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/* The approach of this implementation is heavily inspired by libgrapheme
(written by Laslo Hunhold <dev@frign.de>), and my email-correspondance with
Laslo. */
#include "macros.h"
#include "mbstring.h"
#include "unicode/_wbrk.h"
#include "unicode/string.h"
#define IS_MIDNUMLETQ(xp) ((xp) == WBRK_MB || (xp) == WBRK_SQ)
#define IS_AHLETTER(xp) \
((xp) == WBRK_LE || (xp) == WBRK_EXTPICT_LE || (xp) == WBRK_HL)
#define IS_IGNORE(xp) \
((xp) == WBRK_EXTEND || (xp) == WBRK_FO || (xp) == WBRK_ZWJ)
struct wbrk_state {
struct {
enum uprop_wbrk prev[2], next[2];
} raw, skip;
struct u8view raw_v, skip_v, mid_v;
int ri_parity : 1;
};
static bool advance(struct wbrk_state *);
static size_t findwbrk(struct u8view);
static struct wbrk_state mkwbrkstate(struct u8view);
size_t
u8wnext(struct u8view *w, struct u8view *sv)
{
ASSUME(sv != nullptr);
ASSUME(sv->p != nullptr);
if (sv->len == 0)
return 0;
size_t off = findwbrk(*sv);
if (w != nullptr)
*w = (struct u8view){sv->p, off};
ASSUME(sv->len >= off);
VSHFT(sv, off);
return off;
}
size_t
findwbrk(struct u8view sv)
{
ASSUME(sv.p != nullptr);
struct wbrk_state ws = mkwbrkstate(sv);
while (advance(&ws)) {
#define prev ws.raw.prev
#define next ws.raw.next
/* WB3 */
if (prev[0] == WBRK_CR && next[0] == WBRK_LF)
continue;
/* WB3a */
if (prev[0] == WBRK_NL || prev[0] == WBRK_CR || prev[0] == WBRK_LF)
break;
/* WB3b */
if (next[0] == WBRK_NL || next[0] == WBRK_CR || next[0] == WBRK_LF)
break;
/* WB3c */
if (prev[0] == WBRK_ZWJ
&& (next[0] == WBRK_EXTPICT || next[0] == WBRK_EXTPICT_LE))
{
continue;
}
/* WB3d */
if (prev[0] == WBRK_WSEGSPACE && next[0] == WBRK_WSEGSPACE)
continue;
/* WB4 */
if (next[0] == WBRK_EXTEND || next[0] == WBRK_FO || next[0] == WBRK_ZWJ)
continue;
#undef prev
#undef next
#define prev ws.skip.prev
#define next ws.skip.next
/* WB5 */
if (IS_AHLETTER(prev[0]) && IS_AHLETTER(next[0]))
continue;
/* WB6 */
if (IS_AHLETTER(prev[0])
&& (next[0] == WBRK_ML || IS_MIDNUMLETQ(next[0]))
&& IS_AHLETTER(next[1]))
{
continue;
}
/* WB7 */
if (IS_AHLETTER(prev[1])
&& (prev[0] == WBRK_ML || IS_MIDNUMLETQ(prev[0]))
&& IS_AHLETTER(next[0]))
{
continue;
}
/* WB7a */
if (prev[0] == WBRK_HL && next[0] == WBRK_SQ)
continue;
/* WB7b */
if (prev[0] == WBRK_HL && next[0] == WBRK_DQ && next[1] == WBRK_HL)
continue;
/* WB7c */
if (prev[1] == WBRK_HL && prev[0] == WBRK_DQ && next[0] == WBRK_HL)
continue;
/* WB8 */
if (prev[0] == WBRK_NU && next[0] == WBRK_NU)
continue;
/* WB9 */
if (IS_AHLETTER(prev[0]) && next[0] == WBRK_NU)
continue;
/* WB10 */
if (prev[0] == WBRK_NU && IS_AHLETTER(next[0]))
continue;
/* WB11 */
if (prev[1] == WBRK_NU && (prev[0] == WBRK_MN || IS_MIDNUMLETQ(prev[0]))
&& next[0] == WBRK_NU)
{
continue;
}
/* WB12 */
if (prev[0] == WBRK_NU && (next[0] == WBRK_MN || IS_MIDNUMLETQ(next[0]))
&& next[1] == WBRK_NU)
{
continue;
}
/* WB13 */
if (prev[0] == WBRK_KA && next[0] == WBRK_KA)
continue;
/* WB13a */
if ((IS_AHLETTER(prev[0]) || prev[0] == WBRK_NU || prev[0] == WBRK_KA
|| prev[0] == WBRK_EX)
&& next[0] == WBRK_EX)
{
continue;
}
/* WB13b */
if (prev[0] == WBRK_EX
&& (IS_AHLETTER(next[0]) || next[0] == WBRK_NU
|| next[0] == WBRK_KA))
{
continue;
}
/* WB15 & WB16 */
if (next[0] == WBRK_RI && ws.ri_parity)
continue;
/* WB999 */
break;
#undef prev
#undef next
}
return ws.mid_v.p - sv.p;
}
struct wbrk_state
mkwbrkstate(struct u8view sv)
{
struct wbrk_state ws = {
.raw = {{WBRK_EOT, WBRK_EOT}, {WBRK_EOT, WBRK_EOT}},
.skip = {{WBRK_EOT, WBRK_EOT}, {WBRK_EOT, WBRK_EOT}},
.mid_v = sv,
.raw_v = sv,
.skip_v = sv,
};
static_assert(sizeof(ws.skip.next) == sizeof(ws.raw.next));
rune ch;
for (size_t i = 0; i < lengthof(ws.raw.next) && u8next(&ch, &ws.raw_v) != 0;
i++)
{
ws.raw.next[i] = uprop_get_wbrk(ch);
}
for (size_t i = 0;
i < lengthof(ws.raw.next) && u8next(&ch, &ws.skip_v) != 0;)
{
ws.skip.next[i] = uprop_get_wbrk(ch);
if (!IS_IGNORE(ws.skip.next[i]))
i++;
}
return ws;
}
bool
advance(struct wbrk_state *ws)
{
if (ws->raw.next[0] == WBRK_EOT)
return false;
/* Shift the prop window over by 1 */
rune ch;
ws->raw.prev[1] = ws->raw.prev[0];
ws->raw.prev[0] = ws->raw.next[0];
ws->raw.next[0] = ws->raw.next[1];
ws->raw.next[1] =
u8next(&ch, &ws->raw_v) != 0 ? uprop_get_wbrk(ch) : WBRK_EOT;
/* Increment the midpoint */
u8next(nullptr, &ws->mid_v);
/* Ignore ignorable properties */
if (!IS_IGNORE(ws->raw.prev[0])) {
ws->skip.prev[1] = ws->skip.prev[0];
ws->skip.prev[0] = ws->skip.next[0];
ws->skip.next[0] = ws->skip.next[1];
ws->ri_parity = ws->ri_parity == 0 && ws->skip.prev[0] == WBRK_RI;
do {
if (u8next(&ch, &ws->skip_v) == 0) {
ws->skip.next[1] = WBRK_EOT;
break;
}
ws->skip.next[1] = uprop_get_wbrk(ch);
} while (IS_IGNORE(ws->skip.next[1]));
}
return true;
}
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