From 2874b35e41a85731df8c7583f76c71eb249d3dfd Mon Sep 17 00:00:00 2001
From: Felix Van der Jeugt <felix.vanderjeugt@gmail.com>
Date: Wed, 19 Oct 2016 22:18:21 +0200
Subject: [PATCH] tabcomplete with longest common prefix

when hitting tab, the current input will be set to the longest common prefix
of the current selection instead of the first item of the selection
---
 dmenu.c | 32 ++++++++++++++------------------
 1 file changed, 14 insertions(+), 18 deletions(-)

diff --git a/dmenu.c b/dmenu.c
index f803149..4bb1c23 100644
--- a/dmenu.c
+++ b/dmenu.c
@@ -219,7 +219,7 @@ match(void)
 	char buf[sizeof text], *s;
 	int i, tokc = 0;
 	size_t len, textsize;
-	struct item *item, *lprefix, *lsubstr, *prefixend, *substrend;
+	struct item *item, *lprefix, *prefixend;
 
 	strcpy(buf, text);
 	/* separate input text into tokens to be matched individually */
@@ -228,8 +228,8 @@ match(void)
 			die("cannot realloc %u bytes:", tokn * sizeof *tokv);
 	len = tokc ? strlen(tokv[0]) : 0;
 
-	matches = lprefix = lsubstr = matchend = prefixend = substrend = NULL;
-	textsize = strlen(text) + 1;
+	matches = lprefix = matchend = prefixend = NULL;
+	textsize = strlen(text);
 	for (item = items; item && item->text; item++) {
 		for (i = 0; i < tokc; i++)
 			if (!fstrstr(item->text, tokv[i]))
@@ -241,8 +241,6 @@ match(void)
 			appenditem(item, &matches, &matchend);
 		else if (!fstrncmp(tokv[0], item->text, len))
 			appenditem(item, &lprefix, &prefixend);
-		else
-			appenditem(item, &lsubstr, &substrend);
 	}
 	if (lprefix) {
 		if (matches) {
@@ -252,14 +250,6 @@ match(void)
 			matches = lprefix;
 		matchend = prefixend;
 	}
-	if (lsubstr) {
-		if (matches) {
-			matchend->right = lsubstr;
-			lsubstr->left = matchend;
-		} else
-			matches = lsubstr;
-		matchend = substrend;
-	}
 	curr = sel = matches;
 	calcoffsets();
 }
@@ -309,6 +299,7 @@ keypress(XKeyEvent *ev)
 {
 	char buf[32];
 	int len;
+	struct item * item;
 	KeySym ksym;
 	Status status;
 
@@ -487,12 +478,17 @@ insert:
 		}
 		break;
 	case XK_Tab:
-		if (!sel)
-			return;
-		strncpy(text, sel->text, sizeof text - 1);
+		if (!matches) break; /* cannot complete no matches */
+		strncpy(text, matches->text, sizeof text - 1);
 		text[sizeof text - 1] = '\0';
-		cursor = strlen(text);
-		match();
+		len = cursor = strlen(text); /* length of longest common prefix */
+		for (item = matches; item && item->text; item = item->right) {
+			cursor = 0;
+			while (cursor < len && text[cursor] == item->text[cursor])
+				cursor++;
+			len = cursor;
+		}
+		memset(text + len, '\0', strlen(text) - len);
 		break;
 	}
 
-- 
2.20.1