types CHANGE redefine ly_data_type2str[]
Use constant strings to implement ly_data_type2str array. In contrast
to the array itself, the defined constants are now as constant
initilizers.
diff --git a/src/plugins_internal.h b/src/plugins_internal.h
new file mode 100644
index 0000000..7fc5530
--- /dev/null
+++ b/src/plugins_internal.h
@@ -0,0 +1,39 @@
+/**
+ * @file plugins_internal.h
+ * @author Radek Krejci <rkrejci@cesnet.cz>
+ * @brief internal functions to support extension and type plugins.
+ *
+ * Copyright (c) 2019-2021 CESNET, z.s.p.o.
+ *
+ * This source code is licensed under BSD 3-Clause License (the "License").
+ * You may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://opensource.org/licenses/BSD-3-Clause
+ */
+
+#ifndef LY_PLUGINS_INTERNAL_H_
+#define LY_PLUGINS_INTERNAL_H_
+
+#define LY_TYPE_UNKNOWN_STR "unknown" /**< text representation of ::LY_TYPE_UNKNOWN */
+#define LY_TYPE_BINARY_STR "binary" /**< text representation of ::LY_TYPE_BINARY */
+#define LY_TYPE_UINT8_STR "8bit unsigned integer" /**< text representation of ::LY_TYPE_UINT8 */
+#define LY_TYPE_UINT16_STR "16bit unsigned integer" /**< text representation of ::LY_TYPE_UINT16 */
+#define LY_TYPE_UINT32_STR "32bit unsigned integer" /**< text representation of ::LY_TYPE_UINT32 */
+#define LY_TYPE_UINT64_STR "64bit unsigned integer" /**< text representation of ::LY_TYPE_UINT64 */
+#define LY_TYPE_STRING_STR "string" /**< text representation of ::LY_TYPE_STRING */
+#define LY_TYPE_BITS_STR "bits" /**< text representation of ::LY_TYPE_BITS */
+#define LY_TYPE_BOOL_STR "boolean" /**< text representation of ::LY_TYPE_BOOL */
+#define LY_TYPE_DEC64_STR "decimal64" /**< text representation of ::LY_TYPE_DEC64 */
+#define LY_TYPE_EMPTY_STR "empty" /**< text representation of ::LY_TYPE_EMPTY */
+#define LY_TYPE_ENUM_STR "enumeration" /**< text representation of ::LY_TYPE_ENUM */
+#define LY_TYPE_IDENT_STR "identityref" /**< text representation of ::LY_TYPE_IDENT */
+#define LY_TYPE_INST_STR "instance-identifier" /**< text representation of ::LY_TYPE_INST */
+#define LY_TYPE_LEAFREF_STR "leafref" /**< text representation of ::LY_TYPE_LEAFREF */
+#define LY_TYPE_UNION_STR "union" /**< text representation of ::LY_TYPE_UNION */
+#define LY_TYPE_INT8_STR "8bit integer" /**< text representation of ::LY_TYPE_INT8 */
+#define LY_TYPE_INT16_STR "16bit integer" /**< text representation of ::LY_TYPE_INT16 */
+#define LY_TYPE_INT32_STR "32bit integer" /**< text representation of ::LY_TYPE_INT32 */
+#define LY_TYPE_INT64_STR "64bit integer" /**< text representation of ::LY_TYPE_INT64 */
+
+#endif /* LY_PLUGINS_INTERNAL_H_ */