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130 lines
4.3 KiB
130 lines
4.3 KiB
/*
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* tree.h
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*
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* data type providing a map from a key to a value, where the value is
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* an arbitrary area of storage.
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*
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* The current implementation of this is a binary search tree with no
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* balancing, so it will be inefficient if the data is presented in
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* strict ascending or descending order.
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*
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* all memory is allocated from a gmem_* heap that is passed on
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* creation of the tree.
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*
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* include gutils.h before this.
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*/
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/* handle for a tree */
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typedef struct tree FAR * TREE;
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/* keys in these trees are DWORDs */
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typedef DWORD TREEKEY;
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/* some sort of place-holder understood only by tree_search and
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* tree_addafter
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*/
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typedef struct treeitem FAR * TREEITEM;
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/* pointer to one of these place holders */
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typedef TREEITEM FAR * PTREEITEM;
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/*
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* create an empty tree and return a handle to it. Pass the heap to
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* be used for all memory allocations.
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*/
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TREE APIENTRY tree_create(HANDLE hHeap);
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/* delete a tree and discard any associated memory. The tree need not be
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* empty. This will discard the elements of the tree; but if these
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* contained pointers to further data blocks, these will not be discarded-
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* you must free these before deleting the tree.
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*/
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void APIENTRY tree_delete(TREE tree);
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/* add new element to the tree, mapping the key given to the value
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*
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* a block of data of length bytes will be inserted in the tree, mapped
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* to this key, a pointer to this block will be returned. if the
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* value pointer is non-null, the block value[0..length-1] will be copied
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* to the new block.
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*
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* if the key already exists, the value block will be replaced with the
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* new size and (if value is non-null) contents.
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*/
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LPVOID APIENTRY tree_update(TREE tree, TREEKEY key, LPVOID value, UINT length);
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/* return a pointer to the value associated with a given key in this tree.
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* returns NULL if the key is not found.
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*/
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LPVOID APIENTRY tree_find(TREE tree, TREEKEY key);
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/*
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* a common tree operation is to insert a new element into the
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* tree only if that key is not found, and otherwise to update in some
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* way the existing value. Using the standard functions above, that
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* would require one lookup for the tree_find, and then a second lookup
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* to insert the new element.
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*
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* the two functions below provide an optimisation over this. tree_search
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* will return the value if found; if not, it will return NULL, and set
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* pitem to a pointer to a place holder in the tree where the item
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* should be inserted. tree_addafter takes this placeholder as
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* an argument, and will insert the key/value in the tree at that point.
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*
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* as for tree_update, the value pointer can be NULL - in this case
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* the block is allocated on the tree, but not initialised.
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*
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* the return value from tree_addafter is a pointer to the value block in
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* the tree
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*/
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LPVOID APIENTRY tree_search(TREE tree, TREEKEY key, PTREEITEM place);
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LPVOID APIENTRY tree_addafter(TREE tree, PTREEITEM place, TREEKEY key, LPVOID value,
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UINT length);
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/* -- ctree ---------------
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*
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* this is a type of tree based on the tree_ data type above, that implements
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* counting for insertions of identical keys.
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*
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* ctree_update, if the key is unique, will insert the object and set the count
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* to 1. if the key is not unique, it will just increment the reference count.
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*
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* ctree_getcount returns the reference count for a tree.
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* ctree_find returns the first value inserted for that key, if any
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*/
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/*
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* create an empty counting-tree and return handle. pass in the gmem_init()
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* heap to be used for all memory allocations.
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*/
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TREE APIENTRY ctree_create(HANDLE hHeap);
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/*
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* delete a tree and all memory associated directly with it.
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*/
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void APIENTRY ctree_delete(TREE tree);
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/*
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* if the KEY is unique within the tree, insert the value and
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* set the count for that key to 1. If the key is not unique, add one to
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* the reference count for that key but leave the value untouched.
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*/
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LPVOID APIENTRY ctree_update(TREE tree, TREEKEY key, LPVOID value, UINT length);
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/*
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* find the reference count for the given key
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*/
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long APIENTRY ctree_getcount(TREE tree, TREEKEY key);
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/*
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* return the value for the given key (note this will be the value for
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* the first insertion of this key
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*/
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LPVOID APIENTRY ctree_find(TREE tree, TREEKEY key);
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