2 files changed, 157 insertions, 0 deletions
diff --git a/lib/unicode/string/u8glen.c b/lib/unicode/string/u8glen.c
new file mode 100644
index 0000000..394a62d
--- /dev/null
+++ b/lib/unicode/string/u8glen.c
@@ -0,0 +1,10 @@
+#include "unicode/string.h"
+
+size_t
+u8glen(const char8_t *s, size_t n)
+{
+	size_t m = 0;
+	while (u8gnext(nullptr, &s, &n))
+		m++;
+	return m;
+}
diff --git a/lib/unicode/string/u8gnext.c b/lib/unicode/string/u8gnext.c
new file mode 100644
index 0000000..9824abb
--- /dev/null
+++ b/lib/unicode/string/u8gnext.c
@@ -0,0 +1,147 @@
+#include <stddef.h>
+
+#include "__bsearch.h"
+#include "mbstring.h"
+#include "unicode/__gbrk.h"
+#include "unicode/string.h"
+
+struct gbrk_state {
+	enum {
+		GB9C_NONE,
+		GB9C_CNSNT,
+		GB9C_LNK,
+	} gb9c;
+	bool gb11 : 1;
+	bool gb12 : 1;
+};
+
+static bool u8isgbrk(rune, rune, struct gbrk_state *);
+
+__MLIB_DEFINE_BSEARCH(gbrk_prop, gbrk_prop_tbl, GBP_OTHER)
+
+size_t
+u8gnext(struct u8view *g, const char8_t **s, size_t *n)
+{
+	int m;
+	rune ch1;
+	const char8_t *p;
+	struct gbrk_state gs = {0};
+
+	if (*n == 0)
+		return 0;
+
+	p = *s;
+	if (g)
+		g->p = p;
+	p += u8tor(&ch1, p);
+
+	for (;;) {
+		rune ch2;
+
+		if ((size_t)(p - *s) >= *n)
+			ch2 = 0;
+		else
+			m = u8tor(&ch2, p);
+		if (u8isgbrk(ch1, ch2, &gs)) {
+			ptrdiff_t d = p - *s;
+			*n -= d;
+			*s = p;
+			if (g)
+				g->len = d;
+			return d;
+		}
+
+		ch1 = ch2;
+		p += m;
+	}
+}
+
+bool
+u8isgbrk(rune a, rune b, struct gbrk_state *gs)
+{
+	gbrk_prop ap, bp;
+
+	/* GB1 & GB2 */
+	if (!a || !b)
+		goto do_break;
+
+	/* GB3 & ASCII fast-track */
+	if ((a | b) < 0x300) {
+		if (a == '\r' && b == '\n')
+			return false;
+		goto do_break;
+	}
+
+	/* GB4 */
+	if (a == '\r' || a == '\n' || ((ap = mlib_lookup(a)) & GBP_CTRL))
+		goto do_break;
+
+	/* GB5 */
+	if (b == '\r' || b == '\n' || ((bp = mlib_lookup(b)) & GBP_CTRL))
+		goto do_break;
+
+	/* Setting flags for GB9c */
+	if (ap & GBP_INDC_CNSNT)
+		gs->gb9c = GB9C_CNSNT;
+	else if ((ap & GBP_INDC_LNK) && gs->gb9c == GB9C_CNSNT)
+		gs->gb9c = GB9C_LNK;
+
+	/* GB6 */
+	if ((ap & GBP_HNGL_L)
+	    && (bp & (GBP_HNGL_L | GBP_HNGL_V | GBP_HNGL_LV | GBP_HNGL_LVT)))
+	{
+		return false;
+	}
+
+	/* GB7 */
+	if ((ap & (GBP_HNGL_LV | GBP_HNGL_V)) && (bp & (GBP_HNGL_V | GBP_HNGL_T)))
+		return false;
+
+	/* GB8 */
+	if ((ap & (GBP_HNGL_LVT | GBP_HNGL_T)) && (bp & GBP_HNGL_T))
+		return false;
+
+	/* GB9 */
+	if (bp & (GBP_EXT | GBP_ZWJ)) {
+		if (ap & GBP_PIC)
+			gs->gb11 = true;
+		return false;
+	}
+
+	/* GB9a */
+	if (bp & GBP_SM)
+		return false;
+
+	/* GB9b */
+	if (ap & GBP_PREP)
+		return false;
+
+	/* GB9c */
+	if ((ap & (GBP_INDC_EXT | GBP_INDC_LNK)) && (bp & GBP_INDC_CNSNT)
+	    && gs->gb9c == GB9C_LNK)
+	{
+		return false;
+	}
+
+	/* GB11 */
+	if (gs->gb11) {
+		if ((ap & GBP_EXT) && (bp & (GBP_EXT | GBP_ZWJ)))
+			return false;
+		if ((ap & GBP_ZWJ) && (bp & GBP_PIC))
+			return false;
+	}
+
+	/* GB12 & GB13 */
+	if (ap & GBP_RI) {
+		if (gs->gb12 || !(bp & GBP_RI))
+			goto do_break;
+		gs->gb12 = true;
+		return false;
+	}
+
+	/* GB999 */
+do_break:
+	gs->gb9c = GB9C_NONE;
+	gs->gb11 = gs->gb12 = false;
+	return true;
+}