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    // Copyright 2015 The Servo Project Developers. See the
    // COPYRIGHT file at the top-level directory of this distribution.
    //
    // 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.

    //! Accessor for `Bidi_Class` property from Unicode Character Database (UCD)

    mod tables;

    pub use self::tables::{BidiClass, UNICODE_VERSION};

    use std::cmp::Ordering::{Equal, Less, Greater};
    use std::char;

    use self::tables::bidi_class_table;
    use BidiClass::*;

    /// Find the `BidiClass` of a single char.
    pub fn bidi_class(c: char) -> BidiClass {
        bsearch_range_value_table(c, bidi_class_table)
    }

    pub fn is_rtl(bidi_class: BidiClass) -> bool {
        match bidi_class {
            RLE | RLO | RLI => true,
            _ => false,
        }
    }

    fn bsearch_range_value_table(c: char, r: &'static [(char, char, BidiClass)]) -> BidiClass {
        match r.binary_search_by(|&(lo, hi, _)| if lo <= c && c <= hi {
            Equal
        } else if hi < c {
            Less
        } else {
            Greater
        }) {
            Ok(idx) => {
                let (_, _, cat) = r[idx];
                cat
            }
            // UCD/extracted/DerivedBidiClass.txt: "All code points not explicitly listed
            // for Bidi_Class have the value Left_To_Right (L)."
            Err(_) => L,
        }
    }

    #[cfg(test)]
    mod tests {
        use super::*;

        #[test]
        fn test_ascii() {
            assert_eq!(bidi_class('\u{0000}'), BN);
            assert_eq!(bidi_class('\u{0040}'), ON);
            assert_eq!(bidi_class('\u{0041}'), L);
            assert_eq!(bidi_class('\u{0062}'), L);
            assert_eq!(bidi_class('\u{007F}'), BN);
        }

        #[test]
        fn test_bmp() {
            // Hebrew
            assert_eq!(bidi_class('\u{0590}'), R);
            assert_eq!(bidi_class('\u{05D0}'), R);
            assert_eq!(bidi_class('\u{05D1}'), R);
            assert_eq!(bidi_class('\u{05FF}'), R);

            // Arabic
            assert_eq!(bidi_class('\u{0600}'), AN);
            assert_eq!(bidi_class('\u{0627}'), AL);
            assert_eq!(bidi_class('\u{07BF}'), AL);

            // Default R + Arabic Extras
            assert_eq!(bidi_class('\u{07C0}'), R);
            assert_eq!(bidi_class('\u{085F}'), R);
            assert_eq!(bidi_class('\u{0860}'), AL);
            assert_eq!(bidi_class('\u{0870}'), R);
            assert_eq!(bidi_class('\u{089F}'), R);
            assert_eq!(bidi_class('\u{08A0}'), AL);
            assert_eq!(bidi_class('\u{089F}'), R);
            assert_eq!(bidi_class('\u{08FF}'), NSM);

            // Default ET
            assert_eq!(bidi_class('\u{20A0}'), ET);
            assert_eq!(bidi_class('\u{20CF}'), ET);

            // Arabic Presentation Forms
            assert_eq!(bidi_class('\u{FB1D}'), R);
            assert_eq!(bidi_class('\u{FB4F}'), R);
            assert_eq!(bidi_class('\u{FB50}'), AL);
            assert_eq!(bidi_class('\u{FDCF}'), AL);
            assert_eq!(bidi_class('\u{FDF0}'), AL);
            assert_eq!(bidi_class('\u{FDFF}'), AL);
            assert_eq!(bidi_class('\u{FE70}'), AL);
            assert_eq!(bidi_class('\u{FEFE}'), AL);
            assert_eq!(bidi_class('\u{FEFF}'), BN);

            // noncharacters
            assert_eq!(bidi_class('\u{FDD0}'), L);
            assert_eq!(bidi_class('\u{FDD1}'), L);
            assert_eq!(bidi_class('\u{FDEE}'), L);
            assert_eq!(bidi_class('\u{FDEF}'), L);
            assert_eq!(bidi_class('\u{FFFE}'), L);
            assert_eq!(bidi_class('\u{FFFF}'), L);
        }

        #[test]
        fn test_smp() {
            // Default AL + R
            assert_eq!(bidi_class('\u{10800}'), R);
            assert_eq!(bidi_class('\u{10FFF}'), R);
            assert_eq!(bidi_class('\u{1E800}'), R);
            assert_eq!(bidi_class('\u{1EDFF}'), R);
            assert_eq!(bidi_class('\u{1EE00}'), AL);
            assert_eq!(bidi_class('\u{1EEFF}'), AL);
            assert_eq!(bidi_class('\u{1EF00}'), R);
            assert_eq!(bidi_class('\u{1EFFF}'), R);
        }

        #[test]
        fn test_unassigned_planes() {
            assert_eq!(bidi_class('\u{30000}'), L);
            assert_eq!(bidi_class('\u{40000}'), L);
            assert_eq!(bidi_class('\u{50000}'), L);
            assert_eq!(bidi_class('\u{60000}'), L);
            assert_eq!(bidi_class('\u{70000}'), L);
            assert_eq!(bidi_class('\u{80000}'), L);
            assert_eq!(bidi_class('\u{90000}'), L);
            assert_eq!(bidi_class('\u{a0000}'), L);
        }
    }