support substring pattern mode for history searching

common.go

@@ -22,6 +22,7 @@ type commonState struct {
 	inputRedirected   bool
 	history           []string
 	historyMutex      sync.RWMutex
+	historyMode       HistoryMode
 	completer         WordCompleter
 	columns           int
 	killRing          *ring.Ring
@@ -52,6 +53,21 @@ const (
 	TabPrints
 )
 
+// HistoryMode defines the type of matching is used when searching
+// through previously entered items.
+type HistoryMode int
+
+const (
+	// HistoryModePrefix will match a given item against items in the history
+	// by history items' prefix using the strings.HasPrefix function.
+	HistoryModePrefix HistoryMode = iota
+
+	// HistoryModePattern will match a given item against items in the history
+	// by substring matching. History items matching the given patter will
+	// be returned.
+	HistoryModePattern
+)
+
 // ErrPromptAborted is returned from Prompt or PasswordPrompt when the user presses Ctrl-C
 // if SetCtrlCAborts(true) has been called on the State
 var ErrPromptAborted = errors.New("prompt aborted")
@@ -152,16 +168,6 @@ func (s *State) ClearHistory() {
 	s.history = nil
 }
 
-// Returns the history lines starting with prefix
-func (s *State) getHistoryByPrefix(prefix string) (ph []string) {
-	for _, h := range s.history {
-		if strings.HasPrefix(h, prefix) {
-			ph = append(ph, h)
-		}
-	}
-	return
-}
-
 // Returns the history lines matching the intelligent search
 func (s *State) getHistoryByPattern(pattern string) (ph []string, pos []int) {
 	if pattern == "" {
@@ -234,8 +240,15 @@ func (s *State) SetMultiLineMode(mlmode bool) {
 	s.multiLineMode = mlmode
 }
 
+// SetHistoryMode sets the pattern behavior when searching through the history.
+// The default is HistoryModePrefix; where returned history items are matched
+// by the string prefix of a history item.
+func (s *State) SetHistoryMode(mode HistoryMode) {
+	s.historyMode = mode
+}
+
 // ShouldRestart is passed the error generated by readNext and returns true if
-// the the read should be restarted or false if the error should be returned.
+// the read should be restarted or false if the error should be returned.
 type ShouldRestart func(err error) bool
 
 // SetShouldRestart sets the restart function that Liner will call to determine
@@ -260,3 +273,22 @@ func (s *State) promptUnsupported(p string) (string, error) {
 	}
 	return string(linebuf), nil
 }
+
+func (s *State) getHistory(line string) (ph []string) {
+	switch s.historyMode {
+	case HistoryModePattern:
+		if line == "" {
+			ph = append(ph, s.history...)
+		} else {
+			ph, _ = s.getHistoryByPattern(line)
+		}
+		return ph
+	default:
+		for _, h := range s.history {
+			if strings.HasPrefix(h, line) {
+				ph = append(ph, h)
+			}
+		}
+		return ph
+	}
+}

common_test.go

@@ -0,0 +1,65 @@
+package liner
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestState_getHistory(t *testing.T) {
+	tests := []struct {
+		name        string
+		historyMode HistoryMode
+		line        string
+		history     []string
+		want        []string
+	}{
+		{
+			name:    "no specified mode uses default prefix matching mode",
+			line:    "foo",
+			history: []string{"food", "foot", "tool"},
+			want:    []string{"food", "foot"},
+		},
+		{
+			name:        "explicit prefix mode matches",
+			line:        "foo",
+			historyMode: HistoryModePrefix,
+			history:     []string{"food", "foot", "tool"},
+			want:        []string{"food", "foot"},
+		},
+		{
+			name:        "pattern mode matches history substrings",
+			line:        "oo",
+			historyMode: HistoryModePattern,
+			history:     []string{"food", "foot", "tool"},
+			want:        []string{"food", "foot", "tool"},
+		},
+		{
+			name:        "empty string with pattern mode matches whole history",
+			line:        "",
+			historyMode: HistoryModePattern,
+			history:     []string{"food", "foot", "tool"},
+			want:        []string{"food", "foot", "tool"},
+		},
+		{
+			name:        "empty string with prefix mode matches whole history",
+			line:        "",
+			historyMode: HistoryModePrefix,
+			history:     []string{"food", "foot", "tool"},
+			want:        []string{"food", "foot", "tool"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			s := NewLiner()
+			s.SetHistoryMode(tt.historyMode)
+			for _, line := range tt.history {
+				s.AppendHistory(line)
+			}
+
+			got := s.getHistory(tt.line)
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("getHistory() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

line.go

@@ -728,7 +728,7 @@ mainLoop:
 			case ctrlP: // up
 				historyAction = true
 				if historyStale {
-					historyPrefix = s.getHistoryByPrefix(string(line))
+					historyPrefix = s.getHistory(string(line))
 					historyPos = len(historyPrefix)
 					historyStale = false
 				}
@@ -746,7 +746,7 @@ mainLoop:
 			case ctrlN: // down
 				historyAction = true
 				if historyStale {
-					historyPrefix = s.getHistoryByPrefix(string(line))
+					historyPrefix = s.getHistory(string(line))
 					historyPos = len(historyPrefix)
 					historyStale = false
 				}
@@ -913,7 +913,7 @@ mainLoop:
 			case up:
 				historyAction = true
 				if historyStale {
-					historyPrefix = s.getHistoryByPrefix(string(line))
+					historyPrefix = s.getHistory(string(line))
 					historyPos = len(historyPrefix)
 					historyStale = false
 				}
@@ -930,7 +930,7 @@ mainLoop:
 			case down:
 				historyAction = true
 				if historyStale {
-					historyPrefix = s.getHistoryByPrefix(string(line))
+					historyPrefix = s.getHistory(string(line))
 					historyPos = len(historyPrefix)
 					historyStale = false
 				}