Added support of parsing DateTime with a custom layout (#721)

* Added support of parsing DateTime with a custom layout

pkg/stdlib/datetime/date.go

@@ -9,23 +9,32 @@ import (
 	"github.com/MontFerret/ferret/pkg/runtime/values/types"
 )
 
-// DATE converts RFC3339 date time string to DateTime object.
+// DATE parses a formatted string and returns DateTime object it represents.
-// @param {String} time - String in RFC3339 format.
+// @param {String} time - String representation of DateTime.
+// @param {String} [layout = "2006-01-02T15:04:05Z07:00"] - String layout.
 // @return {DateTime} - New DateTime object derived from timeString.
 func Date(_ context.Context, args ...core.Value) (core.Value, error) {
-	err := core.ValidateArgs(args, 1, 1)
+	if err := core.ValidateArgs(args, 1, 2); err != nil {
-	if err != nil {
 		return values.None, err
 	}
 
-	err = core.ValidateType(args[0], types.String)
+	if err := core.ValidateType(args[0], types.String); err != nil {
-	if err != nil {
 		return values.None, err
 	}
 
-	timeStrings := args[0].(values.String)
+	str := args[0].(values.String)
+	layout := values.DefaultTimeLayout
+
+	if len(args) > 1 {
+		if err := core.ValidateType(args[1], types.String); err != nil {
+			return values.None, err
+		}
+
+		layout = values.ToString(args[1]).String()
+	}
+
+	t, err := time.Parse(layout, str.String())
 
-	t, err := time.Parse(values.DefaultTimeLayout, timeStrings.String())
 	if err != nil {
 		return values.None, err
 	}

pkg/stdlib/datetime/date_test.go

@@ -2,6 +2,7 @@ package datetime_test
 
 import (
 	"testing"
+	"time"
 
 	"github.com/MontFerret/ferret/pkg/runtime/core"
 	"github.com/MontFerret/ferret/pkg/runtime/values"
@@ -10,29 +11,32 @@ import (
 )
 
 func TestDate(t *testing.T) {
+	now := time.Now()
+
 	tcs := []*testCase{
-		&testCase{
+		{
-			Name:     "When more than 1 arguments",
+			Name:     "When more than 2 arguments",
 			Expected: values.None,
 			Args: []core.Value{
-				values.NewString("string"),
+				values.NewString(time.Now().Format(time.RFC3339)),
-				values.NewInt(0),
+				values.NewString(time.RFC3339),
+				values.NewString("foo"),
 			},
 			ShouldErr: true,
 		},
-		&testCase{
+		{
 			Name:      "When 0 arguments",
 			Expected:  values.None,
 			Args:      []core.Value{},
 			ShouldErr: true,
 		},
-		&testCase{
+		{
-			Name:      "When argument isn't DateTime",
+			Name:      "When first argument isn't string",
 			Expected:  values.None,
 			Args:      []core.Value{values.NewInt(0)},
 			ShouldErr: true,
 		},
-		&testCase{
+		{
 			Name:     "When incorrect timeStrings",
 			Expected: values.None,
 			Args: []core.Value{
@@ -40,13 +44,31 @@ func TestDate(t *testing.T) {
 			},
 			ShouldErr: true,
 		},
-		&testCase{
+		{
-			Name:     "When correct timeString in RFC3339 format",
+			Name:     "When string is in default format",
 			Expected: mustDefaultLayoutDt("1999-02-07T15:04:05Z"),
 			Args: []core.Value{
 				values.NewString("1999-02-07T15:04:05Z"),
 			},
 		},
+		{
+			Name:     "When second argument isn't string",
+			Expected: values.None,
+			Args: []core.Value{
+				values.NewString("1999-02-07T15:04:05Z"),
+				values.NewInt(1),
+			},
+			ShouldErr: true,
+		},
+		{
+			Name:     "When string is in custom format",
+			Expected: mustLayoutDt(time.RFC822, now.Format(time.RFC822)),
+			Args: []core.Value{
+				values.NewString(now.Format(time.RFC822)),
+				values.NewString(time.RFC822),
+			},
+			ShouldErr: false,
+		},
 	}
 
 	for _, tc := range tcs {

pkg/stdlib/datetime/format.go

@@ -10,6 +10,7 @@ import (
 
 // DATE_FORMAT format date according to the given format string.
 // @param {DateTime} date - Source DateTime object.
+// @param {String} format - String format.
 // @return {String} - Formatted date.
 func DateFormat(_ context.Context, args ...core.Value) (core.Value, error) {
 	err := core.ValidateArgs(args, 2, 2)