Add marked text support in Markdown

html/html.c

@@ -162,6 +162,15 @@ rndr_blockquote(struct buf *ob, const struct buf *text, void *opaque)
 	BUFPUTSL(ob, "</blockquote>\n");
 }
 
+static void
+rndr_markedtext(struct buf *ob, const struct buf *text, void *opaque)
+{
+	BUFPUTSL(ob, "<mark>");
+	if (text) escape_html(ob, text->data, text->size);
+	BUFPUTSL(ob, "</mark>");
+	return 1;
+}
+
 static void
 rndr_blockspoiler(struct buf *ob, const struct buf *text, void *opaque)
 {
@@ -734,6 +743,7 @@ sdhtml_toc_renderer(struct sd_callbacks *callbacks, struct html_renderopt *optio
 
 		NULL,
 		rndr_codespan,
+		rndr_markedtext,
 		rndr_spoilerspan,
 		rndr_double_emphasis,
 		rndr_emphasis,
@@ -777,6 +787,7 @@ sdhtml_renderer(struct sd_callbacks *callbacks, struct html_renderopt *options,
 
 		rndr_autolink,
 		rndr_codespan,
+		rndr_markedtext,
 		rndr_spoilerspan,
 		rndr_double_emphasis,
 		rndr_emphasis,

html_block_names.txt

@@ -24,3 +24,4 @@ fieldset
 noscript
 blockquote
 span
+mark

src/markdown.c

@@ -629,6 +629,39 @@ parse_spoilerspan(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_
 	return 0;
 }
 
+static size_t
+parse_markedtext(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t size)
+{
+	int (*render_method)(struct buf *ob, const struct buf *text, void *opaque);
+	size_t len;
+	size_t i = 0;
+	struct buf *work = 0;
+	int r;
+
+	render_method = rndr->cb.markedtext;
+
+	if (!render_method) return 0;
+
+	while (i < size) {
+		len = find_emph_char(data + i, size - i, '=');
+		if (!len) return 0;
+		i += len;
+
+		if (i + 1 < size && data[i] == '=' && data[i + 1] == '=') {
+			work = rndr_newbuf(rndr, BUFFER_SPAN);
+			parse_inline(work, rndr, data, i - 1);
+			r = render_method(ob, work, rndr->opaque);
+			rndr_popbuf(rndr, BUFFER_SPAN);
+
+			if (!r) return 0;
+
+			return i + 1;
+		}
+		i++;
+	}
+	return 0;
+}
+
 /* char_emphasis • single and double emphasis parsing */
 static size_t
 char_emphasis(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t max_rewind, size_t max_lookbehind, size_t size)
@@ -644,6 +677,13 @@ char_emphasis(struct buf *ob, struct sd_markdown *rndr, uint8_t *data, size_t ma
 	}
 
 
+	if (size > 3 && c == '=' && data[1] == '=') {
+		if(_isspace(data[2]) || (ret = parse_markedtext(ob, rndr, data + 2, size - 2)) == 0)
+			return 0;
+
+		return ret + 2;
+	}
+
 	if (size > 2 && data[1] != c) {
 		/* whitespace cannot follow an opening emphasis;
 		 * strikethrough only takes two characters '~~' */
@@ -1480,6 +1520,28 @@ prefix_blockspoiler(uint8_t *data, size_t size)
     return 0;
 }
 
+static size_t
+prefix_markedtext(uint8_t *data, size_t size)
+{
+    size_t i = 0;
+    if (i < size && data[i] == ' ') i++;
+    if (i < size && data[i] == ' ') i++;
+    if (i < size && data[i] == ' ') i++;
+
+    if (i + 1 < size && data[i] == '=' && data[i + 1] == '=') {
+		size_t markedtext = find_emph_char(data + i + 1, size - i - 1, '=');
+		if (i + markedtext < size && markedtext > 0 && data[i + markedtext] == '=')
+			return 0;
+
+		if (i + 2 < size && data[i + 2] == ' ')
+			return i + 3;
+
+		return i + 2;
+    }
+
+    return 0;
+}
+
 /* prefix_code • returns prefix length for block code*/
 static size_t
 prefix_code(uint8_t *data, size_t size)

src/markdown.h

@@ -83,6 +83,7 @@ struct sd_callbacks {
 	int (*autolink)(struct buf *ob, const struct buf *link, enum mkd_autolink type, void *opaque);
 	int (*codespan)(struct buf *ob, const struct buf *text, void *opaque);
 	int (*spoilerspan)(struct buf *ob, const struct buf *text, void *opaque);
+	int (*markedtext)(struct buf *ob, const struct buf *text, void *opaque);
 	int (*double_emphasis)(struct buf *ob, const struct buf *text, void *opaque);
 	int (*emphasis)(struct buf *ob, const struct buf *text, void *opaque);
 	int (*image)(struct buf *ob, const struct buf *link, const struct buf *title, const struct buf *alt, void *opaque);