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
// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// 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.

//! This crate provides a native implementation of regular expressions that is
//! heavily based on RE2 both in syntax and in implementation. Notably,
//! backreferences and arbitrary lookahead/lookbehind assertions are not
//! provided. In return, regular expression searching provided by this package
//! has excellent worst-case performance. The specific syntax supported is
//! documented further down.
//!
//! This crate's documentation provides some simple examples, describes Unicode
//! support and exhaustively lists the supported syntax. For more specific
//! details on the API, please see the documentation for the `Regex` type.
//!
//! # Usage
//!
//! This crate is [on crates.io](https://crates.io/crates/regex) and can be
//! used by adding `regex` to your dependencies in your project's `Cargo.toml`.
//!
//! ```toml
//! [dependencies]
//! regex = "0.1"
//! ```
//!
//! and this to your crate root:
//!
//! ```rust
//! extern crate regex;
//! ```
//!
//! # First example: find a date
//!
//! General use of regular expressions in this package involves compiling an
//! expression and then using it to search, split or replace text. For example,
//! to confirm that some text resembles a date:
//!
//! ```rust
//! use regex::Regex;
//! let re = Regex::new(r"^\d{4}-\d{2}-\d{2}$").unwrap();
//! assert!(re.is_match("2014-01-01"));
//! ```
//!
//! Notice the use of the `^` and `$` anchors. In this crate, every expression
//! is executed with an implicit `.*?` at the beginning and end, which allows
//! it to match anywhere in the text. Anchors can be used to ensure that the
//! full text matches an expression.
//!
//! This example also demonstrates the utility of
//! [raw strings](https://doc.rust-lang.org/stable/reference.html#raw-string-literals)
//! in Rust, which
//! are just like regular strings except they are prefixed with an `r` and do
//! not process any escape sequences. For example, `"\\d"` is the same
//! expression as `r"\d"`.
//!
//! # The `regex!` macro
//!
//! Rust's compile-time meta-programming facilities provide a way to write a
//! `regex!` macro which compiles regular expressions *when your program
//! compiles*. Said differently, if you only use `regex!` to build regular
//! expressions in your program, then your program cannot compile with an
//! invalid regular expression. Moreover, the `regex!` macro compiles the
//! given expression to native Rust code, which ideally makes it faster.
//! Unfortunately (or fortunately), the dynamic implementation has had a lot
//! more optimization work put into it currently, so it is faster than
//! the `regex!` macro in most cases.
//!
//! To use the `regex!` macro, you must add `regex_macros` to your dependencies
//! in your project's `Cargo.toml`:
//!
//! ```toml
//! [dependencies]
//! regex = "0.1.8"
//! regex_macros = "0.1.8"
//! ```
//!
//! and then enable the `plugin` feature and import the `regex_macros` crate as
//! a syntax extension:
//!
//! ```ignore
//! #![feature(plugin)]
//! #![plugin(regex_macros)]
//! extern crate regex;
//!
//! fn main() {
//!     let re = regex!(r"^\d{4}-\d{2}-\d{2}$");
//!     assert!(re.is_match("2014-01-01"));
//! }
//! ```
//!
//! There are a few things worth mentioning about using the `regex!` macro.
//! Firstly, the `regex!` macro *only* accepts string *literals*.
//! Secondly, the `regex` crate *must* be linked with the name `regex` since
//! the generated code depends on finding symbols in the `regex` crate.
//!
//! One downside of using the `regex!` macro is that it can increase the
//! size of your program's binary since it generates specialized Rust code.
//! The extra size probably won't be significant for a small number of
//! expressions, but 100+ calls to `regex!` will probably result in a
//! noticeably bigger binary.
//!
//! **NOTE**: This is implemented using a compiler plugin, which is not
//! available on the Rust 1.0 beta/stable channels. Therefore, you'll only
//! be able to use `regex!` on the nightlies.
//!
//! # Example: iterating over capture groups
//!
//! This crate provides convenient iterators for matching an expression
//! repeatedly against a search string to find successive non-overlapping
//! matches. For example, to find all dates in a string and be able to access
//! them by their component pieces:
//!
//! ```rust
//! # extern crate regex; use regex::Regex;
//! # fn main() {
//! let re = Regex::new(r"(\d{4})-(\d{2})-(\d{2})").unwrap();
//! let text = "2012-03-14, 2013-01-01 and 2014-07-05";
//! for cap in re.captures_iter(text) {
//!     println!("Month: {} Day: {} Year: {}",
//!              cap.at(2).unwrap_or(""), cap.at(3).unwrap_or(""),
//!              cap.at(1).unwrap_or(""));
//! }
//! // Output:
//! // Month: 03 Day: 14 Year: 2012
//! // Month: 01 Day: 01 Year: 2013
//! // Month: 07 Day: 05 Year: 2014
//! # }
//! ```
//!
//! Notice that the year is in the capture group indexed at `1`. This is
//! because the *entire match* is stored in the capture group at index `0`.
//!
//! # Example: replacement with named capture groups
//!
//! Building on the previous example, perhaps we'd like to rearrange the date
//! formats. This can be done with text replacement. But to make the code
//! clearer, we can *name*  our capture groups and use those names as variables
//! in our replacement text:
//!
//! ```rust
//! # extern crate regex; use regex::Regex;
//! # fn main() {
//! let re = Regex::new(r"(?P<y>\d{4})-(?P<m>\d{2})-(?P<d>\d{2})").unwrap();
//! let before = "2012-03-14, 2013-01-01 and 2014-07-05";
//! let after = re.replace_all(before, "$m/$d/$y");
//! assert_eq!(after, "03/14/2012, 01/01/2013 and 07/05/2014");
//! # }
//! ```
//!
//! The `replace` methods are actually polymorphic in the replacement, which
//! provides more flexibility than is seen here. (See the documentation for
//! `Regex::replace` for more details.)
//!
//! Note that if your regex gets complicated, you can use the `x` flag to
//! enable insigificant whitespace mode, which also lets you write comments:
//!
//! ```rust
//! # extern crate regex; use regex::Regex;
//! # fn main() {
//! let re = Regex::new(r"(?x)
//!   (?P<y>\d{4}) # the year
//!   -
//!   (?P<m>\d{2}) # the month
//!   -
//!   (?P<d>\d{2}) # the day
//! ").unwrap();
//! let before = "2012-03-14, 2013-01-01 and 2014-07-05";
//! let after = re.replace_all(before, "$m/$d/$y");
//! assert_eq!(after, "03/14/2012, 01/01/2013 and 07/05/2014");
//! # }
//! ```
//!
//! # Pay for what you use
//!
//! With respect to searching text with a regular expression, there are three
//! questions that can be asked:
//!
//! 1. Does the text match this expression?
//! 2. If so, where does it match?
//! 3. Where are the submatches?
//!
//! Generally speaking, this crate could provide a function to answer only #3,
//! which would subsume #1 and #2 automatically. However, it can be
//! significantly more expensive to compute the location of submatches, so it's
//! best not to do it if you don't need to.
//!
//! Therefore, only use what you need. For example, don't use `find` if you
//! only need to test if an expression matches a string. (Use `is_match`
//! instead.)
//!
//! # Unicode
//!
//! This implementation executes regular expressions **only** on sequences of
//! Unicode scalar values while exposing match locations as byte indices into
//! the search string.
//!
//! Currently, only simple case folding is supported. Namely, when matching
//! case-insensitively, the characters are first mapped using the
//! [simple case folding](ftp://ftp.unicode.org/Public/UNIDATA/CaseFolding.txt)
//! mapping.
//!
//! Regular expressions themselves are also **only** interpreted as a sequence
//! of Unicode scalar values. This means you can use Unicode characters
//! directly in your expression:
//!
//! ```rust
//! # extern crate regex; use regex::Regex;
//! # fn main() {
//! let re = Regex::new(r"(?i)Δ+").unwrap();
//! assert_eq!(re.find("ΔδΔ"), Some((0, 6)));
//! # }
//! ```
//!
//! Finally, Unicode general categories and scripts are available as character
//! classes. For example, you can match a sequence of numerals, Greek or
//! Cherokee letters:
//!
//! ```rust
//! # extern crate regex; use regex::Regex;
//! # fn main() {
//! let re = Regex::new(r"[\pN\p{Greek}\p{Cherokee}]+").unwrap();
//! assert_eq!(re.find("abcΔᎠβⅠᏴγδⅡxyz"), Some((3, 23)));
//! # }
//! ```
//!
//! # Syntax
//!
//! The syntax supported in this crate is almost in an exact correspondence
//! with the syntax supported by RE2. It is documented below.
//!
//! Note that the regular expression parser and abstract syntax are exposed in
//! a separate crate,
//! [`regex-syntax`](../regex_syntax/index.html).
//!
//! ## Matching one character
//!
//! <pre class="rust">
//! .           any character except new line (includes new line with s flag)
//! [xyz]       A character class matching either x, y or z.
//! [^xyz]      A character class matching any character except x, y and z.
//! [a-z]       A character class matching any character in range a-z.
//! \d          digit (\p{Nd})
//! \D          not digit
//! [:alpha:]   ASCII character class ([A-Za-z])
//! [:^alpha:]  Negated ASCII character class ([^A-Za-z])
//! \pN         One-letter name Unicode character class
//! \p{Greek}   Unicode character class (general category or script)
//! \PN         Negated one-letter name Unicode character class
//! \P{Greek}   negated Unicode character class (general category or script)
//! </pre>
//!
//! Any named character class may appear inside a bracketed `[...]` character
//! class. For example, `[\p{Greek}\pN]` matches any Greek or numeral
//! character.
//!
//! ## Composites
//!
//! <pre class="rust">
//! xy    concatenation (x followed by y)
//! x|y   alternation (x or y, prefer x)
//! </pre>
//!
//! ## Repetitions
//!
//! <pre class="rust">
//! x*        zero or more of x (greedy)
//! x+        one or more of x (greedy)
//! x?        zero or one of x (greedy)
//! x*?       zero or more of x (ungreedy)
//! x+?       one or more of x (ungreedy)
//! x??       zero or one of x (ungreedy)
//! x{n,m}    at least n x and at most m x (greedy)
//! x{n,}     at least n x (greedy)
//! x{n}      exactly n x
//! x{n,m}?   at least n x and at most m x (ungreedy)
//! x{n,}?    at least n x (ungreedy)
//! x{n}?     exactly n x
//! </pre>
//!
//! ## Empty matches
//!
//! <pre class="rust">
//! ^     the beginning of text (or start-of-line with multi-line mode)
//! $     the end of text (or end-of-line with multi-line mode)
//! \A    only the beginning of text (even with multi-line mode enabled)
//! \z    only the end of text (even with multi-line mode enabled)
//! \b    a Unicode word boundary (\w on one side and \W, \A, or \z on other)
//! \B    not a Unicode word boundary
//! </pre>
//!
//! ## Grouping and flags
//!
//! <pre class="rust">
//! (exp)          numbered capture group (indexed by opening parenthesis)
//! (?P&lt;name&gt;exp)  named (also numbered) capture group (allowed chars: [_0-9a-zA-Z])
//! (?:exp)        non-capturing group
//! (?flags)       set flags within current group
//! (?flags:exp)   set flags for exp (non-capturing)
//! </pre>
//!
//! Flags are each a single character. For example, `(?x)` sets the flag `x`
//! and `(?-x)` clears the flag `x`. Multiple flags can be set or cleared at
//! the same time: `(?xy)` sets both the `x` and `y` flags and `(?x-y)` sets
//! the `x` flag and clears the `y` flag.
//!
//! All flags are by default disabled. They are:
//!
//! <pre class="rust">
//! i     case-insensitive
//! m     multi-line mode: ^ and $ match begin/end of line
//! s     allow . to match \n
//! U     swap the meaning of x* and x*?
//! x     ignore whitespace and allow line comments (starting with `#`)
//! </pre>
//!
//! Here's an example that matches case-insensitively for only part of the
//! expression:
//!
//! ```rust
//! # extern crate regex; use regex::Regex;
//! # fn main() {
//! let re = Regex::new(r"(?i)a+(?-i)b+").unwrap();
//! let cap = re.captures("AaAaAbbBBBb").unwrap();
//! assert_eq!(cap.at(0), Some("AaAaAbb"));
//! # }
//! ```
//!
//! Notice that the `a+` matches either `a` or `A`, but the `b+` only matches
//! `b`.
//!
//! ## Escape sequences
//!
//! <pre class="rust">
//! \*         literal *, works for any punctuation character: \.+*?()|[]{}^$
//! \a         bell (\x07)
//! \f         form feed (\x0C)
//! \t         horizontal tab
//! \n         new line
//! \r         carriage return
//! \v         vertical tab (\x0B)
//! \123       octal character code (up to three digits)
//! \x7F       hex character code (exactly two digits)
//! \x{10FFFF} any hex character code corresponding to a Unicode code point
//! </pre>
//!
//! ## Perl character classes (Unicode friendly)
//!
//! These classes are based on the definitions provided in
//! [UTS#18](http://www.unicode.org/reports/tr18/#Compatibility_Properties):
//!
//! <pre class="rust">
//! \d     digit (\p{Nd})
//! \D     not digit
//! \s     whitespace (\p{White_Space})
//! \S     not whitespace
//! \w     word character (\p{Alphabetic} + \p{M} + \d + \p{Pc} + \p{Join_Control})
//! \W     not word character
//! </pre>
//!
//! ## ASCII character classes
//!
//! <pre class="rust">
//! [:alnum:]    alphanumeric ([0-9A-Za-z])
//! [:alpha:]    alphabetic ([A-Za-z])
//! [:ascii:]    ASCII ([\x00-\x7F])
//! [:blank:]    blank ([\t ])
//! [:cntrl:]    control ([\x00-\x1F\x7F])
//! [:digit:]    digits ([0-9])
//! [:graph:]    graphical ([!-~])
//! [:lower:]    lower case ([a-z])
//! [:print:]    printable ([ -~])
//! [:punct:]    punctuation ([!-/:-@[-`{-~])
//! [:space:]    whitespace ([\t\n\v\f\r ])
//! [:upper:]    upper case ([A-Z])
//! [:word:]     word characters ([0-9A-Za-z_])
//! [:xdigit:]   hex digit ([0-9A-Fa-f])
//! </pre>
//!
//! # Untrusted input
//!
//! This crate can handle both untrusted regular expressions and untrusted
//! search text.
//!
//! Untrusted regular expressions are handled by capping the size of a compiled
//! regular expression. (See `Regex::with_size_limit`.) Without this, it would
//! be trivial for an attacker to exhaust your system's memory with expressions
//! like `a{100}{100}{100}`.
//!
//! Untrusted search text is allowed because the matching engine(s) in this
//! crate have time complexity `O(mn)` (with `m ~ regex` and `n ~ search
//! text`), which means there's no way to cause exponential blow-up like with
//! some other regular expression engines. (We pay for this by disallowing
//! features like arbitrary look-ahead and backreferences.)

#![deny(missing_docs)]
#![cfg_attr(test, deny(warnings))]
#![cfg_attr(feature = "pattern", feature(pattern))]
#![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
       html_favicon_url = "https://www.rust-lang.org/favicon.ico",
       html_root_url = "https://doc.rust-lang.org/regex/")]

extern crate aho_corasick;
extern crate memchr;
extern crate regex_syntax as syntax;

pub use re::{
    Regex, Error, Captures, SubCaptures, SubCapturesPos, SubCapturesNamed,
    CaptureNames, FindCaptures, FindMatches,
    Replacer, NoExpand, RegexSplits, RegexSplitsN,
    quote, is_match,
};

mod backtrack;
mod char;
mod compile;
mod input;
mod inst;
mod pool;
mod prefix;
mod program;
mod nfa;
mod re;

/// The `internal` module exists to support the `regex!` macro and other
/// suspicious activity, such as testing different matching engines.
#[doc(hidden)]
pub mod internal {
    pub use char::Char;
    pub use input::{Input, CharInput, InputAt};
    pub use inst::{Inst, EmptyLook, InstRanges};
    pub use program::{Program, MatchEngine};
    pub use re::ExNative;
    pub use re::Regex::{Dynamic, Native};
}