Implement FROM_BASE64 function (#115)

pkg/stdlib/strings/decode.go

@@ -0,0 +1,31 @@
+package strings
+
+import (
+	"context"
+	"encoding/base64"
+
+	"github.com/MontFerret/ferret/pkg/runtime/values"
+
+	"github.com/MontFerret/ferret/pkg/runtime/core"
+)
+
+/*
+ * Returns the value of a base64 representation.
+ * @param base64String (String) - The string to decode.
+ * @returns value (String) - The decoded string.
+ */
+func FromBase64(_ context.Context, args ...core.Value) (core.Value, error) {
+	err := core.ValidateArgs(args, 1, 1)
+	if err != nil {
+		return values.EmptyString, err
+	}
+
+	value := args[0].String()
+
+	out, err := base64.StdEncoding.DecodeString(value)
+	if err != nil {
+		return values.EmptyString, err
+	}
+
+	return values.NewString(string(out)), nil
+}

pkg/stdlib/strings/decode_test.go

@@ -0,0 +1,46 @@
+package strings_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/MontFerret/ferret/pkg/runtime/values"
+
+	"github.com/MontFerret/ferret/pkg/stdlib/strings"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestFromBase64(t *testing.T) {
+	Convey("When args are not passed", t, func() {
+		Convey("It should return an error", func() {
+			var err error
+			_, err = strings.FromBase64(context.Background())
+
+			So(err, ShouldBeError)
+		})
+	})
+
+	Convey("When hash is not valid base64", t, func() {
+		Convey("It should return an error", func() {
+			var err error
+			_, err = strings.FromBase64(
+				context.Background(),
+				values.NewString("foobar"),
+			)
+
+			So(err, ShouldBeError)
+		})
+	})
+
+	Convey("Should decode a given hash", t, func() {
+		out, err := strings.FromBase64(
+			context.Background(),
+			values.NewString("Zm9vYmFy"),
+		)
+
+		So(err, ShouldBeNil)
+		So(out, ShouldNotEqual, "Zm9vYmFy")
+		So(out, ShouldEqual, "foobar")
+	})
+}

pkg/stdlib/strings/lib.go

@@ -31,6 +31,7 @@ func NewLib() map[string]core.Function {
 		"SUBSTITUTE":           Substitute,
 		"SUBSTRING":            Substring,
 		"TO_BASE64":            ToBase64,
+		"FROM_BASE64":					FromBase64,
 		"TRIM":                 Trim,
 		"UPPER":                Upper,
 	}