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
+}