Optimize the duplication of a hash table and fix comment

src/hash_table.c

@@ -179,6 +179,7 @@ lyht_free(struct ly_ht *ht, void (*val_free)(void *val_p))
  *
  * @param[in] ht Hash table to resize.
  * @param[in] operation Operation to perform. 1 to enlarge, -1 to shrink, 0 to only rehash all records.
+ * @param[in] check Whether to check if the value has already been inserted or not.
  * @return LY_ERR value.
  */
 static LY_ERR

src/tree_data.c

@@ -2148,6 +2148,11 @@ lyd_dup_r(const struct lyd_node *node, const struct ly_ctx *trg_ctx, struct lyd_
         struct lyd_node *child;
 
         if (options & LYD_DUP_RECURSIVE) {
+            /* create a hash table with the size of the previous hash table (duplicate) */
+            if (orig->children_ht) {
+                ((struct lyd_node_inner *)dup)->children_ht = lyht_new(orig->children_ht->size, sizeof(struct lyd_node *), lyd_hash_table_val_equal, NULL, 1);
+            }
+
             /* duplicate all the children */
             LY_LIST_FOR(orig->child, child) {
                 LY_CHECK_GOTO(ret = lyd_dup_r(child, trg_ctx, dup, LYD_INSERT_NODE_LAST, NULL, options, NULL), error);

src/tree_data_hash.c

@@ -84,7 +84,7 @@ lyd_hash(struct lyd_node *node)
  *
  * Implementation of ::lyht_value_equal_cb.
  */
-static ly_bool
+ly_bool
 lyd_hash_table_val_equal(void *val1_p, void *val2_p, ly_bool mod, void *UNUSED(cb_data))
 {
     struct lyd_node *val1, *val2;

src/tree_data_internal.h

@@ -16,6 +16,7 @@
 #ifndef LY_TREE_DATA_INTERNAL_H_
 #define LY_TREE_DATA_INTERNAL_H_
 
+#include "compat.h"
 #include "log.h"
 #include "plugins_types.h"
 #include "tree_data.h"
@@ -600,6 +601,13 @@ LY_ERR ly_value_validate(const struct ly_ctx *ctx, const struct lysc_node *node,
  */
 LY_ERR lyd_hash(struct lyd_node *node);
 
+/**
+ * @brief Compare callback for values in hash table.
+ *
+ * Implementation of ::lyht_value_equal_cb.
+ */
+ly_bool lyd_hash_table_val_equal(void *val1_p, void *val2_p, ly_bool mod, void *cb_data);
+
 /**
  * @brief Insert hash of the node into the hash table of its parent.
  *