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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.

    //! This crate implements the [Unicode Bidirectional Algorithm][tr9] for display of mixed
    //! right-to-left and left-to-right text.  It is written in safe Rust, compatible with the
    //! current stable release.
    //!
    //! ## Example
    //!
    //! ```rust
    //! use unicode_bidi::BidiInfo;
    //!
    //! // This example text is defined using `concat!` because some browsers
    //! // and text editors have trouble displaying bidi strings.
    //! let text = concat![
    //!   "א",
    //!   "ב",
    //!   "ג",
    //!   "a",
    //!   "b",
    //!   "c",
    //! ];
    //!
    //! // Resolve embedding levels within the text.  Pass `None` to detect the
    //! // paragraph level automatically.
    //! let bidi_info = BidiInfo::new(&text, None);
    //!
    //! // This paragraph has embedding level 1 because its first strong character is RTL.
    //! assert_eq!(bidi_info.paragraphs.len(), 1);
    //! let para = &bidi_info.paragraphs[0];
    //! assert_eq!(para.level.number(), 1);
    //! assert_eq!(para.level.is_rtl(), true);
    //!
    //! // Re-ordering is done after wrapping each paragraph into a sequence of
    //! // lines. For this example, I'll just use a single line that spans the
    //! // entire paragraph.
    //! let line = para.range.clone();
    //!
    //! let display = bidi_info.reorder_line(para, line);
    //! assert_eq!(display, concat![
    //!   "a",
    //!   "b",
    //!   "c",
    //!   "ג",
    //!   "ב",
    //!   "א",
    //! ]);
    //! ```
    //!
    //! [tr9]: <http://www.unicode.org/reports/tr9/>

    #![forbid(unsafe_code)]

    #![cfg_attr(feature="flame_it", feature(plugin, custom_attribute))]
    #![cfg_attr(feature="flame_it", plugin(flamer))]

    #[macro_use]
    extern crate matches;

    #[cfg(feature = "serde")]
    #[macro_use]
    extern crate serde;

    #[cfg(all(feature = "serde", test))]
    extern crate serde_test;

    #[cfg(feature = "flame_it")]
    extern crate flame;

    pub mod deprecated;
    pub mod format_chars;
    pub mod level;

    mod char_data;
    mod explicit;
    mod implicit;
    mod prepare;

    pub use char_data::{BidiClass, bidi_class, UNICODE_VERSION};
    pub use level::{Level, LTR_LEVEL, RTL_LEVEL};
    pub use prepare::LevelRun;

    use std::borrow::Cow;
    use std::cmp::{max, min};
    use std::iter::repeat;
    use std::ops::Range;

    use BidiClass::*;
    use format_chars as chars;

    /// Bidi information about a single paragraph
    #[derive(Debug, PartialEq)]
    pub struct ParagraphInfo {
        /// The paragraphs boundaries within the text, as byte indices.
        ///
        /// TODO: Shrink this to only include the starting index?
        pub range: Range<usize>,

        /// The paragraph embedding level.
        ///
        /// <http://www.unicode.org/reports/tr9/#BD4>
        pub level: Level,
    }

    /// Initial bidi information of the text.
    ///
    /// Contains the text paragraphs and `BidiClass` of its characters.
    #[derive(PartialEq, Debug)]
    pub struct InitialInfo<'text> {
        /// The text
        pub text: &'text str,

        /// The BidiClass of the character at each byte in the text.
        /// If a character is multiple bytes, its class will appear multiple times in the vector.
        pub original_classes: Vec<BidiClass>,

        /// The boundaries and level of each paragraph within the text.
        pub paragraphs: Vec<ParagraphInfo>,
    }

    impl<'text> InitialInfo<'text> {
        /// Find the paragraphs and BidiClasses in a string of text.
        ///
        /// <http://www.unicode.org/reports/tr9/#The_Paragraph_Level>
        ///
        /// Also sets the class for each First Strong Isolate initiator (FSI) to LRI or RLI if a strong
        /// character is found before the matching PDI.  If no strong character is found, the class will
        /// remain FSI, and it's up to later stages to treat these as LRI when needed.
        #[cfg_attr(feature = "flame_it", flame)]
        pub fn new(text: &str, default_para_level: Option<Level>) -> InitialInfo {
            let mut original_classes = Vec::with_capacity(text.len());

            // The stack contains the starting byte index for each nested isolate we're inside.
            let mut isolate_stack = Vec::new();
            let mut paragraphs = Vec::new();

            let mut para_start = 0;
            let mut para_level = default_para_level;

            #[cfg(feature = "flame_it")] flame::start("InitialInfo::new(): iter text.char_indices()");

            for (i, c) in text.char_indices() {
                let class = bidi_class(c);

                #[cfg(feature = "flame_it")] flame::start("original_classes.extend()");

                original_classes.extend(repeat(class).take(c.len_utf8()));

                #[cfg(feature = "flame_it")] flame::end("original_classes.extend()");

                match class {

                    B => {
                        // P1. Split the text into separate paragraphs. The paragraph separator is kept
                        // with the previous paragraph.
                        let para_end = i + c.len_utf8();
                        paragraphs.push(ParagraphInfo {
                            range: para_start..para_end,
                            // P3. If no character is found in p2, set the paragraph level to zero.
                            level: para_level.unwrap_or(LTR_LEVEL),
                        });
                        // Reset state for the start of the next paragraph.
                        para_start = para_end;
                        // TODO: Support defaulting to direction of previous paragraph
                        //
                        // <http://www.unicode.org/reports/tr9/#HL1>
                        para_level = default_para_level;
                        isolate_stack.clear();
                    }

                    L | R | AL => {
                        match isolate_stack.last() {
                            Some(&start) => {
                                if original_classes[start] == FSI {
                                    // X5c. If the first strong character between FSI and its matching
                                    // PDI is R or AL, treat it as RLI. Otherwise, treat it as LRI.
                                    for j in 0..chars::FSI.len_utf8() {
                                        original_classes[start + j] =
                                            if class == L { LRI } else { RLI };
                                    }
                                }
                            }

                            None => {
                                if para_level.is_none() {
                                    // P2. Find the first character of type L, AL, or R, while skipping
                                    // any characters between an isolate initiator and its matching
                                    // PDI.
                                    para_level = Some(if class != L { RTL_LEVEL } else { LTR_LEVEL });
                                }
                            }
                        }
                    }

                    RLI | LRI | FSI => {
                        isolate_stack.push(i);
                    }

                    PDI => {
                        isolate_stack.pop();
                    }

                    _ => {}
                }
            }
            if para_start < text.len() {
                paragraphs.push(ParagraphInfo {
                    range: para_start..text.len(),
                    level: para_level.unwrap_or(LTR_LEVEL),
                });
            }
            assert_eq!(original_classes.len(), text.len());

            #[cfg(feature = "flame_it")] flame::end("InitialInfo::new(): iter text.char_indices()");

            InitialInfo {
                text,
                original_classes,
                paragraphs,
            }
        }
    }

    /// Bidi information of the text.
    ///
    /// The `original_classes` and `levels` vectors are indexed by byte offsets into the text.  If a
    /// character is multiple bytes wide, then its class and level will appear multiple times in these
    /// vectors.
    // TODO: Impl `struct StringProperty<T> { values: Vec<T> }` and use instead of Vec<T>
    #[derive(Debug, PartialEq)]
    pub struct BidiInfo<'text> {
        /// The text
        pub text: &'text str,

        /// The BidiClass of the character at each byte in the text.
        pub original_classes: Vec<BidiClass>,

        /// The directional embedding level of each byte in the text.
        pub levels: Vec<Level>,

        /// The boundaries and paragraph embedding level of each paragraph within the text.
        ///
        /// TODO: Use SmallVec or similar to avoid overhead when there are only one or two paragraphs?
        /// Or just don't include the first paragraph, which always starts at 0?
        pub paragraphs: Vec<ParagraphInfo>,
    }

    impl<'text> BidiInfo<'text> {
        /// Split the text into paragraphs and determine the bidi embedding levels for each paragraph.
        ///
        /// TODO: In early steps, check for special cases that allow later steps to be skipped. like
        /// text that is entirely LTR.  See the `nsBidi` class from Gecko for comparison.
        ///
        /// TODO: Support auto-RTL base direction
        #[cfg_attr(feature = "flame_it", flame)]
        pub fn new(text: &str, default_para_level: Option<Level>) -> BidiInfo {
            let InitialInfo {
                original_classes,
                paragraphs,
                ..
            } = InitialInfo::new(text, default_para_level);

            let mut levels = Vec::<Level>::with_capacity(text.len());
            let mut processing_classes = original_classes.clone();

            for para in &paragraphs {
                let text = &text[para.range.clone()];
                let original_classes = &original_classes[para.range.clone()];
                let processing_classes = &mut processing_classes[para.range.clone()];

                let new_len = levels.len() + para.range.len();
                levels.resize(new_len, para.level);
                let levels = &mut levels[para.range.clone()];

                explicit::compute(
                    text,
                    para.level,
                    original_classes,
                    levels,
                    processing_classes,
                );

                let sequences = prepare::isolating_run_sequences(para.level, original_classes, levels);
                for sequence in &sequences {
                    implicit::resolve_weak(sequence, processing_classes);
                    implicit::resolve_neutral(sequence, levels, processing_classes);
                }
                implicit::resolve_levels(processing_classes, levels);

                assign_levels_to_removed_chars(para.level, original_classes, levels);
            }

            BidiInfo {
                text,
                original_classes,
                paragraphs,
                levels,
            }
        }

        /// Re-order a line based on resolved levels and return only the embedding levels, one `Level`
        /// per *byte*.
        #[cfg_attr(feature = "flame_it", flame)]
        pub fn reordered_levels(&self, para: &ParagraphInfo, line: Range<usize>) -> Vec<Level> {
            let (levels, _) = self.visual_runs(para, line.clone());
            levels
        }

        /// Re-order a line based on resolved levels and return only the embedding levels, one `Level`
        /// per *character*.
        #[cfg_attr(feature = "flame_it", flame)]
        pub fn reordered_levels_per_char(
            &self,
            para: &ParagraphInfo,
            line: Range<usize>,
        ) -> Vec<Level> {
            let levels = self.reordered_levels(para, line);
            self.text.char_indices().map(|(i, _)| levels[i]).collect()
        }

        /// Re-order a line based on resolved levels and return the line in display order.
        #[cfg_attr(feature = "flame_it", flame)]
        pub fn reorder_line(&self, para: &ParagraphInfo, line: Range<usize>) -> Cow<'text, str> {
            let (levels, runs) = self.visual_runs(para, line.clone());

            // If all isolating run sequences are LTR, no reordering is needed
            if runs.iter().all(|run| levels[run.start].is_ltr()) {
                return self.text[line.clone()].into();
            }

            let mut result = String::with_capacity(line.len());
            for run in runs {
                if levels[run.start].is_rtl() {
                    result.extend(self.text[run].chars().rev());
                } else {
                    result.push_str(&self.text[run]);
                }
            }
            result.into()
        }

        /// Find the level runs within a line and return them in visual order.
        ///
        /// `line` is a range of bytes indices within `levels`.
        ///
        /// <http://www.unicode.org/reports/tr9/#Reordering_Resolved_Levels>
        #[cfg_attr(feature = "flame_it", flame)]
        pub fn visual_runs(
            &self,
            para: &ParagraphInfo,
            line: Range<usize>,
        ) -> (Vec<Level>, Vec<LevelRun>) {
            assert!(line.start <= self.levels.len());
            assert!(line.end <= self.levels.len());

            let mut levels = self.levels.clone();

            // Reset some whitespace chars to paragraph level.
            // <http://www.unicode.org/reports/tr9/#L1>
            let line_str: &str = &self.text[line.clone()];
            let mut reset_from: Option<usize> = Some(0);
            let mut reset_to: Option<usize> = None;
            for (i, c) in line_str.char_indices() {
                match self.original_classes[i] {
                    // Ignored by X9
                    RLE | LRE | RLO | LRO | PDF | BN => {}
                    // Segment separator, Paragraph separator
                    B | S => {
                        assert_eq!(reset_to, None);
                        reset_to = Some(i + c.len_utf8());
                        if reset_from == None {
                            reset_from = Some(i);
                        }
                    }
                    // Whitespace, isolate formatting
                    WS | FSI | LRI | RLI | PDI => {
                        if reset_from == None {
                            reset_from = Some(i);
                        }
                    }
                    _ => {
                        reset_from = None;
                    }
                }
                if let (Some(from), Some(to)) = (reset_from, reset_to) {
                    #[cfg_attr(feature = "cargo-clippy", allow(needless_range_loop))]
                    for j in from..to {
                        levels[j] = para.level;
                    }
                    reset_from = None;
                    reset_to = None;
                }
            }
            if let Some(from) = reset_from {
                #[cfg_attr(feature = "cargo-clippy", allow(needless_range_loop))]
                for j in from..line_str.len() {
                    levels[j] = para.level;
                }
            }

            // Find consecutive level runs.
            let mut runs = Vec::new();
            let mut start = line.start;
            let mut run_level = levels[start];
            let mut min_level = run_level;
            let mut max_level = run_level;

            for (i, &new_level) in levels.iter().enumerate().take(line.end).skip(start + 1) {
                if new_level != run_level {
                    // End of the previous run, start of a new one.
                    runs.push(start..i);
                    start = i;
                    run_level = new_level;
                    min_level = min(run_level, min_level);
                    max_level = max(run_level, max_level);
                }
            }
            runs.push(start..line.end);

            let run_count = runs.len();

            // Re-order the odd runs.
            // <http://www.unicode.org/reports/tr9/#L2>

            // Stop at the lowest *odd* level.
            min_level = min_level.new_lowest_ge_rtl().expect("Level error");

            while max_level >= min_level {
                // Look for the start of a sequence of consecutive runs of max_level or higher.
                let mut seq_start = 0;
                while seq_start < run_count {
                    if self.levels[runs[seq_start].start] < max_level {
                        seq_start += 1;
                        continue;
                    }

                    // Found the start of a sequence. Now find the end.
                    let mut seq_end = seq_start + 1;
                    while seq_end < run_count {
                        if self.levels[runs[seq_end].start] < max_level {
                            break;
                        }
                        seq_end += 1;
                    }

                    // Reverse the runs within this sequence.
                    runs[seq_start..seq_end].reverse();

                    seq_start = seq_end;
                }
                max_level.lower(1).expect(
                    "Lowering embedding level below zero",
                );
            }

            (levels, runs)
        }

        /// If processed text has any computed RTL levels
        ///
        /// This information is usually used to skip re-ordering of text when no RTL level is present
        #[inline]
        pub fn has_rtl(&self) -> bool {
            level::has_rtl(&self.levels)
        }
    }

    /// Assign levels to characters removed by rule X9.
    ///
    /// The levels assigned to these characters are not specified by the algorithm.  This function
    /// assigns each one the level of the previous character, to avoid breaking level runs.
    #[cfg_attr(feature = "flame_it", flame)]
    fn assign_levels_to_removed_chars(para_level: Level, classes: &[BidiClass], levels: &mut [Level]) {
        for i in 0..levels.len() {
            if prepare::removed_by_x9(classes[i]) {
                levels[i] = if i > 0 { levels[i - 1] } else { para_level };
            }
        }
    }

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

        #[test]
        fn test_initial_text_info() {
            let text = "a1";
            assert_eq!(
                InitialInfo::new(text, None),
                InitialInfo {
                    text,
                    original_classes: vec![L, EN],
                    paragraphs: vec![
                        ParagraphInfo {
                            range: 0..2,
                            level: LTR_LEVEL,
                        },
                    ],
                }
            );

            let text = "غ א";
            assert_eq!(
                InitialInfo::new(text, None),
                InitialInfo {
                    text,
                    original_classes: vec![AL, AL, WS, R, R],
                    paragraphs: vec![
                        ParagraphInfo {
                            range: 0..5,
                            level: RTL_LEVEL,
                        },
                    ],
                }
            );

            let text = "a\u{2029}b";
            assert_eq!(
                InitialInfo::new(text, None),
                InitialInfo {
                    text,
                    original_classes: vec![L, B, B, B, L],
                    paragraphs: vec![
                        ParagraphInfo {
                            range: 0..4,
                            level: LTR_LEVEL,
                        },
                        ParagraphInfo {
                            range: 4..5,
                            level: LTR_LEVEL,
                        },
                    ],
                }
            );

            let text = format!("{}א{}a", chars::FSI, chars::PDI);
            assert_eq!(
                InitialInfo::new(&text, None),
                InitialInfo {
                    text: &text,
                    original_classes: vec![RLI, RLI, RLI, R, R, PDI, PDI, PDI, L],
                    paragraphs: vec![
                        ParagraphInfo {
                            range: 0..9,
                            level: LTR_LEVEL,
                        },
                    ],
                }
            );
        }

        #[test]
        fn test_process_text() {
            let text = "abc123";
            assert_eq!(
                BidiInfo::new(text, Some(LTR_LEVEL)),
                BidiInfo {
                    text,
                    levels: Level::vec(&[0, 0, 0, 0, 0, 0]),
                    original_classes: vec![L, L, L, EN, EN, EN],
                    paragraphs: vec![
                        ParagraphInfo {
                            range: 0..6,
                            level: LTR_LEVEL,
                        },
                    ],
                }
            );

            let text = "abc אבג";
            assert_eq!(
                BidiInfo::new(text, Some(LTR_LEVEL)),
                BidiInfo {
                    text,
                    levels: Level::vec(&[0, 0, 0, 0, 1, 1, 1, 1, 1, 1]),
                    original_classes: vec![L, L, L, WS, R, R, R, R, R, R],
                    paragraphs: vec![
                        ParagraphInfo {
                            range: 0..10,
                            level: LTR_LEVEL,
                        },
                    ],
                }
            );
            assert_eq!(
                BidiInfo::new(text, Some(RTL_LEVEL)),
                BidiInfo {
                    text,
                    levels: Level::vec(&[2, 2, 2, 1, 1, 1, 1, 1, 1, 1]),
                    original_classes: vec![L, L, L, WS, R, R, R, R, R, R],
                    paragraphs: vec![
                        ParagraphInfo {
                            range: 0..10,
                            level: RTL_LEVEL,
                        },
                    ],
                }
            );

            let text = "אבג abc";
            assert_eq!(
                BidiInfo::new(text, Some(LTR_LEVEL)),
                BidiInfo {
                    text,
                    levels: Level::vec(&[1, 1, 1, 1, 1, 1, 0, 0, 0, 0]),
                    original_classes: vec![R, R, R, R, R, R, WS, L, L, L],
                    paragraphs: vec![
                        ParagraphInfo {
                            range: 0..10,
                            level: LTR_LEVEL,
                        },
                    ],
                }
            );
            assert_eq!(
                BidiInfo::new(text, None),
                BidiInfo {
                    text,
                    levels: Level::vec(&[1, 1, 1, 1, 1, 1, 1, 2, 2, 2]),
                    original_classes: vec![R, R, R, R, R, R, WS, L, L, L],
                    paragraphs: vec![
                        ParagraphInfo {
                            range: 0..10,
                            level: RTL_LEVEL,
                        },
                    ],
                }
            );

            let text = "غ2ظ א2ג";
            assert_eq!(
                BidiInfo::new(text, Some(LTR_LEVEL)),
                BidiInfo {
                    text,
                    levels: Level::vec(&[1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1]),
                    original_classes: vec![AL, AL, EN, AL, AL, WS, R, R, EN, R, R],
                    paragraphs: vec![
                        ParagraphInfo {
                            range: 0..11,
                            level: LTR_LEVEL,
                        },
                    ],
                }
            );

            let text = "a א.\nג";
            assert_eq!(
                BidiInfo::new(text, None),
                BidiInfo {
                    text,
                    original_classes: vec![L, WS, R, R, CS, B, R, R],
                    levels: Level::vec(&[0, 0, 1, 1, 0, 0, 1, 1]),
                    paragraphs: vec![
                        ParagraphInfo {
                            range: 0..6,
                            level: LTR_LEVEL,
                        },
                        ParagraphInfo {
                            range: 6..8,
                            level: RTL_LEVEL,
                        },
                    ],
                }
            );

            /// BidiTest:69635 (AL ET EN)
            let bidi_info = BidiInfo::new("\u{060B}\u{20CF}\u{06F9}", None);
            assert_eq!(bidi_info.original_classes, vec![AL, AL, ET, ET, ET, EN, EN]);
        }

        #[test]
        fn test_bidi_info_has_rtl() {
            // ASCII only
            assert_eq!(BidiInfo::new("123", None).has_rtl(), false);
            assert_eq!(BidiInfo::new("123", Some(LTR_LEVEL)).has_rtl(), false);
            assert_eq!(BidiInfo::new("123", Some(RTL_LEVEL)).has_rtl(), false);
            assert_eq!(BidiInfo::new("abc", None).has_rtl(), false);
            assert_eq!(BidiInfo::new("abc", Some(LTR_LEVEL)).has_rtl(), false);
            assert_eq!(BidiInfo::new("abc", Some(RTL_LEVEL)).has_rtl(), false);
            assert_eq!(BidiInfo::new("abc 123", None).has_rtl(), false);
            assert_eq!(BidiInfo::new("abc\n123", None).has_rtl(), false);

            // With Hebrew
            assert_eq!(BidiInfo::new("אבּג", None).has_rtl(), true);
            assert_eq!(BidiInfo::new("אבּג", Some(LTR_LEVEL)).has_rtl(), true);
            assert_eq!(BidiInfo::new("אבּג", Some(RTL_LEVEL)).has_rtl(), true);
            assert_eq!(BidiInfo::new("abc אבּג", None).has_rtl(), true);
            assert_eq!(BidiInfo::new("abc\nאבּג", None).has_rtl(), true);
            assert_eq!(BidiInfo::new("אבּג abc", None).has_rtl(), true);
            assert_eq!(BidiInfo::new("אבּג\nabc", None).has_rtl(), true);
            assert_eq!(BidiInfo::new("אבּג 123", None).has_rtl(), true);
            assert_eq!(BidiInfo::new("אבּג\n123", None).has_rtl(), true);
        }

        fn reorder_paras(text: &str) -> Vec<Cow<str>> {
            let bidi_info = BidiInfo::new(text, None);
            bidi_info
                .paragraphs
                .iter()
                .map(|para| bidi_info.reorder_line(para, para.range.clone()))
                .collect()
        }

        #[test]
        fn test_reorder_line() {
            /// Bidi_Class: L L L B L L L B L L L
            assert_eq!(
                reorder_paras("abc\ndef\nghi"),
                vec!["abc\n", "def\n", "ghi"]
            );

            /// Bidi_Class: L L EN B L L EN B L L EN
            assert_eq!(
                reorder_paras("ab1\nde2\ngh3"),
                vec!["ab1\n", "de2\n", "gh3"]
            );

            /// Bidi_Class: L L L B AL AL AL
            assert_eq!(reorder_paras("abc\nابج"), vec!["abc\n", "جبا"]);

            /// Bidi_Class: AL AL AL B L L L
            assert_eq!(reorder_paras("ابج\nabc"), vec!["\nجبا", "abc"]);

            assert_eq!(reorder_paras("1.-2"), vec!["1.-2"]);
            assert_eq!(reorder_paras("1-.2"), vec!["1-.2"]);
            assert_eq!(reorder_paras("abc אבג"), vec!["abc גבא"]);

            // Numbers being weak LTR characters, cannot reorder strong RTL
            assert_eq!(reorder_paras("123 אבג"), vec!["גבא 123"]);

            assert_eq!(reorder_paras("abc\u{202A}def"), vec!["abc\u{202A}def"]);

            assert_eq!(
                reorder_paras("abc\u{202A}def\u{202C}ghi"),
                vec!["abc\u{202A}def\u{202C}ghi"]
            );

            assert_eq!(
                reorder_paras("abc\u{2066}def\u{2069}ghi"),
                vec!["abc\u{2066}def\u{2069}ghi"]
            );

            // Testing for RLE Character
            assert_eq!(
                reorder_paras("\u{202B}abc אבג\u{202C}"),
                vec!["\u{202B}\u{202C}גבא abc"]
            );

            // Testing neutral characters
            assert_eq!(reorder_paras("אבג? אבג"), vec!["גבא ?גבא"]);

            // Testing neutral characters with special case
            assert_eq!(reorder_paras("A אבג?"), vec!["A גבא?"]);

            // Testing neutral characters with Implicit RTL Marker
            assert_eq!(
                reorder_paras("A אבג?\u{200F}"),
                vec!["A \u{200F}?גבא"]
            );
            assert_eq!(reorder_paras("אבג abc"), vec!["abc גבא"]);
            assert_eq!(
                reorder_paras("abc\u{2067}.-\u{2069}ghi"),
                vec!["abc\u{2067}-.\u{2069}ghi"]
            );

            assert_eq!(
                reorder_paras("Hello, \u{2068}\u{202E}world\u{202C}\u{2069}!"),
                vec!["Hello, \u{2068}\u{202E}\u{202C}dlrow\u{2069}!"]
            );

            // With mirrorable characters in RTL run
            assert_eq!(reorder_paras("א(ב)ג."), vec![".ג)ב(א"]);

            // With mirrorable characters on level boundry
            assert_eq!(
                reorder_paras("אב(גד[&ef].)gh"),
                vec!["ef].)gh&[דג(בא"]
            );
        }

        fn reordered_levels_for_paras(text: &str) -> Vec<Vec<Level>> {
            let bidi_info = BidiInfo::new(text, None);
            bidi_info
                .paragraphs
                .iter()
                .map(|para| bidi_info.reordered_levels(para, para.range.clone()))
                .collect()
        }

        fn reordered_levels_per_char_for_paras(text: &str) -> Vec<Vec<Level>> {
            let bidi_info = BidiInfo::new(text, None);
            bidi_info
                .paragraphs
                .iter()
                .map(|para| {
                    bidi_info.reordered_levels_per_char(para, para.range.clone())
                })
                .collect()
        }

        #[test]
        fn test_reordered_levels() {

            /// BidiTest:946 (LRI PDI)
            let text = "\u{2067}\u{2069}";
            assert_eq!(
                reordered_levels_for_paras(text),
                vec![Level::vec(&[0, 0, 0, 0, 0, 0])]
            );
            assert_eq!(
                reordered_levels_per_char_for_paras(text),
                vec![Level::vec(&[0, 0])]
            );

            /* TODO
            /// BidiTest:69635 (AL ET EN)
            let text = "\u{060B}\u{20CF}\u{06F9}";
            assert_eq!(
                reordered_levels_for_paras(text),
                vec![Level::vec(&[1, 1, 1, 1, 1, 2, 2])]
            );
            assert_eq!(
                reordered_levels_per_char_for_paras(text),
                vec![Level::vec(&[1, 1, 2])]
            );
             */

            /* TODO
            // BidiTest:291284 (AN RLI PDF R)
            assert_eq!(
                reordered_levels_per_char_for_paras("\u{0605}\u{2067}\u{202C}\u{0590}"),
                vec![&["2", "0", "x", "1"]]
            );
             */
        }
    }

    #[cfg(all(feature = "serde", test))]
    mod serde_tests {
        use serde_test::{Token, assert_tokens};
        use super::*;

        #[test]
        fn test_levels() {
            let text = "abc אבג";
            let bidi_info = BidiInfo::new(text, None);
            let levels = bidi_info.levels;
            assert_eq!(text.as_bytes().len(), 10);
            assert_eq!(levels.len(), 10);
            assert_tokens(
                &levels,
                &[
                    Token::Seq { len: Some(10) },
                    Token::NewtypeStruct { name: "Level" },
                    Token::U8(0),
                    Token::NewtypeStruct { name: "Level" },
                    Token::U8(0),
                    Token::NewtypeStruct { name: "Level" },
                    Token::U8(0),
                    Token::NewtypeStruct { name: "Level" },
                    Token::U8(0),
                    Token::NewtypeStruct { name: "Level" },
                    Token::U8(1),
                    Token::NewtypeStruct { name: "Level" },
                    Token::U8(1),
                    Token::NewtypeStruct { name: "Level" },
                    Token::U8(1),
                    Token::NewtypeStruct { name: "Level" },
                    Token::U8(1),
                    Token::NewtypeStruct { name: "Level" },
                    Token::U8(1),
                    Token::NewtypeStruct { name: "Level" },
                    Token::U8(1),
                    Token::SeqEnd,
                ],
            );
        }
    }