+// 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.
+
+use std::char;
+use std::cmp::Ordering;
+use std::fmt;
+use std::u32;
+
+use syntax;
+
+/// An inline representation of `Option<char>`.
+///
+/// This eliminates the need to do case analysis on `Option<char>` to determine
+/// ordinality with other characters.
+///
+/// (The `Option<char>` is not related to encoding. Instead, it is used in the
+/// matching engines to represent the beginning and ending boundaries of the
+/// search text.)
+#[derive(Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
+pub struct Char(u32);
+
+impl fmt::Debug for Char {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match char::from_u32(self.0) {
+            None => write!(f, "Empty"),
+            Some(c) => write!(f, "{:?}", c),
+        }
+    }
+}
+
+impl Char {
+    /// Returns true iff the character is absent.
+    #[inline]
+    pub fn is_none(self) -> bool { self.0 == u32::MAX }
+
+    /// Returns the length of the character's UTF-8 encoding.
+    ///
+    /// If the character is absent, then `0` is returned.
+    #[inline]
+    pub fn len_utf8(self) -> usize {
+        char::from_u32(self.0).map(|c| c.len_utf8()).unwrap_or(0)
+    }
+
+    /// Returns the simple case folding of this character.
+    ///
+    /// If the character is absent, then absence is returned.
+    pub fn case_fold(self) -> Char {
+        char::from_u32(self.0).map(syntax::simple_case_fold).into()
+    }
+
+    /// Returns true iff the character is a word character.
+    ///
+    /// If the character is absent, then false is returned.
+    pub fn is_word_char(self) -> bool {
+        char::from_u32(self.0).map(syntax::is_word_char).unwrap_or(false)
+    }
+
+    /// Converts the character to a real primitive `char`.
+    ///
+    /// If the character is absent, then `None` is returned.
+    pub fn as_char(self) -> Option<char> {
+        // This is only used in the `regex!` macro because it expands char
+        // classes into `match` expressions (instead of binary search).
+        char::from_u32(self.0)
+    }
+}
+
+impl From<char> for Char {
+    fn from(c: char) -> Char { Char(c as u32) }
+}
+
+impl From<Option<char>> for Char {
+    fn from(c: Option<char>) -> Char {
+        c.map(|c| c.into()).unwrap_or(Char(u32::MAX))
+    }
+}
+
+impl PartialEq<char> for Char {
+    #[inline]
+    fn eq(&self, other: &char) -> bool { self.0 == *other as u32 }
+}
+
+impl PartialEq<Char> for char {
+    #[inline]
+    fn eq(&self, other: &Char) -> bool { *self as u32 == other.0 }
+}
+
+impl PartialOrd<char> for Char {
+    #[inline]
+    fn partial_cmp(&self, other: &char) -> Option<Ordering> {
+        self.0.partial_cmp(&(*other as u32))
+    }
+}
+
+impl PartialOrd<Char> for char {
+    #[inline]
+    fn partial_cmp(&self, other: &Char) -> Option<Ordering> {
+        (*self as u32).partial_cmp(&other.0)
+    }
+}
+

+

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