Use trimmed length when --nth is used with --tiebreak=length

This change improves sort ordering for aligned tabular input.
Given the following input:

    apple   juice   100
    apple   pie     200

fzf --nth=2 will now prefer the one with pie. Before this change fzf
compared "juice   " and "pie     ", both of which have the same length.

2 files changed, 46 insertions, 0 deletions

diff --git a/src/util/util.go b/src/util/util.go
index aa5f227c..e7e4f313 100644
--- a/src/util/util.go
+++ b/src/util/util.go
@@ -75,6 +75,7 @@ func IsTty() bool {
 	return int(C.isatty(C.int(os.Stdin.Fd()))) != 0
 }
 
+// TrimRight returns rune array with trailing white spaces cut off
 func TrimRight(runes []rune) []rune {
 	var i int
 	for i = len(runes) - 1; i >= 0; i-- {
@@ -86,6 +87,7 @@ func TrimRight(runes []rune) []rune {
 	return runes[0 : i+1]
 }
 
+// BytesToRunes converts byte array into rune array
 func BytesToRunes(bytea []byte) []rune {
 	runes := make([]rune, 0, len(bytea))
 	for i := 0; i < len(bytea); {
@@ -100,3 +102,27 @@ func BytesToRunes(bytea []byte) []rune {
 	}
 	return runes
 }
+
+// TrimLen returns the length of trimmed rune array
+func TrimLen(runes []rune) int {
+	var i int
+	for i = len(runes) - 1; i >= 0; i-- {
+		char := runes[i]
+		if char != ' ' && char != '\t' {
+			break
+		}
+	}
+	// Completely empty
+	if i < 0 {
+		return 0
+	}
+
+	var j int
+	for j = 0; j < len(runes); j++ {
+		char := runes[j]
+		if char != ' ' && char != '\t' {
+			break
+		}
+	}
+	return i - j + 1
+}
diff --git a/src/util/util_test.go b/src/util/util_test.go
index 06cfd4f2..8aeaeac5 100644
--- a/src/util/util_test.go
+++ b/src/util/util_test.go
@@ -20,3 +20,23 @@ func TestContrain(t *testing.T) {
 		t.Error("Expected", 3)
 	}
 }
+
+func TestTrimLen(t *testing.T) {
+	check := func(str string, exp int) {
+		trimmed := TrimLen([]rune(str))
+		if trimmed != exp {
+			t.Errorf("Invalid TrimLen result for '%s': %d (expected %d)",
+				str, trimmed, exp)
+		}
+	}
+	check("hello", 5)
+	check("hello ", 5)
+	check("hello  ", 5)
+	check(" hello", 5)
+	check("  hello", 5)
+	check(" hello ", 5)
+	check("  hello  ", 5)
+	check("h   o", 5)
+	check("  h   o  ", 5)
+	check("         ", 0)
+}