use std::cmp::Ordering::{Equal, Less, Greater};
use std::ops::FnMut;
use tables::normalization::{canonical_table, compatibility_table, composition_table};
fn bsearch_table<T>(c: char, r: &'static [(char, &'static [T])]) -> Option<&'static [T]> {
match r.binary_search_by(|&(val, _)| {
if c == val { Equal }
else if val < c { Less }
else { Greater }
}) {
Ok(idx) => {
let (_, result) = r[idx];
Some(result)
}
Err(_) => None
}
}
pub fn decompose_canonical<F>(c: char, mut i: F) where F: FnMut(char) { d(c, &mut i, false); }
pub fn decompose_compatible<F>(c: char, mut i: F) where F: FnMut(char) { d(c, &mut i, true); }
fn d<F>(c: char, i: &mut F, k: bool) where F: FnMut(char) {
if c <= '\x7f' { (*i)(c); return; }
if (c as u32) >= S_BASE && (c as u32) < (S_BASE + S_COUNT) {
decompose_hangul(c, i);
return;
}
match bsearch_table(c, canonical_table) {
Some(canon) => {
for x in canon {
d(*x, i, k);
}
return;
}
None => ()
}
if !k { (*i)(c); return; }
match bsearch_table(c, compatibility_table) {
Some(compat) => {
for x in compat {
d(*x, i, k);
}
return;
}
None => ()
}
(*i)(c);
}
pub fn compose(a: char, b: char) -> Option<char> {
compose_hangul(a, b).or_else(|| {
match bsearch_table(a, composition_table) {
None => None,
Some(candidates) => {
match candidates.binary_search_by(|&(val, _)| {
if b == val { Equal }
else if val < b { Less }
else { Greater }
}) {
Ok(idx) => {
let (_, result) = candidates[idx];
Some(result)
}
Err(_) => None
}
}
}
})
}
const S_BASE: u32 = 0xAC00;
const L_BASE: u32 = 0x1100;
const V_BASE: u32 = 0x1161;
const T_BASE: u32 = 0x11A7;
const L_COUNT: u32 = 19;
const V_COUNT: u32 = 21;
const T_COUNT: u32 = 28;
const N_COUNT: u32 = (V_COUNT * T_COUNT);
const S_COUNT: u32 = (L_COUNT * N_COUNT);
#[allow(unsafe_code)]
#[inline(always)]
fn decompose_hangul<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));
}
}
}
#[allow(unsafe_code)]
#[inline(always)]
fn compose_hangul(a: char, b: char) -> Option<char> {
use std::mem::transmute;
let l = a as u32;
let v = b as u32;
if L_BASE <= l && l < (L_BASE + L_COUNT) && V_BASE <= v && v < (V_BASE + V_COUNT) { let r = S_BASE + (l - L_BASE) * N_COUNT + (v - V_BASE) * T_COUNT;
return unsafe { Some(transmute(r)) };
}
if S_BASE <= l && l <= (S_BASE+S_COUNT-T_COUNT) && T_BASE <= v && v < (T_BASE+T_COUNT) && (l - S_BASE) % T_COUNT == 0 { let r = l + (v - T_BASE);
return unsafe { Some(transmute(r)) };
}
None
}