Insert new choices after previously matched ones

If the user already has supplied a query that yields M (where M > 0) matches,
inserting the K newly read choices after index M only requires searching through
M + K choices instead of N (where N being all choices). This improves
performance when the user types a query faster than the input pace on stdin.

Author: mptre

pick.c

@@ -76,7 +76,7 @@ static const char		*choice_string(const struct choice *);
 static void			 delete_between(char *, size_t, size_t, size_t);
 static char			*eager_strpbrk(const char *, const char *);
 static int			 filter_choices(size_t);
-static size_t			 get_choices(int);
+static size_t			 get_choices(int, size_t);
 static enum key			 get_key(const char **);
 static void			 handle_sigwinch(int);
 static int			 isu8cont(unsigned char);
@@ -224,14 +224,16 @@ usage(int status)
 }
 
 size_t
-get_choices(int fd)
+get_choices(int fd, size_t insert)
 {
 	static const char	*ifs;
 	static char		*buf;
 	static size_t		 length, offset;
 	static size_t		 size = BUFSIZ;
+	struct choice		*new, *old, tmp;
 	char		 	*desc, *start, *stop;
 	ssize_t		 	 n;
+	size_t			 dchoices, i, nchoices;
 
 	if (ifs == NULL && ((ifs = getenv("IFS")) == NULL || *ifs == '\0'))
 		ifs = " ";
@@ -256,6 +258,7 @@ get_choices(int fd)
 		choices.size = 16;
 	}
 
+	nchoices = choices.length;
 	start = buf + offset;
 	while ((stop = strchr(start, '\n')) != NULL) {
 		*stop = '\0';
@@ -287,6 +290,18 @@ get_choices(int fd)
 		start = stop + 1;
 	}
 	offset = start - buf;
+	dchoices = choices.length - nchoices;
+	if (dchoices == 0 || nchoices == 0)
+		return n;
+
+	/* Move new choices after the given insert index. */
+	for (i = 0; i < dchoices; i++) {
+		old = choices.v + insert + i;
+		new = choices.v + nchoices + i;
+		tmp = *new;
+		*new = *old;
+		*old = tmp;
+	}
 
 	return n;
 }
@@ -353,9 +368,15 @@ selected_choice(void)
 
 		length = choices.length;
 		if (doread) {
-			if (get_choices(STDIN_FILENO)) {
-				if (query_length > 0)
+			if (get_choices(STDIN_FILENO, choices_count)) {
+				if (query_length > 0) {
 					dofilter = 1;
+					if (choices_count > 0) {
+						query_grew = 1;
+						choices_count +=
+						    choices.length - length;
+					}
+				}
 			} else {
 				nfds = 1; /* EOF */
 			}