refactor: convertArgs

plugin/shared/call.go

@@ -8,91 +8,25 @@ import (
 )
 
 // CallFunc calls function with arguments
-// it is used when calling go plugin or builtin functions
 func CallFunc(fn reflect.Value, args ...interface{}) (interface{}, error) {
-	fnArgsNum := fn.Type().NumIn()
-
-	// function expect 0 argument
-	if fnArgsNum == 0 {
-		if len(args) > 0 {
-			return nil, fmt.Errorf("function expect 0 argument, but got %d", len(args))
-		}
-		return call(fn, nil)
-	}
-
-	// fnArgsNum > 0: function expect more than 0 arguments
-	// function last argument is not slice
-	if fn.Type().In(fnArgsNum-1).Kind() != reflect.Slice {
-		// function arguments should match exactly
-		if fnArgsNum != len(args) {
-			return nil, fmt.Errorf("function expect %d arguments, but got %d", fnArgsNum, len(args))
-		}
-		// prepare arguments
-		argumentsValue, err := convertFirstNArgs(fn, fnArgsNum, args...)
-		if err != nil {
-			return nil, err
-		}
-		return call(fn, argumentsValue)
-	}
-
-	// function last argument is slice
-	// e.g.
-	// ...interface{}
-	// a, b string, c ...interface{}
-	// []int
-	// a, b string, c []int
-
-	// arguments number should >= fnArgsNum-1
-	if len(args) < fnArgsNum-1 {
-		return nil, fmt.Errorf("function expect at least %d arguments, but got %d", fnArgsNum-1, len(args))
-	}
-
-	// prepare first n-1 arguments
-	argumentsValue, err := convertFirstNArgs(fn, fnArgsNum-1, args...)
+	argumentsValue, err := convertArgs(fn, args...)
 	if err != nil {
+		log.Error().Err(err).Msg("convert arguments failed")
 		return nil, err
 	}
-
-	// prepare last slice argument
-	fnLastSliceElemType := fn.Type().In(fnArgsNum - 1).Elem() // slice element type
-	for i := fnArgsNum - 1; i < len(args); i++ {              // loop last len(args)-fnArgsNum+1 arguments
-		argValue := reflect.ValueOf(args[i])
-		argValueType := reflect.TypeOf(args[i])
-
-		// check if slice element type match
-		if fnLastSliceElemType == argValueType {
-			argumentsValue = append(argumentsValue, argValue)
-			continue
-		}
-
-		// last argument is also slice, e.g. []int
-		if argValueType.Kind() == reflect.Slice {
-			if argValueType.Elem() != fnLastSliceElemType {
-				err := fmt.Errorf("function argument %d's slice element type is not match, expect %v, actual %v",
-					i, fnLastSliceElemType, argValueType)
-				return nil, err
-			}
-			argumentsValue = append(argumentsValue, argValue)
-			continue
-		}
-
-		// type not match, check if convertible
-		if !argValueType.ConvertibleTo(fnLastSliceElemType) {
-			// function argument type not match and not convertible
-			err := fmt.Errorf("function argument %d's type is neither match nor convertible, expect %v, actual %v",
-				i, fnLastSliceElemType, argValueType)
-			return nil, err
-		}
-		// convert argument to expect type
-		argumentsValue = append(argumentsValue, argValue.Convert(fnLastSliceElemType))
-	}
-
 	return call(fn, argumentsValue)
 }
 
-func convertFirstNArgs(fn reflect.Value, n int, args ...interface{}) ([]reflect.Value, error) {
-	argumentsValue := make([]reflect.Value, n)
-	for index := 0; index < n; index++ {
+func convertArgs(fn reflect.Value, args ...interface{}) ([]reflect.Value, error) {
+	fnArgsNum := fn.Type().NumIn()
+
+	// function arguments should match exactly if function's last argument is not slice
+	if len(args) != fnArgsNum && (fnArgsNum == 0 || fn.Type().In(fnArgsNum-1).Kind() != reflect.Slice) {
+		return nil, fmt.Errorf("function expect %d arguments, but got %d", fnArgsNum, len(args))
+	}
+
+	argumentsValue := make([]reflect.Value, len(args))
+	for index := 0; index < len(args); index++ {
 		argument := args[index]
 		if argument == nil {
 			argumentsValue[index] = reflect.Zero(fn.Type().In(index))
@@ -100,9 +34,27 @@ func convertFirstNArgs(fn reflect.Value, n int, args ...interface{}) ([]reflect.
 		}
 
 		argumentValue := reflect.ValueOf(argument)
-		expectArgumentType := fn.Type().In(index)
 		actualArgumentType := reflect.TypeOf(argument)
 
+		var expectArgumentType reflect.Type
+		if (index == fnArgsNum-1 && fn.Type().In(fnArgsNum-1).Kind() == reflect.Slice) || index > fnArgsNum-1 {
+			// last fn argument is slice
+			expectArgumentType = fn.Type().In(fnArgsNum - 1).Elem() // slice element type
+
+			// last argument is also slice, e.g. []int
+			if actualArgumentType.Kind() == reflect.Slice {
+				if actualArgumentType.Elem() != expectArgumentType {
+					err := fmt.Errorf("function argument %d's slice element type is not match, expect %v, actual %v",
+						index, expectArgumentType, actualArgumentType)
+					return nil, err
+				}
+				argumentsValue[index] = argumentValue
+				continue
+			}
+		} else {
+			expectArgumentType = fn.Type().In(index)
+		}
+
 		// type match
 		if expectArgumentType == actualArgumentType {
 			argumentsValue[index] = argumentValue
@@ -114,7 +66,6 @@ func convertFirstNArgs(fn reflect.Value, n int, args ...interface{}) ([]reflect.
 			// function argument type not match and not convertible
 			err := fmt.Errorf("function argument %d's type is neither match nor convertible, expect %v, actual %v",
 				index, expectArgumentType, actualArgumentType)
-			log.Error().Err(err).Msg("convert arguments failed")
 			return nil, err
 		}
 		// convert argument to expect type

plugin/shared/call_test.go

@@ -168,8 +168,30 @@ func TestCallFuncComplex(t *testing.T) {
 			args:   []interface{}{1, 2, []int{3, 4}},
 			expVal: 10,
 		},
-
-		// FIXME: return more than 2 values
+	}
+
+	for _, p := range params {
+		fn := reflect.ValueOf(p.f)
+		val, err := CallFunc(fn, p.args...)
+		if !assert.Equal(t, p.expErr, err) {
+			t.Fatal(err)
+		}
+		if !assert.Equal(t, p.expVal, val) {
+			t.Fatal()
+		}
+	}
+
+}
+
+func TestCallFuncAbnormal(t *testing.T) {
+	params := []data{
+		// return more than 2 values
+		{
+			f:      func() (int, int, error) { return 1, 2, nil },
+			args:   []interface{}{},
+			expVal: nil,
+			expErr: fmt.Errorf("function should return at most 2 values"),
+		},
 	}
 
 	for _, p := range params {