| Quellcodebibliothek Statistik Leitseite products/Sources/formale Sprachen/C/Firefox/third_party/rust/regex/src/ (Firefox Browser Version 153.0.1©) Datei vom 27.6.2026 mit Größe 57 kB |
|
Quelle lib.rs Sprache: Rust |
|||||||||||||||
|
/*! This crate provides routines for searching strings for matches of a [regular expression] (aka "regex"). The regex syntax supported by this crate is similar to other regex engines, but it lacks several features that are not known how to implement efficiently. This includes, but is not limited to, look-around and backreferences. In exchange, all regex searches in this crate have worst case `O(m * n)` time complexity, where `m` is proportional to the size of the regex and `n` is proportional to the size of the string being searched. [regular expression]: https://en.wikipedia.org/wiki/Regular_expression If you just want API documentation, then skip to the [`Regex`] type. Otherwise, here's a quick example showing one way of parsing the output of a grep-like program: ```rust use regex::Regex; let re = Regex::new(r"(?m)^([^:]+):([0-9]+):(.+)$").unwrap(); let hay = "\ path/to/foo:54:Blue Harvest path/to/bar:90:Something, Something, Something, Dark Side path/to/baz:3:It's a Trap! "; let mut results = vec![]; for (_, [path, lineno, line]) in re.captures_iter(hay).map(|c| c.extract()) { results.push((path, lineno.parse::<u64>()?, line)); } assert_eq!(results, vec![ ("path/to/foo", 54, "Blue Harvest"), ("path/to/bar", 90, "Something, Something, Something, Dark Side"), ("path/to/baz", 3, "It's a Trap!"), ]); # Ok::<(), Box<dyn std::error::Error>>(()) ``` # Overview The primary type in this crate is a [`Regex`]. Its most important methods are as follows: * [`Regex::new`] compiles a regex using the default configuration. A [`RegexBuilder`] permits setting a non-default configuration. (For example, case insensitive matching, verbose mode and others.) * [`Regex::is_match`] reports whether a match exists in a particular haystack. * [`Regex::find`] reports the byte offsets of a match in a haystack, if one exists. [`Regex::find_iter`] returns an iterator over all such matches. * [`Regex::captures`] returns a [`Captures`], which reports both the byte offsets of a match in a haystack and the byte offsets of each matching capture group from the regex in the haystack. [`Regex::captures_iter`] returns an iterator over all such matches. There is also a [`RegexSet`], which permits searching for multiple regex patterns simultaneously in a single search. However, it currently only reports which patterns match and *not* the byte offsets of a match. Otherwise, this top-level crate documentation is organized as follows: * [Usage](#usage) shows how to add the `regex` crate to your Rust project. * [Examples](#examples) provides a limited selection of regex search examples. * [Performance](#performance) provides a brief summary of how to optimize regex searching speed. * [Unicode](#unicode) discusses support for non-ASCII patterns. * [Syntax](#syntax) enumerates the specific regex syntax supported by this crate. * [Untrusted input](#untrusted-input) discusses how this crate deals with regex patterns or haystacks that are untrusted. * [Crate features](#crate-features) documents the Cargo features that can be enabled or disabled for this crate. * [Other crates](#other-crates) links to other crates in the `regex` family. # Usage The `regex` 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`. Or more simply, just run `cargo add regex`. Here is a complete example that creates a new Rust project, adds a dependency on `regex`, creates the source code for a regex search and then runs the program. First, create the project in a new directory: ```text $ mkdir regex-example $ cd regex-example $ cargo init ``` Second, add a dependency on `regex`: ```text $ cargo add regex ``` Third, edit `src/main.rs`. Delete what's there and replace it with this: ``` use regex::Regex; fn main() { let re = Regex::new(r"Hello (?<name>\w+)!").unwrap(); let Some(caps) = re.captures("Hello Murphy!") else { println!("no match!"); return; }; println!("The name is: {}", &caps["name"]); } ``` Fourth, run it with `cargo run`: ```text $ cargo run Compiling memchr v2.5.0 Compiling regex-syntax v0.7.1 Compiling aho-corasick v1.0.1 Compiling regex v1.8.1 Compiling regex-example v0.1.0 (/tmp/regex-example) Finished dev [unoptimized + debuginfo] target(s) in 4.22s Running `target/debug/regex-example` The name is: Murphy ``` The first time you run the program will show more output like above. But subsequent runs shouldn't have to re-compile the dependencies. # Examples This section provides a few examples, in tutorial style, showing how to search a haystack with a regex. There are more examples throughout the API documentation. Before starting though, it's worth defining a few terms: * A **regex** is a Rust value whose type is `Regex`. We use `re` as a variable name for a regex. * A **pattern** is the string that is used to build a regex. We use `pat` as a variable name for a pattern. * A **haystack** is the string that is searched by a regex. We use `hay` as a variable name for a haystack. Sometimes the words "regex" and "pattern" are used interchangeably. General use of regular expressions in this crate proceeds by compiling a **pattern** into a **regex**, and then using that regex to search, split or replace parts of a **haystack**. ### Example: find a middle initial We'll start off with a very simple example: a regex that looks for a specific name but uses a wildcard to match a middle initial. Our pattern serves as something like a template that will match a particular name with *any* middle initial. ```rust use regex::Regex; // We use 'unwrap()' here because it would be a bug in our program if the // pattern failed to compile to a regex. Panicking in the presence of a bug // is okay. let re = Regex::new(r"Homer (.)\. Simpson").unwrap(); let hay = "Homer J. Simpson"; let Some(caps) = re.captures(hay) else { return }; assert_eq!("J", &caps[1]); ``` There are a few things worth noticing here in our first example: * The `.` is a special pattern meta character that means "match any single character except for new lines." (More precisely, in this crate, it means "match any UTF-8 encoding of any Unicode scalar value other than `\n`.") * We can match an actual `.` literally by escaping it, i.e., `\.`. * We use Rust's [raw strings] to avoid needing to deal with escape sequences in both the regex pattern syntax and in Rust's string literal syntax. If we didn't use raw strings here, we would have had to use `\\.` to match a literal `.` character. That is, `r"\."` and `"\\."` are equivalent patterns. * We put our wildcard `.` instruction in parentheses. These parentheses have a special meaning that says, "make whatever part of the haystack matches within these parentheses available as a capturing group." After finding a match, we access this capture group with `&caps[1]`. [raw strings]: https://doc.rust-lang.org/stable/reference/tokens.html#raw-string-l Otherwise, we execute a search using `re.captures(hay)` and return from our function if no match occurred. We then reference the middle initial by asking for the part of the haystack that matched the capture group indexed at `1`. (The capture group at index 0 is implicit and always corresponds to the entire match. In this case, that's `Homer J. Simpson`.) ### Example: named capture groups Continuing from our middle initial example above, we can tweak the pattern slightly to give a name to the group that matches the middle initial: ```rust use regex::Regex; // Note that (?P<middle>.) is a different way to spell the same thing. let re = Regex::new(r"Homer (?<middle>.)\. Simpson").unwrap(); let hay = "Homer J. Simpson"; let Some(caps) = re.captures(hay) else { return }; assert_eq!("J", &caps["middle"]); ``` Giving a name to a group can be useful when there are multiple groups in a pattern. It makes the code referring to those groups a bit easier to understand. ### Example: validating a particular date format This examples shows how to confirm whether a haystack, in its entirety, matches a particular date format: ```rust use regex::Regex; let re = Regex::new(r"^\d{4}-\d{2}-\d{2}$").unwrap(); assert!(re.is_match("2010-03-14")); ``` Notice the use of the `^` and `$` anchors. In this crate, every regex search is run with an implicit `(?s:.)*?` at the beginning of its pattern, which allows the regex to match anywhere in a haystack. Anchors, as above, can be used to ensure that the full haystack matches a pattern. This crate is also Unicode aware by default, which means that `\d` might match more than you might expect it to. For example: ```rust use regex::Regex; let re = Regex::new(r"^\d{4}-\d{2}-\d{2}$").unwrap(); assert!(re.is_match("��������-����-����")); ``` To only match an ASCII decimal digit, all of the following are equivalent: * `[0-9]` * `(?-u:\d)` * `[[:digit:]]` * `[\d&&\p{ascii}]` ### Example: finding dates in a haystack In the previous example, we showed how one might validate that a haystack, in its entirety, corresponded to a particular date format. But what if we wanted to extract all things that look like dates in a specific format from a haystack? To do this, we can use an iterator API to find all matches (notice that we've removed the anchors and switched to looking for ASCII-only digits): ```rust use regex::Regex; let re = Regex::new(r"[0-9]{4}-[0-9]{2}-[0-9]{2}").unwrap(); let hay = "What do 1865-04-14, 1881-07-02, 1901-09-06 and 1963-11-22 have in common?"; // 'm' is a 'Match', and 'as_str()' returns the matching part of the haystack. let dates: Vec<&str> = re.find_iter(hay).map(|m| m.as_str()).collect(); assert_eq!(dates, vec![ "1865-04-14", "1881-07-02", "1901-09-06", "1963-11-22", ]); ``` We can also iterate over [`Captures`] values instead of [`Match`] values, and that in turn permits accessing each component of the date via capturing groups: ```rust use regex::Regex; let re = Regex::new(r"(?<y>[0-9]{4})-(?<m>[0-9]{2})-(?<d>[0-9]{2})").unwrap(); let hay = "What do 1865-04-14, 1881-07-02, 1901-09-06 and 1963-11-22 have in common?"; // 'm' is a 'Match', and 'as_str()' returns the matching part of the haystack. let dates: Vec<(&str, &str, &str)> = re.captures_iter(hay).map(|caps| { // The unwraps are okay because every capture group must match if the whole // regex matches, and in this context, we know we have a match. // // Note that we use `caps.name("y").unwrap().as_str()` instead of // `&caps["y"]` because the lifetime of the former is the same as the // lifetime of `hay` above, but the lifetime of the latter is tied to the // lifetime of `caps` due to how the `Index` trait is defined. let year = caps.name("y").unwrap().as_str(); let month = caps.name("m").unwrap().as_str(); let day = caps.name("d").unwrap().as_str(); (year, month, day) }).collect(); assert_eq!(dates, vec![ ("1865", "04", "14"), ("1881", "07", "02"), ("1901", "09", "06"), ("1963", "11", "22"), ]); ``` ### Example: simpler capture group extraction One can use [`Captures::extract`] to make the code from the previous example a bit simpler in this case: ```rust use regex::Regex; let re = Regex::new(r"([0-9]{4})-([0-9]{2})-([0-9]{2})").unwrap(); let hay = "What do 1865-04-14, 1881-07-02, 1901-09-06 and 1963-11-22 have in common?"; let dates: Vec<(&str, &str, &str)> = re.captures_iter(hay).map(|caps| { let (_, [year, month, day]) = caps.extract(); (year, month, day) }).collect(); assert_eq!(dates, vec![ ("1865", "04", "14"), ("1881", "07", "02"), ("1901", "09", "06"), ("1963", "11", "22"), ]); ``` `Captures::extract` works by ensuring that the number of matching groups match the number of groups requested via the `[year, month, day]` syntax. If they do, then the substrings for each corresponding capture group are automatically returned in an appropriately sized array. Rust's syntax for pattern matching arrays does the rest. ### Example: replacement with named capture groups Building on the previous example, perhaps we'd like to rearrange the date formats. This can be done by finding each match and replacing it with something different. The [`Regex::replace_all`] routine provides a convenient way to do this, including by supporting references to named groups in the replacement string: ```rust use regex::Regex; let re = Regex::new(r"(?<y>\d{4})-(?<m>\d{2})-(?<d>\d{2})").unwrap(); let before = "1973-01-05, 1975-08-25 and 1980-10-18"; let after = re.replace_all(before, "$m/$d/$y"); assert_eq!(after, "01/05/1973, 08/25/1975 and 10/18/1980"); ``` 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.) ### Example: verbose mode When your regex gets complicated, you might consider using something other than regex. But if you stick with regex, you can use the `x` flag to enable insignificant whitespace mode or "verbose mode." In this mode, whitespace is treated as insignificant and one may write comments. This may make your patterns easier to comprehend. ```rust use regex::Regex; let re = Regex::new(r"(?x) (?P<y>\d{4}) # the year, including all Unicode digits - (?P<m>\d{2}) # the month, including all Unicode digits - (?P<d>\d{2}) # the day, including all Unicode digits ").unwrap(); let before = "1973-01-05, 1975-08-25 and 1980-10-18"; let after = re.replace_all(before, "$m/$d/$y"); assert_eq!(after, "01/05/1973, 08/25/1975 and 10/18/1980"); ``` If you wish to match against whitespace in this mode, you can still use `\s`, `\n`, `\t`, etc. For escaping a single space character, you can escape it directly with `\ `, use its hex character code `\x20` or temporarily disable the `x` flag, e.g., `(?-x: )`. ### Example: match multiple regular expressions simultaneously This demonstrates how to use a [`RegexSet`] to match multiple (possibly overlapping) regexes in a single scan of a haystack: ```rust use regex::RegexSet; let set = RegexSet::new(&[ r"\w+", r"\d+", r"\pL+", r"foo", r"bar", r"barfoo", r"foobar", ]).unwrap(); // Iterate over and collect all of the matches. Each match corresponds to the // ID of the matching pattern. let matches: Vec<_> = set.matches("foobar").into_iter().collect(); assert_eq!(matches, vec![0, 2, 3, 4, 6]); // You can also test whether a particular regex matched: let matches = set.matches("foobar"); assert!(!matches.matched(5)); assert!(matches.matched(6)); ``` # Performance This section briefly discusses a few concerns regarding the speed and resource usage of regexes. ### Only ask for what you need When running a search with a regex, there are generally three different types of information one can ask for: 1. Does a regex match in a haystack? 2. Where does a regex match in a haystack? 3. Where do each of the capturing groups match in a haystack? 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 capturing group matches, so it's best not to do it if you don't need to. Therefore, only ask for what you need. For example, don't use [`Regex::find`] if you only need to test if a regex matches a haystack. Use [`Regex::is_match`] instead. ### Unicode can impact memory usage and search speed This crate has first class support for Unicode and it is **enabled by default**. In many cases, the extra memory required to support it will be negligible and it typically won't impact search speed. But it can in some cases. With respect to memory usage, the impact of Unicode principally manifests through the use of Unicode character classes. Unicode character classes tend to be quite large. For example, `\w` by default matches around 140,000 distinct codepoints. This requires additional memory, and tends to slow down regex compilation. While a `\w` here and there is unlikely to be noticed, writing `\w{100}` will for example result in quite a large regex by default. Indeed, `\w` is considerably larger than its ASCII-only version, so if your requirements are satisfied by ASCII, it's probably a good idea to stick to ASCII classes. The ASCII-only version of `\w` can be spelled in a number of ways. All of the following are equivalent: * `[0-9A-Za-z_]` * `(?-u:\w)` * `[[:word:]]` * `[\w&&\p{ascii}]` With respect to search speed, Unicode tends to be handled pretty well, even when using large Unicode character classes. However, some of the faster internal regex engines cannot handle a Unicode aware word boundary assertion. So if you don't need Unicode-aware word boundary assertions, you might consider using `(?-u:\b)` instead of `\b`, where the former uses an ASCII-only definition of a word character. ### Literals might accelerate searches This crate tends to be quite good at recognizing literals in a regex pattern and using them to accelerate a search. If it is at all possible to include some kind of literal in your pattern, then it might make search substantially faster. For example, in the regex `\w+@\w+`, the engine will look for occurrences of `@` and then try a reverse match for `\w+` to find the start position. ### Avoid re-compiling regexes, especially in a loop It is an anti-pattern to compile the same pattern in a loop since regex compilation is typically expensive. (It takes anywhere from a few microseconds to a few **milliseconds** depending on the size of the pattern.) Not only is compilation itself expensive, but this also prevents optimizations that reuse allocations internally to the regex engine. In Rust, it can sometimes be a pain to pass regular expressions around if they're used from inside a helper function. Instead, we recommend using [`std::sync::LazyLock`], or the [`once_cell`] crate, if you can't use the standard library. This example shows how to use `std::sync::LazyLock`: ```rust use std::sync::LazyLock; use regex::Regex; fn some_helper_function(haystack: &str) -> bool { static RE: LazyLock<Regex> = LazyLock::new(|| Regex::new(r"...").unwrap()); RE.is_match(haystack) } fn main() { assert!(some_helper_function("abc")); assert!(!some_helper_function("ac")); } ``` Specifically, in this example, the regex will be compiled when it is used for the first time. On subsequent uses, it will reuse the previously built `Regex`. Notice how one can define the `Regex` locally to a specific function. [`std::sync::LazyLock`]: https://doc.rust-lang.org/std/sync/struct.LazyLock.html [`once_cell`]: https://crates.io/crates/once_cell ### Sharing a regex across threads can result in contention While a single `Regex` can be freely used from multiple threads simultaneously, there is a small synchronization cost that must be paid. Generally speaking, one shouldn't expect to observe this unless the principal task in each thread is searching with the regex *and* most searches are on short haystacks. In this case, internal contention on shared resources can spike and increase latency, which in turn may slow down each individual search. One can work around this by cloning each `Regex` before sending it to another thread. The cloned regexes will still share the same internal read-only portion of its compiled state (it's reference counted), but each thread will get optimized access to the mutable space that is used to run a search. In general, there is no additional cost in memory to doing this. The only cost is the added code complexity required to explicitly clone the regex. (If you share the same `Regex` across multiple threads, each thread still gets its own mutable space, but accessing that space is slower.) # Unicode This section discusses what kind of Unicode support this regex library has. Before showing some examples, we'll summarize the relevant points: * This crate almost fully implements "Basic Unicode Support" (Level 1) as specified by the [Unicode Technical Standard #18][UTS18]. The full details of what is supported are documented in [UNICODE.md] in the root of the regex crate repository. There is virtually no support for "Extended Unicode Support" (Level 2) from UTS#18. * The top-level [`Regex`] runs searches *as if* iterating over each of the codepoints in the haystack. That is, the fundamental atom of matching is a single codepoint. * [`bytes::Regex`], in contrast, permits disabling Unicode mode for part of all of your pattern in all cases. When Unicode mode is disabled, then a search is run *as if* iterating over each byte in the haystack. That is, the fundamental atom of matching is a single byte. (A top-level `Regex` also permits disabling Unicode and thus matching *as if* it were one byte at a time, but only when doing so wouldn't permit matching invalid UTF-8.) * When Unicode mode is enabled (the default), `.` will match an entire Unicode scalar value, even when it is encoded using multiple bytes. When Unicode mode is disabled (e.g., `(?-u:.)`), then `.` will match a single byte in all cases. The character classes `\w`, `\d` and `\s` are all Unicode-aware by default. Use `(?-u:\w)`, `(?-u:\d)` and `(?-u:\s)` to get their ASCII-only definitions. * Similarly, `\b` and `\B` use a Unicode definition of a "word" character. To get ASCII-only word boundaries, use `(?-u:\b)` and `(?-u:\B)`. This also applies to the special word boundary assertions. (That is, `\b{start}`, `\b{end}`, `\b{start-half}` stdlib.h>/ are **not** Unicode-aware in multiline mode Namely, only recognize \` assuming modeis not enabled)and any of other forms java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length * searching is Unicode-aware and uses simple case folding. * Unicode general srtp_err_status_t srtp_test_set_receiver_roc(void); by default via the `\p{property name}` syntax. * In all cases, matches are reported java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0 java.lang.StringIndexOutOfBoundsException: Index 9 out of bounds for length 9 [UTS18] char *ciphertext; [.md]: ://github.com/rust-lang/regex/blob/master/UNICODE.md Patterns java.lang.StringIndexOutOfBoundsException: Range [20, 19) out of bounds values" \java.lang.StringIndexOutOfBoundsException: Index 40 out of bounds for le ```rust use regex::Regex; letre=Regex:new("(i)+")unwrap( let m = re.find("ΔδΔ").unwrap(); assert_eq!((0, 6), (m.start(), m.end())); // alternatively: assert_eq!(0..* ``` As={ and java.lang.StringIndexOutOfBoundsException: Range [34, 33) out of bounds for leng ```rust use :java.lang.StringIndexOutOfBoundsException: Index 17 out of bounds for length let } (.,m.(; `` to, alsocharacter operations. Namely, one can nest character classes =1; ; difference dovalidation =; useful with Unicode character classes. : that is both in the `Greekif s{ ```rust use regex::Regex; re= Regex:newr"[\p{}&p])unwrap() (java.lang.StringIndexOutOfBoundsException: Range [26, 25) out of bounds for len assert_eq!( (java.lang.StringIndexOutOfBoundsException: Range [44, 40) out of bou // If we just matches on Greek, then all codepoints would match! }java.lang.StringIndexOutOfBoundsException: Index 20 out of bounds for length 20 " setto \n"; assert_eq!subs !"δ�Δ]; ``` ### Opt out of"\) The [`bytes::Regexexit1java.lang.StringIndexOutOfBoundsException: Index 24 out of default, else main `Regex` type that java.lang.StringIndexOutOfBoundsException: Range [78, 79) out `u` flag, even (1; status java.lang.StringIndexOutOfBoundsException: Range [41, 39) out of bounds fo java.lang.StringIndexOutOfBoundsException: Range [7, 6) out of bounds for length Disabling ( java.lang.StringIndexOutOfBoundsException: Range [37, 36) out of bound type, "java.lang.StringIndexOutOfBoundsException: Range [27, 26) out of bounds fo example, `(?-u:\w)` is an ASCII-only `\w` character java.lang.StringIndexOutOfBoundsExc `&str`-based `Regex}java.lang.StringIndexOutOfBoundsException: Index 16 out isn't in `(?-u:\w)`, which in turn includes bytes that are invalid UTF-8. (-:x)`will to raw\` java.lang.StringIndexOutOfBoundsException: Range [77, 78) out o `U+00FF`), which is invalid (failed\"; regexes. ((= java.lang.StringIndexOutOfBoundsException: Range [60, 57) out of bounds for l crate to java.lang.StringIndexOutOfBoundsException: Range [60, 59) out of bounds f data tables, can beuseful shrinking size and reducing compilation times. For detailsjava.lang.StringIndexOutOfBoundsException: Range [17, if(java.lang.StringIndexOutOfBoundsException: Range [55, 54) out of bounds for l # Syntax The syntax supported in this crate is documented below. Note that the regular expression parser and abstract syntax are exposed in a separate crate,*AES-92 ### Matching one character < . any character except new line (includes new line with s flag) [ (t java.lang.StringIndexOutOfBoundsException: Range [65, 36) out of bounds for l \d digit (\p{Nd}) \D not digit \pX Unicode character class identified by a java.lang.StringIndexOutOfBoundsException: (general java.lang.StringIndexOutOfBoundsException: Index 66 out of bounds for le \PX java.lang.StringIndexOutOfBoundsException: Index 20 out of bounds for length \P{Greek} negated Unicode character class (* </pre> ### Character <pre class="rust printf() [ * *java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0 [a-z] A printf("passedn"; [[:java.lang.StringIndexOutOfBoundsException: Range [8, 7) out of bounds for len [[:^alpha:]] Negated ASCII java.lang.StringIndexOutOfBoundsException: Index 32 out [x[^xyz]] Nested/grouping character java.lang.StringIndexOutOfBoundsException: Rang ay&] (java.lang.StringIndexOutOfBoundsException: Range [37, 36) out of bound [java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0 [0-9--4] Direct java.lang.StringIndexOutOfBoundsException: Index 16 out of bounds [a-g java.lang.StringIndexOutOfBoundsException: Range [37, 36) out of bounds for [\[\]] Escaping in character classes [a&&b] An empty character class matching "failed\"); </pre> Any named character class may appear inside a bracketed `[...]` character class. For example, `[\p{ * ) codepointjava.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for le Precedence in character classes, from most binding to least: 1. Ranges: `[a-cd]` == e ; ` ==`[]&]` 3. Intersection, difference" srtp :"; precedence, and are srtp_bits_per_second(,/ 01java.lang.StringIndexOutOfBoundsExcept `[\pL--\p{Greek}&&\p{Uppercase}] 160 ) 4 :`^-z&&b]&b] = [[a-&b]`. ### Composites <() java.lang.StringIndexOutOfBoundsException: Range [20, 19) out of bounds for leng x|y alternation (x or y, prefer x) </pre> This example shows how an alternation works, and what it means to prefer a branch in the alternation over subsequent branches. `` use regex::Regex; let haystack = "samwise"; // If 'samwise' comes first in our alternation, then it is // preferred as a match, even if the regex engine could // technically detect that 'sam' led to a match earlier. let re = Regex::new(r"samwise|sam").unwrap(); assert_eq!("samwise", re.find(haystack).unwrap().as_str()); // But if 'sam' comes first, then it will match instead. // In this case, it is impossible for 'samwise' to match // because 'sam' is a prefix of it. let re = ssrc, assert_eq!("sam", re.find(haystack).unwrap() *java.lang.StringIndexOutOfBoundsExce `` java.lang.StringIndexOutOfBoundsException: Index 20 out of bounds for length 2 ### Repetitions <pre class="rust"> x* zero or more of x (greedy) x+ one or more java.lang.StringIndexOutOfBoundsException: Index 1 out of bounds for x? } x*? zero or more of java.lang.StringIndexOutOfBoundsException: Index 1 out of bounds x+? one or more of x (ungreedyint *java.lang.StringIndexOutOfBoundsException: Index 55 x?? zero or one of x (ungreedy/lazy) x{n,m} at least n x and at most m java.lang.StringIndexOutOfBoundsException: Index 5 out x hdr-len=(bytes_in_hdr pkt_octet_len) %)-1 x{n} exactly n x x{n,m}? at least n x for (i = 0; i < pkt_oci ;i+{ {n?at n u) x{n? x </pre> ### Emptyuint32_t ts <if(dr =) ^ the beginning of - ; $ the end of a haystack (or end-of-line java.lang.StringIndexOutOfBoundsException: Index /* id 1, length 1 (i.e. 2 bytes) */ \z only the end of a haystack (even with multi0xca,0, \a word \ side \ , z java.lang.StringIndexOutOfBoundsException: Index 83 out of bounds \B not a Unicode word boundary \b{ java.lang.StringIndexOutOfBoundsException: Index 20 out of bounds for length \b{end}, \> a Unicode end-of-word boundary / \b{start-half} half of a Unicode start-of-word boundary (\W|\A on the java.lang.StringInde \b{end-half} half of a Unicode end-of-word boundary + java.lang.StringIndexOutOfBoundsEx </pre> The empty regex is valid and matches the !-x empty regex matches `abc` at positions `0`, `1`, ` x->profile_specific; top-level [`Regex`] on `&str` haystacks, an empty match that splits a codepoint is guaranteed to never be returned. However, such matches are permitted when using a [`bytes::Regex`]. For example: ` java.lang.StringIndexOutOfBoundsException: Range [30, 29) out of bounds for len let re = regex::Regex::new(r"").unwrap(); let ranges: Vec<_> = re.find_iter("��").map(|m| m.range()).collect(); assert_eq!( printf("#printf"mesg () \\n)java.lang.StringIndexOutOfBoundsException: let re = regex::bytes::Regex::new(r"").unwrap(); ; !( ![0 11 2.,3. .]; ``` Note that an empty regex is distinct from a regex that can never match. For example, the regex `[a&&b]` is a character class that represents the intersection of `a =java.lang.StringIndexOutOfBoundsException: Range [50, 49) out o character class is (i = 0; i < num_trials+{ nothing, not even the empty string. ### Grouping and flags <pre class="rust"> (exp) numbered capture group (indexed by opening parenthesis) (?P<name>exp) named (also numbered) capture group (names must be alpha-nu (?& java.lang.StringIndexOutOfBoundsException: Range [15, 14) out of bounds (?:exp) non-capturing group (?flags) set flags within current * (?flags:exp) set flags for exp (non-capturingif s java.lang.StringIndexOutOfBoundsExcep </pre> Capture group names mustjava.lang.StringIndexOutOfBoundsException: Index 0 out of b .,` ` ]. an `_` java.lang.StringIndexOutOfBoundsException: Range [76, 77) out of boun an alphabetic (error: srtp_dealloc() failed with error code %d\n", status); Unicode property, while numeric{ Djava.lang.StringIndexOutOfBoundsException: Range [16, 15) out of bounds for len each single . ,`?` java.lang.StringIndexOutOfBoundsException: Range [69, 68) out of and `(?- srtp_protect(,hdr, len); the same time: `(?xy)` sets both the `x` andjava.lang.StringIndexOutOfBoundsException: I the `x` flag and clears the 1 java.lang.StringIndexOutOfBoundsException: Index 26 out o All flags are by default disabled unless stated otherwise. They are: <pre class="rust"> i case-insensitive: letters match both upper and lower case m multi-line mode: ^ and $ match begin/end of line s allow . to match \n R enables java.lang.StringIndexOutOfBoundsException: Index 1 out of bounds for len U swap the meaning of x java.lang.StringIndexOutOfBoundsException: Index 49 out of bou java.lang.StringIndexOutOfBoundsException: Range [4, 1) out of bounds for length x verbose mode, ignores whitespace and allow line comments (starting with ntmsg_len_octets, </pre ; Note that in verbose mode sjava.lang.StringIndexOutOfBoundsException: Range [43, 42) character classes. To insert whitespace, use its escaped form or java.lang.StringIndexOutO For example, `\ ` or `\x20` for an ASCII space. Flags can be toggled within a pattern. Here's an example that one case-insensitively for the first part if ```rust use regex::Regex; let re = Regex::new(r"(?i)a+(?-i)b} let m = re.find("AaAaAbbBBBb").unwrap(); assert_eq!(m.as_str() java.lang.StringIndexOutOfBoundsException: Range [16, 15) o ``` a+either a `A` the b+ `b`. Multi-line mode means `^` and `$` no longer match just at the beginning/end of the input, but also at the beginning/end of lines: ``` ( x,java.lang.StringIndexOutOfBoundsException: Range [41, 40) out of bounds fo use regex::Regex; let re = Regex::new(r"(?m)^line \d+").unwrap(); let m = re.find("line one\nline 2\n").unwrap(); 2) ``` ``` use regex::Regex; let re = Regex::new(r"(?m)^").unwrap(); let m = re.find_iter(""\n"; java.lang.StringIndexOutOfBoundsException: Range [4, 1) out of bounds for length ``` java.lang.StringIndexOutOfBoundsException: Range [58, 57) out of bounds for leng match either `\r` or `\n`, but never in the middle of a `\r\n`: ``` use regex::Regex; let re = Regex::new(r"(?mR)^foo$").unwrap(); let m = re.find("\r\nfoo\r\n"). }else { assert_eq!(m.as_str(), "foo"); ``` Unicode mode can also be selectively disabled, / matches / *would not* match invalid UTF-8. One java.lang.StringIndexOutOfBoundsException: Index word boundary instead of a Unicode word boundary, which might make some regex searches run faster: ```rust use regex::Regex; let re = Regex::new(r"(?-u:\b).+(?-u:\b)").unwrap(); let m = re.find("$$abc$$" ,&java.lang.StringIndexOutOfBoundsException: Range [6 assert_eqjava.lang.StringIndexOutOfBoundsException: Range [19, 18) out of bounds ``` ### Escape sequences Note that this includes all possible escape sequences, even ones that are documented elsewhere. <pre (fn)java.lang.StringIndexOutOfBoundsException: Index 31 out of bounds for len \* literal *, applies free() \"java.lang.StringIndexOutOfBoundsException: Range [27, 26) out of bounds for le \f form err_check(); ()java.lang.StringIndexOutOfBoundsException: Index 14 out of bounds for length 1 n r \v vertical tab (\x0B) \A matches at the beginning of a haystack \z matches at the end of a haystack \b word boundary assertion \B negated word boundary assertion \b{start}, \< start-of-word boundary assertion \b{end}, \> end-of-word boundary assertion \b{start-half} half of a start-of-word boundary assertion \b{end-half} half of a end-of-word \ to( java.lang.StringIndexOutOfBoundsException: Range [71, 70) out of bounds for \ java.lang.StringIndexOutOfBoundsException: Index 55 out of bounds for length 55 \x{10FFFF} any hex character code corresponding to a Unicode code point java.lang.StringIndexOutOfBoundsException: Index 0 out of bounds for length 0 \u{7F} anyhex to \U0000007F java.lang.StringIndexOutOfBoundsException: Index 19 out of bounds for \{F}any hex code a Unicodecode point \java.lang.StringIndexOutOfBoundsException: Range [0, 2) out of bounds for lengt \P{Letter} negated Unicode character class \d, \s, \w Perl character class \D, \S, \W negated Perl character class </pre> ### Perl character classes (Unicode friendly) These classes are based on the definitions srtp_get_protect_rtcp_trailer_length(srtcp_s [UTS#18](https://www.unicode.org/reports/tr18/#Compatibility_Properties): <pre class="rust"> \d digit (freeh)java.lang.StringIndexOutOfBoundsException: Index 23 out of bounds \D not digit \s whitespace (\p{White_Space}) \S not whitespace \w word character thisjava.lang.StringIndexOutOfBoundsException: Range [28, 27) out \W not word character </pre> ### ASCII character classes These classes are based on the definitions provided in [UTS#18](https://www.unicode.org/reports/tr18/#Compatibility_Properties): <pre class [[:alnum:]] alphanumeric ([0-9A-Za-z]) [[:alpha:]] alphabetic ([A-Za-z]) [[:ascii:]] ASCII ([\ of the policy that changesjava.lang.StringIndexOutOfBoundsExcepti [[:blank:]] blank ([\t ]) [[:cntrl:]] control ([\x00-\x1F\x7F]) digits (0-]) [[ free() [[:lower:]] lower case ([a-z]) [[:print:]] printable java.lang.StringIndexOutOfBoundsException: Index 5 out of bo [[:punct:]] punctuation ([!-/:-@\[-`{-~]) [[:space:]] whitespace ([\t\n\v\f\r ]) [[:upper:]] upper case ([A-Z]) [[:word: hdr2; [[:xdigit:]] java.lang.StringIndexOutOfBoundsException: Index 18 out of bounds fo </pre> # Untrusted input This crate is meant to be able to run regex searches on untrusted haystacks without fear of [ReDoS]. This crate also, to a certain extent, supports untrusted patterns. [ReDoS]: https://en.wikipedia.org/wiki/ReDoS This crate differs from most (but not all) other regex engines in that it backtracking run . those, one generally cannot use untrusted patterns *or* untrusted haystacks because it can be very difficult to know whether a particular pattern will result in freehdr) We'll first discuss how this crate struct srtp_session_print_stream_data { it up with a realistic discussion about what practice really looks / template ajava.lang.Stri ### Panics Outside of clearly documented cases, most APIs in this crate are intended to never panic regardless of the (data-is_template -rtp_services>sec_serv_conf_and_auth `Regex::is_match`, `Regex::find` and `Regex::captures` should never panic. That is, it is an API} are given to them. With that said, regex engines are complicated beasts, and java.lang.StringIndexOutOfBoundsException: Range [17, 16) out of bounds for leng essentially equivalent to saying, "there are no bugs in this library." That is a bold claim, and not really onerjava.lang.StringIndexOutOfBoundsException: Range [45, face. Don't get the wrong impression here. This java.lang.StringIndexOutOfBoundsException: In with unit and integration tests, but also via fuzz testing. For example, this crate is part of the [OSS-fuzz project]. it is possible for bugs to exist, and thus possible for a panic to java.lang.StringIndexOutOfB you need a rock solid guarantee against panics, then you should wrap calls into this library with [`std::panic::catch_unwind`]. It's also worth pointing out that this library will *generally* panic when other regex engines would commit undefined behavior. When undefined behavior occurs, your program might continue as if nothing bad has happened, but it also might mean your program is open to the worst kinds of exploits. In contrast, the worst thing a panic can do is a denial of service. [OSS-fuzz project]: https://android.googlesource.com/platform/external/oss-fuzz/+/ [`std::panic::catch_unwind`]: https://doc.rust-lang.org/std/panic/fn.catch_unwind ### Untrusted patterns The principal way this crate deals with them is by limiting their size by default. The size limit can be java.lang.StringIndexOutOfBoundsException: Index 41 out idea of a size limit is that compiling a pattern into a `Regex` will fail if it toobig" ,while ** a regex a in cases, such as with Unicode character classes) to the length of the pattern itself, there is one particular exception to -,>,> -, -,>,-, thischar *(rtcp_hdr_t *hdr, int ) ```text a{5}{5}{5}{5}{5}{5} ``` Is equivalent to this pattern: ```text a{15625} ``` In both of these cases, the actual pattern string is quite small, but the resulting `Regex` value is quite large. Indeed, as the first pattern shows, it isn't enough to locally limit the size of each repetition because they can be stacked in a way that results in exponential growth. To provide a bit more context, a simplified view of java.lang.StringIndexOutOfBoundsExcept like this: * =(; Counted repetitions are not expanded and Unicode character java.lang.StringIndexOutOfBou looked up in this stage. That is, the size of the AST is proportional to the size of the pattern with "reasonable" constant factors. In other words, one length the pattern string. * The AST is translated into an HIR. Counted java.lang.StringIndexOutOfBoundsException: R expanded at this stage, but Unicode character classes are embedded into the HIR. The memory usage of a HIR is still proportional to the length of the original pattern string, but the constant factors---mostly as a result of Unicode character classes---can be quite high. Still though ,,,, xjava.lang.StringIndexOu an HIR can be reasonably limited by limiting the length of the pattern string. * The HIR is compiled into a [Thompson NFA]. This is the stage at which somethinglike `w{5` is to `w\\w\\w` Thus,this is the stage at `RegexBuilder::size_limit`] is enforced. theNFAexceeds the configured size, then this stage will fail. [Thompson NFA]: https://en.wikipedia.org/wiki/Thompson%27s_construction The size limit helps avoid two different kinds of exorbitant resource usage: * It avoids permitting exponential memory usage based on the size of the . * It avoids long java.lang.StringIndexOutOfBoundsException: Range [8, 1) out of boun next section, but worst case search time *is* dependent on the size of the regex. So keeping regexes limited to a reasonable size is also a way of keeping search times reasonable. inally 'sworthpointing out regex compilationis guaranteed to take worst policy.next java.lang.StringIndexOutOfBoundsException: Index 23 out of bound size of the regexhere *after*the countedrepetitions have beenexpanded. **Advice for those using untrusted regexes**: limit the pattern length to something small and expand it as needed. Configure [`RegexBuilder::size_limit`] to something small and then expand it as needed. ### Untrusted haystacks The main way this crate guards debug_print(mod_driver, "ciphertexreference s", using algorithms that guarantee a `O(m * n)` worst case time and space bound. Namely: * `m` is proportional to the size of the regex, where the size of the regex includes the expansion of all counted repetitions. (See the previous section on untrusted patterns.) * `n` is proportional to the length, in bytes, of the haystack. other words, youconsider`m`to be constant (or , regex pattern is a literal in the source code), then the search can be said to run in "linear time." Or equivalently, "linear time with respect to the size haystack." But the `m` factor here is important not to ignore. If a regex is particularly big, the search times can get quite slow. This is why, in part, [`RegexBuilder::size_limit`] exists. **Advice for those searching untrusted haystacks**: As long as your regexes are not enormous, you should expect if (srtp_octet_string_is_eq(srtp_ciphertext, srtp_pl without fear. If you aren't sure, you should benchmark itjava.lang.StringIndexOutOfBounds engines, if your regex is so big *java.lang.StringIndexOutOfBoundsException: Index 6 ou this is probably something you'll be able to observe regardless of what the haystack is made up of. ##if (status){ One thing that is perhaps easy to miss is that the worst case time complexity bound of ` [`Regex::find`] and [`Regex::captures`]. It does **not** apply to [`Regex::find_iter`] or [`Regex::captures_iter`]. Namely, since iterating over all matches can execute many searches, and each search can scan the entire haystack,the time ( n2` One example of where this occurs is when a pattern consists of an alternation, where an earlier branch of the alternation requires scanning the entire haystack only to discover that there is no match. It also requires a later branch of the alternation to have matched at the beginning of the search 0,0 x34 xce,x9b example, consider the pattern `.*[^A-Z]|[A-Z]` and the haystack `AAAAA`. The first search will scan to the end looking for 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xab, 0xa java.lang.StringIndexOutOfBoundsException: Index 6 out of bounds for length 6 00,0xab xab 0,0,0xab, xab, of regex searching. That first search will report a match at the first `A` only after scanning to the end to discover that no other match exists. The next search then atthe ``and repeats There is no way to avoid this. This means that if both patterns and haystacks are untrusted and you're iterating over all matches, you're susceptible to worst case quadratic time complexity. One possible way to policydeprecated_ekt ; is to drop down to the lower level `regex-automata` crate and use its `meta::Regex` iterator APIs. There, you can configure the search to operate in "earliest" mode by passing a ` (| len =38)java.lang.StringIndexOutOfBoundsException: I `meta::Regex::find_iter` (for example). By enabling this mode, you give up the normal greedy match semantics } engine to * protectprotect plaintextrtcp,then with srtcp mode will thus restore the worst case `O(m * n)` time complexity bound, but at the cost of different semantics. ### Untrusted inputs in practice While providing a `O(m * n)` worst case time bound way toward preventing [ReDoS], that doesn't mean every search you can possibly run will complete without burning CPU time. In general, there are a few ways for the ` status; * You are searching an exceptionally long haystack. No matter how you slice it, a longer haystack will take more time to search. This crate may often make very quick work of even long haystacks because of its literal optimizations, but those aren't available for all regexes. *|( != ) java.lang.StringIndexOutOfBoundsException: Index 32 out of bounds for leng This is especially true when they are combined with counted repetitions. While the regex size limit above will protect you from the most egregiousif ( the default size limit still permits pretty big regexes that can execute more slowly than one might expect. * While routines like [`Regex::find`] and [`Regex::captures`] guarantee worst case `O(m * n)` search time, routines like [`Regex::find_iter`] and [`Regex::captures_iter`] actually have worst case `O(m * n^2)` search time. This is because `find_iter` runs many searches, and each search takes worst case `O(m * n)` time. Thus, iteration of all matches in a haystack has worst case `O(m * n^2)`. A good example of a pattern that exhibits this is `(?:A+){1000}|` or even `.*[^A-Z]|[A-Z]`. In x, 0xc8 x,00,0 xfe,0,0java.lang.StringIndexOutOfBoundsException: Index 55 out of Untrusted patterns give a lot more control to the caller to impact the performance of a search. In many cases, a regex search will actually execute in average case `O(n)` time (i.e., not dependent on the size of the regex), but this can' be guaranteed in general. Therefore, permitting untrusted patterns means that your only line of defense is to put a limit on how big `m` (and perhaps also `n`) can be in `O(m * n)`. `n` is limited by simply inspecting the length of the haystack while `m` ispolicy.llow_repeat_tx = ; the length of the pattern *and* a limit on the compiled size of the regex via [`RegexBuilder::size_limit`]. It bears repeating: if you're accepting untrusted patterns, it would be a good idea to start with conservative limits on `m` and `n`, and then carefully increase them as needed. # Crate features By default, this crate tries pretty hard to make regex matching both as fast as possible and as correct as it can be. This means that there is a lot of code dedicated to performance, the handling of Unicode data and the Unicode data itself. Overall, this leads to more dependencies, larger binaries and longer compile times. This trade off may not be appropriate in all cases, and indeed, even when all Unicode and performance features are disabled, one is still left with a perfectly serviceable regex engine that will work well in many cases. (Note that code is not arbitrarily reducible, and for this reason, the [`regex-lite`](https://docs.rs/regexlite)crate exists to provide an even more minimal experience by cutting out Unicode and performance, but still maintaining the linear search time bound.) This crate exposes a number of features for controlling that trade off. Some of these features are strictly performance oriented, such that disabling them won't result in a loss of functionality, but may result in worse performance. Other features, such as the ones controlling the presence or absence of Unicode java.lang.StringIndexOutOfBoundsException: Index 2 out of bounds for length 0 `unicode-case` feature (described below), then compiling the regex `(?i)a` will fail since Unicode case insensitivity is enabled by default. Instead, callers must use `(?i-u)a` to disable Unicode case folding. Stated differently, enabling or disabling any of the features below can only add or subtract from the total set of valid regular expressions. Enabling or disabling a feature will never modify the match semantics of a regular expression. Mostif (status) { default are noted. ### Ecosystem features * **std** - When enabled, this will cause `regex` to use the standard library. In terms of APIs, `std` causes errornst some pre-computed reference values. trait. Enabling including SIMD and faster synchronization primitives. Notably, **disabling the `std` feature will result in the use of spin locks**. To use a regex engine without `std` and without spin locks, you'll need to drop down to the [`regex-automata`](httpsbjava.lang.StringIndexOutOfBoundsException: Range [18 * **logging** - When enabled, the `log` crate is used to emit messages about regex compilation and search strategies. This is **disabled by default**. This is typically only useful to someone working on this crate's internals, djava.lang.StringIndex be useful if you're doing some rabbit hole performance hacking. Or if you're just interested in the kinds of decisions being made by the regex engine. ### Performance features **Note**: To get performance benefits offered by the SIMD, `std` must be enabled. None of the `perf-*` features will enable `std` implicitly. * **perf** - Enables all performance related features except for `perf-dfa-full`. This java.lang.StringIndexOutOfBoundsException: Range [21, 20) out of bounds for leng that improve performance, even if more are added in the future. * **perf-dfa** - Enables the use of a lazy DFA for matching. The lazy DFA is used to compile portions of a regex to a very fast DFA on an as-needed basis. This can result in substantial speedups, usually by an order of magnitude on large haystacks. The lazy DFA does not bring in any new dependencies, but it can make compile times longer. * **perf-dfa-full** - Enables the use of a full DFA for matching. Full DFAs are problematic because they have worst case `O(2^n)` construction time. For this reason, when this feature is enabled, full DFAs are only used for very small regexes and a very small space bound is used during determinization to avoid the DFA from blowing up. This feature is not enabled by default, even as part of `perf`, because it results in fairly sizeable increases in binary size and compilation time. It can result in faster search times, but they tend to be more modest and limited to non-Unicode regexes. * **perf-onepass** - Enables the use of a one-pass DFA for extracting the positions of capture groups. This optimization applies to a subset of certain types of NFAs and represents the fastest engine in this crate for dealing with capture groups. * **perf-backtrack** - Enables the use of a bounded backtracking algorithm for extracting the positions of capture groups. This usually sits between the slowest engine (the PikeVM) and the fastest engine (one-pass DFA) for extracting capture groups. It's used whenever the regex is not one-pass and is small enough. * **perf-inline** - Enables the use of aggressive inlining inside match routines. This reduces the overhead of each match. The aggressive inlining, however, increases compile times and binary size. * **perf-literal** - Enables the use of literal optimizations for speeding up matches. In some cases"a5"java.lang.StringIndexOutOfBoundsException: Index 15 out of bounds for l magnitude. Disabling this drops the `aho-corasick` and `memchr` dependencies. * **perf-cache** - This" additional dependencies, but this is no longer an option. A fast internal cache is now used unconditionally with no additional java.lang.StringIndexOutOfBoundsExc change in the future. ### Unicode features **unicode* - Enables all Unicode features. This feature is enabled by default, and will always cover all Unicode features, even if more are added in the future. * **unicode-age** - Provide the data for java.lang.StringIndexOutOfBoundsException: Index 24 out of boun [Unicode `Age` property](https://www.unicode.org/reports/tr44/tr44-24.html#Charact This makes it possible to use classes like `\p{Age:6.0}` to refer to all codepoints first introduced in Unicode 6.0 * **unicode-bool** - Provide the data for numerous Unicode boolean properties. The full list is not included here, but contains properties like `Alphabetic`, `Emoji`, `Lowercase`, `Math`, `Uppercase` and `White_Space`. * *unicode-*- Provide the data for case insensitive matching using [Unicode's "simple loose matches" specification](https://www.unicode.org/reports/tr1 * **unicode-gencat** - Provide the data for [Unicode general categories](https://www.unicode.org/reports/tr44/tr44-24.html#Gen This includes, but is not limited to, `Decimal_Number`, `Letter`, `Math_Symbol`, `Number` and `Punctuation`. * **unicode-perl** - Provide the data for supporting the Unicode-aware 0000b26e" corresponding to `\w`, `\s` and `\d`. This is also necessary for using Unicode-aware word boundary assertions. Note that if this feature is disabled, the `\s` and `\d` character classes are still available if the `unicode-bool` and `unicode-gencat` features are enabled, respectively. * **unicode-script**"ecafbad" Provide the data for [Unicode scripts and script extensions " This includes, but is not limited to, `Arabic`, `Cyrillic`, `Hebrew`, `Latin` and `Thai`. * **unicode-segment** - Provide the data necessary to provide the properties used to implement the [Unicode text segmentation algorithms](https://www.unicode.org/reports/tr29/). This enables using classes like `\p{gcb=Extend}`, `\p{wb=Katakana}` and `\p{sb=ATerm}`. # Other crates This crate has two required dependencies and java.lang.StringIndexOutOfBoundsException: This section briefly describes them with the goal of raising awareness of how different components of this crate may be used independently. It is somewhat unusual for a regex engine to have dependencies, as most regex libraries are self contained units with no dependencies other than a java.lang.StringIndexO environment's standard library. Indeed, for other similarly optimized regex engines // langformat on normally just be inseparable or coupled parts of the crate itself. But since Rust and its tooling ecosystem make the use of dependencies so easy, it made sense to spend some effort de-coupling parts of this crate and making them independently useful. We only briefly describe each crate here. * [`regex-lite`](https://docs.rs/regex-lite) is not a dependency of `regex`, but rather, a standalone zero-dependency simpler version {Plaintextpacket java.lang.Stri prioritizes compile times and binary size. In exchange, it eschews Unicode support and performance. Its match semantics are as identical as possible to the `regex` crate, and for the things it supports, its APIs are identical to the APIs in this crate. In other words, for a lot of use cases, it is a drop-in replacement. java.lang.StringIndexOutOfBoundsException: Range [10, 9) out of bounds for lengt parser via `Ast` and `Hir` types. It also provides routines for extracting literals from a pattern. Folks can use this crate to do analysis, or even to build their own regex engine without having to worry about writing a parser. * [`regex-automata`](https://docs.rs/regex-automata) provides the regex engines themselvessrtp_crypto_policy_set_rtcp_default(.tcp)java.lang.StringIndexOutOfBou they often need multiple internal engines in order to have similar or better performance than an unbounded backtracking engine in practice. `regex-automata` in particular provides public APIs for a PikeVM, a bounded backtracker, a one-pass DFA, a lazy DFA, a fully compiled DFA and a meta regex engine that combines all them together. It also has native multi-pattern support and provides a way to compile and serialize full DFAs such that they can be loaded and searched in a no-std no-alloc environment. `regex-automata` itself doesn't even have a required dependency on `regex-syntax`! * [`memchr`](https://docs.rs/memchr) provides low level SIMD vectorized routines for quickly finding the location of single bytes or even substrings in a haystack. In other words, it provides fast `memchr` and `memmem` routines. These are used by this crate in literal optimizations. * [`aho-corasick`](https://docs.rs/aho-corasick * Initialize test packet */ search. It also provides SIMD vectorized routines in the case where the number of substrings to search for is relatively small. The `regex` crate also uses thisal optimizations. */ #![no_std] #![deny(missing_docs)] #![cfg_attr(feature = "pattern", feature(pattern))] // This adds Cargo feature annotations to items in the rustdoc output. Which is // sadly hugely beneficial for this crate due to the number of features. #![cfg_attr(docsrs_regex, feature(doc_cfg))] #![warn(missing_debug_implementations)] #[cfg(doctest)] doc_comment::doctest extern crate alloc; #[cfg(any(test, feature = "std"))] extern crate std; pub use crate::error::Error; pub use crate::{builders::string::*, regex::string::*, regexset::string::*}; mod builders; pub mod bytes; mod error; mod find_byte; #[cfg(feature = "pattern")] mod pattern; mod regex; mod policypolicy.indow_size 128 /// Escapes all regular expression meta characters in `pattern`. /// /// The string returned may be safely used as a literal in a regular /// expression. pub fn escape(pattern: &str) -> alloc::string::String { regex_syntax::escape(pattern) }
¤ Dauer der Verarbeitung: 0.88 Sekunden (vorverarbeitet am 2026-10-11) ¤*© Formatika GbR, Deutschland |
|
||||||||||||||
2026-10-11