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
//-
// Copyright 2017 Jason Lingle
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! Strategies for generating strings and byte strings from regular
//! expressions.

use crate::std_facade::{Box, Cow, String, ToOwned, Vec};
use core::fmt;
use core::mem;
use core::ops::RangeInclusive;
use core::u32;

use regex_syntax::hir::{
    self, Hir,
    HirKind::*,
    Literal::*,
    RepetitionKind::{self, *},
    RepetitionRange::*,
};
use regex_syntax::{Error as ParseError, Parser};

use crate::bool;
use crate::char;
use crate::collection::{size_range, vec, SizeRange};
use crate::strategy::*;
use crate::test_runner::*;

/// Wraps the regex that forms the `Strategy` for `String` so that a sensible
/// `Default` can be given. The default is a string of non-control characters.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct StringParam(&'static str);

impl From<StringParam> for &'static str {
    fn from(x: StringParam) -> Self {
        x.0
    }
}

impl From<&'static str> for StringParam {
    fn from(x: &'static str) -> Self {
        StringParam(x)
    }
}

impl Default for StringParam {
    fn default() -> Self {
        StringParam("\\PC*")
    }
}

// quick_error! uses bare trait objects, so we enclose its invocation here in a
// module so the lint can be disabled just for it. Also suppress deprecation
// due to .description().
#[allow(bare_trait_objects, deprecated)]
mod error_container {
    use super::*;

    quick_error! {
        /// Errors which may occur when preparing a regular expression for use with
        /// string generation.
        #[derive(Debug)]
        pub enum Error {
            /// The string passed as the regex was not syntactically valid.
            RegexSyntax(err: ParseError) {
                from()
                    cause(err)
                    description(err.description())
                    display("{}", err)
            }
            /// The regex was syntactically valid, but contains elements not
            /// supported by proptest.
            UnsupportedRegex(message: &'static str) {
                description(message)
            }
        }
    }
}

pub use self::error_container::Error;

opaque_strategy_wrapper! {
    /// Strategy which generates values (i.e., `String` or `Vec<u8>`) matching
    /// a regular expression.
    ///
    /// Created by various functions in this module.
    #[derive(Debug)]
    pub struct RegexGeneratorStrategy[<T>][where T : fmt::Debug]
        (SBoxedStrategy<T>) -> RegexGeneratorValueTree<T>;
    /// `ValueTree` corresponding to `RegexGeneratorStrategy`.
    pub struct RegexGeneratorValueTree[<T>][where T : fmt::Debug]
        (Box<dyn ValueTree<Value = T>>) -> T;
}

impl Strategy for str {
    type Tree = RegexGeneratorValueTree<String>;
    type Value = String;

    fn new_tree(&self, runner: &mut TestRunner) -> NewTree<Self> {
        string_regex(self).unwrap().new_tree(runner)
    }
}

type ParseResult<T> = Result<RegexGeneratorStrategy<T>, Error>;

#[doc(hidden)]
/// A type which knows how to produce a `Strategy` from a regular expression
/// generating the type.
///
/// This trait exists for the benefit of `#[proptest(regex = "...")]`.
/// It is semver exempt, so use at your own risk.
/// If you found a use for the trait beyond `Vec<u8>` and `String`,
/// please file an issue at https://github.com/AltSysrq/proptest.
pub trait StrategyFromRegex: Sized + fmt::Debug {
    type Strategy: Strategy<Value = Self>;

    /// Produce a strategy for `Self` from the `regex`.
    fn from_regex(regex: &str) -> Self::Strategy;
}

impl StrategyFromRegex for String {
    type Strategy = RegexGeneratorStrategy<Self>;

    fn from_regex(regex: &str) -> Self::Strategy {
        string_regex(regex).unwrap()
    }
}

impl StrategyFromRegex for Vec<u8> {
    type Strategy = RegexGeneratorStrategy<Self>;

    fn from_regex(regex: &str) -> Self::Strategy {
        bytes_regex(regex).unwrap()
    }
}

/// Creates a strategy which generates strings matching the given regular
/// expression.
///
/// If you don't need error handling and aren't limited by setup time, it is
/// also possible to directly use a `&str` as a strategy with the same effect.
pub fn string_regex(regex: &str) -> ParseResult<String> {
    string_regex_parsed(&regex_to_hir(regex)?)
}

/// Like `string_regex()`, but allows providing a pre-parsed expression.
pub fn string_regex_parsed(expr: &Hir) -> ParseResult<String> {
    bytes_regex_parsed(expr)
        .map(|v| {
            v.prop_map(|bytes| {
                String::from_utf8(bytes).expect("non-utf8 string")
            })
            .sboxed()
        })
        .map(RegexGeneratorStrategy)
}

/// Creates a strategy which generates byte strings matching the given regular
/// expression.
pub fn bytes_regex(regex: &str) -> ParseResult<Vec<u8>> {
    bytes_regex_parsed(&regex_to_hir(regex)?)
}

/// Like `bytes_regex()`, but allows providing a pre-parsed expression.
pub fn bytes_regex_parsed(expr: &Hir) -> ParseResult<Vec<u8>> {
    match expr.kind() {
        Empty => Ok(Just(vec![]).sboxed()),

        Literal(lit) => Ok(Just(match lit {
            Unicode(scalar) => to_bytes(*scalar),
            Byte(byte) => vec![*byte],
        })
        .sboxed()),

        Class(class) => Ok(match class {
            hir::Class::Unicode(class) => {
                unicode_class_strategy(class).prop_map(to_bytes).sboxed()
            }
            hir::Class::Bytes(class) => {
                let subs = class.iter().map(|r| r.start()..=r.end());
                Union::new(subs).prop_map(|b| vec![b]).sboxed()
            }
        }),

        Repetition(rep) => Ok(vec(
            bytes_regex_parsed(&rep.hir)?,
            to_range(rep.kind.clone())?,
        )
        .prop_map(|parts| {
            parts.into_iter().fold(vec![], |mut acc, child| {
                acc.extend(child);
                acc
            })
        })
        .sboxed()),

        Group(group) => bytes_regex_parsed(&group.hir).map(|v| v.0),

        Concat(subs) => {
            let subs = ConcatIter {
                iter: subs.iter(),
                buf: vec![],
                next: None,
            };
            let ext = |(mut lhs, rhs): (Vec<_>, _)| {
                lhs.extend(rhs);
                lhs
            };
            Ok(subs
                .fold(Ok(None), |accum: Result<_, Error>, rhs| {
                    Ok(match accum? {
                        None => Some(rhs?.sboxed()),
                        Some(accum) => {
                            Some((accum, rhs?).prop_map(ext).sboxed())
                        }
                    })
                })?
                .unwrap_or_else(|| Just(vec![]).sboxed()))
        }

        Alternation(subs) => {
            Ok(Union::try_new(subs.iter().map(bytes_regex_parsed))?.sboxed())
        }

        Anchor(_) => {
            unsupported("line/text anchors not supported for string generation")
        }

        WordBoundary(_) => unsupported(
            "word boundary tests not supported for string generation",
        ),
    }
    .map(RegexGeneratorStrategy)
}

fn unicode_class_strategy(
    class: &hir::ClassUnicode,
) -> char::CharStrategy<'static> {
    static NONL_RANGES: &[RangeInclusive<char>] = &[
        '\x00'..='\x09',
        // Multiple instances of the latter range to partially make up
        // for the bias of having such a tiny range in the control
        // characters.
        '\x0B'..=::core::char::MAX,
        '\x0B'..=::core::char::MAX,
        '\x0B'..=::core::char::MAX,
        '\x0B'..=::core::char::MAX,
        '\x0B'..=::core::char::MAX,
    ];

    let dotnnl = |x: &hir::ClassUnicodeRange, y: &hir::ClassUnicodeRange| {
        x.start() == '\0'
            && x.end() == '\x09'
            && y.start() == '\x0B'
            && y.end() == '\u{10FFFF}'
    };

    char::ranges(match class.ranges() {
        [x, y] if dotnnl(x, y) || dotnnl(y, x) => Cow::Borrowed(NONL_RANGES),
        _ => Cow::Owned(class.iter().map(|r| r.start()..=r.end()).collect()),
    })
}

struct ConcatIter<'a, I> {
    buf: Vec<u8>,
    iter: I,
    next: Option<&'a Hir>,
}

fn flush_lit_buf<I>(
    it: &mut ConcatIter<'_, I>,
) -> Option<ParseResult<Vec<u8>>> {
    Some(Ok(RegexGeneratorStrategy(
        Just(mem::replace(&mut it.buf, vec![])).sboxed(),
    )))
}

impl<'a, I: Iterator<Item = &'a Hir>> Iterator for ConcatIter<'a, I> {
    type Item = ParseResult<Vec<u8>>;

    fn next(&mut self) -> Option<Self::Item> {
        // A left-over node, process it first:
        if let Some(next) = self.next.take() {
            return Some(bytes_regex_parsed(next));
        }

        // Accumulate a literal sequence as long as we can:
        while let Some(next) = self.iter.next() {
            match next.kind() {
                // A literal. Accumulate:
                Literal(Unicode(scalar)) => self.buf.extend(to_bytes(*scalar)),
                Literal(Byte(byte)) => self.buf.push(*byte),
                // Encountered a non-literal.
                _ => {
                    return if !self.buf.is_empty() {
                        // We've accumulated a literal from before, flush it out.
                        // Store this node so we deal with it the next call.
                        self.next = Some(next);
                        flush_lit_buf(self)
                    } else {
                        // We didn't; just yield this node.
                        Some(bytes_regex_parsed(next))
                    };
                }
            }
        }

        // Flush out any accumulated literal from before.
        if !self.buf.is_empty() {
            flush_lit_buf(self)
        } else {
            self.next.take().map(bytes_regex_parsed)
        }
    }
}

fn to_range(kind: RepetitionKind) -> Result<SizeRange, Error> {
    Ok(match kind {
        ZeroOrOne => size_range(0..=1),
        ZeroOrMore => size_range(0..=32),
        OneOrMore => size_range(1..=32),
        Range(range) => match range {
            Exactly(count) if u32::MAX == count => {
                return unsupported(
                    "Cannot have repetition of exactly u32::MAX",
                )
            }
            Exactly(count) => size_range(count as usize),
            AtLeast(min) => {
                let max = if min < u32::MAX as u32 / 2 {
                    min as usize * 2
                } else {
                    u32::MAX as usize
                };
                size_range((min as usize)..max)
            }
            Bounded(_, max) if u32::MAX == max => {
                return unsupported("Cannot have repetition max of u32::MAX")
            }
            Bounded(min, max) => size_range((min as usize)..(max as usize + 1)),
        },
    })
}

fn to_bytes(khar: char) -> Vec<u8> {
    let mut buf = [0u8; 4];
    khar.encode_utf8(&mut buf).as_bytes().to_owned()
}

fn regex_to_hir(pattern: &str) -> Result<Hir, Error> {
    Ok(Parser::new().parse(pattern)?)
}

fn unsupported<T>(error: &'static str) -> Result<T, Error> {
    Err(Error::UnsupportedRegex(error))
}

#[cfg(test)]
mod test {
    use std::collections::HashSet;

    use regex::Regex;

    use super::*;

    fn do_test(
        pattern: &str,
        min_distinct: usize,
        max_distinct: usize,
        iterations: usize,
    ) {
        let generated = generate_values_matching_regex(pattern, iterations);
        assert!(
            generated.len() >= min_distinct,
            "Expected to generate at least {} strings, but only \
             generated {}",
            min_distinct,
            generated.len()
        );
        assert!(
            generated.len() <= max_distinct,
            "Expected to generate at most {} strings, but \
             generated {}",
            max_distinct,
            generated.len()
        );
    }

    fn generate_values_matching_regex(
        pattern: &str,
        iterations: usize,
    ) -> HashSet<String> {
        let rx = Regex::new(pattern).unwrap();
        let mut generated = HashSet::new();

        let strategy = string_regex(pattern).unwrap();
        let mut runner = TestRunner::deterministic();
        for _ in 0..iterations {
            let mut value = strategy.new_tree(&mut runner).unwrap();

            loop {
                let s = value.current();
                let ok = if let Some(matsch) = rx.find(&s) {
                    0 == matsch.start() && s.len() == matsch.end()
                } else {
                    false
                };
                if !ok {
                    panic!(
                        "Generated string {:?} which does not match {:?}",
                        s, pattern
                    );
                }

                generated.insert(s);

                if !value.simplify() {
                    break;
                }
            }
        }
        generated
    }

    #[test]
    fn test_case_insensitive_produces_all_available_values() {
        let mut expected: HashSet<String> = HashSet::new();
        expected.insert("a".into());
        expected.insert("b".into());
        expected.insert("A".into());
        expected.insert("B".into());
        assert_eq!(generate_values_matching_regex("(?i:a|B)", 64), expected);
    }

    #[test]
    fn test_literal() {
        do_test("foo", 1, 1, 8);
    }

    #[test]
    fn test_casei_literal() {
        do_test("(?i:fOo)", 8, 8, 64);
    }

    #[test]
    fn test_alternation() {
        do_test("foo|bar|baz", 3, 3, 16);
    }

    #[test]
    fn test_repitition() {
        do_test("a{0,8}", 9, 9, 64);
    }

    #[test]
    fn test_question() {
        do_test("a?", 2, 2, 16);
    }

    #[test]
    fn test_star() {
        do_test("a*", 33, 33, 256);
    }

    #[test]
    fn test_plus() {
        do_test("a+", 32, 32, 256);
    }

    #[test]
    fn test_n_to_range() {
        do_test("a{4,}", 4, 4, 64);
    }

    #[test]
    fn test_concatenation() {
        do_test("(foo|bar)(xyzzy|plugh)", 4, 4, 32);
    }

    #[test]
    fn test_ascii_class() {
        do_test("[[:digit:]]", 10, 10, 256);
    }

    #[test]
    fn test_unicode_class() {
        do_test("\\p{Greek}", 24, 512, 256);
    }

    #[test]
    fn test_dot() {
        do_test(".", 200, 65536, 256);
    }

    #[test]
    fn test_dot_s() {
        do_test("(?s).", 200, 65536, 256);
    }

    #[test]
    fn test_backslash_d_plus() {
        do_test("\\d+", 1, 65536, 256);
    }

    fn assert_send_and_sync<T: Send + Sync>(_: T) {}

    #[test]
    fn regex_strategy_is_send_and_sync() {
        assert_send_and_sync(string_regex(".").unwrap());
    }

    macro_rules! consistent {
        ($name:ident, $value:expr) => {
            #[test]
            fn $name() {
                test_generates_matching_strings($value);
            }
        };
    }

    fn test_generates_matching_strings(pattern: &str) {
        use std::time;

        let mut runner = TestRunner::default();
        let start = time::Instant::now();

        // If we don't support this regex, just move on quietly
        if let Ok(strategy) = string_regex(pattern) {
            let rx = Regex::new(pattern).unwrap();

            for _ in 0..1000 {
                let mut val = strategy.new_tree(&mut runner).unwrap();
                // No more than 1000 simplify steps to keep test time down
                for _ in 0..1000 {
                    let s = val.current();
                    assert!(
                        rx.is_match(&s),
                        "Produced string {:?}, which does not match {:?}",
                        s,
                        pattern
                    );

                    if !val.simplify() {
                        break;
                    }
                }

                // Quietly stop testing if we've run for >10 s
                if start.elapsed().as_secs() > 10 {
                    break;
                }
            }
        }
    }

    include!("regex-contrib/crates_regex.rs");
}