collections, unicode: Add support for NFC and NFKC

1 files changed, 153 insertions, 0 deletions

diff --git a/src/libunicode/normalize.rs b/src/libunicode/normalize.rs
new file mode 100644
index 00000000000..df0be09aea1
--- /dev/null
+++ b/src/libunicode/normalize.rs
@@ -0,0 +1,153 @@
+// Copyright 2012-2014 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 core::cmp::{Equal, Less, Greater};
+use core::option::{Option, Some, None};
+use core::slice::ImmutableVector;
+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.bsearch(|&(val, _)| {
+        if c == val { Equal }
+        else if val < c { Less }
+        else { Greater }
+    }) {
+        Some(idx) => {
+            let (_, result) = r[idx];
+            Some(result)
+        }
+        None => None
+    }
+}
+
+/// Compute canonical Unicode decomposition for character
+pub fn decompose_canonical(c: char, i: |char|) { d(c, i, false); }
+
+/// Compute canonical or compatible Unicode decomposition for character
+pub fn decompose_compatible(c: char, i: |char|) { d(c, i, true); }
+
+fn d(c: char, i: |char|, k: bool) {
+    #[cfg(stage0)]
+    use core::iter::Iterator;
+
+    // 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) {
+        Some(canon) => {
+            for x in canon.iter() {
+                d(*x, |b| i(b), 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) {
+        Some(compat) => {
+            for x in compat.iter() {
+                d(*x, |b| i(b), k);
+            }
+            return;
+        }
+        None => ()
+    }
+
+    // Finally bottom out.
+    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.bsearch(|&(val, _)| {
+                    if b == val { Equal }
+                    else if val < b { Less }
+                    else { Greater }
+                }) {
+                    Some(idx) => {
+                        let (_, result) = candidates[idx];
+                        Some(result)
+                    }
+                    None => None
+                }
+            }
+        }
+    })
+}
+
+// Constants from Unicode 6.3.0 Section 3.12 Conjoining Jamo Behavior
+static S_BASE: u32 = 0xAC00;
+static L_BASE: u32 = 0x1100;
+static V_BASE: u32 = 0x1161;
+static T_BASE: u32 = 0x11A7;
+static L_COUNT: u32 = 19;
+static V_COUNT: u32 = 21;
+static T_COUNT: u32 = 28;
+static N_COUNT: u32 = (V_COUNT * T_COUNT);
+static S_COUNT: u32 = (L_COUNT * N_COUNT);
+
+// Decompose a precomposed Hangul syllable
+#[inline(always)]
+fn decompose_hangul(s: char, f: |char|) {
+    use core::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
+#[inline(always)]
+fn compose_hangul(a: char, b: char) -> Option<char> {
+    use core::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) && 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)) };
+    }
+    // Compose an LVPart and a TPart
+    if S_BASE <= l && l <= (S_BASE+S_COUNT-T_COUNT) && T_BASE <= v && v < (T_BASE+T_COUNT) {
+        let r = l + (v - T_BASE);
+        return unsafe { Some(transmute(r)) };
+    }
+    None
+}