1.1 --- a/src/cx/tree.h Wed Feb 14 22:32:13 2024 +0100
1.2 +++ b/src/cx/tree.h Thu Feb 15 21:54:43 2024 +0100
1.3 @@ -47,6 +47,8 @@
1.4 * Links a node to a (new) parent.
1.5 *
1.6 * If the node has already a parent, it is unlinked, first.
1.7 + * If the parent has children already, the node is prepended to the list
1.8 + * of all currently existing children.
1.9 *
1.10 * @param parent the parent node
1.11 * @param node the node that shall be linked
1.12 @@ -94,22 +96,59 @@
1.13 * contains the given \p data or if one of the children might contain
1.14 * the data.
1.15 *
1.16 + * The function should use the returned integer to indicate how close the
1.17 + * match is, where a negative number means that it does not match at all.
1.18 + *
1.19 * For example if a tree stores file path information, a node that is
1.20 * describing a parent directory of a filename that is searched, shall
1.21 - * return 1 to indicate that a child node might contain the searched item.
1.22 - * On the other hand, if the node denotes a path that is not a prefix of
1.23 - * the searched filename, the function would return -1 to indicate that
1.24 - * the search does not need to be continued in that branch.
1.25 + * return a positive number to indicate that a child node might contain the
1.26 + * searched item. On the other hand, if the node denotes a path that is not a
1.27 + * prefix of the searched filename, the function would return -1 to indicate
1.28 + * that * the search does not need to be continued in that branch.
1.29 *
1.30 * @param node the node that is currently investigated
1.31 * @param data the data that is searched for
1.32 *
1.33 * @return 0 if the node contains the data,
1.34 - * 1 if one of the children might contain the data,
1.35 - * -1 if neither the node, nor the children contains the data
1.36 + * positive if one of the children might contain the data,
1.37 + * negative if neither the node, nor the children contains the data
1.38 */
1.39 typedef int (*cx_tree_search_func)(void const *node, void const* data);
1.40
1.41 +
1.42 +/**
1.43 + * Searches for data in a tree.
1.44 + *
1.45 + * When the data cannot be found exactly, the search function might return a
1.46 + * closest result which might be a good starting point for adding a new node
1.47 + * to the tree.
1.48 + *
1.49 + * Depending on the tree structure it is not necessarily guaranteed that the
1.50 + * "closest" match is uniquely defined. This function will search for a node
1.51 + * with the best match according to the \p sfunc (meaning: the return value of
1.52 + * \p sfunc which is closest to zero). If that is also ambiguous, an arbitrary
1.53 + * node matching the criteria is returned.
1.54 + *
1.55 + * @param root the root node
1.56 + * @param data the data to search for
1.57 + * @param sfunc the search function
1.58 + * @param result where the result shall be stored
1.59 + * @param loc_children offset in the node struct for the children linked list
1.60 + * @param loc_next offset in the node struct for the next pointer
1.61 + * @return zero if the node was found exactly, positive if a node was found that
1.62 + * could contain the node (but doesn't right now), negative if the tree does not
1.63 + * contain any node that might be related to the searched data
1.64 + */
1.65 +__attribute__((__nonnull__))
1.66 +int cx_tree_search(
1.67 + void const *root,
1.68 + void const *data,
1.69 + cx_tree_search_func sfunc,
1.70 + void **result,
1.71 + ptrdiff_t loc_children,
1.72 + ptrdiff_t loc_next
1.73 +);
1.74 +
1.75 #ifdef __cplusplus
1.76 } // extern "C"
1.77 #endif
