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      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 
     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