1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
//! This crate provides the [`quote!`] macro for turning Rust syntax tree data
//! structures into tokens of source code.
//!
//! [`quote!`]: macro.quote.html
//!
//! Procedural macros in Rust receive a stream of tokens as input, execute
//! arbitrary Rust code to determine how to manipulate those tokens, and produce
//! a stream of tokens to hand back to the compiler to compile into the caller's
//! crate. Quasi-quoting is a solution to one piece of that -- producing tokens
//! to return to the compiler.
//!
//! The idea of quasi-quoting is that we write *code* that we treat as *data*.
//! Within the `quote!` macro, we can write what looks like code to our text
//! editor or IDE. We get all the benefits of the editor's brace matching,
//! syntax highlighting, indentation, and maybe autocompletion. But rather than
//! compiling that as code into the current crate, we can treat it as data, pass
//! it around, mutate it, and eventually hand it back to the compiler as tokens
//! to compile into the macro caller's crate.
//!
//! This crate is motivated by the procedural macro use case, but is a
//! general-purpose Rust quasi-quoting library and is not specific to procedural
//! macros.
//!
//! *Version requirement: Quote supports any compiler version back to Rust's
//! very first support for procedural macros in Rust 1.15.0.*
//!
//! ```toml
//! [dependencies]
//! quote = "0.6"
//! ```
//!
//! # Example
//!
//! The following quasi-quoted block of code is something you might find in [a]
//! procedural macro having to do with data structure serialization. The `#var`
//! syntax performs interpolation of runtime variables into the quoted tokens.
//! Check out the documentation of the [`quote!`] macro for more detail about
//! the syntax. See also the [`quote_spanned!`] macro which is important for
//! implementing hygienic procedural macros.
//!
//! [a]: https://serde.rs/
//! [`quote_spanned!`]: macro.quote_spanned.html
//!
//! ```edition2018
//! # use quote::quote;
//! #
//! # let generics = "";
//! # let where_clause = "";
//! # let field_ty = "";
//! # let item_ty = "";
//! # let path = "";
//! # let value = "";
//! #
//! let tokens = quote! {
//!     struct SerializeWith #generics #where_clause {
//!         value: &'a #field_ty,
//!         phantom: core::marker::PhantomData<#item_ty>,
//!     }
//!
//!     impl #generics serde::Serialize for SerializeWith #generics #where_clause {
//!         fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
//!         where
//!             S: serde::Serializer,
//!         {
//!             #path(self.value, serializer)
//!         }
//!     }
//!
//!     SerializeWith {
//!         value: #value,
//!         phantom: core::marker::PhantomData::<#item_ty>,
//!     }
//! };
//! ```
//!
//! # Recursion limit
//!
//! The `quote!` macro relies on deep recursion so some large invocations may
//! fail with "recursion limit reached" when you compile. If it fails, bump up
//! the recursion limit by adding `#![recursion_limit = "128"]` to your crate.
//! An even higher limit may be necessary for especially large invocations.

// Quote types in rustdoc of other crates get linked to here.
#![doc(html_root_url = "https://docs.rs/quote/0.6.13")]

#[cfg(all(
    not(all(target_arch = "wasm32", target_os = "unknown")),
    feature = "proc-macro"
))]
extern crate proc_macro;
extern crate proc_macro2;

mod ext;
pub use ext::TokenStreamExt;

mod to_tokens;
pub use to_tokens::ToTokens;

// Not public API.
#[doc(hidden)]
#[path = "runtime.rs"]
pub mod __rt;

/// The whole point.
///
/// Performs variable interpolation against the input and produces it as
/// [`TokenStream`]. For returning tokens to the compiler in a procedural macro, use
/// `into()` to build a `TokenStream`.
///
/// [`TokenStream`]: https://docs.rs/proc-macro2/0.4/proc_macro2/struct.TokenStream.html
///
/// # Interpolation
///
/// Variable interpolation is done with `#var` (similar to `$var` in
/// `macro_rules!` macros). This grabs the `var` variable that is currently in
/// scope and inserts it in that location in the output tokens. Any type
/// implementing the [`ToTokens`] trait can be interpolated. This includes most
/// Rust primitive types as well as most of the syntax tree types from the [Syn]
/// crate.
///
/// [`ToTokens`]: trait.ToTokens.html
/// [Syn]: https://github.com/dtolnay/syn
///
/// Repetition is done using `#(...)*` or `#(...),*` again similar to
/// `macro_rules!`. This iterates through the elements of any variable
/// interpolated within the repetition and inserts a copy of the repetition body
/// for each one. The variables in an interpolation may be anything that
/// implements `IntoIterator`, including `Vec` or a pre-existing iterator.
///
/// - `#(#var)*` — no separators
/// - `#(#var),*` — the character before the asterisk is used as a separator
/// - `#( struct #var; )*` — the repetition can contain other tokens
/// - `#( #k => println!("{}", #v), )*` — even multiple interpolations
///
/// There are two limitations around interpolations in a repetition:
///
/// - Every interpolation inside of a repetition must be a distinct variable.
///   That is, `#(#a #a)*` is not allowed. Work around this by collecting `a`
///   into a vector and taking references `a1 = &a` and `a2 = &a` which you use
///   inside the repetition: `#(#a1 #a2)*`. Where possible, use meaningful names
///   that indicate the distinct role of each copy.
///
/// - Every interpolation inside of a repetition must be iterable. If we have
///   `vec` which is a vector and `ident` which is a single identifier,
///   `#(#ident #vec)*` is not allowed. Work around this by using
///   `std::iter::repeat(ident)` to produce an iterable that can be used from
///   within the repetition.
///
/// # Hygiene
///
/// Any interpolated tokens preserve the `Span` information provided by their
/// `ToTokens` implementation. Tokens that originate within the `quote!`
/// invocation are spanned with [`Span::call_site()`].
///
/// [`Span::call_site()`]: https://docs.rs/proc-macro2/0.4/proc_macro2/struct.Span.html#method.call_site
///
/// A different span can be provided through the [`quote_spanned!`] macro.
///
/// [`quote_spanned!`]: macro.quote_spanned.html
///
/// # Return type
///
/// The macro evaluates to an expression of type `proc_macro2::TokenStream`.
/// Meanwhile Rust procedural macros are expected to return the type
/// `proc_macro::TokenStream`.
///
/// The difference between the two types is that `proc_macro` types are entirely
/// specific to procedural macros and cannot ever exist in code outside of a
/// procedural macro, while `proc_macro2` types may exist anywhere including
/// tests and non-macro code like main.rs and build.rs. This is why even the
/// procedural macro ecosystem is largely built around `proc_macro2`, because
/// that ensures the libraries are unit testable and accessible in non-macro
/// contexts.
///
/// There is a [`From`]-conversion in both directions so returning the output of
/// `quote!` from a procedural macro usually looks like `tokens.into()` or
/// `proc_macro::TokenStream::from(tokens)`.
///
/// [`From`]: https://doc.rust-lang.org/std/convert/trait.From.html
///
/// # Examples
///
/// ## Procedural macro
///
/// The structure of a basic procedural macro is as follows. Refer to the [Syn]
/// crate for further useful guidance on using `quote!` as part of a procedural
/// macro.
///
/// [Syn]: https://github.com/dtolnay/syn
///
/// ```edition2018
/// # #[cfg(any())]
/// extern crate proc_macro;
/// # use proc_macro2 as proc_macro;
///
/// use proc_macro::TokenStream;
/// use quote::quote;
///
/// # const IGNORE_TOKENS: &'static str = stringify! {
/// #[proc_macro_derive(HeapSize)]
/// # };
/// pub fn derive_heap_size(input: TokenStream) -> TokenStream {
///     // Parse the input and figure out what implementation to generate...
///     # const IGNORE_TOKENS: &'static str = stringify! {
///     let name = /* ... */;
///     let expr = /* ... */;
///     # };
///     #
///     # let name = 0;
///     # let expr = 0;
///
///     let expanded = quote! {
///         // The generated impl.
///         impl heapsize::HeapSize for #name {
///             fn heap_size_of_children(&self) -> usize {
///                 #expr
///             }
///         }
///     };
///
///     // Hand the output tokens back to the compiler.
///     TokenStream::from(expanded)
/// }
/// ```
///
/// ## Combining quoted fragments
///
/// Usually you don't end up constructing an entire final `TokenStream` in one
/// piece. Different parts may come from different helper functions. The tokens
/// produced by `quote!` themselves implement `ToTokens` and so can be
/// interpolated into later `quote!` invocations to build up a final result.
///
/// ```edition2018
/// # use quote::quote;
/// #
/// let type_definition = quote! {...};
/// let methods = quote! {...};
///
/// let tokens = quote! {
///     #type_definition
///     #methods
/// };
/// ```
///
/// ## Constructing identifiers
///
/// Suppose we have an identifier `ident` which came from somewhere in a macro
/// input and we need to modify it in some way for the macro output. Let's
/// consider prepending the identifier with an underscore.
///
/// Simply interpolating the identifier next to an underscore will not have the
/// behavior of concatenating them. The underscore and the identifier will
/// continue to be two separate tokens as if you had written `_ x`.
///
/// ```edition2018
/// # use proc_macro2::{self as syn, Span};
/// # use quote::quote;
/// #
/// # let ident = syn::Ident::new("i", Span::call_site());
/// #
/// // incorrect
/// quote! {
///     let mut _#ident = 0;
/// }
/// # ;
/// ```
///
/// The solution is to perform token-level manipulations using the APIs provided
/// by Syn and proc-macro2.
///
/// ```edition2018
/// # use proc_macro2::{self as syn, Span};
/// # use quote::quote;
/// #
/// # let ident = syn::Ident::new("i", Span::call_site());
/// #
/// let concatenated = format!("_{}", ident);
/// let varname = syn::Ident::new(&concatenated, ident.span());
/// quote! {
///     let mut #varname = 0;
/// }
/// # ;
/// ```
///
/// ## Making method calls
///
/// Let's say our macro requires some type specified in the macro input to have
/// a constructor called `new`. We have the type in a variable called
/// `field_type` of type `syn::Type` and want to invoke the constructor.
///
/// ```edition2018
/// # use quote::quote;
/// #
/// # let field_type = quote!(...);
/// #
/// // incorrect
/// quote! {
///     let value = #field_type::new();
/// }
/// # ;
/// ```
///
/// This works only sometimes. If `field_type` is `String`, the expanded code
/// contains `String::new()` which is fine. But if `field_type` is something
/// like `Vec<i32>` then the expanded code is `Vec<i32>::new()` which is invalid
/// syntax. Ordinarily in handwritten Rust we would write `Vec::<i32>::new()`
/// but for macros often the following is more convenient.
///
/// ```edition2018
/// # use quote::quote;
/// #
/// # let field_type = quote!(...);
/// #
/// quote! {
///     let value = <#field_type>::new();
/// }
/// # ;
/// ```
///
/// This expands to `<Vec<i32>>::new()` which behaves correctly.
///
/// A similar pattern is appropriate for trait methods.
///
/// ```edition2018
/// # use quote::quote;
/// #
/// # let field_type = quote!(...);
/// #
/// quote! {
///     let value = <#field_type as core::default::Default>::default();
/// }
/// # ;
/// ```
#[macro_export(local_inner_macros)]
macro_rules! quote {
    ($($tt:tt)*) => {
        quote_spanned!($crate::__rt::Span::call_site()=> $($tt)*)
    };
}

/// Same as `quote!`, but applies a given span to all tokens originating within
/// the macro invocation.
///
/// # Syntax
///
/// A span expression of type [`Span`], followed by `=>`, followed by the tokens
/// to quote. The span expression should be brief -- use a variable for anything
/// more than a few characters. There should be no space before the `=>` token.
///
/// [`Span`]: https://docs.rs/proc-macro2/0.4/proc_macro2/struct.Span.html
///
/// ```edition2018
/// # use proc_macro2::Span;
/// # use quote::quote_spanned;
/// #
/// # const IGNORE_TOKENS: &'static str = stringify! {
/// let span = /* ... */;
/// # };
/// # let span = Span::call_site();
/// # let init = 0;
///
/// // On one line, use parentheses.
/// let tokens = quote_spanned!(span=> Box::into_raw(Box::new(#init)));
///
/// // On multiple lines, place the span at the top and use braces.
/// let tokens = quote_spanned! {span=>
///     Box::into_raw(Box::new(#init))
/// };
/// ```
///
/// The lack of space before the `=>` should look jarring to Rust programmers
/// and this is intentional. The formatting is designed to be visibly
/// off-balance and draw the eye a particular way, due to the span expression
/// being evaluated in the context of the procedural macro and the remaining
/// tokens being evaluated in the generated code.
///
/// # Hygiene
///
/// Any interpolated tokens preserve the `Span` information provided by their
/// `ToTokens` implementation. Tokens that originate within the `quote_spanned!`
/// invocation are spanned with the given span argument.
///
/// # Example
///
/// The following procedural macro code uses `quote_spanned!` to assert that a
/// particular Rust type implements the [`Sync`] trait so that references can be
/// safely shared between threads.
///
/// [`Sync`]: https://doc.rust-lang.org/std/marker/trait.Sync.html
///
/// ```edition2018
/// # use quote::{quote_spanned, TokenStreamExt, ToTokens};
/// # use proc_macro2::{Span, TokenStream};
/// #
/// # struct Type;
/// #
/// # impl Type {
/// #     fn span(&self) -> Span {
/// #         Span::call_site()
/// #     }
/// # }
/// #
/// # impl ToTokens for Type {
/// #     fn to_tokens(&self, _tokens: &mut TokenStream) {}
/// # }
/// #
/// # let ty = Type;
/// # let call_site = Span::call_site();
/// #
/// let ty_span = ty.span();
/// let assert_sync = quote_spanned! {ty_span=>
///     struct _AssertSync where #ty: Sync;
/// };
/// ```
///
/// If the assertion fails, the user will see an error like the following. The
/// input span of their type is hightlighted in the error.
///
/// ```text
/// error[E0277]: the trait bound `*const (): std::marker::Sync` is not satisfied
///   --> src/main.rs:10:21
///    |
/// 10 |     static ref PTR: *const () = &();
///    |                     ^^^^^^^^^ `*const ()` cannot be shared between threads safely
/// ```
///
/// In this example it is important for the where-clause to be spanned with the
/// line/column information of the user's input type so that error messages are
/// placed appropriately by the compiler. But it is also incredibly important
/// that `Sync` resolves at the macro definition site and not the macro call
/// site. If we resolve `Sync` at the same span that the user's type is going to
/// be resolved, then they could bypass our check by defining their own trait
/// named `Sync` that is implemented for their type.
#[macro_export(local_inner_macros)]
macro_rules! quote_spanned {
    ($span:expr=> $($tt:tt)*) => {{
        let mut _s = $crate::__rt::TokenStream::new();
        let _span = $span;
        quote_each_token!(_s _span $($tt)*);
        _s
    }};
}

// Extract the names of all #metavariables and pass them to the $finish macro.
//
// in:   pounded_var_names!(then () a #b c #( #d )* #e)
// out:  then!(() b d e)
#[macro_export(local_inner_macros)]
#[doc(hidden)]
macro_rules! pounded_var_names {
    ($finish:ident ($($found:ident)*) # ( $($inner:tt)* ) $($rest:tt)*) => {
        pounded_var_names!($finish ($($found)*) $($inner)* $($rest)*)
    };

    ($finish:ident ($($found:ident)*) # [ $($inner:tt)* ] $($rest:tt)*) => {
        pounded_var_names!($finish ($($found)*) $($inner)* $($rest)*)
    };

    ($finish:ident ($($found:ident)*) # { $($inner:tt)* } $($rest:tt)*) => {
        pounded_var_names!($finish ($($found)*) $($inner)* $($rest)*)
    };

    ($finish:ident ($($found:ident)*) # $first:ident $($rest:tt)*) => {
        pounded_var_names!($finish ($($found)* $first) $($rest)*)
    };

    ($finish:ident ($($found:ident)*) ( $($inner:tt)* ) $($rest:tt)*) => {
        pounded_var_names!($finish ($($found)*) $($inner)* $($rest)*)
    };

    ($finish:ident ($($found:ident)*) [ $($inner:tt)* ] $($rest:tt)*) => {
        pounded_var_names!($finish ($($found)*) $($inner)* $($rest)*)
    };

    ($finish:ident ($($found:ident)*) { $($inner:tt)* } $($rest:tt)*) => {
        pounded_var_names!($finish ($($found)*) $($inner)* $($rest)*)
    };

    ($finish:ident ($($found:ident)*) $ignore:tt $($rest:tt)*) => {
        pounded_var_names!($finish ($($found)*) $($rest)*)
    };

    ($finish:ident ($($found:ident)*)) => {
        $finish!(() $($found)*)
    };
}

// in:   nested_tuples_pat!(() a b c d e)
// out:  ((((a b) c) d) e)
//
// in:   nested_tuples_pat!(() a)
// out:  a
#[macro_export(local_inner_macros)]
#[doc(hidden)]
macro_rules! nested_tuples_pat {
    (()) => {
        &()
    };

    (() $first:ident $($rest:ident)*) => {
        nested_tuples_pat!(($first) $($rest)*)
    };

    (($pat:pat) $first:ident $($rest:ident)*) => {
        nested_tuples_pat!((($pat, $first)) $($rest)*)
    };

    (($done:pat)) => {
        $done
    };
}

// in:   multi_zip_expr!(() a b c d e)
// out:  a.into_iter().zip(b).zip(c).zip(d).zip(e)
//
// in:   multi_zip_iter!(() a)
// out:  a
#[macro_export(local_inner_macros)]
#[doc(hidden)]
macro_rules! multi_zip_expr {
    (()) => {
        &[]
    };

    (() $single:ident) => {
        $single
    };

    (() $first:ident $($rest:ident)*) => {
        multi_zip_expr!(($first.into_iter()) $($rest)*)
    };

    (($zips:expr) $first:ident $($rest:ident)*) => {
        multi_zip_expr!(($zips.zip($first)) $($rest)*)
    };

    (($done:expr)) => {
        $done
    };
}

#[macro_export(local_inner_macros)]
#[doc(hidden)]
macro_rules! quote_each_token {
    ($tokens:ident $span:ident) => {};

    ($tokens:ident $span:ident # ! $($rest:tt)*) => {
        quote_each_token!($tokens $span #);
        quote_each_token!($tokens $span !);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident # ( $($inner:tt)* ) * $($rest:tt)*) => {
        for pounded_var_names!(nested_tuples_pat () $($inner)*)
        in pounded_var_names!(multi_zip_expr () $($inner)*) {
            quote_each_token!($tokens $span $($inner)*);
        }
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident # ( $($inner:tt)* ) $sep:tt * $($rest:tt)*) => {
        for (_i, pounded_var_names!(nested_tuples_pat () $($inner)*))
        in pounded_var_names!(multi_zip_expr () $($inner)*).into_iter().enumerate() {
            if _i > 0 {
                quote_each_token!($tokens $span $sep);
            }
            quote_each_token!($tokens $span $($inner)*);
        }
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident # [ $($inner:tt)* ] $($rest:tt)*) => {
        quote_each_token!($tokens $span #);
        $tokens.extend({
            let mut g = $crate::__rt::Group::new(
                $crate::__rt::Delimiter::Bracket,
                quote_spanned!($span=> $($inner)*),
            );
            g.set_span($span);
            Some($crate::__rt::TokenTree::from(g))
        });
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident # $first:ident $($rest:tt)*) => {
        $crate::ToTokens::to_tokens(&$first, &mut $tokens);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident ( $($first:tt)* ) $($rest:tt)*) => {
        $tokens.extend({
            let mut g = $crate::__rt::Group::new(
                $crate::__rt::Delimiter::Parenthesis,
                quote_spanned!($span=> $($first)*),
            );
            g.set_span($span);
            Some($crate::__rt::TokenTree::from(g))
        });
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident [ $($first:tt)* ] $($rest:tt)*) => {
        $tokens.extend({
            let mut g = $crate::__rt::Group::new(
                $crate::__rt::Delimiter::Bracket,
                quote_spanned!($span=> $($first)*),
            );
            g.set_span($span);
            Some($crate::__rt::TokenTree::from(g))
        });
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident { $($first:tt)* } $($rest:tt)*) => {
        $tokens.extend({
            let mut g = $crate::__rt::Group::new(
                $crate::__rt::Delimiter::Brace,
                quote_spanned!($span=> $($first)*),
            );
            g.set_span($span);
            Some($crate::__rt::TokenTree::from(g))
        });
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident + $($rest:tt)*) => {
        $crate::__rt::push_add(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident += $($rest:tt)*) => {
        $crate::__rt::push_add_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident & $($rest:tt)*) => {
        $crate::__rt::push_and(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident && $($rest:tt)*) => {
        $crate::__rt::push_and_and(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident &= $($rest:tt)*) => {
        $crate::__rt::push_and_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident @ $($rest:tt)*) => {
        $crate::__rt::push_at(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident ! $($rest:tt)*) => {
        $crate::__rt::push_bang(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident ^ $($rest:tt)*) => {
        $crate::__rt::push_caret(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident ^= $($rest:tt)*) => {
        $crate::__rt::push_caret_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident : $($rest:tt)*) => {
        $crate::__rt::push_colon(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident :: $($rest:tt)*) => {
        $crate::__rt::push_colon2(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident , $($rest:tt)*) => {
        $crate::__rt::push_comma(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident / $($rest:tt)*) => {
        $crate::__rt::push_div(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident /= $($rest:tt)*) => {
        $crate::__rt::push_div_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident . $($rest:tt)*) => {
        $crate::__rt::push_dot(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident .. $($rest:tt)*) => {
        $crate::__rt::push_dot2(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident ... $($rest:tt)*) => {
        $crate::__rt::push_dot3(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident ..= $($rest:tt)*) => {
        $crate::__rt::push_dot_dot_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident = $($rest:tt)*) => {
        $crate::__rt::push_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident == $($rest:tt)*) => {
        $crate::__rt::push_eq_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident >= $($rest:tt)*) => {
        $crate::__rt::push_ge(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident > $($rest:tt)*) => {
        $crate::__rt::push_gt(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident <= $($rest:tt)*) => {
        $crate::__rt::push_le(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident < $($rest:tt)*) => {
        $crate::__rt::push_lt(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident *= $($rest:tt)*) => {
        $crate::__rt::push_mul_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident != $($rest:tt)*) => {
        $crate::__rt::push_ne(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident | $($rest:tt)*) => {
        $crate::__rt::push_or(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident |= $($rest:tt)*) => {
        $crate::__rt::push_or_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident || $($rest:tt)*) => {
        $crate::__rt::push_or_or(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident # $($rest:tt)*) => {
        $crate::__rt::push_pound(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident ? $($rest:tt)*) => {
        $crate::__rt::push_question(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident -> $($rest:tt)*) => {
        $crate::__rt::push_rarrow(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident <- $($rest:tt)*) => {
        $crate::__rt::push_larrow(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident % $($rest:tt)*) => {
        $crate::__rt::push_rem(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident %= $($rest:tt)*) => {
        $crate::__rt::push_rem_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident => $($rest:tt)*) => {
        $crate::__rt::push_fat_arrow(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident ; $($rest:tt)*) => {
        $crate::__rt::push_semi(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident << $($rest:tt)*) => {
        $crate::__rt::push_shl(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident <<= $($rest:tt)*) => {
        $crate::__rt::push_shl_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident >> $($rest:tt)*) => {
        $crate::__rt::push_shr(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident >>= $($rest:tt)*) => {
        $crate::__rt::push_shr_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident * $($rest:tt)*) => {
        $crate::__rt::push_star(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident - $($rest:tt)*) => {
        $crate::__rt::push_sub(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident -= $($rest:tt)*) => {
        $crate::__rt::push_sub_eq(&mut $tokens, $span);
        quote_each_token!($tokens $span $($rest)*);
    };

    ($tokens:ident $span:ident $first:tt $($rest:tt)*) => {
        $crate::__rt::parse(&mut $tokens, $span, quote_stringify!($first));
        quote_each_token!($tokens $span $($rest)*);
    };
}

// Unhygienically invoke whatever `stringify` the caller has in scope i.e. not a
// local macro. The macros marked `local_inner_macros` above cannot invoke
// `stringify` directly.
#[macro_export]
#[doc(hidden)]
macro_rules! quote_stringify {
    ($tt:tt) => {
        stringify!($tt)
    };
}