cosmopolitan/libc/str/strnwidth.c
Justine Tunney 0a24b4fc3c
Clean up more code
The *NSYNC linked list API is good enough that it deserves to be part of
the C libray, so this change writes an improved version of it which uses
that offsetof() trick from the Linux Kernel. We vendor all of the *NSYNC
tests in third_party which helped confirm the needed refactoring is safe

This change also deletes more old code that didn't pan out. My goal here
is to work towards a vision where the Cosmopolitan core libraries become
less experimental and more focused on curation. This better reflects the
current level of quality we've managed to achieve.
2023-07-06 08:03:24 -07:00

92 lines
3.6 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 │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/bsf.h"
#include "libc/intrin/pcmpgtb.h"
#include "libc/intrin/pmovmskb.h"
#include "libc/macros.internal.h"
#include "libc/str/str.h"
#include "libc/str/thompike.h"
#include "libc/str/unicode.h"
/**
* Returns monospace display width of UTF-8 string.
*
* - Control codes are discounted
* - ANSI escape sequences are discounted
* - East asian glyphs, emoji, etc. count as two
*
* @param s is NUL-terminated string
* @param n is max bytes to consider
* @param o is offset for doing tabs
* @return monospace display width
*/
int strnwidth(const char *s, size_t n, size_t o) {
size_t i;
wint_t c, w;
unsigned l, r, k;
enum { kAscii, kUtf8, kEsc, kCsi } t;
for (w = r = t = l = i = 0; i < n;) {
if ((c = s[i++] & 0xff)) {
switch (t) {
case kAscii:
if (0x20 <= c && c <= 0x7E) {
++l;
} else if (c == '\t') {
if ((k = (o + i - 1) & 7)) {
l += 8 - k;
} else {
l += 8;
}
} else if (c == 033) {
t = kEsc;
} else if (c >= 0300) {
t = kUtf8;
w = ThomPikeByte(c);
r = ThomPikeLen(c) - 1;
}
break;
case kUtf8:
if (ThomPikeCont(c)) {
w = ThomPikeMerge(w, c);
if (--r) break;
}
l += MAX(0, wcwidth(w));
t = kAscii;
break;
case kEsc:
if (c == '[') {
t = kCsi;
} else if (!(040 <= c && c < 060)) {
t = kAscii;
}
break;
case kCsi:
if (!(060 <= c && c < 0100)) {
t = kAscii;
}
break;
default:
__builtin_unreachable();
}
} else {
break;
}
}
return l;
}