Implement INDEX_OF function

query_executors/memory_executor/memory_executor.go

@@ -186,6 +186,8 @@ func getFieldValue(field parsers.SelectItem, queryParameters map[string]interfac
 			return strings_StartsWith(typedValue.Arguments, queryParameters, row)
 		case parsers.FunctionCallConcat:
 			return strings_Concat(typedValue.Arguments, queryParameters, row)
+		case parsers.FunctionCallIndexOf:
+			return strings_IndexOf(typedValue.Arguments, queryParameters, row)
 		case parsers.FunctionCallIsDefined:
 			return typeChecking_IsDefined(typedValue.Arguments, queryParameters, row)
 		}

query_executors/memory_executor/memory_executor_string_functions_test.go

@@ -9,9 +9,9 @@ import (
 
 func Test_Execute_StringFunctions(t *testing.T) {
 	mockData := []memoryexecutor.RowType{
-		map[string]interface{}{"id": "123", "pk": "aaa"},
-		map[string]interface{}{"id": "456", "pk": "bbb"},
-		map[string]interface{}{"id": "789", "pk": "AAA"},
+		map[string]interface{}{"id": "123", "pk": "aaa", "str": "hello"},
+		map[string]interface{}{"id": "456", "pk": "bbb", "str": "world"},
+		map[string]interface{}{"id": "789", "pk": "AAA", "str": "cool world"},
 	}
 
 	t.Run("Should execute function STRINGEQUALS(ex1, ex2, ignoreCase)", func(t *testing.T) {
@@ -295,4 +295,52 @@ func Test_Execute_StringFunctions(t *testing.T) {
 			},
 		)
 	})
+
+	t.Run("Should execute function INDEX_OF()", func(t *testing.T) {
+		testQueryExecute(
+			t,
+			parsers.SelectStmt{
+				SelectItems: []parsers.SelectItem{
+					{
+						Path: []string{"c", "str"},
+						Type: parsers.SelectItemTypeField,
+					},
+					{
+						Alias: "index",
+						Type:  parsers.SelectItemTypeFunctionCall,
+						Value: parsers.FunctionCall{
+							Type: parsers.FunctionCallIndexOf,
+							Arguments: []interface{}{
+								parsers.SelectItem{
+									Path: []string{"c", "str"},
+									Type: parsers.SelectItemTypeField,
+								},
+								parsers.SelectItem{
+									Type: parsers.SelectItemTypeConstant,
+									Value: parsers.Constant{
+										Type:  parsers.ConstantTypeString,
+										Value: "o",
+									},
+								},
+								parsers.SelectItem{
+									Type: parsers.SelectItemTypeConstant,
+									Value: parsers.Constant{
+										Type:  parsers.ConstantTypeInteger,
+										Value: 4,
+									},
+								},
+							},
+						},
+					},
+				},
+				Table: parsers.Table{Value: "c"},
+			},
+			mockData,
+			[]memoryexecutor.RowType{
+				map[string]interface{}{"str": "hello", "index": 4},
+				map[string]interface{}{"str": "world", "index": -1},
+				map[string]interface{}{"str": "cool world", "index": 6},
+			},
+		)
+	})
 }

query_executors/memory_executor/string_functions.go

@@ -71,6 +71,31 @@ func strings_Concat(arguments []interface{}, queryParameters map[string]interfac
 	return result
 }
 
+func strings_IndexOf(arguments []interface{}, queryParameters map[string]interface{}, row RowType) int {
+	str1 := parseString(arguments[0], queryParameters, row)
+	str2 := parseString(arguments[1], queryParameters, row)
+
+	start := 0
+	if len(arguments) > 2 && arguments[2] != nil {
+		if startPos, ok := getFieldValue(arguments[2].(parsers.SelectItem), queryParameters, row).(int); ok {
+			start = startPos
+		}
+	}
+
+	if len(str1) <= start {
+		return -1
+	}
+
+	str1 = str1[start:]
+	result := strings.Index(str1, str2)
+
+	if result == -1 {
+		return result
+	} else {
+		return result + start
+	}
+}
+
 func getBoolFlag(arguments []interface{}, queryParameters map[string]interface{}, row RowType) bool {
 	ignoreCase := false
 	if len(arguments) > 2 && arguments[2] != nil {