1 | //! Common tokens that implement the [`Parse`] trait which are otherwise not |
2 | //! associated specifically with the wasm text format per se (useful in other |
3 | //! contexts too perhaps). |
4 | |
5 | use crate::annotation; |
6 | use crate::lexer::Float; |
7 | use crate::parser::{Cursor, Parse, Parser, Peek, Result}; |
8 | use std::fmt; |
9 | use std::hash::{Hash, Hasher}; |
10 | use std::str; |
11 | |
12 | /// A position in the original source stream, used to render errors. |
13 | #[derive (Copy, Clone, Debug, PartialOrd, Ord, PartialEq, Eq, Hash)] |
14 | pub struct Span { |
15 | pub(crate) offset: usize, |
16 | } |
17 | |
18 | impl Span { |
19 | /// Construct a `Span` from a byte offset in the source file. |
20 | pub fn from_offset(offset: usize) -> Self { |
21 | Span { offset } |
22 | } |
23 | |
24 | /// Returns the line/column information of this span within `text`. |
25 | /// Line and column numbers are 0-indexed. User presentation is typically |
26 | /// 1-indexed, but 0-indexing is appropriate for internal use with |
27 | /// iterators and slices. |
28 | pub fn linecol_in(&self, text: &str) -> (usize, usize) { |
29 | let mut cur = 0; |
30 | // Use split_terminator instead of lines so that if there is a `\r`, |
31 | // it is included in the offset calculation. The `+1` values below |
32 | // account for the `\n`. |
33 | for (i, line) in text.split_terminator(' \n' ).enumerate() { |
34 | if cur + line.len() + 1 > self.offset { |
35 | return (i, self.offset - cur); |
36 | } |
37 | cur += line.len() + 1; |
38 | } |
39 | (text.lines().count(), 0) |
40 | } |
41 | |
42 | /// Returns the byte offset of this span. |
43 | pub fn offset(&self) -> usize { |
44 | self.offset |
45 | } |
46 | } |
47 | |
48 | /// An identifier in a WebAssembly module, prefixed by `$` in the textual |
49 | /// format. |
50 | /// |
51 | /// An identifier is used to symbolically refer to items in a a wasm module, |
52 | /// typically via the [`Index`] type. |
53 | #[derive (Copy, Clone)] |
54 | pub struct Id<'a> { |
55 | name: &'a str, |
56 | generation: u32, |
57 | span: Span, |
58 | } |
59 | |
60 | impl<'a> Id<'a> { |
61 | /// Construct a new identifier from given string. |
62 | /// |
63 | /// Note that `name` can be any arbitrary string according to the |
64 | /// WebAssembly/annotations proposal. |
65 | pub fn new(name: &'a str, span: Span) -> Id<'a> { |
66 | Id { |
67 | name, |
68 | generation: 0, |
69 | span, |
70 | } |
71 | } |
72 | |
73 | #[cfg (feature = "wasm-module" )] |
74 | pub(crate) fn gensym(span: Span, generation: u32) -> Id<'a> { |
75 | Id { |
76 | name: "gensym" , |
77 | generation, |
78 | span, |
79 | } |
80 | } |
81 | |
82 | /// Returns the underlying name of this identifier. |
83 | /// |
84 | /// The name returned does not contain the leading `$`. |
85 | pub fn name(&self) -> &'a str { |
86 | self.name |
87 | } |
88 | |
89 | /// Returns span of this identifier in the original source |
90 | pub fn span(&self) -> Span { |
91 | self.span |
92 | } |
93 | |
94 | #[cfg (feature = "wasm-module" )] |
95 | pub(crate) fn is_gensym(&self) -> bool { |
96 | self.generation != 0 |
97 | } |
98 | } |
99 | |
100 | impl<'a> Hash for Id<'a> { |
101 | fn hash<H: Hasher>(&self, hasher: &mut H) { |
102 | self.name.hash(state:hasher); |
103 | self.generation.hash(state:hasher); |
104 | } |
105 | } |
106 | |
107 | impl<'a> PartialEq for Id<'a> { |
108 | fn eq(&self, other: &Id<'a>) -> bool { |
109 | self.name == other.name && self.generation == other.generation |
110 | } |
111 | } |
112 | |
113 | impl<'a> Eq for Id<'a> {} |
114 | |
115 | impl<'a> Parse<'a> for Id<'a> { |
116 | fn parse(parser: Parser<'a>) -> Result<Self> { |
117 | parser.step(|c: Cursor<'a>| { |
118 | if let Some((name: &'a str, rest: Cursor<'a>)) = c.id()? { |
119 | return Ok(( |
120 | Id { |
121 | name, |
122 | generation: 0, |
123 | span: c.cur_span(), |
124 | }, |
125 | rest, |
126 | )); |
127 | } |
128 | Err(c.error(msg:"expected an identifier" )) |
129 | }) |
130 | } |
131 | } |
132 | |
133 | impl fmt::Debug for Id<'_> { |
134 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
135 | if self.generation != 0 { |
136 | f&mut DebugStruct<'_, '_>.debug_struct("Id" ) |
137 | .field(name:"generation" , &self.generation) |
138 | .finish() |
139 | } else { |
140 | self.name.fmt(f) |
141 | } |
142 | } |
143 | } |
144 | |
145 | impl Peek for Id<'_> { |
146 | fn peek(cursor: Cursor<'_>) -> Result<bool> { |
147 | cursor.peek_id() |
148 | } |
149 | |
150 | fn display() -> &'static str { |
151 | "an identifier" |
152 | } |
153 | } |
154 | |
155 | /// A reference to another item in a wasm module. |
156 | /// |
157 | /// This type is used for items referring to other items (such as `call $foo` |
158 | /// referencing function `$foo`). References can be either an index (u32) or an |
159 | /// [`Id`] in the textual format. |
160 | /// |
161 | /// The emission phase of a module will ensure that `Index::Id` is never used |
162 | /// and switch them all to `Index::Num`. |
163 | #[derive (Copy, Clone, Debug)] |
164 | pub enum Index<'a> { |
165 | /// A numerical index that this references. The index space this is |
166 | /// referencing is implicit based on where this [`Index`] is stored. |
167 | Num(u32, Span), |
168 | /// A human-readable identifier this references. Like `Num`, the namespace |
169 | /// this references is based on where this is stored. |
170 | Id(Id<'a>), |
171 | } |
172 | |
173 | impl Index<'_> { |
174 | /// Returns the source location where this `Index` was defined. |
175 | pub fn span(&self) -> Span { |
176 | match self { |
177 | Index::Num(_, span: &Span) => *span, |
178 | Index::Id(id: &Id<'_>) => id.span(), |
179 | } |
180 | } |
181 | |
182 | #[cfg (feature = "wasm-module" )] |
183 | pub(crate) fn is_resolved(&self) -> bool { |
184 | matches!(self, Index::Num(..)) |
185 | } |
186 | } |
187 | |
188 | impl<'a> Parse<'a> for Index<'a> { |
189 | fn parse(parser: Parser<'a>) -> Result<Self> { |
190 | if parser.peek::<Id>()? { |
191 | Ok(Index::Id(parser.parse()?)) |
192 | } else if parser.peek::<u32>()? { |
193 | let (val: u32, span: Span) = parser.parse()?; |
194 | Ok(Index::Num(val, span)) |
195 | } else { |
196 | Err(parser.error(msg:format!( |
197 | "unexpected token, expected an index or an identifier" |
198 | ))) |
199 | } |
200 | } |
201 | } |
202 | |
203 | impl Peek for Index<'_> { |
204 | fn peek(cursor: Cursor<'_>) -> Result<bool> { |
205 | Ok(u32::peek(cursor)? || Id::peek(cursor)?) |
206 | } |
207 | |
208 | fn display() -> &'static str { |
209 | "an index" |
210 | } |
211 | } |
212 | |
213 | impl<'a> From<Id<'a>> for Index<'a> { |
214 | fn from(id: Id<'a>) -> Index<'a> { |
215 | Index::Id(id) |
216 | } |
217 | } |
218 | |
219 | impl PartialEq for Index<'_> { |
220 | fn eq(&self, other: &Index<'_>) -> bool { |
221 | match (self, other) { |
222 | (Index::Num(a: &u32, _), Index::Num(b: &u32, _)) => a == b, |
223 | (Index::Id(a: &Id<'_>), Index::Id(b: &Id<'_>)) => a == b, |
224 | _ => false, |
225 | } |
226 | } |
227 | } |
228 | |
229 | impl Eq for Index<'_> {} |
230 | |
231 | impl Hash for Index<'_> { |
232 | fn hash<H: Hasher>(&self, hasher: &mut H) { |
233 | match self { |
234 | Index::Num(a: &u32, _) => { |
235 | 0u8.hash(state:hasher); |
236 | a.hash(state:hasher); |
237 | } |
238 | Index::Id(a: &Id<'_>) => { |
239 | 1u8.hash(state:hasher); |
240 | a.hash(state:hasher); |
241 | } |
242 | } |
243 | } |
244 | } |
245 | |
246 | /// Parses `(func $foo)` |
247 | #[derive (Clone, Debug)] |
248 | #[allow (missing_docs)] |
249 | pub struct ItemRef<'a, K> { |
250 | pub kind: K, |
251 | pub idx: Index<'a>, |
252 | } |
253 | |
254 | impl<'a, K: Parse<'a>> Parse<'a> for ItemRef<'a, K> { |
255 | fn parse(parser: Parser<'a>) -> Result<Self> { |
256 | parser.parens(|parser: Parser<'a>| { |
257 | let kind: K = parser.parse::<K>()?; |
258 | let idx: Index<'_> = parser.parse()?; |
259 | Ok(ItemRef { kind, idx }) |
260 | }) |
261 | } |
262 | } |
263 | |
264 | impl<'a, K: Peek> Peek for ItemRef<'a, K> { |
265 | fn peek(cursor: Cursor<'_>) -> Result<bool> { |
266 | match cursor.lparen()? { |
267 | Some(remaining: Cursor<'_>) => K::peek(cursor:remaining), |
268 | None => Ok(false), |
269 | } |
270 | } |
271 | |
272 | fn display() -> &'static str { |
273 | "an item reference" |
274 | } |
275 | } |
276 | |
277 | /// An `@name` annotation in source, currently of the form `@name "foo"` |
278 | #[derive (Copy, Clone, PartialEq, Eq, Debug)] |
279 | pub struct NameAnnotation<'a> { |
280 | /// The name specified for the item |
281 | pub name: &'a str, |
282 | } |
283 | |
284 | impl<'a> Parse<'a> for NameAnnotation<'a> { |
285 | fn parse(parser: Parser<'a>) -> Result<Self> { |
286 | parser.parse::<annotation::name>()?; |
287 | let name: &str = parser.parse()?; |
288 | Ok(NameAnnotation { name }) |
289 | } |
290 | } |
291 | |
292 | impl<'a> Parse<'a> for Option<NameAnnotation<'a>> { |
293 | fn parse(parser: Parser<'a>) -> Result<Self> { |
294 | Ok(if parser.peek2::<annotation::name>()? { |
295 | Some(parser.parens(|p: Parser<'a>| p.parse())?) |
296 | } else { |
297 | None |
298 | }) |
299 | } |
300 | } |
301 | |
302 | macro_rules! integers { |
303 | ($($i:ident($u:ident))*) => ($( |
304 | impl<'a> Parse<'a> for $i { |
305 | fn parse(parser: Parser<'a>) -> Result<Self> { |
306 | Ok(parser.parse::<($i, Span)>()?.0) |
307 | } |
308 | } |
309 | |
310 | impl<'a> Parse<'a> for ($i, Span) { |
311 | fn parse(parser: Parser<'a>) -> Result<Self> { |
312 | parser.step(|c| { |
313 | if let Some((i, rest)) = c.integer()? { |
314 | let (s, base) = i.val(); |
315 | let val = $i::from_str_radix(s, base) |
316 | .or_else(|_| { |
317 | $u::from_str_radix(s, base).map(|i| i as $i) |
318 | }); |
319 | return match val { |
320 | Ok(n) => Ok(((n, c.cur_span()), rest)), |
321 | Err(_) => Err(c.error(concat!( |
322 | "invalid " , |
323 | stringify!($i), |
324 | " number: constant out of range" , |
325 | ))), |
326 | }; |
327 | } |
328 | Err(c.error(concat!("expected a " , stringify!($i)))) |
329 | }) |
330 | } |
331 | } |
332 | |
333 | impl Peek for $i { |
334 | fn peek(cursor: Cursor<'_>) -> Result<bool> { |
335 | cursor.peek_integer() |
336 | } |
337 | |
338 | fn display() -> &'static str { |
339 | stringify!($i) |
340 | } |
341 | } |
342 | )*) |
343 | } |
344 | |
345 | integers! { |
346 | u8(u8) u16(u16) u32(u32) u64(u64) |
347 | i8(u8) i16(u16) i32(u32) i64(u64) |
348 | } |
349 | |
350 | impl<'a> Parse<'a> for &'a [u8] { |
351 | fn parse(parser: Parser<'a>) -> Result<Self> { |
352 | parser.step(|c: Cursor<'a>| { |
353 | if let Some((i: &'a [u8], rest: Cursor<'a>)) = c.string()? { |
354 | return Ok((i, rest)); |
355 | } |
356 | Err(c.error(msg:"expected a string" )) |
357 | }) |
358 | } |
359 | } |
360 | |
361 | impl Peek for &'_ [u8] { |
362 | fn peek(cursor: Cursor<'_>) -> Result<bool> { |
363 | cursor.peek_string() |
364 | } |
365 | |
366 | fn display() -> &'static str { |
367 | "string" |
368 | } |
369 | } |
370 | |
371 | impl<'a> Parse<'a> for &'a str { |
372 | fn parse(parser: Parser<'a>) -> Result<Self> { |
373 | str::from_utf8(parser.parse()?) |
374 | .map_err(|_| parser.error_at(parser.prev_span(), msg:"malformed UTF-8 encoding" )) |
375 | } |
376 | } |
377 | |
378 | impl Parse<'_> for String { |
379 | fn parse(parser: Parser<'_>) -> Result<Self> { |
380 | Ok(<&str>::parse(parser)?.to_string()) |
381 | } |
382 | } |
383 | |
384 | impl Peek for &'_ str { |
385 | fn peek(cursor: Cursor<'_>) -> Result<bool> { |
386 | <&[u8]>::peek(cursor) |
387 | } |
388 | |
389 | fn display() -> &'static str { |
390 | <&[u8]>::display() |
391 | } |
392 | } |
393 | |
394 | macro_rules! float { |
395 | ($($name:ident => { |
396 | bits: $int:ident, |
397 | float: $float:ident, |
398 | exponent_bits: $exp_bits:tt, |
399 | name: $parse:ident, |
400 | })*) => ($( |
401 | /// A parsed floating-point type |
402 | #[derive(Debug, Copy, Clone)] |
403 | pub struct $name { |
404 | /// The raw bits that this floating point number represents. |
405 | pub bits: $int, |
406 | } |
407 | |
408 | impl<'a> Parse<'a> for $name { |
409 | fn parse(parser: Parser<'a>) -> Result<Self> { |
410 | parser.step(|c| { |
411 | let (val, rest) = if let Some((f, rest)) = c.float()? { |
412 | ($parse(&f), rest) |
413 | } else if let Some((i, rest)) = c.integer()? { |
414 | let (s, base) = i.val(); |
415 | ( |
416 | $parse(&Float::Val { |
417 | hex: base == 16, |
418 | integral: s.into(), |
419 | fractional: None, |
420 | exponent: None, |
421 | }), |
422 | rest, |
423 | ) |
424 | } else { |
425 | return Err(c.error("expected a float" )); |
426 | }; |
427 | match val { |
428 | Some(bits) => Ok(($name { bits }, rest)), |
429 | None => Err(c.error("invalid float value: constant out of range" )), |
430 | } |
431 | }) |
432 | } |
433 | } |
434 | |
435 | fn $parse(val: &Float<'_>) -> Option<$int> { |
436 | // Compute a few well-known constants about the float representation |
437 | // given the parameters to the macro here. |
438 | let width = std::mem::size_of::<$int>() * 8; |
439 | let neg_offset = width - 1; |
440 | let exp_offset = neg_offset - $exp_bits; |
441 | let signif_bits = width - 1 - $exp_bits; |
442 | let signif_mask = (1 << exp_offset) - 1; |
443 | let bias = (1 << ($exp_bits - 1)) - 1; |
444 | let msb = 1 << neg_offset; |
445 | |
446 | let (hex, integral, fractional, exponent_str) = match val { |
447 | // Infinity is when the exponent bits are all set and |
448 | // the significand is zero. |
449 | Float::Inf { negative } => { |
450 | let exp_bits = (1 << $exp_bits) - 1; |
451 | let neg_bit = *negative as $int; |
452 | return Some( |
453 | (neg_bit << neg_offset) | |
454 | (exp_bits << exp_offset) |
455 | ); |
456 | } |
457 | |
458 | // NaN is when the exponent bits are all set and |
459 | // the significand is nonzero. The default of NaN is |
460 | // when only the highest bit of the significand is set. |
461 | Float::Nan { negative, val } => { |
462 | let exp_bits = (1 << $exp_bits) - 1; |
463 | let neg_bit = *negative as $int; |
464 | let signif = match val { |
465 | Some(val) => $int::from_str_radix(val,16).ok()?, |
466 | None => 1 << (signif_bits - 1), |
467 | }; |
468 | // If the significand is zero then this is actually infinity |
469 | // so we fail to parse it. |
470 | if signif & signif_mask == 0 { |
471 | return None; |
472 | } |
473 | return Some( |
474 | (neg_bit << neg_offset) | |
475 | (exp_bits << exp_offset) | |
476 | (signif & signif_mask) |
477 | ); |
478 | } |
479 | |
480 | // This is trickier, handle this below |
481 | Float::Val { hex, integral, fractional, exponent } => { |
482 | (hex, integral, fractional, exponent) |
483 | } |
484 | }; |
485 | |
486 | // Rely on Rust's standard library to parse base 10 floats |
487 | // correctly. |
488 | if !*hex { |
489 | let mut s = integral.to_string(); |
490 | if let Some(fractional) = fractional { |
491 | s.push_str("." ); |
492 | s.push_str(&fractional); |
493 | } |
494 | if let Some(exponent) = exponent_str { |
495 | s.push_str("e" ); |
496 | s.push_str(&exponent); |
497 | } |
498 | let float = s.parse::<$float>().ok()?; |
499 | // looks like the `*.wat` format considers infinite overflow to |
500 | // be invalid. |
501 | if float.is_infinite() { |
502 | return None; |
503 | } |
504 | return Some(float.to_bits()); |
505 | } |
506 | |
507 | // Parse a hexadecimal floating-point value. |
508 | // |
509 | // The main loop here is simpler than for parsing decimal floats, |
510 | // because we can just parse hexadecimal digits and then shift |
511 | // their bits into place in the significand. But in addition to |
512 | // that, we also need to handle non-normalized representations, |
513 | // where the integral part is not "1", to convert them to |
514 | // normalized results, to round, in case we get more digits than |
515 | // the target format supports, and to handle overflow and subnormal |
516 | // cases. |
517 | |
518 | // Get slices of digits for the integral and fractional parts. We |
519 | // can trivially skip any leading zeros in the integral part. |
520 | let is_negative = integral.starts_with('-' ); |
521 | let integral = integral.trim_start_matches('-' ).trim_start_matches('0' ); |
522 | let fractional = fractional.as_ref().map(|s| &**s).unwrap_or("" ); |
523 | |
524 | // Locate the first non-zero digit to determine the initial exponent. |
525 | // |
526 | // If there's no integral part, skip past leading zeros so that |
527 | // something like "0x.0000000000000000000002" doesn't cause us to hit |
528 | // a shift overflow when we try to shift the value into place. We'll |
529 | // adjust the exponent below to account for these skipped zeros. |
530 | let fractional_no_leading = fractional.trim_start_matches('0' ); |
531 | let fractional_iter = if integral.is_empty() { |
532 | fractional_no_leading.chars() |
533 | } else { |
534 | fractional.chars() |
535 | }; |
536 | |
537 | // Create a unified iterator over the digits of the integral part |
538 | // followed by the digits of the fractional part. The boolean value |
539 | // indicates which of these parts we're in. |
540 | let mut digits = integral.chars() |
541 | .map(|c| (to_hex(c) as $int, false)) |
542 | .chain(fractional_iter.map(|c| (to_hex(c) as $int, true))); |
543 | |
544 | // Compute the number of leading zeros in the first non-zero digit, |
545 | // since if the first digit is not "1" we'll need to adjust for |
546 | // normalization. |
547 | let lead_nonzero_digit = match digits.next() { |
548 | Some((c, _)) => c, |
549 | // No non-zero digits? Must be `+0` or `-0`, being careful to |
550 | // handle the sign encoding here. |
551 | None if is_negative => return Some(msb), |
552 | None => return Some(0), |
553 | }; |
554 | let lz = (lead_nonzero_digit as u8).leading_zeros() as i32 - 4; |
555 | |
556 | // Prepare for the main parsing loop. Calculate the initial values |
557 | // of `exponent` and `significand` based on what we've seen so far. |
558 | let mut exponent = if !integral.is_empty() { |
559 | 1 |
560 | } else { |
561 | // Adjust the exponent digits to account for any leading zeros |
562 | // in the fractional part that we skipped above. |
563 | -((fractional.len() - fractional_no_leading.len() + 1) as i32) + 1 |
564 | }; |
565 | let mut significand_pos = (width - (4 - (lz as usize))) as isize; |
566 | let mut significand: $int = lead_nonzero_digit << significand_pos; |
567 | let mut discarded_extra_nonzero = false; |
568 | |
569 | assert!(significand_pos >= 0, "$int should be at least 4 bits wide" ); |
570 | |
571 | // Adjust for leading zeros in the first digit. |
572 | exponent = exponent.checked_mul(4)?.checked_sub(lz + 1)?; |
573 | |
574 | // Now that we've got an anchor in the string we parse the remaining |
575 | // hexadecimal digits. |
576 | for (digit, in_fractional) in digits { |
577 | if !in_fractional { |
578 | exponent += 4; |
579 | } |
580 | if significand_pos > -4 { |
581 | significand_pos -= 4; |
582 | } |
583 | |
584 | if significand_pos >= 0 { |
585 | significand |= digit << significand_pos; |
586 | } else if significand_pos > -4 { |
587 | significand |= digit >> (4 - significand_pos); |
588 | discarded_extra_nonzero = (digit & !((!0) >> (4 - significand_pos))) != 0; |
589 | } else if digit != 0 { |
590 | discarded_extra_nonzero = true; |
591 | } |
592 | } |
593 | |
594 | debug_assert!(significand != 0, "The case of no non-zero digits should have been handled above" ); |
595 | |
596 | // Parse the exponent string, which despite this being a hexadecimal |
597 | // syntax, is a decimal number, and add it the exponent we've |
598 | // computed from the potentially non-normalized significand. |
599 | exponent = exponent.checked_add(match exponent_str { |
600 | Some(s) => s.parse::<i32>().ok()?, |
601 | None => 0, |
602 | })?; |
603 | |
604 | // Encode the exponent and significand. Also calculate the bits of |
605 | // the significand which are discarded, as we'll use them to |
606 | // determine if we need to round up. |
607 | let (encoded_exponent, encoded_significand, discarded_significand) = |
608 | if exponent <= -bias { |
609 | // Underflow to subnormal or zero. |
610 | let shift = exp_offset as i32 + exponent + bias; |
611 | if shift == 0 { |
612 | (0, 0, significand) |
613 | } else if shift < 0 || shift >= width as i32 { |
614 | (0, 0, 0) |
615 | } else { |
616 | ( |
617 | 0, |
618 | significand >> (width as i32 - shift), |
619 | significand << shift, |
620 | ) |
621 | } |
622 | } else if exponent <= bias { |
623 | // Normal (non-zero). The significand's leading 1 is encoded |
624 | // implicitly. |
625 | ( |
626 | ((exponent + bias) as $int) << exp_offset, |
627 | (significand >> (width - exp_offset - 1)) & signif_mask, |
628 | significand << (exp_offset + 1), |
629 | ) |
630 | } else { |
631 | // Overflow to infinity. |
632 | ( |
633 | ((1 << $exp_bits) - 1) << exp_offset, |
634 | 0, |
635 | 0, |
636 | ) |
637 | }; |
638 | |
639 | // Combine the encoded exponent and encoded significand to produce |
640 | // the raw result, except for the sign bit, which we'll apply at |
641 | // the end. |
642 | let bits = encoded_exponent | encoded_significand; |
643 | |
644 | // Apply rounding. Do an integer add of `0` or `1` on the raw |
645 | // result, depending on whether rounding is needed. Rounding can |
646 | // lead to a floating-point overflow, but we don't need to |
647 | // special-case that here because it turns out that IEEE 754 floats |
648 | // are encoded such that when an integer add of `1` carries into |
649 | // the bits of the exponent field, it produces the correct encoding |
650 | // for infinity. |
651 | let bits = bits |
652 | + (((discarded_significand & msb != 0) |
653 | && ((discarded_significand & !msb != 0) || |
654 | discarded_extra_nonzero || |
655 | // ties to even |
656 | (encoded_significand & 1 != 0))) as $int); |
657 | |
658 | // Just before we return the bits, be sure to handle the sign bit we |
659 | // found at the beginning. |
660 | let bits = if is_negative { |
661 | bits | msb |
662 | } else { |
663 | bits |
664 | }; |
665 | // looks like the `*.wat` format considers infinite overflow to |
666 | // be invalid. |
667 | if $float::from_bits(bits).is_infinite() { |
668 | return None; |
669 | } |
670 | Some(bits) |
671 | } |
672 | |
673 | )*) |
674 | } |
675 | |
676 | float! { |
677 | F32 => { |
678 | bits: u32, |
679 | float: f32, |
680 | exponent_bits: 8, |
681 | name: strtof, |
682 | } |
683 | F64 => { |
684 | bits: u64, |
685 | float: f64, |
686 | exponent_bits: 11, |
687 | name: strtod, |
688 | } |
689 | } |
690 | |
691 | fn to_hex(c: char) -> u8 { |
692 | match c { |
693 | 'a' ..='f' => c as u8 - b'a' + 10, |
694 | 'A' ..='F' => c as u8 - b'A' + 10, |
695 | _ => c as u8 - b'0' , |
696 | } |
697 | } |
698 | |
699 | /// A convenience type to use with [`Parser::peek`](crate::parser::Parser::peek) |
700 | /// to see if the next token is an s-expression. |
701 | pub struct LParen { |
702 | _priv: (), |
703 | } |
704 | |
705 | impl Peek for LParen { |
706 | fn peek(cursor: Cursor<'_>) -> Result<bool> { |
707 | cursor.peek_lparen() |
708 | } |
709 | |
710 | fn display() -> &'static str { |
711 | "left paren" |
712 | } |
713 | } |
714 | |
715 | /// A convenience type to use with [`Parser::peek`](crate::parser::Parser::peek) |
716 | /// to see if the next token is the end of an s-expression. |
717 | pub struct RParen { |
718 | _priv: (), |
719 | } |
720 | |
721 | impl Peek for RParen { |
722 | fn peek(cursor: Cursor<'_>) -> Result<bool> { |
723 | cursor.peek_rparen() |
724 | } |
725 | |
726 | fn display() -> &'static str { |
727 | "right paren" |
728 | } |
729 | } |
730 | |
731 | #[cfg (test)] |
732 | mod tests { |
733 | #[test ] |
734 | fn hex_strtof() { |
735 | macro_rules! f { |
736 | ($a:tt) => (f!(@mk $a, None, None)); |
737 | ($a:tt p $e:tt) => (f!(@mk $a, None, Some($e.into()))); |
738 | ($a:tt . $b:tt) => (f!(@mk $a, Some($b.into()), None)); |
739 | ($a:tt . $b:tt p $e:tt) => (f!(@mk $a, Some($b.into()), Some($e.into()))); |
740 | (@mk $a:tt, $b:expr, $e:expr) => (crate::lexer::Float::Val { |
741 | hex: true, |
742 | integral: $a.into(), |
743 | fractional: $b, |
744 | exponent: $e |
745 | }); |
746 | } |
747 | assert_eq!(super::strtof(&f!("0" )), Some(0)); |
748 | assert_eq!(super::strtof(&f!("0" . "0" )), Some(0)); |
749 | assert_eq!(super::strtof(&f!("0" . "0" p "2354" )), Some(0)); |
750 | assert_eq!(super::strtof(&f!("-0" )), Some(1 << 31)); |
751 | assert_eq!(super::strtof(&f!("f32" )), Some(0x45732000)); |
752 | assert_eq!(super::strtof(&f!("0" . "f32" )), Some(0x3f732000)); |
753 | assert_eq!(super::strtof(&f!("1" . "2" )), Some(0x3f900000)); |
754 | assert_eq!( |
755 | super::strtof(&f!("0" . "00000100000000000" p "-126" )), |
756 | Some(0) |
757 | ); |
758 | assert_eq!( |
759 | super::strtof(&f!("1" . "fffff4" p "-106" )), |
760 | Some(0x0afffffa) |
761 | ); |
762 | assert_eq!(super::strtof(&f!("fffff98" p "-133" )), Some(0x0afffffa)); |
763 | assert_eq!(super::strtof(&f!("0" . "081" p "023" )), Some(0x48810000)); |
764 | assert_eq!( |
765 | super::strtof(&f!("1" . "00000100000000000" p "-50" )), |
766 | Some(0x26800000) |
767 | ); |
768 | } |
769 | } |
770 | |