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unic-ucd-normal 0.4.0

UNIC - Unicode Character Database - Normalization Properties
Documentation 
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// Copyright 2015 The Servo Project Developers.
// Copyright 2017 The UNIC 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.


use std::cmp::Ordering;


pub struct Slice {
    pub offset: u16,
    pub length: u16,
}

fn bsearch_lookup_table<T>(
    c: char,
    r: &'static [(char, Slice)],
    chars_table: &'static [T],
) -> Option<&'static [T]> {
    match r.binary_search_by(|&(val, _)| if c == val {
        Ordering::Equal
    } else if val < c {
        Ordering::Less
    } else {
        Ordering::Greater
    }) {
        Ok(idx) => {
            let ref slice = r[idx].1;
            let offset = slice.offset as usize;
            let length = slice.length as usize;
            Some(&chars_table[offset..(offset + length)])
        }
        Err(_) => None,
    }
}

// == Canonical Composition (C) ==
const CANONICAL_COMPOSITION_LOOKUP: &'static [(char, Slice)] =
    include!("tables/canonical_composition_lookup.rsv");
const CANONICAL_COMPOSITION_VALUES: &'static [(char, char)] =
    include!("tables/canonical_composition_values.rsv");

/// Canonical Composition of the character.
pub fn canonical_composition(c: char) -> Option<&'static ([(char, char)])> {
    bsearch_lookup_table(
        c,
        CANONICAL_COMPOSITION_LOOKUP,
        CANONICAL_COMPOSITION_VALUES,
    )
}

// == Canonical Decomposition (D) ==
const CANONICAL_DECOMPOSITION_LOOKUP: &'static [(char, Slice)] =
    include!("tables/canonical_decomposition_lookup.rsv");
const CANONICAL_DECOMPOSITION_VALUES: &'static [char] =
    include!("tables/canonical_decomposition_values.rsv");

/// Canonical Decomposition of the character.
pub fn canonical_decomposition(c: char) -> Option<&'static [char]> {
    bsearch_lookup_table(
        c,
        CANONICAL_DECOMPOSITION_LOOKUP,
        CANONICAL_DECOMPOSITION_VALUES,
    )
}

// == Compatibility Decomposition (KD) ==
const COMPATIBILITY_DECOMPOSITION_LOOKUP: &'static [(char, Slice)] =
    include!("tables/compatibility_decomposition_lookup.rsv");
const COMPATIBILITY_DECOMPOSITION_VALUES: &'static [char] =
    include!("tables/compatibility_decomposition_values.rsv");

/// Compatibility Decomposition of the character.
pub fn compatibility_decomposition(c: char) -> Option<&'static [char]> {
    bsearch_lookup_table(
        c,
        COMPATIBILITY_DECOMPOSITION_LOOKUP,
        COMPATIBILITY_DECOMPOSITION_VALUES,
    )
}

// == Canonical Combining Class (ccc) ==
const CANONICAL_COMBINING_CLASS_VALUES: &'static [(char, char, u8)] =
    include!("tables/canonical_combining_class_values.rsv");

/// Lookup Canonical Combining Class of the character
pub fn canonical_combining_class(c: char) -> u8 {
    bsearch_range_value_table(c, CANONICAL_COMBINING_CLASS_VALUES)
}

fn bsearch_range_value_table(c: char, r: &'static [(char, char, u8)]) -> u8 {
    match r.binary_search_by(|&(lo, hi, _)| if lo <= c && c <= hi {
        Ordering::Equal
    } else if hi < c {
        Ordering::Less
    } else {
        Ordering::Greater
    }) {
        Ok(idx) => {
            let (_, _, result) = r[idx];
            result
        }
        Err(_) => 0,
    }
}