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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` 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.
    //!
    //! # The `regex!` macro
    //!
    //! Rust's compile-time meta-programming facilities provide a way to write a
    //! `regex!` macro which compiles regular expressions *when your program
    //! compiles*. Said differently, if you only use `regex!` to build regular
    //! expressions in your program, then your program cannot compile with an
    //! invalid regular expression. Moreover, the `regex!` macro compiles the
    //! given expression to native Rust code, which ideally makes it faster.
    //! Unfortunately (or fortunately), the dynamic implementation has had a lot
    //! more optimization work put into it currently, so it is faster than
    //! the `regex!` macro in almost every case.
    //!
    //! To use the `regex!` macro, you must add `regex_macros` to your dependencies
    //! in your project's `Cargo.toml`:
    //!
    //! ```toml
    //! [dependencies]
    //! regex = "0.1"
    //! regex_macros = "0.1"
    //! ```
    //!
    //! and then enable the `plugin` feature and import the `regex_macros` crate as
    //! a syntax extension:
    //!
    //! ```ignore
    //! #![feature(plugin)]
    //! #![plugin(regex_macros)]
    //! extern crate regex;
    //!
    //! fn main() {
    //!     let re = regex!(r"^\d{4}-\d{2}-\d{2}$");
    //!     assert!(re.is_match("2014-01-01"));
    //! }
    //! ```
    //!
    //! There are a few things worth mentioning about using the `regex!` macro.
    //! Firstly, the `regex!` macro *only* accepts string *literals*.
    //! Secondly, the `regex` crate *must* be linked with the name `regex` since
    //! the generated code depends on finding symbols in the `regex` crate.
    //!
    //! One downside of using the `regex!` macro is that it can increase the
    //! size of your program's binary since it generates specialized Rust code.
    //! The extra size probably won't be significant for a small number of
    //! expressions, but 100+ calls to `regex!` will probably result in a
    //! noticeably bigger binary.
    //!
    //! **NOTE**: This is implemented using a compiler plugin, which is not
    //! available on the Rust 1.0 beta/stable channels. Therefore, you'll only
    //! be able to use `regex!` on the nightly Rust releases.
    //!
    //! # 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.
    //!
    //! Currently, only simple case folding is supported. Namely, when matching
    //! case-insensitively, the characters are first mapped using the
    //! [simple case folding](ftp://ftp.unicode.org/Public/UNIDATA/CaseFolding.txt)
    //! mapping.
    //!
    //! Regular expressions themselves are **only** interpreted as a sequence of
    //! Unicode scalar values. This means you can use Unicode characters directly
    //! in your expression:
    //!
    //! ```rust
    //! # extern crate regex; use regex::Regex;
    //! # fn main() {
    //! let re = Regex::new(r"(?i)Δ+").unwrap();
    //! assert_eq!(re.find("ΔδΔ"), Some((0, 6)));
    //! # }
    //! ```
    //!
    //! Finally, Unicode general categories and scripts are available as character
    //! classes. For example, you can match a sequence of numerals, Greek or
    //! Cherokee letters:
    //!
    //! ```rust
    //! # extern crate regex; use regex::Regex;
    //! # fn main() {
    //! let re = Regex::new(r"[\pN\p{Greek}\p{Cherokee}]+").unwrap();
    //! assert_eq!(re.find("abcΔᎠβⅠᏴγδⅡxyz"), Some((3, 23)));
    //! # }
    //! ```
    //!
    //! # Syntax
    //!
    //! The syntax supported in this crate is almost in an exact correspondence
    //! with the syntax supported by RE2. It is documented below.
    //!
    //! Note that the regular expression parser and abstract syntax are exposed in
    //! a separate crate, [`regex-syntax`](../regex_syntax/index.html).
    //!
    //! ## Matching one character
    //!
    //! <pre class="rust">
    //! .           any character except new line (includes new line with s flag)
    //! [xyz]       A character class matching either x, y or z.
    //! [^xyz]      A character class matching any character except x, y and z.
    //! [a-z]       A character class matching any character in range a-z.
    //! \d          digit (\p{Nd})
    //! \D          not digit
    //! [:alpha:]   ASCII character class ([A-Za-z])
    //! [:^alpha:]  Negated ASCII character class ([^A-Za-z])
    //! \pN         One-letter name Unicode character class
    //! \p{Greek}   Unicode character class (general category or script)
    //! \PN         Negated one-letter name Unicode character class
    //! \P{Greek}   negated Unicode character class (general category or script)
    //! </pre>
    //!
    //! Any named character class may appear inside a bracketed `[...]` character
    //! class. For example, `[\p{Greek}\pN]` matches any Greek or numeral
    //! character.
    //!
    //! ## Composites
    //!
    //! <pre class="rust">
    //! xy    concatenation (x followed by y)
    //! x|y   alternation (x or y, prefer x)
    //! </pre>
    //!
    //! ## Repetitions
    //!
    //! <pre class="rust">
    //! x*        zero or more of x (greedy)
    //! x+        one or more of x (greedy)
    //! x?        zero or one of x (greedy)
    //! x*?       zero or more of x (ungreedy)
    //! x+?       one or more of x (ungreedy)
    //! x??       zero or one of x (ungreedy)
    //! x{n,m}    at least n x and at most m x (greedy)
    //! x{n,}     at least n x (greedy)
    //! x{n}      exactly n x
    //! x{n,m}?   at least n x and at most m x (ungreedy)
    //! x{n,}?    at least n x (ungreedy)
    //! x{n}?     exactly n x
    //! </pre>
    //!
    //! ## Empty matches
    //!
    //! <pre class="rust">
    //! ^     the beginning of text (or start-of-line with multi-line mode)
    //! $     the end of text (or end-of-line with multi-line mode)
    //! \A    only the beginning of text (even with multi-line mode enabled)
    //! \z    only the end of text (even with multi-line mode enabled)
    //! \b    a Unicode word boundary (\w on one side and \W, \A, or \z on other)
    //! \B    not a Unicode word boundary
    //! </pre>
    //!
    //! ## Grouping and flags
    //!
    //! <pre class="rust">
    //! (exp)          numbered capture group (indexed by opening parenthesis)
    //! (?P&lt;name&gt;exp)  named (also numbered) capture group (allowed chars: [_0-9a-zA-Z])
    //! (?:exp)        non-capturing group
    //! (?flags)       set flags within current group
    //! (?flags:exp)   set flags for exp (non-capturing)
    //! </pre>
    //!
    //! Flags are each a single character. For example, `(?x)` sets the flag `x`
    //! and `(?-x)` clears the flag `x`. Multiple flags can be set or cleared at
    //! the same time: `(?xy)` sets both the `x` and `y` flags and `(?x-y)` sets
    //! the `x` flag and clears the `y` flag.
    //!
    //! All flags are by default disabled. They are:
    //!
    //! <pre class="rust">
    //! i     case-insensitive
    //! m     multi-line mode: ^ and $ match begin/end of line
    //! s     allow . to match \n
    //! U     swap the meaning of x* and x*?
    //! x     ignore whitespace and allow line comments (starting with `#`)
    //! </pre>
    //!
    //! Here's an example that matches case-insensitively for only part of the
    //! expression:
    //!
    //! ```rust
    //! # extern crate regex; use regex::Regex;
    //! # fn main() {
    //! let re = Regex::new(r"(?i)a+(?-i)b+").unwrap();
    //! let cap = re.captures("AaAaAbbBBBb").unwrap();
    //! assert_eq!(cap.at(0), Some("AaAaAbb"));
    //! # }
    //! ```
    //!
    //! Notice that the `a+` matches either `a` or `A`, but the `b+` only matches
    //! `b`.
    //!
    //! ## Escape sequences
    //!
    //! <pre class="rust">
    //! \*         literal *, works for any punctuation character: \.+*?()|[]{}^$
    //! \a         bell (\x07)
    //! \f         form feed (\x0C)
    //! \t         horizontal tab
    //! \n         new line
    //! \r         carriage return
    //! \v         vertical tab (\x0B)
    //! \123       octal character code (up to three digits)
    //! \x7F       hex character code (exactly two digits)
    //! \x{10FFFF} any hex character code corresponding to a Unicode code point
    //! </pre>
    //!
    //! ## Perl character classes (Unicode friendly)
    //!
    //! These classes are based on the definitions provided in
    //! [UTS#18](http://www.unicode.org/reports/tr18/#Compatibility_Properties):
    //!
    //! <pre class="rust">
    //! \d     digit (\p{Nd})
    //! \D     not digit
    //! \s     whitespace (\p{White_Space})
    //! \S     not whitespace
    //! \w     word character (\p{Alphabetic} + \p{M} + \d + \p{Pc} + \p{Join_Control})
    //! \W     not word character
    //! </pre>
    //!
    //! ## ASCII character classes
    //!
    //! <pre class="rust">
    //! [:alnum:]    alphanumeric ([0-9A-Za-z])
    //! [:alpha:]    alphabetic ([A-Za-z])
    //! [:ascii:]    ASCII ([\x00-\x7F])
    //! [:blank:]    blank ([\t ])
    //! [:cntrl:]    control ([\x00-\x1F\x7F])
    //! [:digit:]    digits ([0-9])
    //! [:graph:]    graphical ([!-~])
    //! [:lower:]    lower case ([a-z])
    //! [:print:]    printable ([ -~])
    //! [:punct:]    punctuation ([!-/:-@[-`{-~])
    //! [:space:]    whitespace ([\t\n\v\f\r ])
    //! [:upper:]    upper case ([A-Z])
    //! [:word:]     word characters ([0-9A-Za-z_])
    //! [:xdigit:]   hex digit ([0-9A-Fa-f])
    //! </pre>
    //!
    //! # Untrusted input
    //!
    //! This crate can handle both untrusted regular expressions and untrusted
    //! search text.
    //!
    //! Untrusted regular expressions are handled by capping the size of a compiled
    //! regular expression. (See `Regex::with_size_limit`.) Without this, it would
    //! be trivial for an attacker to exhaust your system's memory with expressions
    //! like `a{100}{100}{100}`.
    //!
    //! Untrusted search text is allowed because the matching engine(s) in this
    //! crate have time complexity `O(mn)` (with `m ~ regex` and `n ~ search
    //! text`), which means there's no way to cause exponential blow-up like with
    //! some other regular expression engines. (We pay for this by disallowing
    //! features like arbitrary look-ahead and backreferences.)
    //!
    //! 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.)

    #![allow(dead_code, unused_imports, unused_variables)]

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

    extern crate aho_corasick;
    extern crate memchr;
    extern crate regex_syntax as syntax;
    extern crate utf8_ranges;

    // The re module is essentially our public interface.
    pub use re::{
        Regex, Error, Captures, SubCaptures, SubCapturesPos, SubCapturesNamed,
        CaptureNames, FindCaptures, FindMatches,
        Replacer, NoExpand, RegexSplits, RegexSplitsN,
        quote, is_match,
    };
    pub use set::{RegexSet, SetMatches, SetMatchesIntoIter, SetMatchesIter};

    mod backtrack;
    mod char;
    mod char_utf8;
    mod compile;
    mod dfa;
    mod exec;
    mod input;
    mod literals;
    mod nfa;
    mod pool;
    mod prog;
    mod re;
    mod set;
    mod sparse;

    /// The `internal` module exists to support the `regex!` macro and other
    /// suspicious activity, such as testing different matching engines.
    #[doc(hidden)]
    pub mod internal {
        pub use char::Char;
        pub use compile::Compiler;
        pub use exec::{Exec, ExecBuilder};
        pub use input::{Input, CharInput, InputAt};
        pub use literals::{BuildPrefixes, Literals};
        pub use prog::{Program, Inst, EmptyLook, InstRanges};
        pub use re::ExNative;
    }

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