cosmopolitan/libc/unicode/wcwidth.c

43 lines
2.5 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/unicode/unicode.h"
extern const uint8_t kEastAsianWidth[];
extern const uint32_t kEastAsianWidthBits;
extern const uint8_t kCombiningChars[];
extern const uint32_t kCombiningCharsBits;
/**
* Returns cell width of monospace character.
*/
int wcwidth(wchar_t ucs) {
if (ucs == 0) return 0;
if ((0 <= ucs && ucs < 32) || (0x7f <= ucs && ucs < 0xA0)) {
return -1;
} else if ((0 <= ucs && ucs < kCombiningCharsBits) &&
!!(kCombiningChars[ucs >> 3] & (1 << (ucs & 7)))) {
return 0;
} else if (0 <= ucs && ucs < kEastAsianWidthBits) {
return 1 + !!(kEastAsianWidth[ucs >> 3] & (1 << (ucs & 7)));
} else {
return 1;
}
}