TWEAK: escape placeholder by repeating it twice

fix #106

interpolate.go

@@ -43,11 +43,9 @@ func InterpolateForDialect(query string, value []interface{}, d Dialect) (string
 	return i.String(), nil
 }
 
-func (i *interpolator) interpolate(query string, value []interface{}, topLevel bool) error {
-	if strings.Count(query, placeholder) != len(value) {
-		return ErrPlaceholderCount
-	}
+var escapedPlaceholder = strings.Repeat(placeholder, 2)
 
+func (i *interpolator) interpolate(query string, value []interface{}, topLevel bool) error {
 	valueIndex := 0
 
 	for {
@@ -56,6 +54,17 @@ func (i *interpolator) interpolate(query string, value []interface{}, topLevel b
 			break
 		}
 
+		// escape placeholder by repeating it twice
+		if strings.HasPrefix(query[index:], escapedPlaceholder) {
+			i.WriteString(query[:index+len(escapedPlaceholder)])
+			query = query[index+len(escapedPlaceholder):]
+			continue
+		}
+
+		if valueIndex >= len(value) {
+			break
+		}
+
 		i.WriteString(query[:index])
 		if _, ok := value[valueIndex].([]byte); ok && i.IgnoreBinary {
 			i.WriteString(i.Placeholder(i.N))
@@ -71,6 +80,10 @@ func (i *interpolator) interpolate(query string, value []interface{}, topLevel b
 		valueIndex++
 	}
 
+	if valueIndex != len(value) {
+		return ErrPlaceholderCount
+	}
+
 	// placeholder not found; write remaining query
 	i.WriteString(query)
 

interpolate_test.go

@@ -136,6 +136,16 @@ func TestInterpolateForDialect(t *testing.T) {
 			value: []interface{}{(*int64)(nil)},
 			want:  "NULL",
 		},
+		{
+			query: "???? ? ?? ? ??",
+			value: []interface{}{1, 2},
+			want:  "???? 1 ?? 2 ??",
+		},
+		{
+			query: "???",
+			value: []interface{}{1},
+			want:  "??1",
+		},
 	} {
 		s, err := InterpolateForDialect(test.query, test.value, dialect.MySQL)
 		require.NoError(t, err)