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// 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`](struct.Regex.html) 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; //! ``` //! //! # 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"`. //! //! # Example: Avoid compiling the same regex in a loop //! //! It is an anti-pattern to compile the same regular expression in a loop //! since compilation is typically expensive. (It takes anywhere from a few //! microseconds to a few **milliseconds** depending on the size of the //! regex.) Not only is compilation itself expensive, but this also prevents //! optimizations that reuse allocations internally to the matching engines. //! //! 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 the //! [`lazy_static`](https://crates.io/crates/lazy_static) crate to ensure that //! regular expressions are compiled exactly once. //! //! For example: //! //! ```rust //! #[macro_use] extern crate lazy_static; //! extern crate regex; //! //! use regex::Regex; //! //! fn some_helper_function(text: &str) -> bool { //! lazy_static! { //! static ref RE: Regex = Regex::new("...").unwrap(); //! } //! RE.is_match(text) //! } //! //! fn main() {} //! ``` //! //! Specifically, in this example, the regex will be compiled when it is used for //! the first time. On subsequent uses, it will reuse the previous compilation. //! //! # 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"); //! # } //! ``` //! //! # Example: match multiple regular expressions simultaneously //! //! This demonstrates how to use a `RegexSet` to match multiple (possibly //! overlapping) regular expressions in a single scan of the search text: //! //! ```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. //! 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)); //! ``` //! //! # 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 valid UTF-8 //! while exposing match locations as byte indices into the search string. //! //! 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 //! before matching. //! //! Regular expressions themselves are **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))); //! # } //! ``` //! //! # Opt out of Unicode support //! //! The `bytes` sub-module provides a `Regex` type that can be used to match //! on `&[u8]`. By default, text is interpreted as ASCII compatible text with //! all Unicode support disabled (e.g., `.` matches any byte instead of any //! Unicode codepoint). Unicode support can be selectively enabled with the //! `u` flag. See the `bytes` module documentation for more details. //! //! Unicode support can also be selectively *disabled* with the main `Regex` //! type that matches on `&str`. For example, `(?-u:\b)` will match an ASCII //! word boundary. Note though that invalid UTF-8 is not allowed to be matched //! even when the `u` flag is disabled. For example, `(?-u:.)` will return an //! error, since `.` matches *any byte* when Unicode support is disabled. //! //! # 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/lazy) //! x+? one or more of x (ungreedy/lazy) //! x?? zero or one of x (ungreedy/lazy) //! 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/lazy) //! x{n,}? at least n x (ungreedy/lazy) //! 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<name>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 unless stated otherwise. 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*? //! u Unicode support (enabled by default) //! 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`. //! //! Here is an example that uses an ASCII word boundary instead of a Unicode //! word boundary: //! //! ```rust //! # extern crate regex; use regex::Regex; //! # fn main() { //! let re = Regex::new(r"(?-u:\b).+(?-u:\b)").unwrap(); //! let cap = re.captures("$$abc$$").unwrap(); //! assert_eq!(cap.at(0), Some("abc")); //! # } //! ``` //! //! ## 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.) //! //! When a DFA is used, pathological cases with exponential state blow up are //! avoided by constructing the DFA lazily or in an "online" manner. Therefore, //! at most one new state can be created for each byte of input. This satisfies //! our time complexity guarantees, but can lead to unbounded memory growth //! proportional to the size of the input. As a stopgap, the DFA is only //! allowed to store a fixed number of states. (When the limit is reached, its //! states are wiped and continues on, possibly duplicating previous work. If //! the limit is reached too frequently, it gives up and hands control off to //! another matching engine with fixed memory requirements.) #![deny(missing_docs)] #![cfg_attr(test, deny(warnings))] #![cfg_attr(feature = "pattern", feature(pattern))] #![cfg_attr(feature = "simd-accel", feature(cfg_target_feature))] #![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 thread_local; #[cfg(test)] extern crate quickcheck; extern crate regex_syntax as syntax; #[cfg(feature = "simd-accel")] extern crate simd; extern crate utf8_ranges; pub use error::Error; pub use re_builder::unicode::*; pub use re_set::unicode::*; pub use re_unicode::{ Regex, Captures, SubCaptures, SubCapturesPos, SubCapturesNamed, CaptureNames, FindCaptures, FindMatches, Replacer, NoExpand, RegexSplits, RegexSplitsN, quote, is_match, }; /** Match regular expressions on arbitrary bytes. This module provides a nearly identical API to the one found in the top-level of this crate. There are two important differences: 1. Matching is done on `&[u8]` instead of `&str`. Additionally, `Vec<u8>` is used where `String` would have been used. 2. Regular expressions are compiled with Unicode support *disabled* by default. This means that while Unicode regular expressions can only match valid UTF-8, regular expressions in this module can match arbitrary bytes. Unicode support can be selectively enabled via the `u` flag in regular expressions provided by this sub-module. # Example: match null terminated string This shows how to find all null-terminated strings in a slice of bytes: ```rust # use regex::bytes::Regex; let re = Regex::new(r"(?P<cstr>[^\x00]+)\x00").unwrap(); let text = b"foo\x00bar\x00baz\x00"; // Extract all of the strings without the null terminator from each match. // The unwrap is OK here since a match requires the `cstr` capture to match. let cstrs: Vec<&[u8]> = re.captures_iter(text) .map(|c| c.name("cstr").unwrap()) .collect(); assert_eq!(vec![&b"foo"[..], &b"bar"[..], &b"baz"[..]], cstrs); ``` # Example: selectively enable Unicode support This shows how to match an arbitrary byte pattern followed by a UTF-8 encoded string (e.g., to extract a title from a Matroska file): ```rust # use std::str; # use regex::bytes::Regex; let re = Regex::new(r"\x7b\xa9(?:[\x80-\xfe]|[\x40-\xff].)(?u:(.*))").unwrap(); let text = b"\x12\xd0\x3b\x5f\x7b\xa9\x85\xe2\x98\x83\x80\x98\x54\x76\x68\x65"; let caps = re.captures(text).unwrap(); // Notice that despite the `.*` at the end, it will only match valid UTF-8 // because Unicode mode was enabled with the `u` flag. Without the `u` flag, // the `.*` would match the rest of the bytes. assert_eq!((7, 10), caps.pos(1).unwrap()); // If there was a match, Unicode mode guarantees that `title` is valid UTF-8. let title = str::from_utf8(caps.at(1).unwrap()).unwrap(); assert_eq!("☃", title); ``` In general, if the Unicode flag is enabled in a capture group and that capture is part of the overall match, then the capture is *guaranteed* to be valid UTF-8. # Syntax The supported syntax is pretty much the same as the syntax for Unicode regular expressions with a few changes that make sense for matching arbitrary bytes: 1. The `u` flag is *disabled* by default, but can be selectively enabled. (The opposite is true for the main `Regex` type.) Disabling the `u` flag is said to invoke "ASCII compatible" mode. 2. In ASCII compatible mode, neither Unicode codepoints nor Unicode character classes are allowed. 3. In ASCII compatible mode, Perl character classes (`\w`, `\d` and `\s`) revert to their typical ASCII definition. `\w` maps to `[[:word:]]`, `\d` maps to `[[:digit:]]` and `\s` maps to `[[:space:]]`. 4. In ASCII compatible mode, word boundaries use the ASCII compatible `\w` to determine whether a byte is a word byte or not. 5. Hexadecimal notation can be used to specify arbitrary bytes instead of Unicode codepoints. For example, in ASCII compatible mode, `\xFF` matches the literal byte `\xFF`, while in Unicode mode, `\xFF` is a Unicode codepoint that matches its UTF-8 encoding of `\xC3\xBF`. Similarly for octal notation. 6. `.` matches any *byte* except for `\n` instead of any codepoint. When the `s` flag is enabled, `.` matches any byte. # Performance In general, one should expect performance on `&[u8]` to be roughly similar to performance on `&str`. */ pub mod bytes { pub use re_builder::bytes::*; pub use re_set::bytes::*; pub use re_bytes::*; } mod backtrack; mod utf8; mod compile; mod dfa; mod error; mod exec; mod expand; mod freqs; mod input; mod literals; #[cfg(feature = "pattern")] mod pattern; mod pikevm; mod prog; mod re_builder; mod re_bytes; mod re_plugin; mod re_set; mod re_trait; mod re_unicode; #[cfg(feature = "simd-accel")] mod simd_accel; #[cfg(not(feature = "simd-accel"))] #[path = "simd_fallback/mod.rs"] mod simd_accel; mod sparse; /// The `internal` module exists to support the `regex!` macro and other /// suspicious activity, such as testing different matching engines and /// supporting the `regex-debug` CLI utility. #[doc(hidden)] pub mod internal { pub use compile::Compiler; pub use exec::{Exec, ExecBuilder}; pub use input::{Char, Input, CharInput, InputAt}; pub use literals::LiteralSearcher; pub use prog::{Program, Inst, EmptyLook, InstRanges}; pub use re_plugin::Plugin; pub use re_unicode::_Regex; }