Implement casefolding

2 files changed, 30 insertions, 0 deletions

diff --git a/include/unicode/string.h b/include/unicode/string.h
index 0c1786c..d80f04c 100644
--- a/include/unicode/string.h
+++ b/include/unicode/string.h
@@ -6,6 +6,8 @@
 #include "__charN_t.h"
 #include "__u8view.h"
 
+/* clang-format off */
+
 enum [[clang::__flag_enum__]] caseflags {
 	CF_LANG_AZ = 1 << 0, /* Azeri; alias for UF_LANG_TR */
 	CF_LANG_TR = 1 << 0, /* Turkish; alias for UF_LANG_AZ */
@@ -13,9 +15,13 @@ enum [[clang::__flag_enum__]] caseflags {
 	CF_ẞ       = 1 << 2, /* Use ‘ẞ’ as the uppercase of ‘ß’ */
 };
 
+/* clang-format on */
+
 size_t u8glen(const char8_t *, size_t);
 size_t u8gnext(struct u8view *, const char8_t **, size_t *);
 
+size_t u8casefold(char8_t *restrict, size_t, const char8_t *, size_t,
+                  enum caseflags);
 size_t u8lower(char8_t *restrict, size_t, const char8_t *, size_t,
                enum caseflags);
 size_t u8upper(char8_t *restrict, size_t, const char8_t *, size_t,
diff --git a/lib/unicode/string/u8casefold.c b/lib/unicode/string/u8casefold.c
new file mode 100644
index 0000000..6c0b61d
--- /dev/null
+++ b/lib/unicode/string/u8casefold.c
@@ -0,0 +1,24 @@
+#include "mbstring.h"
+#include "unicode/prop.h"
+#include "unicode/string.h"
+
+size_t
+u8casefold(char8_t *restrict dst, size_t dstn, const char8_t *src, size_t srcn,
+           enum caseflags flags)
+{
+	rune ch;
+	size_t n = 0;
+
+	while (u8next(&ch, &src, &srcn)) {
+		struct rview rv = uprop_get_cf(ch, flags & CF_LANG_AZ);
+		for (size_t i = 0; i < rv.len; i++) {
+			if (n >= dstn) {
+				char8_t buf[U8_LEN_MAX];
+				n += rtou8(buf, sizeof(buf), rv.p[i]);
+			} else
+				n += rtou8(dst + n, dstn - n, rv.p[i]);
+		}
+	}
+
+	return n;
+}