1 /*
2 * Copyright (C) 2017 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <wchar.h>
30
31 #include "private/icu.h"
32
wcwidth(wchar_t wc)33 int wcwidth(wchar_t wc) {
34 // Fast-path ASCII.
35 if (wc >= 0x20 && wc < 0x7f) return 1;
36
37 // ASCII NUL is a special case.
38 if (wc == 0) return 0;
39
40 // C0.
41 if (wc < ' ' || (wc >= 0x7f && wc <= 0xa0)) return -1;
42
43 // Now for the i18n part. This isn't defined or standardized, so a lot of the choices are
44 // pretty arbitrary. See https://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c for more details.
45
46 // Fancy unicode control characters?
47 switch (__icu_charType(wc)) {
48 case -1:
49 // No icu4c available; give up.
50 return -1;
51 case U_CONTROL_CHAR:
52 return -1;
53 case U_NON_SPACING_MARK:
54 case U_ENCLOSING_MARK:
55 case U_FORMAT_CHAR:
56 return 0;
57 }
58 if (__icu_hasBinaryProperty(wc, UCHAR_DEFAULT_IGNORABLE_CODE_POINT, nullptr)) return 0;
59
60 // Medial and final jamo render as zero width when used correctly.
61 switch (__icu_getIntPropertyValue(wc, UCHAR_HANGUL_SYLLABLE_TYPE)) {
62 case U_HST_VOWEL_JAMO:
63 case U_HST_TRAILING_JAMO:
64 return 0;
65 case U_HST_LEADING_JAMO:
66 case U_HST_LV_SYLLABLE:
67 case U_HST_LVT_SYLLABLE:
68 return 2;
69 }
70
71 if (wc >= 0x3248 && wc <= 0x4dff) {
72 // Circled two-digit CJK "speed sign" numbers. EastAsianWidth is ambiguous,
73 // but wide makes more sense.
74 if (wc <= 0x324f) return 2;
75 // Hexagrams. EastAsianWidth is neutral, but wide seems better.
76 if (wc >= 0x4dc0) return 2;
77 }
78
79 // The EastAsianWidth property is at least defined by the Unicode standard!
80 switch (__icu_getIntPropertyValue(wc, UCHAR_EAST_ASIAN_WIDTH)) {
81 case U_EA_AMBIGUOUS:
82 case U_EA_HALFWIDTH:
83 case U_EA_NARROW:
84 case U_EA_NEUTRAL:
85 return 1;
86 case U_EA_FULLWIDTH:
87 case U_EA_WIDE:
88 return 2;
89 }
90
91 return 0;
92 }
93