data tree FEATURE initial implementation of YANG data support
diff --git a/src/tree.h b/src/tree.h
new file mode 100644
index 0000000..d700a5b
--- /dev/null
+++ b/src/tree.h
@@ -0,0 +1,158 @@
+/**
+ * @file tree.h
+ * @author Radek Krejci <rkrejci@cesnet.cz>
+ * @brief libyang geenric macros and functions to work with YANG schema or data trees.
+ *
+ * Copyright (c) 2019 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_TREE_H_
+#define LY_TREE_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Macro selector for other LY_ARRAY_* macros, do not use directly!
+ */
+#define LY_ARRAY_SELECT(_1, _2, NAME, ...) NAME
+
+/**
+ * @brief Helper macro to go through sized-arrays with a pointer iterator.
+ *
+ * Use with opening curly bracket (`{`).
+ *
+ * @param[in] ARRAY Array to go through
+ * @param[in] TYPE Type of the records in the ARRAY
+ * @param[out] ITER Iterating pointer to the item being processed in each loop
+ */
+#define LY_ARRAY_FOR_ITER(ARRAY, TYPE, ITER) \
+ for (ITER = ARRAY; \
+ (ARRAY) && ((void*)ITER - (void*)ARRAY)/(sizeof(TYPE)) < (*((uint32_t*)(ARRAY) - 1)); \
+ ITER = (void*)((TYPE*)ITER + 1))
+
+/**
+ * @brief Helper macro to go through sized-arrays with a numeric iterator.
+ *
+ * Use with opening curly bracket (`{`).
+ *
+ * To access an item with the INDEX value, use always LY_ARRAY_INDEX macro!
+ *
+ * @param[in] ARRAY Array to go through
+ * @param[out] INDEX Iterating index of the item being processed in each loop
+ */
+#define LY_ARRAY_FOR_INDEX(ARRAY, INDEX) \
+ for (INDEX = 0; \
+ ARRAY && INDEX < (*((uint32_t*)(ARRAY) - 1)); \
+ ++INDEX)
+
+/**
+ * @defgroup schematree Schema Tree
+ * @{
+ *
+ * Data structures and functions to manipulate and access schema tree.
+ */
+
+/**
+ * @brief Get a number of records in the ARRAY.
+ *
+ * Does not check if array exists!
+ */
+#define LY_ARRAY_SIZE(ARRAY) (*((uint32_t*)(ARRAY) - 1))
+
+/**
+ * @brief Sized-array iterator (for-loop).
+ *
+ * Use with opening curly bracket (`{`).
+ *
+ * There are 2 variants:
+ *
+ * LY_ARRAY_FOR(ARRAY, TYPE, ITER)
+ *
+ * Where ARRAY is a sized-array to go through, TYPE is the type of the items in the ARRAY and ITER is a pointer variable
+ * providing the items of the ARRAY in the loops. This functionality is provided by LY_ARRAY_FOR_ITER macro
+ *
+ * LY_ARRAY_FOR(ARRAY, INDEX)
+ *
+ * The ARRAY is again a sized-array to go through, the INDEX is a variable (unsigned integer) for storing iterating ARRAY's index
+ * to access the items of ARRAY in the loops. This functionality is provided by LY_ARRAY_FOR_INDEX macro.
+ */
+#define LY_ARRAY_FOR(ARRAY, ...) LY_ARRAY_SELECT(__VA_ARGS__, LY_ARRAY_FOR_ITER, LY_ARRAY_FOR_INDEX)(ARRAY, __VA_ARGS__)
+
+/**
+ * @brief Macro to iterate via all sibling elements without affecting the list itself
+ *
+ * Works for all types of nodes despite it is data or schema tree, but all the
+ * parameters must be pointers to the same type.
+ *
+ * Use with opening curly bracket (`{`). All parameters must be of the same type.
+ *
+ * @param START Pointer to the starting element.
+ * @param ELEM Iterator.
+ */
+#define LY_LIST_FOR(START, ELEM) \
+ for ((ELEM) = (START); \
+ (ELEM); \
+ (ELEM) = (ELEM)->next)
+
+/**
+ * @brief Macro to iterate via all sibling elements allowing to modify the list itself (e.g. removing elements)
+ *
+ * Use with opening curly bracket (`{`). All parameters must be of the same type.
+ *
+ * @param START Pointer to the starting element.
+ * @param NEXT Temporary storage to allow removing of the current iterator content.
+ * @param ELEM Iterator.
+ */
+#define LY_LIST_FOR_SAFE(START, NEXT, ELEM) \
+ for ((ELEM) = (START); \
+ (ELEM) ? (NEXT = (ELEM)->next, 1) : 0; \
+ (ELEM) = (NEXT))
+
+/**
+ * @brief YANG built-in types
+ */
+typedef enum
+{
+ LY_TYPE_UNKNOWN = 0, /**< Unknown type */
+ LY_TYPE_BINARY, /**< Any binary data ([RFC 6020 sec 9.8](http://tools.ietf.org/html/rfc6020#section-9.8)) */
+ LY_TYPE_UINT8, /**< 8-bit unsigned integer ([RFC 6020 sec 9.2](http://tools.ietf.org/html/rfc6020#section-9.2)) */
+ LY_TYPE_UINT16, /**< 16-bit unsigned integer ([RFC 6020 sec 9.2](http://tools.ietf.org/html/rfc6020#section-9.2)) */
+ LY_TYPE_UINT32, /**< 32-bit unsigned integer ([RFC 6020 sec 9.2](http://tools.ietf.org/html/rfc6020#section-9.2)) */
+ LY_TYPE_UINT64, /**< 64-bit unsigned integer ([RFC 6020 sec 9.2](http://tools.ietf.org/html/rfc6020#section-9.2)) */
+ LY_TYPE_STRING, /**< Human-readable string ([RFC 6020 sec 9.4](http://tools.ietf.org/html/rfc6020#section-9.4)) */
+ LY_TYPE_BITS, /**< A set of bits or flags ([RFC 6020 sec 9.7](http://tools.ietf.org/html/rfc6020#section-9.7)) */
+ LY_TYPE_BOOL, /**< "true" or "false" ([RFC 6020 sec 9.5](http://tools.ietf.org/html/rfc6020#section-9.5)) */
+ LY_TYPE_DEC64, /**< 64-bit signed decimal number ([RFC 6020 sec 9.3](http://tools.ietf.org/html/rfc6020#section-9.3))*/
+ LY_TYPE_EMPTY, /**< A leaf that does not have any value ([RFC 6020 sec 9.11](http://tools.ietf.org/html/rfc6020#section-9.11)) */
+ LY_TYPE_ENUM, /**< Enumerated strings ([RFC 6020 sec 9.6](http://tools.ietf.org/html/rfc6020#section-9.6)) */
+ LY_TYPE_IDENT, /**< A reference to an abstract identity ([RFC 6020 sec 9.10](http://tools.ietf.org/html/rfc6020#section-9.10)) */
+ LY_TYPE_INST, /**< References a data tree node ([RFC 6020 sec 9.13](http://tools.ietf.org/html/rfc6020#section-9.13)) */
+ LY_TYPE_LEAFREF, /**< A reference to a leaf instance ([RFC 6020 sec 9.9](http://tools.ietf.org/html/rfc6020#section-9.9))*/
+ LY_TYPE_UNION, /**< Choice of member types ([RFC 6020 sec 9.12](http://tools.ietf.org/html/rfc6020#section-9.12)) */
+ LY_TYPE_INT8, /**< 8-bit signed integer ([RFC 6020 sec 9.2](http://tools.ietf.org/html/rfc6020#section-9.2)) */
+ LY_TYPE_INT16, /**< 16-bit signed integer ([RFC 6020 sec 9.2](http://tools.ietf.org/html/rfc6020#section-9.2)) */
+ LY_TYPE_INT32, /**< 32-bit signed integer ([RFC 6020 sec 9.2](http://tools.ietf.org/html/rfc6020#section-9.2)) */
+ LY_TYPE_INT64, /**< 64-bit signed integer ([RFC 6020 sec 9.2](http://tools.ietf.org/html/rfc6020#section-9.2)) */
+} LY_DATA_TYPE;
+#define LY_DATA_TYPE_COUNT 20 /**< Number of different types */
+
+/**
+ * @brief Stringified YANG built-in data types
+ */
+extern const char* ly_data_type2str[LY_DATA_TYPE_COUNT];
+
+/** @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* LY_TREE_H_ */