /// All tokens in the parsed stream get `Span::call_site()` spans.
127 /// NOTE: some errors may cause panics instead of returning `LexError`. We reserve the right to
128 /// change these errors into `LexError`s later.
129 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
130 impl FromStr for TokenStream {
133 fn from_str(src: &str) -> Result<TokenStream, LexError> {
134 Ok(TokenStream(bridge::client::TokenStream::from_str(src)))
138 // N.B., the bridge only provides `to_string`, implement `fmt::Display`
139 // based on it (the reverse of the usual relationship between the two).
140 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
141 impl ToString for TokenStream {
142 fn to_string(&self) -> String {
147 /// Prints the token stream as a string that is supposed to be losslessly convertible back
148 /// into the same token stream (modulo spans), except for possibly `TokenTree::Group`s
149 /// with `Delimiter::None` delimiters and negative numeric literals.
150 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
151 impl fmt::Display for TokenStream {
152 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
153 f.write_str(&self.to_string())
157 /// Prints token in a form convenient for debugging.
158 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
159 impl fmt::Debug for TokenStream {
160 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
161 f.write_str("TokenStream ")?;
162 f.debug_list().entries(self.clone()).finish()
166 #[stable(feature = "proc_macro_token_stream_default", since = "1.45.0")]
167 impl Default for TokenStream {
168 fn default() -> Self {
173 #[unstable(feature = "proc_macro_quote", issue = "54722")]
174 pub use quote::{quote, quote_span};
176 /// Creates a token stream containing a single token tree.
177 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
178 impl From<TokenTree> for TokenStream {
179 fn from(tree: TokenTree) -> TokenStream {
180 TokenStream(bridge::client::TokenStream::from_token_tree(match tree {
181 TokenTree::Group(tt) => bridge::TokenTree::Group(tt.0),
182 TokenTree::Punct(tt) => bridge::TokenTree::Punct(tt.0),
183 TokenTree::Ident(tt) => bridge::TokenTree::Ident(tt.0),
184 TokenTree::Literal(tt) => bridge::TokenTree::Literal(tt.0),
189 /// Collects a number of token trees into a single stream.
190 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
191 impl iter::FromIterator<TokenTree> for TokenStream {
192 fn from_iter<I: IntoIterator<Item = TokenTree>>(trees: I) -> Self {
193 trees.into_iter().map(TokenStream::from).collect()
197 /// A "flattening" operation on token streams, collects token trees
198 /// from multiple token streams into a single stream.
199 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
200 impl iter::FromIterator<TokenStream> for TokenStream {
201 fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
202 let mut builder = bridge::client::TokenStreamBuilder::new();
203 streams.into_iter().for_each(|stream| builder.push(stream.0));
204 TokenStream(builder.build())
208 #[stable(feature = "token_stream_extend", since = "1.30.0")]
209 impl Extend<TokenTree> for TokenStream {
210 fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, trees: I) {
211 self.extend(trees.into_iter().map(TokenStream::from));
215 #[stable(feature = "token_stream_extend", since = "1.30.0")]
216 impl Extend<TokenStream> for TokenStream {
217 fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
218 // FIXME(eddyb) Use an optimized implementation if/when possible.
219 *self = iter::once(mem::replace(self, Self::new())).chain(streams).collect();
223 /// Public implementation details for the `TokenStream` type, such as iterators.
224 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
225 pub mod token_stream {
226 use crate::{bridge, Group, Ident, Literal, Punct, TokenStream, TokenTree};
228 /// An iterator over `TokenStream`'s `TokenTree`s.
229 /// The iteration is "shallow", e.g., the iterator doesn't recurse into delimited groups,
230 /// and returns whole groups as token trees.
232 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
233 pub struct IntoIter(bridge::client::TokenStreamIter);
235 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
236 impl Iterator for IntoIter {
237 type Item = TokenTree;
239 fn next(&mut self) -> Option<TokenTree> {
240 self.0.next().map(|tree| match tree {
241 bridge::TokenTree::Group(tt) => TokenTree::Group(Group(tt)),
242 bridge::TokenTree::Punct(tt) => TokenTree::Punct(Punct(tt)),
243 bridge::TokenTree::Ident(tt) => TokenTree::Ident(Ident(tt)),
244 bridge::TokenTree::Literal(tt) => TokenTree::Literal(Literal(tt)),
249 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
250 impl IntoIterator for TokenStream {
251 type Item = TokenTree;
252 type IntoIter = IntoIter;
254 fn into_iter(self) -> IntoIter {
255 IntoIter(self.0.into_iter())
260 /// `quote!(..)` accepts arbitrary tokens and expands into a `TokenStream` describing the input.
261 /// For example, `quote!(a + b)` will produce a expression, that, when evaluated, constructs
262 /// the `TokenStream` `[Ident("a"), Punct('+', Alone), Ident("b")]`.
264 /// Unquoting is done with `$`, and works by taking the single next ident as the unquoted term.
265 /// To quote `$` itself, use `$$`.
266 #[unstable(feature = "proc_macro_quote", issue = "54722")]
267 #[allow_internal_unstable(proc_macro_def_site)]
268 #[rustc_builtin_macro]
269 pub macro quote($($t:tt)*) {
270 /* compiler built-in */
273 #[unstable(feature = "proc_macro_internals", issue = "27812")]
277 /// A region of source code, along with macro expansion information.
278 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
279 #[derive(Copy, Clone)]
280 pub struct Span(bridge::client::Span);
282 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
283 impl !Send for Span {}
284 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
285 impl !Sync for Span {}
287 macro_rules! diagnostic_method {
288 ($name:ident, $level:expr) => {
289 /// Creates a new `Diagnostic` with the given `message` at the span
291 #[unstable(feature = "proc_macro_diagnostic", issue = "54140")]
292 pub fn $name<T: Into<String>>(self, message: T) -> Diagnostic {
293 Diagnostic::spanned(self, $level, message)
299 /// A span that resolves at the macro definition site.
300 #[unstable(feature = "proc_macro_def_site", issue = "54724")]
301 pub fn def_site() -> Span {
302 Span(bridge::client::Span::def_site())
305 /// The span of the invocation of the current procedural macro.
306 /// Identifiers created with this span will be resolved as if they were written
307 /// directly at the macro call location (call-site hygiene) and other code
308 /// at the macro call site will be able to refer to them as well.
309 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
310 pub fn call_site() -> Span {
311 Span(bridge::client::Span::call_site())
314 /// A span that represents `macro_rules` hygiene, and sometimes resolves at the macro
315 /// definition site (local variables, labels, `$crate`) and sometimes at the macro
316 /// call site (everything else).
317 /// The span location is taken from the call-site.
318 #[stable(feature = "proc_macro_mixed_site", since = "1.45.0")]
319 pub fn mixed_site() -> Span {
320 Span(bridge::client::Span::mixed_site())
323 /// The original source file into which this span points.
324 #[unstable(feature = "proc_macro_span", issue = "54725")]
325 pub fn source_file(&self) -> SourceFile {
326 SourceFile(self.0.source_file())
329 /// The `Span` for the tokens in the previous macro expansion from which
330 /// `self` was generated from, if any.
331 #[unstable(feature = "proc_macro_span", issue = "54725")]
332 pub fn parent(&self) -> Option<Span> {
333 self.0.parent().map(Span)
336 /// The span for the origin source code that `self` was generated from. If
337 /// this `Span` wasn't generated from other macro expansions then the return
338 /// value is the same as `*self`.
339 #[unstable(feature = "proc_macro_span", issue = "54725")]
340 pub fn source(&self) -> Span {
341 Span(self.0.source())
344 /// Gets the starting line/column in the source file for this span.
345 #[unstable(feature = "proc_macro_span", issue = "54725")]
346 pub fn start(&self) -> LineColumn {
350 /// Gets the ending line/column in the source file for this span.
351 #[unstable(feature = "proc_macro_span", issue = "54725")]
352 pub fn end(&self) -> LineColumn {
356 /// Creates a new span encompassing `self` and `other`.
358 /// Returns `None` if `self` and `other` are from different files.
359 #[unstable(feature = "proc_macro_span", issue = "54725")]
360 pub fn join(&self, other: Span) -> Option<Span> {
361 self.0.join(other.0).map(Span)
364 /// Creates a new span with the same line/column information as `self` but
365 /// that resolves symbols as though it were at `other`.
366 #[stable(feature = "proc_macro_span_resolved_at", since = "1.45.0")]
367 pub fn resolved_at(&self, other: Span) -> Span {
368 Span(self.0.resolved_at(other.0))
371 /// Creates a new span with the same name resolution behavior as `self` but
372 /// with the line/column information of `other`.
373 #[stable(feature = "proc_macro_span_located_at", since = "1.45.0")]
374 pub fn located_at(&self, other: Span) -> Span {
375 other.resolved_at(*self)
378 /// Compares to spans to see if they're equal.
379 #[unstable(feature = "proc_macro_span", issue = "54725")]
380 pub fn eq(&self, other: &Span) -> bool {
384 /// Returns the source text behind a span. This preserves the original source
385 /// code, including spaces and comments. It only returns a result if the span
386 /// corresponds to real source code.
388 /// Note: The observable result of a macro should only rely on the tokens and
389 /// not on this source text. The result of this function is a best effort to
390 /// be used for diagnostics only.
391 #[unstable(feature = "proc_macro_span", issue = "54725")]
392 pub fn source_text(&self) -> Option<String> {
396 diagnostic_method!(error, Level::Error);
397 diagnostic_method!(warning, Level::Warning);
398 diagnostic_method!(note, Level::Note);
399 diagnostic_method!(help, Level::Help);
402 /// Prints a span in a form convenient for debugging.
403 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
404 impl fmt::Debug for Span {
405 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
410 /// A line-column pair representing the start or end of a `Span`.
411 #[unstable(feature = "proc_macro_span", issue = "54725")]
412 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
413 pub struct LineColumn {
414 /// The 1-indexed line in the source file on which the span starts or ends (inclusive).
415 #[unstable(feature = "proc_macro_span", issue = "54725")]
417 /// The 0-indexed column (in UTF-8 characters) in the source file on which
418 /// the span starts or ends (inclusive).
419 #[unstable(feature = "proc_macro_span", issue = "54725")]
423 #[unstable(feature = "proc_macro_span", issue = "54725")]
424 impl !Send for LineColumn {}
425 #[unstable(feature = "proc_macro_span", issue = "54725")]
426 impl !Sync for LineColumn {}
428 #[unstable(feature = "proc_macro_span", issue = "54725")]
429 impl Ord for LineColumn {
430 fn cmp(&self, other: &Self) -> Ordering {
431 self.line.cmp(&other.line).then(self.column.cmp(&other.column))
435 #[unstable(feature = "proc_macro_span", issue = "54725")]
436 impl PartialOrd for LineColumn {
437 fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
438 Some(self.cmp(other))
442 /// The source file of a given `Span`.
443 #[unstable(feature = "proc_macro_span", issue = "54725")]
445 pub struct SourceFile(bridge::client::SourceFile);
448 /// Gets the path to this source file.
451 /// If the code span associated with this `SourceFile` was generated by an external macro, this
452 /// macro, this may not be an actual path on the filesystem. Use [`is_real`] to check.
454 /// Also note that even if `is_real` returns `true`, if `--remap-path-prefix` was passed on
455 /// the command line, the path as given may not actually be valid.
457 /// [`is_real`]: Self::is_real
458 #[unstable(feature = "proc_macro_span", issue = "54725")]
459 pub fn path(&self) -> PathBuf {
460 PathBuf::from(self.0.path())
463 /// Returns `true` if this source file is a real source file, and not generated by an external
464 /// macro's expansion.
465 #[unstable(feature = "proc_macro_span", issue = "54725")]
466 pub fn is_real(&self) -> bool {
467 // This is a hack until intercrate spans are implemented and we can have real source files
468 // for spans generated in external macros.
469 // https://github.com/rust-lang/rust/pull/43604#issuecomment-333334368
474 #[unstable(feature = "proc_macro_span", issue = "54725")]
475 impl fmt::Debug for SourceFile {
476 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
477 f.debug_struct("SourceFile")
478 .field("path", &self.path())
479 .field("is_real", &self.is_real())
484 #[unstable(feature = "proc_macro_span", issue = "54725")]
485 impl PartialEq for SourceFile {
486 fn eq(&self, other: &Self) -> bool {
491 #[unstable(feature = "proc_macro_span", issue = "54725")]
492 impl Eq for SourceFile {}
494 /// A single token or a delimited sequence of token trees (e.g., `[1, (), ..]`).
495 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
498 /// A token stream surrounded by bracket delimiters.
499 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
500 Group(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Group),
502 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
503 Ident(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Ident),
504 /// A single punctuation character (`+`, `,`, `$`, etc.).
505 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
506 Punct(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Punct),
507 /// A literal character (`'a'`), string (`"hello"`), number (`2.3`), etc.
508 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
509 Literal(#[stable(feature = "proc_macro_lib2", since = "1.29.0")] Literal),
512 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
513 impl !Send for TokenTree {}
514 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
515 impl !Sync for TokenTree {}
518 /// Returns the span of this tree, delegating to the `span` method of
519 /// the contained token or a delimited stream.
520 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
521 pub fn span(&self) -> Span {
523 TokenTree::Group(ref t) => t.span(),
524 TokenTree::Ident(ref t) => t.span(),
525 TokenTree::Punct(ref t) => t.span(),
526 TokenTree::Literal(ref t) => t.span(),
530 /// Configures the span for *only this token*.
532 /// Note that if this token is a `Group` then this method will not configure
533 /// the span of each of the internal tokens, this will simply delegate to
534 /// the `set_span` method of each variant.
535 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
536 pub fn set_span(&mut self, span: Span) {
538 TokenTree::Group(ref mut t) => t.set_span(span),
539 TokenTree::Ident(ref mut t) => t.set_span(span),
540 TokenTree::Punct(ref mut t) => t.set_span(span),
541 TokenTree::Literal(ref mut t) => t.set_span(span),
546 /// Prints token tree in a form convenient for debugging.
547 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
548 impl fmt::Debug for TokenTree {
549 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
550 // Each of these has the name in the struct type in the derived debug,
551 // so don't bother with an extra layer of indirection
553 TokenTree::Group(ref tt) => tt.fmt(f),
554 TokenTree::Ident(ref tt) => tt.fmt(f),
555 TokenTree::Punct(ref tt) => tt.fmt(f),
556 TokenTree::Literal(ref tt) => tt.fmt(f),
561 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
562 impl From<Group> for TokenTree {
563 fn from(g: Group) -> TokenTree {
568 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
569 impl From<Ident> for TokenTree {
570 fn from(g: Ident) -> TokenTree {
575 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
576 impl From<Punct> for TokenTree {
577 fn from(g: Punct) -> TokenTree {
582 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
583 impl From<Literal> for TokenTree {
584 fn from(g: Literal) -> TokenTree {
585 TokenTree::Literal(g)
589 // N.B., the bridge only provides `to_string`, implement `fmt::Display`
590 // based on it (the reverse of the usual relationship between the two).
591 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
592 impl ToString for TokenTree {
593 fn to_string(&self) -> String {
595 TokenTree::Group(ref t) => t.to_string(),
596 TokenTree::Ident(ref t) => t.to_string(),
597 TokenTree::Punct(ref t) => t.to_string(),
598 TokenTree::Literal(ref t) => t.to_string(),
603 /// Prints the token tree as a string that is supposed to be losslessly convertible back
604 /// into the same token tree (modulo spans), except for possibly `TokenTree::Group`s
605 /// with `Delimiter::None` delimiters and negative numeric literals.
606 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
607 impl fmt::Display for TokenTree {
608 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
609 f.write_str(&self.to_string())
613 /// A delimited token stream.
615 /// A `Group` internally contains a `TokenStream` which is surrounded by `Delimiter`s.
617 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
618 pub struct Group(bridge::client::Group);
620 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
621 impl !Send for Group {}
622 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
623 impl !Sync for Group {}
625 /// Describes how a sequence of token trees is delimited.
626 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
627 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
630 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
633 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
636 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
639 /// An implicit delimiter, that may, for example, appear around tokens coming from a
640 /// "macro variable" `$var`. It is important to preserve operator priorities in cases like
641 /// `$var * 3` where `$var` is `1 + 2`.
642 /// Implicit delimiters may not survive roundtrip of a token stream through a string.
643 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
648 /// Creates a new `Group` with the given delimiter and token stream.
650 /// This constructor will set the span for this group to
651 /// `Span::call_site()`. To change the span you can use the `set_span`
653 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
654 pub fn new(delimiter: Delimiter, stream: TokenStream) -> Group {
655 Group(bridge::client::Group::new(delimiter, stream.0))
658 /// Returns the delimiter of this `Group`
659 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
660 pub fn delimiter(&self) -> Delimiter {
664 /// Returns the `TokenStream` of tokens that are delimited in this `Group`.
666 /// Note that the returned token stream does not include the delimiter
668 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
669 pub fn stream(&self) -> TokenStream {
670 TokenStream(self.0.stream())
673 /// Returns the span for the delimiters of this token stream, spanning the
677 /// pub fn span(&self) -> Span {
680 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
681 pub fn span(&self) -> Span {
685 /// Returns the span pointing to the opening delimiter of this group.
688 /// pub fn span_open(&self) -> Span {
691 #[unstable(feature = "proc_macro_span", issue = "54725")]
692 pub fn span_open(&self) -> Span {
693 Span(self.0.span_open())
696 /// Returns the span pointing to the closing delimiter of this group.
699 /// pub fn span_close(&self) -> Span {
702 #[unstable(feature = "proc_macro_span", issue = "54725")]
703 pub fn span_close(&self) -> Span {
704 Span(self.0.span_close())
707 /// Configures the span for this `Group`'s delimiters, but not its internal
710 /// This method will **not** set the span of all the internal tokens spanned
711 /// by this group, but rather it will only set the span of the delimiter
712 /// tokens at the level of the `Group`.
713 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
714 pub fn set_span(&mut self, span: Span) {
715 self.0.set_span(span.0);
719 // N.B., the bridge only provides `to_string`, implement `fmt::Display`
720 // based on it (the reverse of the usual relationship between the two).
721 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
722 impl ToString for Group {
723 fn to_string(&self) -> String {
724 TokenStream::from(TokenTree::from(self.clone())).to_string()
728 /// Prints the group as a string that should be losslessly convertible back
729 /// into the same group (modulo spans), except for possibly `TokenTree::Group`s
730 /// with `Delimiter::None` delimiters.
731 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
732 impl fmt::Display for Group {
733 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
734 f.write_str(&self.to_string())
738 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
739 impl fmt::Debug for Group {
740 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
741 f.debug_struct("Group")
742 .field("delimiter", &self.delimiter())
743 .field("stream", &self.stream())
744 .field("span", &self.span())
749 /// An `Punct` is an single punctuation character like `+`, `-` or `#`.
751 /// Multi-character operators like `+=` are represented as two instances of `Punct` with different
752 /// forms of `Spacing` returned.
753 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
755 pub struct Punct(bridge::client::Punct);
757 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
758 impl !Send for Punct {}
759 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
760 impl !Sync for Punct {}
762 /// Whether an `Punct` is followed immediately by another `Punct` or
763 /// followed by another token or whitespace.
764 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
765 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
767 /// e.g., `+` is `Alone` in `+ =`, `+ident` or `+()`.
768 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
770 /// e.g., `+` is `Joint` in `+=` or `'#`.
771 /// Additionally, single quote `'` can join with identifiers to form lifetimes `'ident`.
772 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
777 /// Creates a new `Punct` from the given character and spacing.
778 /// The `ch` argument must be a valid punctuation character permitted by the language,
779 /// otherwise the function will panic.
781 /// The returned `Punct` will have the default span of `Span::call_site()`
782 /// which can be further configured with the `set_span` method below.
783 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
784 pub fn new(ch: char, spacing: Spacing) -> Punct {
785 Punct(bridge::client::Punct::new(ch, spacing))
788 /// Returns the value of this punctuation character as `char`.
789 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
790 pub fn as_char(&self) -> char {
794 /// Returns the spacing of this punctuation character, indicating whether it's immediately
795 /// followed by another `Punct` in the token stream, so they can potentially be combined into
796 /// a multi-character operator (`Joint`), or it's followed by some other token or whitespace
797 /// (`Alone`) so the operator has certainly ended.
798 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
799 pub fn spacing(&self) -> Spacing {
803 /// Returns the span for this punctuation character.
804 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
805 pub fn span(&self) -> Span {
809 /// Configure the span for this punctuation character.
810 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
811 pub fn set_span(&mut self, span: Span) {
812 self.0 = self.0.with_span(span.0);
816 // N.B., the bridge only provides `to_string`, implement `fmt::Display`
817 // based on it (the reverse of the usual relationship between the two).
818 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
819 impl ToString for Punct {
820 fn to_string(&self) -> String {
821 TokenStream::from(TokenTree::from(self.clone())).to_string()
825 /// Prints the punctuation character as a string that should be losslessly convertible
826 /// back into the same character.
827 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
828 impl fmt::Display for Punct {
829 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
830 f.write_str(&self.to_string())
834 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
835 impl fmt::Debug for Punct {
836 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
837 f.debug_struct("Punct")
838 .field("ch", &self.as_char())
839 .field("spacing", &self.spacing())
840 .field("span", &self.span())
845 #[stable(feature = "proc_macro_punct_eq", since = "1.49.0")]
846 impl PartialEq<char> for Punct {
847 fn eq(&self, rhs: &char) -> bool {
848 self.as_char() == *rhs
852 /// An identifier (`ident`).
854 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
855 pub struct Ident(bridge::client::Ident);
858 /// Creates a new `Ident` with the given `string` as well as the specified
860 /// The `string` argument must be a valid identifier permitted by the
861 /// language (including keywords, e.g. `self` or `fn`). Otherwise, the function will panic.
863 /// Note that `span`, currently in rustc, configures the hygiene information
864 /// for this identifier.
866 /// As of this time `Span::call_site()` explicitly opts-in to "call-site" hygiene
867 /// meaning that identifiers created with this span will be resolved as if they were written
868 /// directly at the location of the macro call, and other code at the macro call site will be
869 /// able to refer to them as well.
871 /// Later spans like `Span::def_site()` will allow to opt-in to "definition-site" hygiene
872 /// meaning that identifiers created with this span will be resolved at the location of the
873 /// macro definition and other code at the macro call site will not be able to refer to them.
875 /// Due to the current importance of hygiene this constructor, unlike other
876 /// tokens, requires a `Span` to be specified at construction.
877 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
878 pub fn new(string: &str, span: Span) -> Ident {
879 Ident(bridge::client::Ident::new(string, span.0, false))
882 /// Same as `Ident::new`, but creates a raw identifier (`r#ident`).
883 /// The `string` argument be a valid identifier permitted by the language
884 /// (including keywords, e.g. `fn`). Keywords which are usable in path segments
885 /// (e.g. `self`, `super`) are not supported, and will cause a panic.
886 #[stable(feature = "proc_macro_raw_ident", since = "1.47.0")]
887 pub fn new_raw(string: &str, span: Span) -> Ident {
888 Ident(bridge::client::Ident::new(string, span.0, true))
891 /// Returns the span of this `Ident`, encompassing the entire string returned
892 /// by [`to_string`](Self::to_string).
893 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
894 pub fn span(&self) -> Span {
898 /// Configures the span of this `Ident`, possibly changing its hygiene context.
899 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
900 pub fn set_span(&mut self, span: Span) {
901 self.0 = self.0.with_span(span.0);
905 // N.B., the bridge only provides `to_string`, implement `fmt::Display`
906 // based on it (the reverse of the usual relationship between the two).
907 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
908 impl ToString for Ident {
909 fn to_string(&self) -> String {
910 TokenStream::from(TokenTree::from(self.clone())).to_string()
914 /// Prints the identifier as a string that should be losslessly convertible
915 /// back into the same identifier.
916 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
917 impl fmt::Display for Ident {
918 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
919 f.write_str(&self.to_string())
923 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
924 impl fmt::Debug for Ident {
925 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
926 f.debug_struct("Ident")
927 .field("ident", &self.to_string())
928 .field("span", &self.span())
933 /// A literal string (`"hello"`), byte string (`b"hello"`),
934 /// character (`'a'`), byte character (`b'a'`), an integer or floating point number
935 /// with or without a suffix (`1`, `1u8`, `2.3`, `2.3f32`).
936 /// Boolean literals like `true` and `false` do not belong here, they are `Ident`s.
938 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
939 pub struct Literal(bridge::client::Literal);
941 macro_rules! suffixed_int_literals {
942 ($($name:ident => $kind:ident,)*) => ($(
943 /// Creates a new suffixed integer literal with the specified value.
945 /// This function will create an integer like `1u32` where the integer
946 /// value specified is the first part of the token and the integral is
947 /// also suffixed at the end.
948 /// Literals created from negative numbers may not survive round-trips through
949 /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
951 /// Literals created through this method have the `Span::call_site()`
952 /// span by default, which can be configured with the `set_span` method
954 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
955 pub fn $name(n: $kind) -> Literal {
956 Literal(bridge::client::Literal::typed_integer(&n.to_string(), stringify!($kind)))
961 macro_rules! unsuffixed_int_literals {
962 ($($name:ident => $kind:ident,)*) => ($(
963 /// Creates a new unsuffixed integer literal with the specified value.
965 /// This function will create an integer like `1` where the integer
966 /// value specified is the first part of the token. No suffix is
967 /// specified on this token, meaning that invocations like
968 /// `Literal::i8_unsuffixed(1)` are equivalent to
969 /// `Literal::u32_unsuffixed(1)`.
970 /// Literals created from negative numbers may not survive rountrips through
971 /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
973 /// Literals created through this method have the `Span::call_site()`
974 /// span by default, which can be configured with the `set_span` method
976 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
977 pub fn $name(n: $kind) -> Literal {
978 Literal(bridge::client::Literal::integer(&n.to_string()))
984 suffixed_int_literals! {
989 u128_suffixed => u128,
990 usize_suffixed => usize,
995 i128_suffixed => i128,
996 isize_suffixed => isize,
999 unsuffixed_int_literals! {
1000 u8_unsuffixed => u8,
1001 u16_unsuffixed => u16,
1002 u32_unsuffixed => u32,
1003 u64_unsuffixed => u64,
1004 u128_unsuffixed => u128,
1005 usize_unsuffixed => usize,
1006 i8_unsuffixed => i8,
1007 i16_unsuffixed => i16,
1008 i32_unsuffixed => i32,
1009 i64_unsuffixed => i64,
1010 i128_unsuffixed => i128,
1011 isize_unsuffixed => isize,
1014 /// Creates a new unsuffixed floating-point literal.
1016 /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1017 /// the float's value is emitted directly into the token but no suffix is
1018 /// used, so it may be inferred to be a `f64` later in the compiler.
1019 /// Literals created from negative numbers may not survive rountrips through
1020 /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1024 /// This function requires that the specified float is finite, for
1025 /// example if it is infinity or NaN this function will panic.
1026 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1027 pub fn f32_unsuffixed(n: f32) -> Literal {
1029 panic!("Invalid float literal {}", n);
1031 Literal(bridge::client::Literal::float(&n.to_string()))
1034 /// Creates a new suffixed floating-point literal.
1036 /// This constructor will create a literal like `1.0f32` where the value
1037 /// specified is the preceding part of the token and `f32` is the suffix of
1038 /// the token. This token will always be inferred to be an `f32` in the
1040 /// Literals created from negative numbers may not survive rountrips through
1041 /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1045 /// This function requires that the specified float is finite, for
1046 /// example if it is infinity or NaN this function will panic.
1047 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1048 pub fn f32_suffixed(n: f32) -> Literal {
1050 panic!("Invalid float literal {}", n);
1052 Literal(bridge::client::Literal::f32(&n.to_string()))
1055 /// Creates a new unsuffixed floating-point literal.
1057 /// This constructor is similar to those like `Literal::i8_unsuffixed` where
1058 /// the float's value is emitted directly into the token but no suffix is
1059 /// used, so it may be inferred to be a `f64` later in the compiler.
1060 /// Literals created from negative numbers may not survive rountrips through
1061 /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1065 /// This function requires that the specified float is finite, for
1066 /// example if it is infinity or NaN this function will panic.
1067 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1068 pub fn f64_unsuffixed(n: f64) -> Literal {
1070 panic!("Invalid float literal {}", n);
1072 Literal(bridge::client::Literal::float(&n.to_string()))
1075 /// Creates a new suffixed floating-point literal.
1077 /// This constructor will create a literal like `1.0f64` where the value
1078 /// specified is the preceding part of the token and `f64` is the suffix of
1079 /// the token. This token will always be inferred to be an `f64` in the
1081 /// Literals created from negative numbers may not survive rountrips through
1082 /// `TokenStream` or strings and may be broken into two tokens (`-` and positive literal).
1086 /// This function requires that the specified float is finite, for
1087 /// example if it is infinity or NaN this function will panic.
1088 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1089 pub fn f64_suffixed(n: f64) -> Literal {
1091 panic!("Invalid float literal {}", n);
1093 Literal(bridge::client::Literal::f64(&n.to_string()))
1097 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1098 pub fn string(string: &str) -> Literal {
1099 Literal(bridge::client::Literal::string(string))
1102 /// Character literal.
1103 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1104 pub fn character(ch: char) -> Literal {
1105 Literal(bridge::client::Literal::character(ch))
1108 /// Byte string literal.
1109 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1110 pub fn byte_string(bytes: &[u8]) -> Literal {
1111 Literal(bridge::client::Literal::byte_string(bytes))
1114 /// Returns the span encompassing this literal.
1115 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1116 pub fn span(&self) -> Span {
1120 /// Configures the span associated for this literal.
1121 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1122 pub fn set_span(&mut self, span: Span) {
1123 self.0.set_span(span.0);
1126 /// Returns a `Span` that is a subset of `self.span()` containing only the
1127 /// source bytes in range `range`. Returns `None` if the would-be trimmed
1128 /// span is outside the bounds of `self`.
1129 // FIXME(SergioBenitez): check that the byte range starts and ends at a
1130 // UTF-8 boundary of the source. otherwise, it's likely that a panic will
1131 // occur elsewhere when the source text is printed.
1132 // FIXME(SergioBenitez): there is no way for the user to know what
1133 // `self.span()` actually maps to, so this method can currently only be
1134 // called blindly. For example, `to_string()` for the character 'c' returns
1135 // "'\u{63}'"; there is no way for the user to know whether the source text
1136 // was 'c' or whether it was '\u{63}'.
1137 #[unstable(feature = "proc_macro_span", issue = "54725")]
1138 pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
1139 // HACK(eddyb) something akin to `Option::cloned`, but for `Bound<&T>`.
1140 fn cloned_bound<T: Clone>(bound: Bound<&T>) -> Bound<T> {
1142 Bound::Included(x) => Bound::Included(x.clone()),
1143 Bound::Excluded(x) => Bound::Excluded(x.clone()),
1144 Bound::Unbounded => Bound::Unbounded,
1148 self.0.subspan(cloned_bound(range.start_bound()), cloned_bound(range.end_bound())).map(Span)
1152 // N.B., the bridge only provides `to_string`, implement `fmt::Display`
1153 // based on it (the reverse of the usual relationship between the two).
1154 #[stable(feature = "proc_macro_lib", since = "1.15.0")]
1155 impl ToString for Literal {
1156 fn to_string(&self) -> String {
1157 TokenStream::from(TokenTree::from(self.clone())).to_string()
1161 /// Prints the literal as a string that should be losslessly convertible
1162 /// back into the same literal (except for possible rounding for floating point literals).
1163 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1164 impl fmt::Display for Literal {
1165 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1166 f.write_str(&self.to_string())
1170 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
1171 impl fmt::Debug for Literal {
1172 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1177 /// Tracked access to environment variables.
1178 #[unstable(feature = "proc_macro_tracked_env", issue = "74690")]
1179 pub mod tracked_env {
1180 use std::env::{self, VarError};
1181 use std::ffi::OsStr;
1183 /// Retrieve an environment variable and add it to build dependency info.
1184 /// Build system executing the compiler will know that the variable was accessed during
1185 /// compilation, and will be able to rerun the build when the value of that variable changes.
1186 /// Besides the dependency tracking this function should be equivalent to `env::var` from the
1187 /// standard library, except that the argument must be UTF-8.
1188 #[unstable(feature = "proc_macro_tracked_env", issue = "74690")]
1189 pub fn var<K: AsRef<OsStr> + AsRef<str>>(key: K) -> Result<String, VarError> {
1190 let key: &str = key.as_ref();
1191 let value = env::var(key);
1192 crate::bridge::client::FreeFunctions::track_env_var(key, value.as_deref().ok());