Merge pull request Masterminds#133 from mortent/StringHandleNil

Handle untyped nil values as parameters to string functions

strings.go

@@ -81,22 +81,27 @@ func untitle(str string) string {
 }
 
 func quote(str ...interface{}) string {
-	out := make([]string, len(str))
-	for i, s := range str {
-		out[i] = fmt.Sprintf("%q", strval(s))
+	out := make([]string, 0, len(str))
+	for _, s := range str {
+		if s != nil {
+			out = append(out, fmt.Sprintf("%q", strval(s)))
+		}
 	}
 	return strings.Join(out, " ")
 }
 
 func squote(str ...interface{}) string {
-	out := make([]string, len(str))
-	for i, s := range str {
-		out[i] = fmt.Sprintf("'%v'", s)
+	out := make([]string, 0, len(str))
+	for _, s := range str {
+		if s != nil {
+			out = append(out, fmt.Sprintf("'%v'", s))
+		}
 	}
 	return strings.Join(out, " ")
 }
 
 func cat(v ...interface{}) string {
+	v = removeNilElements(v)
 	r := strings.TrimSpace(strings.Repeat("%v ", len(v)))
 	return fmt.Sprintf(r, v...)
 }
@@ -126,26 +131,44 @@ func strslice(v interface{}) []string {
 	case []string:
 		return v
 	case []interface{}:
-		l := len(v)
-		b := make([]string, l)
-		for i := 0; i < l; i++ {
-			b[i] = strval(v[i])
+		b := make([]string, 0, len(v))
+		for _, s := range v {
+			if s != nil {
+				b = append(b, strval(s))
+			}
 		}
 		return b
 	default:
 		val := reflect.ValueOf(v)
 		switch val.Kind() {
 		case reflect.Array, reflect.Slice:
 			l := val.Len()
-			b := make([]string, l)
+			b := make([]string, 0, l)
 			for i := 0; i < l; i++ {
-				b[i] = strval(val.Index(i).Interface())
+				value := val.Index(i).Interface()
+				if value != nil {
+					b = append(b, strval(value))
+				}
 			}
 			return b
 		default:
-			return []string{strval(v)}
+			if v == nil {
+				return []string{}
+			} else {
+				return []string{strval(v)}
+			}
+		}
+	}
+}
+
+func removeNilElements(v []interface{}) []interface{} {
+	newSlice := make([]interface{}, 0, len(v))
+	for _, i := range v {
+		if i != nil {
+			newSlice = append(newSlice, i)
 		}
 	}
+	return newSlice
 }
 
 func strval(v interface{}) string {

strings_test.go

@@ -38,6 +38,11 @@ func TestQuote(t *testing.T) {
 	if err := runt(tpl, `"1" "2" "3"`); err != nil {
 		t.Error(err)
 	}
+	tpl = `{{ .value | quote }}`
+	values := map[string]interface{}{"value": nil}
+	if err := runtv(tpl, ``, values); err != nil {
+		t.Error(err)
+	}
 }
 func TestSquote(t *testing.T) {
 	tpl := `{{squote "a" "b" "c"}}`
@@ -48,6 +53,11 @@ func TestSquote(t *testing.T) {
 	if err := runt(tpl, `'1' '2' '3'`); err != nil {
 		t.Error(err)
 	}
+	tpl = `{{ .value | squote }}`
+	values := map[string]interface{}{"value": nil}
+	if err := runtv(tpl, ``, values); err != nil {
+		t.Error(err)
+	}
 }
 
 func TestContains(t *testing.T) {
@@ -100,6 +110,11 @@ func TestToString(t *testing.T) {
 func TestToStrings(t *testing.T) {
 	tpl := `{{ $s := list 1 2 3 | toStrings }}{{ index $s 1 | kindOf }}`
 	assert.NoError(t, runt(tpl, "string"))
+	tpl = `{{ list 1 .value 2 | toStrings }}`
+	values := map[string]interface{}{"value": nil}
+	if err := runtv(tpl, `[1 2]`, values); err != nil {
+		t.Error(err)
+	}
 }
 
 func TestJoin(t *testing.T) {
@@ -108,6 +123,7 @@ func TestJoin(t *testing.T) {
 	assert.NoError(t, runtv(`{{ join "-" .V }}`, "a-b-c", map[string]interface{}{"V": []string{"a", "b", "c"}}))
 	assert.NoError(t, runtv(`{{ join "-" .V }}`, "abc", map[string]interface{}{"V": "abc"}))
 	assert.NoError(t, runtv(`{{ join "-" .V }}`, "1-2-3", map[string]interface{}{"V": []int{1, 2, 3}}))
+	assert.NoError(t, runtv(`{{ join "-" .value }}`, "1-2", map[string]interface{}{"value": []interface{}{"1", nil, "2"}}))
 }
 
 func TestSortAlpha(t *testing.T) {
@@ -199,6 +215,11 @@ func TestCat(t *testing.T) {
 	if err := runt(tpl, "a b c"); err != nil {
 		t.Error(err)
 	}
+	tpl = `{{ .value | cat "a" "b"}}`
+	values := map[string]interface{}{"value": nil}
+	if err := runtv(tpl, "a b", values); err != nil {
+		t.Error(err)
+	}
 }
 
 func TestIndent(t *testing.T) {