regex/
re_set.rs

1macro_rules! define_set {
2    ($name:ident, $builder_mod:ident, $text_ty:ty, $as_bytes:expr,
3     $(#[$doc_regexset_example:meta])* ) => {
4        pub mod $name {
5            use std::fmt;
6            use std::iter;
7            use std::slice;
8            use std::vec;
9
10            use error::Error;
11            use exec::Exec;
12            use re_builder::$builder_mod::RegexSetBuilder;
13            use re_trait::RegularExpression;
14
15/// Match multiple (possibly overlapping) regular expressions in a single scan.
16///
17/// A regex set corresponds to the union of two or more regular expressions.
18/// That is, a regex set will match text where at least one of its
19/// constituent regular expressions matches. A regex set as its formulated here
20/// provides a touch more power: it will also report *which* regular
21/// expressions in the set match. Indeed, this is the key difference between
22/// regex sets and a single `Regex` with many alternates, since only one
23/// alternate can match at a time.
24///
25/// For example, consider regular expressions to match email addresses and
26/// domains: `[a-z]+@[a-z]+\.(com|org|net)` and `[a-z]+\.(com|org|net)`. If a
27/// regex set is constructed from those regexes, then searching the text
28/// `foo@example.com` will report both regexes as matching. Of course, one
29/// could accomplish this by compiling each regex on its own and doing two
30/// searches over the text. The key advantage of using a regex set is that it
31/// will report the matching regexes using a *single pass through the text*.
32/// If one has hundreds or thousands of regexes to match repeatedly (like a URL
33/// router for a complex web application or a user agent matcher), then a regex
34/// set can realize huge performance gains.
35///
36/// # Example
37///
38/// This shows how the above two regexes (for matching email addresses and
39/// domains) might work:
40///
41$(#[$doc_regexset_example])*
42///
43/// Note that it would be possible to adapt the above example to using `Regex`
44/// with an expression like:
45///
46/// ```ignore
47/// (?P<email>[a-z]+@(?P<email_domain>[a-z]+[.](com|org|net)))|(?P<domain>[a-z]+[.](com|org|net))
48/// ```
49///
50/// After a match, one could then inspect the capture groups to figure out
51/// which alternates matched. The problem is that it is hard to make this
52/// approach scale when there are many regexes since the overlap between each
53/// alternate isn't always obvious to reason about.
54///
55/// # Limitations
56///
57/// Regex sets are limited to answering the following two questions:
58///
59/// 1. Does any regex in the set match?
60/// 2. If so, which regexes in the set match?
61///
62/// As with the main `Regex` type, it is cheaper to ask (1) instead of (2)
63/// since the matching engines can stop after the first match is found.
64///
65/// Other features like finding the location of successive matches or their
66/// sub-captures aren't supported. If you need this functionality, the
67/// recommended approach is to compile each regex in the set independently and
68/// selectively match them based on which regexes in the set matched.
69///
70/// # Performance
71///
72/// A `RegexSet` has the same performance characteristics as `Regex`. Namely,
73/// search takes `O(mn)` time, where `m` is proportional to the size of the
74/// regex set and `n` is proportional to the length of the search text.
75#[derive(Clone)]
76pub struct RegexSet(Exec);
77
78impl RegexSet {
79    /// Create a new regex set with the given regular expressions.
80    ///
81    /// This takes an iterator of `S`, where `S` is something that can produce
82    /// a `&str`. If any of the strings in the iterator are not valid regular
83    /// expressions, then an error is returned.
84    ///
85    /// # Example
86    ///
87    /// Create a new regex set from an iterator of strings:
88    ///
89    /// ```rust
90    /// # use regex::RegexSet;
91    /// let set = RegexSet::new(&[r"\w+", r"\d+"]).unwrap();
92    /// assert!(set.is_match("foo"));
93    /// ```
94    pub fn new<I, S>(exprs: I) -> Result<RegexSet, Error>
95            where S: AsRef<str>, I: IntoIterator<Item=S> {
96        RegexSetBuilder::new(exprs).build()
97    }
98
99    /// Returns true if and only if one of the regexes in this set matches
100    /// the text given.
101    ///
102    /// This method should be preferred if you only need to test whether any
103    /// of the regexes in the set should match, but don't care about *which*
104    /// regexes matched. This is because the underlying matching engine will
105    /// quit immediately after seeing the first match instead of continuing to
106    /// find all matches.
107    ///
108    /// Note that as with searches using `Regex`, the expression is unanchored
109    /// by default. That is, if the regex does not start with `^` or `\A`, or
110    /// end with `$` or `\z`, then it is permitted to match anywhere in the
111    /// text.
112    ///
113    /// # Example
114    ///
115    /// Tests whether a set matches some text:
116    ///
117    /// ```rust
118    /// # use regex::RegexSet;
119    /// let set = RegexSet::new(&[r"\w+", r"\d+"]).unwrap();
120    /// assert!(set.is_match("foo"));
121    /// assert!(!set.is_match("☃"));
122    /// ```
123    pub fn is_match(&self, text: $text_ty) -> bool {
124        self.is_match_at(text, 0)
125    }
126
127    /// Returns the same as is_match, but starts the search at the given
128    /// offset.
129    ///
130    /// The significance of the starting point is that it takes the surrounding
131    /// context into consideration. For example, the `\A` anchor can only
132    /// match when `start == 0`.
133    #[doc(hidden)]
134    pub fn is_match_at(&self, text: $text_ty, start: usize) -> bool {
135        self.0.searcher().is_match_at($as_bytes(text), start)
136    }
137
138    /// Returns the set of regular expressions that match in the given text.
139    ///
140    /// The set returned contains the index of each regular expression that
141    /// matches in the given text. The index is in correspondence with the
142    /// order of regular expressions given to `RegexSet`'s constructor.
143    ///
144    /// The set can also be used to iterate over the matched indices.
145    ///
146    /// Note that as with searches using `Regex`, the expression is unanchored
147    /// by default. That is, if the regex does not start with `^` or `\A`, or
148    /// end with `$` or `\z`, then it is permitted to match anywhere in the
149    /// text.
150    ///
151    /// # Example
152    ///
153    /// Tests which regular expressions match the given text:
154    ///
155    /// ```rust
156    /// # use regex::RegexSet;
157    /// let set = RegexSet::new(&[
158    ///     r"\w+",
159    ///     r"\d+",
160    ///     r"\pL+",
161    ///     r"foo",
162    ///     r"bar",
163    ///     r"barfoo",
164    ///     r"foobar",
165    /// ]).unwrap();
166    /// let matches: Vec<_> = set.matches("foobar").into_iter().collect();
167    /// assert_eq!(matches, vec![0, 2, 3, 4, 6]);
168    ///
169    /// // You can also test whether a particular regex matched:
170    /// let matches = set.matches("foobar");
171    /// assert!(!matches.matched(5));
172    /// assert!(matches.matched(6));
173    /// ```
174    pub fn matches(&self, text: $text_ty) -> SetMatches {
175        let mut matches = vec![false; self.0.regex_strings().len()];
176        let any = self.read_matches_at(&mut matches, text, 0);
177        SetMatches {
178            matched_any: any,
179            matches: matches,
180        }
181    }
182
183    /// Returns the same as matches, but starts the search at the given
184    /// offset and stores the matches into the slice given.
185    ///
186    /// The significance of the starting point is that it takes the surrounding
187    /// context into consideration. For example, the `\A` anchor can only
188    /// match when `start == 0`.
189    ///
190    /// `matches` must have a length that is at least the number of regexes
191    /// in this set.
192    ///
193    /// This method returns true if and only if at least one member of
194    /// `matches` is true after executing the set against `text`.
195    #[doc(hidden)]
196    pub fn read_matches_at(
197        &self,
198        matches: &mut [bool],
199        text: $text_ty,
200        start: usize,
201    ) -> bool {
202        self.0.searcher().many_matches_at(matches, $as_bytes(text), start)
203    }
204
205    /// Returns the total number of regular expressions in this set.
206    pub fn len(&self) -> usize {
207        self.0.regex_strings().len()
208    }
209
210    /// Returns the patterns that this set will match on.
211    ///
212    /// This function can be used to determine the pattern for a match. The
213    /// slice returned has exactly as many patterns givens to this regex set,
214    /// and the order of the slice is the same as the order of the patterns
215    /// provided to the set.
216    ///
217    /// # Example
218    ///
219    /// ```rust
220    /// # use regex::RegexSet;
221    /// let set = RegexSet::new(&[
222    ///     r"\w+",
223    ///     r"\d+",
224    ///     r"\pL+",
225    ///     r"foo",
226    ///     r"bar",
227    ///     r"barfoo",
228    ///     r"foobar",
229    /// ]).unwrap();
230    /// let matches: Vec<_> = set
231    ///     .matches("foobar")
232    ///     .into_iter()
233    ///     .map(|match_idx| &set.patterns()[match_idx])
234    ///     .collect();
235    /// assert_eq!(matches, vec![r"\w+", r"\pL+", r"foo", r"bar", r"foobar"]);
236    /// ```
237    pub fn patterns(&self) -> &[String] {
238        self.0.regex_strings()
239    }
240}
241
242/// A set of matches returned by a regex set.
243#[derive(Clone, Debug)]
244pub struct SetMatches {
245    matched_any: bool,
246    matches: Vec<bool>,
247}
248
249impl SetMatches {
250    /// Whether this set contains any matches.
251    pub fn matched_any(&self) -> bool {
252        self.matched_any
253    }
254
255    /// Whether the regex at the given index matched.
256    ///
257    /// The index for a regex is determined by its insertion order upon the
258    /// initial construction of a `RegexSet`, starting at `0`.
259    ///
260    /// # Panics
261    ///
262    /// If `regex_index` is greater than or equal to `self.len()`.
263    pub fn matched(&self, regex_index: usize) -> bool {
264        self.matches[regex_index]
265    }
266
267    /// The total number of regexes in the set that created these matches.
268    pub fn len(&self) -> usize {
269        self.matches.len()
270    }
271
272    /// Returns an iterator over indexes in the regex that matched.
273    ///
274    /// This will always produces matches in ascending order of index, where
275    /// the index corresponds to the index of the regex that matched with
276    /// respect to its position when initially building the set.
277    pub fn iter(&self) -> SetMatchesIter {
278        SetMatchesIter((&*self.matches).into_iter().enumerate())
279    }
280}
281
282impl IntoIterator for SetMatches {
283    type IntoIter = SetMatchesIntoIter;
284    type Item = usize;
285
286    fn into_iter(self) -> Self::IntoIter {
287        SetMatchesIntoIter(self.matches.into_iter().enumerate())
288    }
289}
290
291impl<'a> IntoIterator for &'a SetMatches {
292    type IntoIter = SetMatchesIter<'a>;
293    type Item = usize;
294
295    fn into_iter(self) -> Self::IntoIter {
296        self.iter()
297    }
298}
299
300/// An owned iterator over the set of matches from a regex set.
301///
302/// This will always produces matches in ascending order of index, where the
303/// index corresponds to the index of the regex that matched with respect to
304/// its position when initially building the set.
305pub struct SetMatchesIntoIter(iter::Enumerate<vec::IntoIter<bool>>);
306
307impl Iterator for SetMatchesIntoIter {
308    type Item = usize;
309
310    fn next(&mut self) -> Option<usize> {
311        loop {
312            match self.0.next() {
313                None => return None,
314                Some((_, false)) => {}
315                Some((i, true)) => return Some(i),
316            }
317        }
318    }
319
320    fn size_hint(&self) -> (usize, Option<usize>) {
321        self.0.size_hint()
322    }
323}
324
325impl DoubleEndedIterator for SetMatchesIntoIter {
326    fn next_back(&mut self) -> Option<usize> {
327        loop {
328            match self.0.next_back() {
329                None => return None,
330                Some((_, false)) => {}
331                Some((i, true)) => return Some(i),
332            }
333        }
334    }
335}
336
337/// A borrowed iterator over the set of matches from a regex set.
338///
339/// The lifetime `'a` refers to the lifetime of a `SetMatches` value.
340///
341/// This will always produces matches in ascending order of index, where the
342/// index corresponds to the index of the regex that matched with respect to
343/// its position when initially building the set.
344#[derive(Clone)]
345pub struct SetMatchesIter<'a>(iter::Enumerate<slice::Iter<'a, bool>>);
346
347impl<'a> Iterator for SetMatchesIter<'a> {
348    type Item = usize;
349
350    fn next(&mut self) -> Option<usize> {
351        loop {
352            match self.0.next() {
353                None => return None,
354                Some((_, &false)) => {}
355                Some((i, &true)) => return Some(i),
356            }
357        }
358    }
359
360    fn size_hint(&self) -> (usize, Option<usize>) {
361        self.0.size_hint()
362    }
363}
364
365impl<'a> DoubleEndedIterator for SetMatchesIter<'a> {
366    fn next_back(&mut self) -> Option<usize> {
367        loop {
368            match self.0.next_back() {
369                None => return None,
370                Some((_, &false)) => {}
371                Some((i, &true)) => return Some(i),
372            }
373        }
374    }
375}
376
377#[doc(hidden)]
378impl From<Exec> for RegexSet {
379    fn from(exec: Exec) -> Self {
380        RegexSet(exec)
381    }
382}
383
384impl fmt::Debug for RegexSet {
385    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
386        write!(f, "RegexSet({:?})", self.0.regex_strings())
387    }
388}
389
390#[allow(dead_code)] fn as_bytes_str(text: &str) -> &[u8] { text.as_bytes() }
391#[allow(dead_code)] fn as_bytes_bytes(text: &[u8]) -> &[u8] { text }
392        }
393    }
394}
395
396define_set! {
397    unicode,
398    set_unicode,
399    &str,
400    as_bytes_str,
401/// ```rust
402/// # use regex::RegexSet;
403/// let set = RegexSet::new(&[
404///     r"[a-z]+@[a-z]+\.(com|org|net)",
405///     r"[a-z]+\.(com|org|net)",
406/// ]).unwrap();
407///
408/// // Ask whether any regexes in the set match.
409/// assert!(set.is_match("foo@example.com"));
410///
411/// // Identify which regexes in the set match.
412/// let matches: Vec<_> = set.matches("foo@example.com").into_iter().collect();
413/// assert_eq!(vec![0, 1], matches);
414///
415/// // Try again, but with text that only matches one of the regexes.
416/// let matches: Vec<_> = set.matches("example.com").into_iter().collect();
417/// assert_eq!(vec![1], matches);
418///
419/// // Try again, but with text that doesn't match any regex in the set.
420/// let matches: Vec<_> = set.matches("example").into_iter().collect();
421/// assert!(matches.is_empty());
422/// ```
423}
424
425define_set! {
426    bytes,
427    set_bytes,
428    &[u8],
429    as_bytes_bytes,
430/// ```rust
431/// # use regex::bytes::RegexSet;
432/// let set = RegexSet::new(&[
433///     r"[a-z]+@[a-z]+\.(com|org|net)",
434///     r"[a-z]+\.(com|org|net)",
435/// ]).unwrap();
436///
437/// // Ask whether any regexes in the set match.
438/// assert!(set.is_match(b"foo@example.com"));
439///
440/// // Identify which regexes in the set match.
441/// let matches: Vec<_> = set.matches(b"foo@example.com").into_iter().collect();
442/// assert_eq!(vec![0, 1], matches);
443///
444/// // Try again, but with text that only matches one of the regexes.
445/// let matches: Vec<_> = set.matches(b"example.com").into_iter().collect();
446/// assert_eq!(vec![1], matches);
447///
448/// // Try again, but with text that doesn't match any regex in the set.
449/// let matches: Vec<_> = set.matches(b"example").into_iter().collect();
450/// assert!(matches.is_empty());
451/// ```
452}