feat: call function without argument

builtin/function.go

@@ -1,15 +1,23 @@
 package builtin
 
 import (
+	"crypto/md5"
+	"encoding/hex"
 	"math"
 	"math/rand"
 	"time"
 )
 
 var Functions = map[string]interface{}{
+	"get_timestamp":     getTimestamp,    // call without arguments
 	"sleep":             sleep,           // call with one argument
 	"gen_random_string": genRandomString, // call with one argument
 	"max":               math.Max,        // call with two arguments
+	"md5":               MD5,
+}
+
+func getTimestamp() int64 {
+	return time.Now().UnixNano() / int64(time.Millisecond)
 }
 
 func sleep(nSecs int) {
@@ -26,3 +34,9 @@ func genRandomString(n int) string {
 	}
 	return string(b)
 }
+
+func MD5(str string) string {
+	hasher := md5.New()
+	hasher.Write([]byte(str))
+	return hex.EncodeToString(hasher.Sum(nil))
+}

parser.go

@@ -171,7 +171,7 @@ func mergeVariables(variables, overriddenVariables map[string]interface{}) map[s
 
 // callFunc call function with arguments
 // only support return at most one result value
-func callFunc(funcName string, arguments []interface{}) (interface{}, error) {
+func callFunc(funcName string, arguments ...interface{}) (interface{}, error) {
 	function, ok := builtin.Functions[funcName]
 	if !ok {
 		// function not found

parser_test.go

@@ -282,10 +282,14 @@ func TestMergeVariables(t *testing.T) {
 
 func TestCallFunction(t *testing.T) {
 	// call function without arguments
-	funcName := "sleep"
-	arguments := []interface{}{1}
+	_, err := callFunc("get_timestamp")
+	if !assert.Nil(t, err) {
+		t.Fail()
+	}
+
+	// call function with one argument
 	timeStart := time.Now()
-	_, err := callFunc(funcName, arguments)
+	_, err = callFunc("sleep", 1)
 	if !assert.Nil(t, err) {
 		t.Fail()
 	}
@@ -294,9 +298,7 @@ func TestCallFunction(t *testing.T) {
 	}
 
 	// call function with one argument
-	funcName = "gen_random_string"
-	arguments = []interface{}{10}
-	result, err := callFunc(funcName, arguments)
+	result, err := callFunc("gen_random_string", 10)
 	if !assert.Nil(t, err) {
 		t.Fail()
 	}
@@ -305,9 +307,7 @@ func TestCallFunction(t *testing.T) {
 	}
 
 	// call function with two argument
-	funcName = "max"
-	arguments = []interface{}{float64(10), 9.99}
-	result, err = callFunc(funcName, arguments)
+	result, err = callFunc("max", float64(10), 9.99)
 	if !assert.Nil(t, err) {
 		t.Fail()
 	}