From a723977b9f9ac95fb8ff2596e098b4dbb6017fc4 Mon Sep 17 00:00:00 2001
From: Junegunn Choi <junegunn.c@gmail.com>
Date: Thu, 19 Mar 2015 13:06:20 +0900
Subject: [PATCH] Fix #149 - panic on empty string filter

---
 src/algo/algo.go      | 12 ++++++++++++
 src/algo/algo_test.go |  8 ++++++++
 2 files changed, 20 insertions(+)

diff --git a/src/algo/algo.go b/src/algo/algo.go
index bc4e538..60c436e 100644
--- a/src/algo/algo.go
+++ b/src/algo/algo.go
@@ -12,6 +12,10 @@ import "strings"
 
 // FuzzyMatch performs fuzzy-match
 func FuzzyMatch(caseSensitive bool, input *string, pattern []rune) (int, int) {
+	if len(pattern) == 0 {
+		return 0, 0
+	}
+
 	runes := []rune(*input)
 
 	// 0. (FIXME) How to find the shortest match?
@@ -66,6 +70,10 @@ func FuzzyMatch(caseSensitive bool, input *string, pattern []rune) (int, int) {
 // ExactMatchStrings performs exact-match using strings package.
 // Currently not used.
 func ExactMatchStrings(caseSensitive bool, input *string, pattern []rune) (int, int) {
+	if len(pattern) == 0 {
+		return 0, 0
+	}
+
 	var str string
 	if caseSensitive {
 		str = *input
@@ -88,6 +96,10 @@ func ExactMatchStrings(caseSensitive bool, input *string, pattern []rune) (int,
 // We might try to implement better algorithms in the future:
 // http://en.wikipedia.org/wiki/String_searching_algorithm
 func ExactMatchNaive(caseSensitive bool, input *string, pattern []rune) (int, int) {
+	if len(pattern) == 0 {
+		return 0, 0
+	}
+
 	runes := []rune(*input)
 	numRunes := len(runes)
 	plen := len(pattern)
diff --git a/src/algo/algo_test.go b/src/algo/algo_test.go
index 363b6ee..ac7aad5 100644
--- a/src/algo/algo_test.go
+++ b/src/algo/algo_test.go
@@ -42,3 +42,11 @@ func TestSuffixMatch(t *testing.T) {
 	assertMatch(t, SuffixMatch, false, "fooBarbaz", "baz", 6, 9)
 	assertMatch(t, SuffixMatch, true, "fooBarbaz", "Baz", -1, -1)
 }
+
+func TestEmptyPattern(t *testing.T) {
+	assertMatch(t, FuzzyMatch, true, "foobar", "", 0, 0)
+	assertMatch(t, ExactMatchStrings, true, "foobar", "", 0, 0)
+	assertMatch(t, ExactMatchNaive, true, "foobar", "", 0, 0)
+	assertMatch(t, PrefixMatch, true, "foobar", "", 0, 0)
+	assertMatch(t, SuffixMatch, true, "foobar", "", 6, 6)
+}