unic-ucd-normal 0.1.0

UNIC - Unicode Character Database - Normalization Properties
Documentation 
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// Copyright 2012-2015 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.


//! Conjoining Jamo composition to/decomposition from Hangul syllables.
//!
//! Ref: Section 3.12 Conjoining Jamo Behavior, Unicode 9.0.0
//! http://www.unicode.org/versions/Unicode9.0.0/ch03.pdf#M9.32468.Heading.310.Combining.Jamo.Behavior


pub const S_BASE: u32 = 0xAC00;
pub const L_BASE: u32 = 0x1100;
pub const V_BASE: u32 = 0x1161;
pub const T_BASE: u32 = 0x11A7;
pub const L_COUNT: u32 = 19;
pub const V_COUNT: u32 = 21;
pub const T_COUNT: u32 = 28;
pub const N_COUNT: u32 = (V_COUNT * T_COUNT);
pub const S_COUNT: u32 = (L_COUNT * N_COUNT);


/// Decompose a precomposed Hangul syllable
// FIXME: This is a workaround, we should use `F` instead of `&mut F`
#[allow(unsafe_code)]
#[inline(always)]
pub fn decompose<F>(s: char, f: &mut F)
    where F: FnMut(char)
{
    use std::mem::transmute;

    let si = s as u32 - S_BASE;

    let li = si / N_COUNT;
    unsafe {
        (*f)(transmute(L_BASE + li));

        let vi = (si % N_COUNT) / T_COUNT;
        (*f)(transmute(V_BASE + vi));

        let ti = si % T_COUNT;
        if ti > 0 {
            (*f)(transmute(T_BASE + ti));
        }
    }
}

/// Compose a pair of Hangul Jamo
#[allow(unsafe_code)]
#[inline(always)]
pub fn compose(a: char, b: char) -> Option<char> {
    use std::mem::transmute;

    let l = a as u32;
    let v = b as u32;
    // Compose an LPart and a VPart
    if L_BASE <= l && l < (L_BASE + L_COUNT) // l should be an L choseong jamo
        && V_BASE <= v && v < (V_BASE + V_COUNT) {
        // v should be a V jungseong jamo
        let r = S_BASE + (l - L_BASE) * N_COUNT + (v - V_BASE) * T_COUNT;
        return unsafe { Some(transmute(r)) };
    }
    // Compose an LVPart and a TPart
    if S_BASE <= l && l <= (S_BASE+S_COUNT-T_COUNT) // l should be a syllable block
        && T_BASE <= v && v < (T_BASE+T_COUNT) // v should be a T jongseong jamo
        && (l - S_BASE) % T_COUNT == 0 {
        // l should be an LV syllable block (not LVT)
        let r = l + (v - T_BASE);
        return unsafe { Some(transmute(r)) };
    }
    None
}