82 lines
3.3 KiB
C
82 lines
3.3 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/macros.h"
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#include "libc/str/thompike.h"
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#include "libc/unicode/unicode.h"
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/**
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* Returns monospace display width of UTF-8 string.
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*
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* - Control codes are discounted
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* - ANSI escape sequences are discounted
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* - East asian glyphs, emoji, etc. count as two
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*
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* @param s is NUL-terminated string
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* @param n is max bytes to consider
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* @return monospace display width
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*/
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int strnwidth(const char *s, size_t n) {
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wint_t c, w;
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unsigned l, r;
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enum { kAscii, kUtf8, kEsc, kCsi } t;
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for (w = r = t = l = 0; n--;) {
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if ((c = *s++ & 0xff)) {
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switch (t) {
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case kAscii:
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if (0x20 <= c && c <= 0x7E || c == '\t') {
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++l;
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} else if (c == 033) {
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t = kEsc;
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} else if (c >= 0300) {
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t = kUtf8;
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w = ThomPikeByte(c);
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r = ThomPikeLen(c) - 1;
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}
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break;
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case kUtf8:
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if (ThomPikeCont(c)) {
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w = ThomPikeMerge(w, c);
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if (--r) break;
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}
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l += MAX(0, wcwidth(w));
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t = kAscii;
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break;
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case kEsc:
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if (c == '[') {
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t = kCsi;
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} else if (!(040 <= c && c < 060)) {
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t = kAscii;
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}
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break;
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case kCsi:
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if (!(060 <= c && c < 0100)) {
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t = kAscii;
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}
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break;
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default:
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unreachable;
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}
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} else {
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break;
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}
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}
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return l;
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}
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