1 files changed, 177 insertions, 0 deletions
diff --git a/text-iterator.c b/text-iterator.c
new file mode 100644
index 0000000..a70a5a9
--- /dev/null
+++ b/text-iterator.c
@@ -0,0 +1,177 @@
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE /* memrchr(3) is non-standard */
+#endif
+#include <limits.h>
+#include <stddef.h>
+#include <errno.h>
+#include <wchar.h>
+#include <string.h>
+#include "text.h"
+#include "util.h"
+
+bool text_iterator_byte_get(const Iterator *it, char *b) {
+	if (text_iterator_valid(it)) {
+		const Text *txt = text_iterator_text(it);
+		if (it->start <= it->text && it->text < it->end) {
+			*b = *it->text;
+			return true;
+		} else if (it->pos == text_size(txt)) {
+			*b = '\0';
+			return true;
+		}
+	}
+	return false;
+}
+
+bool text_iterator_byte_next(Iterator *it, char *b) {
+	if (!text_iterator_has_next(it))
+		return false;
+	bool eof = true;
+	if (it->text < it->end) {
+		it->text++;
+		it->pos++;
+		eof = false;
+	} else if (!text_iterator_has_prev(it)) {
+		eof = false;
+	}
+
+	while (it->text == it->end) {
+		if (!text_iterator_next(it)) {
+			if (eof)
+				return false;
+			if (b)
+				*b = '\0';
+			return text_iterator_prev(it);
+		}
+	}
+
+	if (b)
+		*b = *it->text;
+	return true;
+}
+
+bool text_iterator_byte_prev(Iterator *it, char *b) {
+	if (!text_iterator_has_prev(it))
+		return false;
+	bool eof = !text_iterator_has_next(it);
+	while (it->text == it->start) {
+		if (!text_iterator_prev(it)) {
+			if (!eof)
+				return false;
+			if (b)
+				*b = '\0';
+			return text_iterator_next(it);
+		}
+	}
+
+	--it->text;
+	--it->pos;
+
+	if (b)
+		*b = *it->text;
+	return true;
+}
+
+bool text_iterator_byte_find_prev(Iterator *it, char b) {
+	while (it->text) {
+		const char *match = memrchr(it->start, b, it->text - it->start);
+		if (match) {
+			it->pos -= it->text - match;
+			it->text = match;
+			return true;
+		}
+		text_iterator_prev(it);
+	}
+	text_iterator_next(it);
+	return false;
+}
+
+bool text_iterator_byte_find_next(Iterator *it, char b) {
+	while (it->text) {
+		const char *match = memchr(it->text, b, it->end - it->text);
+		if (match) {
+			it->pos += match - it->text;
+			it->text = match;
+			return true;
+		}
+		text_iterator_next(it);
+	}
+	text_iterator_prev(it);
+	return false;
+}
+
+bool text_iterator_codepoint_next(Iterator *it, char *c) {
+	while (text_iterator_byte_next(it, NULL)) {
+		if (ISUTF8(*it->text)) {
+			if (c)
+				*c = *it->text;
+			return true;
+		}
+	}
+	return false;
+}
+
+bool text_iterator_codepoint_prev(Iterator *it, char *c) {
+	while (text_iterator_byte_prev(it, NULL)) {
+		if (ISUTF8(*it->text)) {
+			if (c)
+				*c = *it->text;
+			return true;
+		}
+	}
+	return false;
+}
+
+bool text_iterator_char_next(Iterator *it, char *c) {
+	if (!text_iterator_codepoint_next(it, c))
+		return false;
+	mbstate_t ps = { 0 };
+	const Text *txt = text_iterator_text(it);
+	for (;;) {
+		char buf[MB_LEN_MAX];
+		size_t len = text_bytes_get(txt, it->pos, sizeof buf, buf);
+		wchar_t wc;
+		size_t wclen = mbrtowc(&wc, buf, len, &ps);
+		if (wclen == (size_t)-1 && errno == EILSEQ) {
+			return true;
+		} else if (wclen == (size_t)-2) {
+			return false;
+		} else if (wclen == 0) {
+			return true;
+		} else {
+			int width = wcwidth(wc);
+			if (width != 0)
+				return true;
+			if (!text_iterator_codepoint_next(it, c))
+				return false;
+		}
+	}
+	return true;
+}
+
+bool text_iterator_char_prev(Iterator *it, char *c) {
+	if (!text_iterator_codepoint_prev(it, c))
+		return false;
+	const Text *txt = text_iterator_text(it);
+	for (;;) {
+		char buf[MB_LEN_MAX];
+		size_t len = text_bytes_get(txt, it->pos, sizeof buf, buf);
+		wchar_t wc;
+		mbstate_t ps = { 0 };
+		size_t wclen = mbrtowc(&wc, buf, len, &ps);
+		if (wclen == (size_t)-1 && errno == EILSEQ) {
+			return true;
+		} else if (wclen == (size_t)-2) {
+			return false;
+		} else if (wclen == 0) {
+			return true;
+		} else {
+			int width = wcwidth(wc);
+			if (width != 0)
+				return true;
+			if (!text_iterator_codepoint_prev(it, c))
+				return false;
+		}
+	}
+	return true;
+}