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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.

    macro_rules! define_set {
        ($name:ident, $exec_build:expr, $text_ty:ty, $as_bytes:expr) => {
            pub mod $name {
                use std::fmt;
                use std::iter;
                use std::slice;
                use std::vec;

                use error::Error;
                use exec::{Exec, ExecBuilder};
                use re_trait::RegularExpression;

    /// Match multiple (possibly overlapping) regular expressions in a single scan.
    ///
    /// A regex set corresponds to the union of two or more regular expressions.
    /// That is, a regex set will match text where at least one of its
    /// constituent regular expressions matches. A regex set as its formulated here
    /// provides a touch more power: it will also report *which* regular
    /// expressions in the set match. Indeed, this is the key difference between
    /// regex sets and a single `Regex` with many alternates, since only one
    /// alternate can match at a time.
    ///
    /// For example, consider regular expressions to match email addresses and
    /// domains: `[a-z]+@[a-z]+\.(com|org|net)` and `[a-z]+\.(com|org|net)`. If a
    /// regex set is constructed from those regexes, then searching the text
    /// `foo@example.com` will report both regexes as matching. Of course, one
    /// could accomplish this by compiling each regex on its own and doing two
    /// searches over the text. The key advantage of using a regex set is that it
    /// will report the matching regexes using a *single pass through the text*.
    /// If one has hundreds or thousands of regexes to match repeatedly (like a URL
    /// router for a complex web application or a user agent matcher), then a regex
    /// set can realize huge performance gains.
    ///
    /// # Example
    ///
    /// This shows how the above two regexes (for matching email addresses and
    /// domains) might work:
    ///
    /// ```rust
    /// # use regex::RegexSet;
    /// let set = RegexSet::new(&[
    ///     r"[a-z]+@[a-z]+\.(com|org|net)",
    ///     r"[a-z]+\.(com|org|net)",
    /// ]).unwrap();
    ///
    /// // Ask whether any regexes in the set match.
    /// assert!(set.is_match("foo@example.com"));
    ///
    /// // Identify which regexes in the set match.
    /// let matches: Vec<_> = set.matches("foo@example.com").into_iter().collect();
    /// assert_eq!(vec![0, 1], matches);
    ///
    /// // Try again, but with text that only matches one of the regexes.
    /// let matches: Vec<_> = set.matches("example.com").into_iter().collect();
    /// assert_eq!(vec![1], matches);
    ///
    /// // Try again, but with text that doesn't match any regex in the set.
    /// let matches: Vec<_> = set.matches("example").into_iter().collect();
    /// assert!(matches.is_empty());
    /// ```
    ///
    /// Note that it would be possible to adapt the above example to using `Regex`
    /// with an expression like:
    ///
    /// ```ignore
    /// (?P<email>[a-z]+@(?P<email_domain>[a-z]+[.](com|org|net)))|(?P<domain>[a-z]+[.](com|org|net))
    /// ```
    ///
    /// After a match, one could then inspect the capture groups to figure out
    /// which alternates matched. The problem is that it is hard to make this
    /// approach scale when there are many regexes since the overlap between each
    /// alternate isn't always obvious to reason about.
    ///
    /// # Limitations
    ///
    /// Regex sets are limited to answering the following two questions:
    ///
    /// 1. Does any regex in the set match?
    /// 2. If so, which regexes in the set match?
    ///
    /// As with the main `Regex` type, it is cheaper to ask (1) instead of (2)
    /// since the matching engines can stop after the first match is found.
    ///
    /// Other features like finding the location of successive matches or their
    /// sub-captures aren't supported. If you need this functionality, the
    /// recommended approach is to compile each regex in the set independently and
    /// selectively match them based on which regexes in the set matched.
    ///
    /// # Performance
    ///
    /// A `RegexSet` has the same performance characteristics as `Regex`. Namely,
    /// search takes `O(mn)` time, where `m` is proportional to the size of the
    /// regex set and `n` is proportional to the length of the search text.
    #[derive(Clone)]
    pub struct RegexSet(Exec);

    impl RegexSet {
        /// Create a new regex set with the given regular expressions.
        ///
        /// This takes an iterator of `S`, where `S` is something that can produce
        /// a `&str`. If any of the strings in the iterator are not valid regular
        /// expressions, then an error is returned.
        ///
        /// # Example
        ///
        /// Create a new regex set from an iterator of strings:
        ///
        /// ```rust
        /// # use regex::RegexSet;
        /// let set = RegexSet::new(&[r"\w+", r"\d+"]).unwrap();
        /// assert!(set.is_match("foo"));
        /// ```
        pub fn new<I, S>(exprs: I) -> Result<RegexSet, Error>
                where S: AsRef<str>, I: IntoIterator<Item=S> {
            let exec = try!($exec_build(exprs));
            Ok(RegexSet(exec))
        }

        /// Returns true if and only if one of the regexes in this set matches
        /// the text given.
        ///
        /// This method should be preferred if you only need to test whether any
        /// of the regexes in the set should match, but don't care about *which*
        /// regexes matched. This is because the underlying matching engine will
        /// quit immediately after seeing the first match instead of continuing to
        /// find all matches.
        ///
        /// Note that as with searches using `Regex`, the expression is unanchored
        /// by default. That is, if the regex does not start with `^` or `\A`, or
        /// end with `$` or `\z`, then it is permitted to match anywhere in the
        /// text.
        ///
        /// # Example
        ///
        /// Tests whether a set matches some text:
        ///
        /// ```rust
        /// # use regex::RegexSet;
        /// let set = RegexSet::new(&[r"\w+", r"\d+"]).unwrap();
        /// assert!(set.is_match("foo"));
        /// assert!(!set.is_match("☃"));
        /// ```
        pub fn is_match(&self, text: $text_ty) -> bool {
            self.0.searcher().is_match_at($as_bytes(text), 0)
        }

        /// Returns the set of regular expressions that match in the given text.
        ///
        /// The set returned contains the index of each regular expression that
        /// matches in the given text. The index is in correspondence with the
        /// order of regular expressions given to `RegexSet`'s constructor.
        ///
        /// The set can also be used to iterate over the matched indices.
        ///
        /// Note that as with searches using `Regex`, the expression is unanchored
        /// by default. That is, if the regex does not start with `^` or `\A`, or
        /// end with `$` or `\z`, then it is permitted to match anywhere in the
        /// text.
        ///
        /// # Example
        ///
        /// Tests which regular expressions match the given text:
        ///
        /// ```rust
        /// # use regex::RegexSet;
        /// let set = RegexSet::new(&[
        ///     r"\w+",
        ///     r"\d+",
        ///     r"\pL+",
        ///     r"foo",
        ///     r"bar",
        ///     r"barfoo",
        ///     r"foobar",
        /// ]).unwrap();
        /// 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));
        /// ```
        pub fn matches(&self, text: $text_ty) -> SetMatches {
            let mut matches = vec![false; self.0.regex_strings().len()];
            let any = self.0.searcher().many_matches_at(
                &mut matches, $as_bytes(text), 0);
            SetMatches {
                matched_any: any,
                matches: matches,
            }
        }

        /// Returns the total number of regular expressions in this set.
        pub fn len(&self) -> usize {
            self.0.regex_strings().len()
        }
    }

    /// A set of matches returned by a regex set.
    #[derive(Clone, Debug)]
    pub struct SetMatches {
        matched_any: bool,
        matches: Vec<bool>,
    }

    impl SetMatches {
        /// Whether this set contains any matches.
        pub fn matched_any(&self) -> bool {
            self.matched_any
        }

        /// Whether the regex at the given index matched.
        ///
        /// The index for a regex is determined by its insertion order upon the
        /// initial construction of a `RegexSet`, starting at `0`.
        ///
        /// # Panics
        ///
        /// If `regex_index` is greater than or equal to `self.len()`.
        pub fn matched(&self, regex_index: usize) -> bool {
            self.matches[regex_index]
        }

        /// The total number of regexes in the set that created these matches.
        pub fn len(&self) -> usize {
            self.matches.len()
        }

        /// Returns an iterator over indexes in the regex that matched.
        pub fn iter(&self) -> SetMatchesIter {
            SetMatchesIter((&*self.matches).into_iter().enumerate())
        }
    }

    impl IntoIterator for SetMatches {
        type IntoIter = SetMatchesIntoIter;
        type Item = usize;

        fn into_iter(self) -> Self::IntoIter {
            SetMatchesIntoIter(self.matches.into_iter().enumerate())
        }
    }

    impl<'a> IntoIterator for &'a SetMatches {
        type IntoIter = SetMatchesIter<'a>;
        type Item = usize;

        fn into_iter(self) -> Self::IntoIter {
            self.iter()
        }
    }

    /// An owned iterator over the set of matches from a regex set.
    pub struct SetMatchesIntoIter(iter::Enumerate<vec::IntoIter<bool>>);

    impl Iterator for SetMatchesIntoIter {
        type Item = usize;

        fn next(&mut self) -> Option<usize> {
            loop {
                match self.0.next() {
                    None => return None,
                    Some((_, false)) => {}
                    Some((i, true)) => return Some(i),
                }
            }
        }
    }

    /// A borrowed iterator over the set of matches from a regex set.
    ///
    /// The lifetime `'a` refers to the lifetime of a `SetMatches` value.
    #[derive(Clone)]
    pub struct SetMatchesIter<'a>(iter::Enumerate<slice::Iter<'a, bool>>);

    impl<'a> Iterator for SetMatchesIter<'a> {
        type Item = usize;

        fn next(&mut self) -> Option<usize> {
            loop {
                match self.0.next() {
                    None => return None,
                    Some((_, &false)) => {}
                    Some((i, &true)) => return Some(i),
                }
            }
        }
    }

    #[doc(hidden)]
    impl From<Exec> for RegexSet {
        fn from(exec: Exec) -> Self {
            RegexSet(exec)
        }
    }

    impl fmt::Debug for RegexSet {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            write!(f, "RegexSet({:?})", self.0.regex_strings())
        }
    }

    #[allow(dead_code)] fn as_bytes_str(text: &str) -> &[u8] { text.as_bytes() }
    #[allow(dead_code)] fn as_bytes_bytes(text: &[u8]) -> &[u8] { text }
            }
        }
    }

    define_set! {
        unicode,
        |exprs| ExecBuilder::new_many(exprs).build(),
        &str,
        as_bytes_str
    }

    define_set! {
        bytes,
        |exprs| ExecBuilder::new_many(exprs).only_utf8(false).build(),
        &[u8],
        as_bytes_bytes
    }

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