a4b354ca02
These are like the existing bsearch methods but if the search fails, it returns the next insertion point. The new `binary_search` returns a `BinarySearchResult` that is either `Found` or `NotFound`. For convenience, the `found` and `not_found` methods convert to `Option`, ala `Result`. Deprecate bsearch and bsearch_elem.
152 lines
4.3 KiB
Rust
152 lines
4.3 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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/*!
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Functions for computing canonical and compatible decompositions
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for Unicode characters.
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*/
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use core::cmp::{Equal, Less, Greater};
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use core::option::{Option, Some, None};
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use core::slice;
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use core::slice::ImmutableSlice;
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use tables::normalization::{canonical_table, compatibility_table, composition_table};
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fn bsearch_table<T>(c: char, r: &'static [(char, &'static [T])]) -> Option<&'static [T]> {
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match r.binary_search(|&(val, _)| {
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if c == val { Equal }
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else if val < c { Less }
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else { Greater }
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}) {
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slice::Found(idx) => {
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let (_, result) = r[idx];
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Some(result)
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}
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slice::NotFound(_) => None
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}
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}
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/// Compute canonical Unicode decomposition for character
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pub fn decompose_canonical(c: char, i: |char|) { d(c, i, false); }
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/// Compute canonical or compatible Unicode decomposition for character
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pub fn decompose_compatible(c: char, i: |char|) { d(c, i, true); }
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fn d(c: char, i: |char|, k: bool) {
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// 7-bit ASCII never decomposes
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if c <= '\x7f' { i(c); return; }
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// Perform decomposition for Hangul
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if (c as u32) >= S_BASE && (c as u32) < (S_BASE + S_COUNT) {
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decompose_hangul(c, i);
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return;
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}
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// First check the canonical decompositions
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match bsearch_table(c, canonical_table) {
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Some(canon) => {
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for x in canon.iter() {
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d(*x, |b| i(b), k);
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}
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return;
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}
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None => ()
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}
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// Bottom out if we're not doing compat.
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if !k { i(c); return; }
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// Then check the compatibility decompositions
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match bsearch_table(c, compatibility_table) {
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Some(compat) => {
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for x in compat.iter() {
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d(*x, |b| i(b), k);
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}
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return;
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}
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None => ()
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}
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// Finally bottom out.
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i(c);
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}
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pub fn compose(a: char, b: char) -> Option<char> {
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compose_hangul(a, b).or_else(|| {
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match bsearch_table(a, composition_table) {
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None => None,
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Some(candidates) => {
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match candidates.binary_search(|&(val, _)| {
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if b == val { Equal }
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else if val < b { Less }
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else { Greater }
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}) {
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slice::Found(idx) => {
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let (_, result) = candidates[idx];
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Some(result)
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}
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slice::NotFound(_) => None
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}
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}
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}
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})
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}
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// Constants from Unicode 6.3.0 Section 3.12 Conjoining Jamo Behavior
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static S_BASE: u32 = 0xAC00;
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static L_BASE: u32 = 0x1100;
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static V_BASE: u32 = 0x1161;
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static T_BASE: u32 = 0x11A7;
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static L_COUNT: u32 = 19;
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static V_COUNT: u32 = 21;
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static T_COUNT: u32 = 28;
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static N_COUNT: u32 = (V_COUNT * T_COUNT);
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static S_COUNT: u32 = (L_COUNT * N_COUNT);
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// Decompose a precomposed Hangul syllable
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#[inline(always)]
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fn decompose_hangul(s: char, f: |char|) {
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use core::mem::transmute;
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let si = s as u32 - S_BASE;
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let li = si / N_COUNT;
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unsafe {
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f(transmute(L_BASE + li));
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let vi = (si % N_COUNT) / T_COUNT;
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f(transmute(V_BASE + vi));
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let ti = si % T_COUNT;
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if ti > 0 {
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f(transmute(T_BASE + ti));
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}
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}
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}
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// Compose a pair of Hangul Jamo
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#[inline(always)]
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fn compose_hangul(a: char, b: char) -> Option<char> {
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use core::mem::transmute;
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let l = a as u32;
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let v = b as u32;
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// Compose an LPart and a VPart
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if L_BASE <= l && l < (L_BASE + L_COUNT) && V_BASE <= v && v < (V_BASE + V_COUNT) {
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let r = S_BASE + (l - L_BASE) * N_COUNT + (v - V_BASE) * T_COUNT;
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return unsafe { Some(transmute(r)) };
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}
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// Compose an LVPart and a TPart
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if S_BASE <= l && l <= (S_BASE+S_COUNT-T_COUNT) && T_BASE <= v && v < (T_BASE+T_COUNT) {
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let r = l + (v - T_BASE);
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return unsafe { Some(transmute(r)) };
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}
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None
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}
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