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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.
//! Functions for computing canonical and compatible decompositions for Unicode characters.
use std::cmp::Ordering::{Equal, Less, Greater};
use std::ops::FnMut;
use tables::normalization::{canonical_table, canonical_table_STRTAB};
use tables::normalization::{compatibility_table, compatibility_table_STRTAB};
use tables::normalization::{composition_table, composition_table_STRTAB};
use tables::normalization::Slice;
fn bsearch_table<T>(c: char, r: &'static [(char, Slice)], strtab: &'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 ref slice = r[idx].1;
let offset = slice.offset as usize;
let length = slice.length as usize;
Some(&strtab[offset..(offset + length)])
}
Err(_) => None
}
}
/// Compute canonical Unicode decomposition for character.
/// See [Unicode Standard Annex #15](http://www.unicode.org/reports/tr15/)
/// for more information.
pub fn decompose_canonical<F>(c: char, mut i: F) where F: FnMut(char) { d(c, &mut i, false); }
/// Compute canonical or compatible Unicode decomposition for character.
/// See [Unicode Standard Annex #15](http://www.unicode.org/reports/tr15/)
/// for more information.
pub fn decompose_compatible<F>(c: char, mut i: F) where F: FnMut(char) { d(c, &mut i, true); }
// FIXME(#19596) This is a workaround, we should use `F` instead of `&mut F`
fn d<F>(c: char, i: &mut F, k: bool) where F: FnMut(char) {
// 7-bit ASCII never decomposes
if c <= '\x7f' { (*i)(c); return; }
// Perform decomposition for Hangul
if (c as u32) >= S_BASE && (c as u32) < (S_BASE + S_COUNT) {
decompose_hangul(c, i);
return;
}
// First check the canonical decompositions
match bsearch_table(c, canonical_table, canonical_table_STRTAB) {
Some(canon) => {
for x in canon {
d(*x, i, k);
}
return;
}
None => ()
}
// Bottom out if we're not doing compat.
if !k { (*i)(c); return; }
// Then check the compatibility decompositions
match bsearch_table(c, compatibility_table, compatibility_table_STRTAB) {
Some(compat) => {
for x in compat {
d(*x, i, k);
}
return;
}
None => ()
}
// Finally bottom out.
(*i)(c);
}
/// Compose two characters into a single character, if possible.
/// See [Unicode Standard Annex #15](http://www.unicode.org/reports/tr15/)
/// for more information.
pub fn compose(a: char, b: char) -> Option<char> {
compose_hangul(a, b).or_else(|| {
match bsearch_table(a, composition_table, composition_table_STRTAB) {
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
}
}
}
})
}
// Constants from Unicode 9.0.0 Section 3.12 Conjoining Jamo Behavior
// http://www.unicode.org/versions/Unicode9.0.0/ch03.pdf#M9.32468.Heading.310.Combining.Jamo.Behavior
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);
// FIXME(#19596) This is a workaround, we should use `F` instead of `&mut F`
// Decompose a precomposed Hangul syllable
#[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));
}
}
}
// Compose a pair of Hangul Jamo
#[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;
// 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
}
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