support insert tag char (#74)

complete_tag.go

@@ -0,0 +1,7 @@
+package readline
+
+type TabCompleter struct{}
+
+func (t *TabCompleter) Do([]rune, int) ([][]rune, int) {
+	return [][]rune{[]rune("\t")}, 0
+}

readline.go

@@ -93,6 +93,9 @@ func (c *Config) Init() error {
 		c.EOFPrompt = ""
 	}
 
+	if c.AutoComplete == nil {
+		c.AutoComplete = &TabCompleter{}
+	}
 	if c.FuncGetWidth == nil {
 		c.FuncGetWidth = GetScreenWidth
 	}

runebuf.go

@@ -430,7 +430,13 @@ func (r *RuneBuffer) output() []byte {
 		}
 
 	} else {
-		buf.Write([]byte(string(r.buf)))
+		for idx := range r.buf {
+			if r.buf[idx] == '\t' {
+				buf.WriteString(strings.Repeat(" ", TabWidth))
+			} else {
+				buf.WriteRune(r.buf[idx])
+			}
+		}
 		if r.isInLineEdge() {
 			buf.Write([]byte(" \b"))
 		}

runes.go

@@ -6,6 +6,7 @@ import (
 )
 
 var runes = Runes{}
+var TabWidth = 4
 
 type Runes struct{}
 
@@ -98,6 +99,9 @@ var doubleWidth = []*unicode.RangeTable{
 }
 
 func (Runes) Width(r rune) int {
+	if r == '\t' {
+		return TabWidth
+	}
 	if unicode.IsOneOf(zeroWidth, r) {
 		return 0
 	}