feat(history): add ignore duplicates option

history.go

@@ -2,14 +2,25 @@ package prompt
 
 // History stores the texts that are entered.
 type History struct {
-	histories []string
-	tmp       []string
-	selected  int
+	histories        []string
+	tmp              []string
+	selected         int
+	ignoreDuplicates bool
 }
 
 // Add to add text in history.
 func (h *History) Add(input string) {
-	h.histories = append(h.histories, input)
+	if h.ignoreDuplicates {
+		var histories []string
+		for _, history := range h.histories {
+			if history != input {
+				histories = append(histories, history)
+			}
+		}
+		h.histories = append(histories, input)
+	} else {
+		h.histories = append(h.histories, input)
+	}
 	h.Clear()
 }
 

history_test.go

@@ -10,9 +10,10 @@ func TestHistoryClear(t *testing.T) {
 	h.Add("foo")
 	h.Clear()
 	expected := &History{
-		histories: []string{"foo"},
-		tmp:       []string{"foo", ""},
-		selected:  1,
+		histories:        []string{"foo"},
+		tmp:              []string{"foo", ""},
+		selected:         1,
+		ignoreDuplicates: false,
 	}
 	if !reflect.DeepEqual(expected, h) {
 		t.Errorf("Should be %#v, but got %#v", expected, h)
@@ -23,9 +24,27 @@ func TestHistoryAdd(t *testing.T) {
 	h := NewHistory()
 	h.Add("echo 1")
 	expected := &History{
-		histories: []string{"echo 1"},
-		tmp:       []string{"echo 1", ""},
-		selected:  1,
+		histories:        []string{"echo 1"},
+		tmp:              []string{"echo 1", ""},
+		selected:         1,
+		ignoreDuplicates: false,
+	}
+	if !reflect.DeepEqual(h, expected) {
+		t.Errorf("Should be %v, but got %v", expected, h)
+	}
+}
+
+func TestHistoryAddIgnoreDuplicates(t *testing.T) {
+	h := NewHistory()
+	h.ignoreDuplicates = true
+	h.Add("echo 1")
+	h.Add("echo 2")
+	h.Add("echo 1")
+	expected := &History{
+		histories:        []string{"echo 2", "echo 1"},
+		tmp:              []string{"echo 2", "echo 1", ""},
+		selected:         2,
+		ignoreDuplicates: true,
 	}
 	if !reflect.DeepEqual(h, expected) {
 		t.Errorf("Should be %v, but got %v", expected, h)

option.go

@@ -206,6 +206,15 @@ func OptionHistory(x []string) Option {
 	}
 }
 
+// OptionHistoryIgnoreDuplicates to set history not display a line previously found
+func OptionHistoryIgnoreDuplicates() Option {
+	return func(p *Prompt) error {
+		p.history.ignoreDuplicates = true
+		p.history.Clear()
+		return nil
+	}
+}
+
 // OptionSwitchKeyBindMode set a key bind mode.
 func OptionSwitchKeyBindMode(m KeyBindMode) Option {
 	return func(p *Prompt) error {