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
//! A crate for low-level parsing of the WebAssembly text formats: WAT and WAST.
//!
//! This crate is intended to be a low-level detail of the `wat` crate,
//! providing a low-level parsing API for parsing WebAssembly text format
//! structures. The API provided by this crate is very similar to
//! [`syn`](https://docs.rs/syn) and provides the ability to write customized
//! parsers which may be an extension to the core WebAssembly text format. For
//! more documentation see the [`parser`] module.
//!
//! # High-level Overview
//!
//! This crate provides a few major pieces of functionality
//!
//! * [`lexer`] - this is a raw lexer for the wasm text format. This is not
//!   customizable, but if you'd like to iterate over raw tokens this is the
//!   module for you. You likely won't use this much.
//!
//! * [`parser`] - this is the workhorse of this crate. The [`parser`] module
//!   provides the [`Parse`][] trait primarily and utilities
//!   around working with a [`Parser`](`parser::Parser`) to parse streams of
//!   tokens.
//!
//! * [`Module`](crate::core::Module) - this contains an Abstract Syntax Tree
//!   (AST) of the WebAssembly Text format (WAT) as well as the unofficial WAST
//!   format. This also has a [`Module::encode`](crate::core::Module::encode)
//!   method to emit a module in its binary form.
//!
//! # Stability and WebAssembly Features
//!
//! This crate provides support for many in-progress WebAssembly features such
//! as reference types, multi-value, etc. Be sure to check out the documentation
//! of the [`wast` crate](https://docs.rs/wast) for policy information on crate
//! stability vs WebAssembly Features. The tl;dr; version is that this crate
//! will issue semver-non-breaking releases which will break the parsing of the
//! text format. This crate, unlike `wast`, is expected to have numerous Rust
//! public API changes, all of which will be accompanied with a semver-breaking
//! release.
//!
//! # Compile-time Cargo features
//!
//! This crate has a `wasm-module` feature which is turned on by default which
//! includes all necessary support to parse full WebAssembly modules. If you
//! don't need this (for example you're parsing your own s-expression format)
//! then this feature can be disabled.
//!
//! [`Parse`]: parser::Parse
//! [`LexError`]: lexer::LexError

#![deny(missing_docs, rustdoc::broken_intra_doc_links)]

/// A macro to create a custom keyword parser.
///
/// This macro is invoked in one of two forms:
///
/// ```
/// // keyword derived from the Rust identifier:
/// wast::custom_keyword!(foo);
///
/// // or an explicitly specified string representation of the keyword:
/// wast::custom_keyword!(my_keyword = "the-wasm-keyword");
/// ```
///
/// This can then be used to parse custom keyword for custom items, such as:
///
/// ```
/// use wast::parser::{Parser, Result, Parse};
///
/// struct InlineModule<'a> {
///     inline_text: &'a str,
/// }
///
/// mod kw {
///     wast::custom_keyword!(inline);
/// }
///
/// // Parse an inline string module of the form:
/// //
/// //    (inline "(module (func))")
/// impl<'a> Parse<'a> for InlineModule<'a> {
///     fn parse(parser: Parser<'a>) -> Result<Self> {
///         parser.parse::<kw::inline>()?;
///         Ok(InlineModule {
///             inline_text: parser.parse()?,
///         })
///     }
/// }
/// ```
///
/// Note that the keyword name can only start with a lower-case letter, i.e. 'a'..'z'.
#[macro_export]
macro_rules! custom_keyword {
    ($name:ident) => {
        $crate::custom_keyword!($name = stringify!($name));
    };
    ($name:ident = $kw:expr) => {
        #[allow(non_camel_case_types)]
        #[allow(missing_docs)]
        #[derive(Debug, Copy, Clone)]
        pub struct $name(pub $crate::token::Span);

        impl<'a> $crate::parser::Parse<'a> for $name {
            fn parse(parser: $crate::parser::Parser<'a>) -> $crate::parser::Result<Self> {
                parser.step(|c| {
                    if let Some((kw, rest)) = c.keyword()? {
                        if kw == $kw {
                            return Ok(($name(c.cur_span()), rest));
                        }
                    }
                    Err(c.error(concat!("expected keyword `", $kw, "`")))
                })
            }
        }

        impl $crate::parser::Peek for $name {
            fn peek(cursor: $crate::parser::Cursor<'_>) -> $crate::parser::Result<bool> {
                Ok(if let Some((kw, _rest)) = cursor.keyword()? {
                    kw == $kw
                } else {
                    false
                })
            }

            fn display() -> &'static str {
                concat!("`", $kw, "`")
            }
        }
    };
}

/// A macro for defining custom reserved symbols.
///
/// This is like `custom_keyword!` but for reserved symbols (`Token::Reserved`)
/// instead of keywords (`Token::Keyword`).
///
/// ```
/// use wast::parser::{Parser, Result, Parse};
///
/// // Define a custom reserved symbol, the "spaceship" operator: `<=>`.
/// wast::custom_reserved!(spaceship = "<=>");
///
/// /// A "three-way comparison" like `(<=> a b)` that returns -1 if `a` is less
/// /// than `b`, 0 if they're equal, and 1 if `a` is greater than `b`.
/// struct ThreeWayComparison<'a> {
///     lhs: wast::core::Expression<'a>,
///     rhs: wast::core::Expression<'a>,
/// }
///
/// impl<'a> Parse<'a> for ThreeWayComparison<'a> {
///     fn parse(parser: Parser<'a>) -> Result<Self> {
///         parser.parse::<spaceship>()?;
///         let lhs = parser.parse()?;
///         let rhs = parser.parse()?;
///         Ok(ThreeWayComparison { lhs, rhs })
///     }
/// }
/// ```
#[macro_export]
macro_rules! custom_reserved {
    ($name:ident) => {
        $crate::custom_reserved!($name = stringify!($name));
    };
    ($name:ident = $rsv:expr) => {
        #[allow(non_camel_case_types)]
        #[allow(missing_docs)]
        #[derive(Debug)]
        pub struct $name(pub $crate::token::Span);

        impl<'a> $crate::parser::Parse<'a> for $name {
            fn parse(parser: $crate::parser::Parser<'a>) -> $crate::parser::Result<Self> {
                parser.step(|c| {
                    if let Some((rsv, rest)) = c.reserved()? {
                        if rsv == $rsv {
                            return Ok(($name(c.cur_span()), rest));
                        }
                    }
                    Err(c.error(concat!("expected reserved symbol `", $rsv, "`")))
                })
            }
        }

        impl $crate::parser::Peek for $name {
            fn peek(cursor: $crate::parser::Cursor<'_>) -> Result<bool> {
                if let Some((rsv, _rest)) = cursor.reserved()? {
                    Ok(rsv == $rsv)
                } else {
                    Ok(false)
                }
            }

            fn display() -> &'static str {
                concat!("`", $rsv, "`")
            }
        }
    };
}

/// A macro, like [`custom_keyword`], to create a type which can be used to
/// parse/peek annotation directives.
///
/// Note that when you're parsing custom annotations it can be somewhat tricky
/// due to the nature that most of them are skipped. You'll want to be sure to
/// consult the documentation of [`Parser::register_annotation`][register] when
/// using this macro.
///
/// # Examples
///
/// To see an example of how to use this macro, let's invent our own syntax for
/// the [producers section][section] which looks like:
///
/// ```wat
/// (@producer "wat" "1.0.2")
/// ```
///
/// Here, for simplicity, we'll assume everything is a `processed-by` directive,
/// but you could get much more fancy with this as well.
///
/// ```
/// # use wast::*;
/// # use wast::parser::*;
///
/// // First we define the custom annotation keyword we're using, and by
/// // convention we define it in an `annotation` module.
/// mod annotation {
///     wast::annotation!(producer);
/// }
///
/// struct Producer<'a> {
///     name: &'a str,
///     version: &'a str,
/// }
///
/// impl<'a> Parse<'a> for Producer<'a> {
///     fn parse(parser: Parser<'a>) -> Result<Self> {
///         // Remember that parser conventionally parse the *interior* of an
///         // s-expression, so we parse our `@producer` annotation and then we
///         // parse the payload of our annotation.
///         parser.parse::<annotation::producer>()?;
///         Ok(Producer {
///             name: parser.parse()?,
///             version: parser.parse()?,
///         })
///     }
/// }
/// ```
///
/// Note though that this is only half of the parser for annotations. The other
/// half is calling the [`register_annotation`][register] method at the right
/// time to ensure the parser doesn't automatically skip our `@producer`
/// directive. Note that we *can't* call it inside the `Parse for Producer`
/// definition because that's too late and the annotation would already have
/// been skipped.
///
/// Instead we'll need to call it from a higher level-parser before the
/// parenthesis have been parsed, like so:
///
/// ```
/// # use wast::*;
/// # use wast::parser::*;
/// struct Module<'a> {
///     fields: Vec<ModuleField<'a>>,
/// }
///
/// impl<'a> Parse<'a> for Module<'a> {
///     fn parse(parser: Parser<'a>) -> Result<Self> {
///         // .. parse module header here ...
///
///         // register our custom `@producer` annotation before we start
///         // parsing the parentheses of each field
///         let _r = parser.register_annotation("producer");
///
///         let mut fields = Vec::new();
///         while !parser.is_empty() {
///             fields.push(parser.parens(|p| p.parse())?);
///         }
///         Ok(Module { fields })
///     }
/// }
///
/// enum ModuleField<'a> {
///     Producer(Producer<'a>),
///     // ...
/// }
/// # struct Producer<'a>(&'a str);
/// # impl<'a> Parse<'a> for Producer<'a> {
/// #   fn parse(parser: Parser<'a>) -> Result<Self> { Ok(Producer(parser.parse()?)) }
/// # }
/// # mod annotation { wast::annotation!(producer); }
///
/// impl<'a> Parse<'a> for ModuleField<'a> {
///     fn parse(parser: Parser<'a>) -> Result<Self> {
///         // and here `peek` works and our delegated parsing works because the
///         // annotation has been registered.
///         if parser.peek::<annotation::producer>()? {
///             return Ok(ModuleField::Producer(parser.parse()?));
///         }
///
///         // .. typically we'd parse other module fields here...
///
///         Err(parser.error("unknown module field"))
///     }
/// }
/// ```
///
/// [register]: crate::parser::Parser::register_annotation
/// [section]: https://github.com/WebAssembly/tool-conventions/blob/master/ProducersSection.md
#[macro_export]
macro_rules! annotation {
    ($name:ident) => {
        $crate::annotation!($name = stringify!($name));
    };
    ($name:ident = $annotation:expr) => {
        #[allow(non_camel_case_types)]
        #[allow(missing_docs)]
        #[derive(Debug)]
        pub struct $name(pub $crate::token::Span);

        impl<'a> $crate::parser::Parse<'a> for $name {
            fn parse(parser: $crate::parser::Parser<'a>) -> $crate::parser::Result<Self> {
                parser.step(|c| {
                    if let Some((a, rest)) = c.reserved()? {
                        if a == concat!("@", $annotation) {
                            return Ok(($name(c.cur_span()), rest));
                        }
                    }
                    Err(c.error(concat!("expected annotation `@", $annotation, "`")))
                })
            }
        }

        impl $crate::parser::Peek for $name {
            fn peek(cursor: $crate::parser::Cursor<'_>) -> $crate::parser::Result<bool> {
                Ok(if let Some((a, _rest)) = cursor.reserved()? {
                    a == concat!("@", $annotation)
                } else {
                    false
                })
            }

            fn display() -> &'static str {
                concat!("`@", $annotation, "`")
            }
        }
    };
}

pub mod lexer;
pub mod parser;
pub mod token;

mod encode;
mod error;
mod gensym;
mod names;
pub use self::error::*;

macro_rules! id {
    ($($t:tt)*) => ($($t)*)
}

#[cfg(feature = "wasm-module")]
id! {
    mod wast;
    mod wat;
    pub use self::wast::*;
    pub use self::wat::*;

    // Support for core wasm parsing
    pub mod core;

    // Support for component model parsing
    pub mod component;
}

/// Common keyword used to parse WebAssembly text files.
pub mod kw {
    custom_keyword!(after);
    custom_keyword!(alias);
    custom_keyword!(any);
    custom_keyword!(anyfunc);
    custom_keyword!(anyref);
    custom_keyword!(arg);
    custom_keyword!(array);
    custom_keyword!(arrayref);
    custom_keyword!(assert_exception);
    custom_keyword!(assert_exhaustion);
    custom_keyword!(assert_invalid);
    custom_keyword!(assert_malformed);
    custom_keyword!(assert_return);
    custom_keyword!(assert_trap);
    custom_keyword!(assert_unlinkable);
    custom_keyword!(before);
    custom_keyword!(binary);
    custom_keyword!(block);
    custom_keyword!(borrow);
    custom_keyword!(catch);
    custom_keyword!(catch_ref);
    custom_keyword!(catch_all);
    custom_keyword!(catch_all_ref);
    custom_keyword!(code);
    custom_keyword!(component);
    custom_keyword!(data);
    custom_keyword!(declare);
    custom_keyword!(delegate);
    custom_keyword!(r#do = "do");
    custom_keyword!(dtor);
    custom_keyword!(elem);
    custom_keyword!(end);
    custom_keyword!(tag);
    custom_keyword!(exn);
    custom_keyword!(exnref);
    custom_keyword!(export);
    custom_keyword!(r#extern = "extern");
    custom_keyword!(externref);
    custom_keyword!(eq);
    custom_keyword!(eqref);
    custom_keyword!(f32);
    custom_keyword!(f32x4);
    custom_keyword!(f64);
    custom_keyword!(f64x2);
    custom_keyword!(field);
    custom_keyword!(first);
    custom_keyword!(func);
    custom_keyword!(funcref);
    custom_keyword!(get);
    custom_keyword!(global);
    custom_keyword!(i16);
    custom_keyword!(i16x8);
    custom_keyword!(i31);
    custom_keyword!(i31ref);
    custom_keyword!(i32);
    custom_keyword!(i32x4);
    custom_keyword!(i64);
    custom_keyword!(i64x2);
    custom_keyword!(i8);
    custom_keyword!(i8x16);
    custom_keyword!(import);
    custom_keyword!(instance);
    custom_keyword!(instantiate);
    custom_keyword!(interface);
    custom_keyword!(invoke);
    custom_keyword!(item);
    custom_keyword!(last);
    custom_keyword!(local);
    custom_keyword!(memory);
    custom_keyword!(module);
    custom_keyword!(modulecode);
    custom_keyword!(nan_arithmetic = "nan:arithmetic");
    custom_keyword!(nan_canonical = "nan:canonical");
    custom_keyword!(nofunc);
    custom_keyword!(noextern);
    custom_keyword!(none);
    custom_keyword!(null);
    custom_keyword!(nullfuncref);
    custom_keyword!(nullexternref);
    custom_keyword!(nullref);
    custom_keyword!(offset);
    custom_keyword!(outer);
    custom_keyword!(own);
    custom_keyword!(param);
    custom_keyword!(parent);
    custom_keyword!(passive);
    custom_keyword!(quote);
    custom_keyword!(r#else = "else");
    custom_keyword!(r#if = "if");
    custom_keyword!(r#loop = "loop");
    custom_keyword!(r#mut = "mut");
    custom_keyword!(r#type = "type");
    custom_keyword!(r#ref = "ref");
    custom_keyword!(ref_func = "ref.func");
    custom_keyword!(ref_null = "ref.null");
    custom_keyword!(register);
    custom_keyword!(rec);
    custom_keyword!(rep);
    custom_keyword!(resource);
    custom_keyword!(resource_new = "resource.new");
    custom_keyword!(resource_drop = "resource.drop");
    custom_keyword!(resource_rep = "resource.rep");
    custom_keyword!(result);
    custom_keyword!(shared);
    custom_keyword!(start);
    custom_keyword!(sub);
    custom_keyword!(r#final = "final");
    custom_keyword!(table);
    custom_keyword!(then);
    custom_keyword!(r#try = "try");
    custom_keyword!(v128);
    custom_keyword!(value);
    custom_keyword!(s8);
    custom_keyword!(s16);
    custom_keyword!(s32);
    custom_keyword!(s64);
    custom_keyword!(u8);
    custom_keyword!(u16);
    custom_keyword!(u32);
    custom_keyword!(u64);
    custom_keyword!(char);
    custom_keyword!(case);
    custom_keyword!(refines);
    custom_keyword!(record);
    custom_keyword!(string);
    custom_keyword!(bool_ = "bool");
    custom_keyword!(float32);
    custom_keyword!(float64);
    custom_keyword!(variant);
    custom_keyword!(flags);
    custom_keyword!(option);
    custom_keyword!(tuple);
    custom_keyword!(list);
    custom_keyword!(error);
    custom_keyword!(canon);
    custom_keyword!(lift);
    custom_keyword!(lower);
    custom_keyword!(enum_ = "enum");
    custom_keyword!(string_utf8 = "string-encoding=utf8");
    custom_keyword!(string_utf16 = "string-encoding=utf16");
    custom_keyword!(string_latin1_utf16 = "string-encoding=latin1+utf16");
    custom_keyword!(r#struct = "struct");
    custom_keyword!(structref);
    custom_keyword!(realloc);
    custom_keyword!(post_return = "post-return");
    custom_keyword!(with);
    custom_keyword!(core);
    custom_keyword!(true_ = "true");
    custom_keyword!(false_ = "false");
    custom_keyword!(language);
    custom_keyword!(sdk);
    custom_keyword!(processed_by = "processed-by");
    custom_keyword!(mem_info = "mem-info");
    custom_keyword!(needed);
    custom_keyword!(export_info = "export-info");
    custom_keyword!(import_info = "import-info");
    custom_keyword!(thread);
    custom_keyword!(wait);
}

/// Common annotations used to parse WebAssembly text files.
pub mod annotation {
    annotation!(custom);
    annotation!(name);
    annotation!(producers);
    annotation!(dylink_0 = "dylink.0");
}