144 lines
5.3 KiB
C
144 lines
5.3 KiB
C
#ifndef LIBDS_SPRS_HEADER
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#define LIBDS_SPRS_HEADER
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#include <stddef.h>
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#include "libds.h"
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/**
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* Sparse set implementation with the capacity to store data.
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* Sparse sets are initially defined as having two arrays of integers,
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* one "dense" array, into which new elements are added sequentially, and another
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* "sparse" array into which the elements' indexes in the dense array are put at
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* their index.
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*
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* For instance, after adding the elements 1, 0, and 3 to a sparse array,
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* it may look like:
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* (Size) (Capacity)
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* | |
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* [1 ][0 ][3 ][..][..][..] (Dense)
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* [1 ][0 ][..][2 ][..][..] (Sparse)
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* As seen in the above representation, the element in the dense array at index 0 is 1,
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* and the element at index 1 in the sparse array points to its location in the dense array.
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* It's very quick to check whether an element is part of this sparse set:
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* if sparse[element] < size && dense[sparse[element]] == element.
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* Iteration is also O(n), thanks to the dense array, and no initial memory clearing is required.
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*
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* The below implementation adds an additional piece of data to the sparse array, a void* so that an item
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* can be associated with an integer index and stored / retrieved / ismember'ed together with it.
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*/
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/**
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* A single element in a sparse array.
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*/
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struct sprs_element_s {
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/**
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* The index of this element in the dense array.
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*/
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size_t index;
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/**
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* A piece of data (optional) associated with this index.
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*/
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void* data;
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};
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/**
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* A sparse array / set.
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*/
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struct sprs_s {
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/**
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* The maximum size of the set. This is the limit for integer indices.
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*/
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size_t capacity;
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/**
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* The current size of the sparse set, and the next available index in the dense array.
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*/
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size_t size;
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/**
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* The dense array.
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* This is a pointer so that an array of a certain size can be allocated as needed.
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*/
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size_t* dense;
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/**
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* The sparse array.
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* This is a pointer so that an array of a certain size can be allocated as needed.
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*/
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struct sprs_element_s* sparse;
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};
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typedef struct sprs_s sprs;
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/**
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* Initializes a sparse set with default values.
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* This does not allocate any memory for the arrays.
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* @param sprs the sparse set / array to initialize.
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*/
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void sprs_init(sprs* sprs);
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/**
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* Allocates the necessary memory for a sparse set's
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* dense and sparse arrays.
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* @param sprs the sparse set for which memory should be allocated.
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* @param size the maximum capacity of the sparse set to use.
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* @return LIBDS_SUCCESS if all goes well, or LIBDS_MALLOC if an allocation failed.
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*/
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libds_result sprs_setup(sprs* sprs, size_t size);
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/**
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* Frees memory allocated by the sparse set, and resets its capacity and size.
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* @param sprs the sparse set to free.
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*/
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void sprs_free(sprs* sprs);
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/**
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* Stores a value in the sparse set under a given index.
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* @param sprs the sparse set into which to store the value.
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* @param index the index at which to store the value
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* @param data the value to store.
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*/
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void sprs_put(sprs* sprs, size_t index, void* data);
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/**
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* Checks if the sparse set contains data under a given index.
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* @param sprs the sparse set to check.
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* @param index the index for which to check.
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* @return 1 if the index exists, 0 if not.
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*/
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int sprs_contains(sprs* sprs, size_t index);
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/**
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* Gets the value stored under the given sparse set index.
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* This will check for whether the index is in the sparse set first,
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* and return NULL if it's not.
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* Please not that this exhibit the !exact same! behavior if a NULL was stored
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* under the index or if the index was never populated. use sprs_contains to
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* check whether the index is populated if this is important.
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* @param sprs the sparse set to check.
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* @param index the index from under which to retrieve the value.
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* @return the value stored under the index, or NULL if there is nothing there.
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*/
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void* sprs_get(sprs* sprs, size_t index);
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/**
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* Runs through every element in the sparse set, and compares it against the
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* given data using the given comparison function. If the comparison function returns
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* true, returns the element that was passed to it. If the comparison function returns
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* true for no element, returns NULL.
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* @param sprs the sparse set to iterate through.
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* @param data the data to compare elements against
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* @param compare the comparison function
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* @return the first element that is matched by the comparison function, or NULL if none are matched.
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*/
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void* sprs_find(sprs* sprs, void* data, compare_func compare);
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/**
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* Runs through every element in the sparse set, and compares it against the
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* given data using the given comparison function. If the comparison function returns
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* true, calls the foreach function, passing it the element and the variable argument list.
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* Stops if any foreach function returns a nonzero code.
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* @param sprs the sparse set to perform the operation on
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* @param data the data to pass the comparison function
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* @param compare the comparison function operating on the data and each element in the list.
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* @param foreach the function to be called on every element recognized by the comparison function
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* @param ... variable arguments to be passed on to the foreach function
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* @return 0 if all goes well, or the first nonzero code returned by foreach.
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*/
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int sprs_foreach(sprs* sprs, void* data, compare_func compare, foreach_func foreach, ...);
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#endif
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