feat: call function with two argument

builtin/function.go

@@ -1,13 +1,15 @@
 package builtin
 
 import (
+	"math"
 	"math/rand"
 	"time"
 )
 
 var Functions = map[string]interface{}{
-	"sleep":             sleep,
-	"gen_random_string": genRandomString,
+	"sleep":             sleep,           // call with one argument
+	"gen_random_string": genRandomString, // call with one argument
+	"max":               math.Max,        // call with two arguments
 }
 
 func sleep(nSecs int) {

parser.go

@@ -169,9 +169,9 @@ func mergeVariables(variables, overriddenVariables map[string]interface{}) map[s
 	return mergedVariables
 }
 
-// callFunction call function with arguments
+// callFunc call function with arguments
 // only support return at most one result value
-func callFunction(funcName string, arguments []interface{}) (interface{}, error) {
+func callFunc(funcName string, arguments []interface{}) (interface{}, error) {
 	function, ok := builtin.Functions[funcName]
 	if !ok {
 		// function not found
@@ -184,25 +184,45 @@ func callFunction(funcName string, arguments []interface{}) (interface{}, error)
 		return nil, fmt.Errorf("function %s is invalid", funcName)
 	}
 
+	if funcValue.Type().NumIn() != len(arguments) {
+		// function arguments not match
+		return nil, fmt.Errorf("function %s arguments number not match", funcName)
+	}
+
 	argumentsValue := make([]reflect.Value, len(arguments))
 	for index, argument := range arguments {
+		// ensure each argument type match
+		expectArgumentType := funcValue.Type().In(index)
+		actualArgumentType := reflect.TypeOf(argument)
+		if expectArgumentType != actualArgumentType {
+			// function argument type not match
+			err := fmt.Errorf("function %s argument %d type not match, expect %v, actual %v",
+				funcName, index, expectArgumentType, actualArgumentType)
+			log.Printf("[callFunction] error: %s", err.Error())
+			return nil, err
+		}
 		argumentsValue[index] = reflect.ValueOf(argument)
 	}
 
 	log.Printf("[callFunction] func: %v, input arguments: %v", funcName, arguments)
 	resultValues := funcValue.Call(argumentsValue)
-	log.Printf("[callFunction] output results: %v", resultValues)
+	log.Printf("[callFunction] output values: %v", resultValues)
 
-	if len(resultValues) == 0 {
-		return nil, nil
-	} else if len(resultValues) > 1 {
+	if len(resultValues) > 1 {
 		// function should return at most one value
 		err := fmt.Errorf("function %s should return at most one value", funcName)
 		log.Printf("[callFunction] error: %s", err.Error())
 		return nil, err
 	}
 
+	// no return value
+	if len(resultValues) == 0 {
+		return nil, nil
+	}
+
+	// return one value
 	// convert reflect.Value to interface{}
 	result := resultValues[0].Interface()
+	log.Printf("[callFunction] output result: %+v(%T)", result, result)
 	return result, nil
 }

parser_test.go

@@ -283,9 +283,9 @@ func TestMergeVariables(t *testing.T) {
 func TestCallFunction(t *testing.T) {
 	// call function without arguments
 	funcName := "sleep"
-	params := []interface{}{1}
+	arguments := []interface{}{1}
 	timeStart := time.Now()
-	_, err := callFunction(funcName, params)
+	_, err := callFunc(funcName, arguments)
 	if !assert.Nil(t, err) {
 		t.Fail()
 	}
@@ -295,12 +295,23 @@ func TestCallFunction(t *testing.T) {
 
 	// call function with one argument
 	funcName = "gen_random_string"
-	params = []interface{}{10}
-	result, err := callFunction(funcName, params)
+	arguments = []interface{}{10}
+	result, err := callFunc(funcName, arguments)
 	if !assert.Nil(t, err) {
 		t.Fail()
 	}
 	if !assert.Equal(t, 10, len(result.(string))) {
 		t.Fail()
 	}
+
+	// call function with two argument
+	funcName = "max"
+	arguments = []interface{}{float64(10), 9.99}
+	result, err = callFunc(funcName, arguments)
+	if !assert.Nil(t, err) {
+		t.Fail()
+	}
+	if !assert.Equal(t, float64(10), result.(float64)) {
+		t.Fail()
+	}
 }