From 1bbf61864f06ad0dd63dca1784a4f9a96bc873dc Mon Sep 17 00:00:00 2001
From: NeilBrown <neil@brown.name>
Date: Fri, 23 Jun 2023 13:09:48 +1000
Subject: [PATCH] render-complete: add highlight more correctly.

As the original might have attributes in it, we need to find the
character that we want to highlight, and highlight just those.  Possibly
there will be multiple ranges if the characters already have differing
highlights.

Signed-off-by: NeilBrown <neil@brown.name>
---
 render-complete.c | 117 +++++++++++++++++++++++++++++++++-------------
 1 file changed, 85 insertions(+), 32 deletions(-)

diff --git a/render-complete.c b/render-complete.c
index 4ff4b69d..a44f663e 100644
--- a/render-complete.c
+++ b/render-complete.c
@@ -77,41 +77,88 @@ static void strip_attrs(char *c safe)
 	*n = 0;
 }
 
-static char *add_highlight_prefix(const char *orig, int start, int plen,
-				  const char *attr safe, int *offset)
+static const char *add_highlight(const char *orig, int start, int len,
+				 const char *attr safe, int *offset)
 {
+	/* Create a copy of 'orig' with all non-attr chars from start for len
+	 * given the extra 'attr'.  start and len count non-attr chars.
+	 * If offset!=NULL, stop when we get to that place in the result,
+	 * and update *offset with that place in orig.
+	 */
 	struct buf ret;
 	const char *c safe;
+	bool use_lt = True;
+
+	if (!len)
+		return orig;
 
 	if (orig == NULL)
 		return NULL;
 	buf_init(&ret);
 	c = orig;
-	while (start > 0 && *c && (!offset || ret.len < *offset)) {
-		if (*c == '<')
-			buf_append_byte(&ret, *c++);
-		buf_append_byte(&ret, *c++);
-		start -= 1;
-	}
-	if (!*c || (offset && ret.len >= *offset)) {
-		/* Nothing here to highlight */
-		if (offset)
-			*offset = c - orig;
-		return buf_final(&ret);
-	}
-
-	buf_concat(&ret, attr);
-	while (plen > 0 && *c && (!offset || ret.len < *offset)) {
-		if (*c == '<')
-			buf_append_byte(&ret, *c++);
-		buf_append_byte(&ret, *c++);
-		plen -= 1;
+	if (*c == ack) {
+		use_lt = False;
+		buf_append_byte(&ret, ack);
+		c++;
 	}
-	buf_concat(&ret, "</>");
 	while (*c && (!offset || ret.len < *offset)) {
-		if (*c == '<')
+		if ((use_lt && (*c != '<' || c[1] == '<')) ||
+		    (!use_lt && (*c != ack && *c != soh && *c != etx))) {
+			/* This is regular text */
+			if (start > 0)
+				start -= 1;
+			else if (start == 0) {
+				if (use_lt) {
+					buf_append(&ret, '<');
+					buf_concat(&ret, attr);
+					buf_append(&ret, '>');
+				} else {
+					buf_append(&ret, soh);
+					buf_concat(&ret, attr);
+					buf_append(&ret, stx);
+				}
+				start = -1;
+			}
+			if (use_lt && *c == '<')
+				buf_append_byte(&ret, *c++);
 			buf_append_byte(&ret, *c++);
-		buf_append_byte(&ret, *c++);
+			if (start < 0 && len > 0) {
+				len -= 1;
+				if (len == 0) {
+					if (use_lt)
+						buf_concat(&ret, "</>");
+					else
+						buf_append(&ret, etx);
+				}
+			}
+			continue;
+		}
+		/* Not regular text. */
+		if (start < 0 && len > 0) {
+			/* Close the attr highlight */
+			start = 0;
+			if (use_lt)
+				buf_concat(&ret, "</>");
+			else
+				buf_append(&ret, etx);
+		}
+		if (!use_lt) {
+			buf_append(&ret, *c);
+			if (*c == ack || *c == etx) {
+				c++;
+				continue;
+			}
+			c++;
+			while (*c && *c != etx)
+				buf_append(&ret, *c++);
+			if (*c)
+				buf_append(&ret, *c++);
+		} else {
+			while (*c && *c != '>')
+				buf_append_byte(&ret, *c++);
+			if (*c)
+				buf_append(&ret, *c++);
+		}
 	}
 	if (offset)
 		*offset = c - orig;
@@ -121,7 +168,8 @@ static char *add_highlight_prefix(const char *orig, int start, int plen,
 DEF_CMD(render_complete_line)
 {
 	struct complete_data *cd = ci->home->data;
-	char *line, *start, *hl;
+	char *line, *l2, *start = NULL;
+	const char *hl;
 	const char *match;
 	int ret, startlen;
 	struct mark *m;
@@ -136,20 +184,24 @@ DEF_CMD(render_complete_line)
 		return Efail;
 	}
 	match = cd->stk->substr;
-	start = strcasestr(line, match);
+	l2 = strsave(ci->home, line);
+	if (l2){
+		strip_attrs(l2);
+		start = strcasestr(l2, match);
+	}
 	if (!start)
 		startlen = 0;
 	else
-		startlen = start - line;
+		startlen = start - l2;
 	if (ci->num >= 0) {
 		/* Only want 'num' bytes from start, with ->mark positioned.
 		 * So need to find how many bytes of 'line' produce num bytes
 		 * of highlighted line.
 		 */
 		int num = ci->num;
-		hl = add_highlight_prefix(line, startlen, strlen(match),
-					  "<fg:red>", &num);
-		free(hl);
+		hl = add_highlight(line, startlen, strlen(match), "fg:red", &num);
+		if (hl != line)
+			free((void*)hl);
 		free(line);
 		mark_free(m);
 		line = call_ret(str, ci->key, ci->home->parent,
@@ -170,10 +222,11 @@ DEF_CMD(render_complete_line)
 	}
 	if (!line)
 		return Efail;
-	hl = add_highlight_prefix(line, startlen, strlen(match), "<fg:red>", NULL);
+	hl = add_highlight(line, startlen, strlen(match), "fg:red", NULL);
 
 	ret = comm_call(ci->comm2, "callback:render", ci->focus, 0, NULL, hl);
-	free(hl);
+	if (hl != line)
+		free((void*)hl);
 	free(line);
 	return ret;
 }
-- 
2.39.5