forked from Telodendria/Telodendria
Apply #71: Add ArrayUnique() function.
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commit
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2 changed files with 64 additions and 6 deletions
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@ -274,6 +274,49 @@ ArraySort(Array * array, int (*compare) (void *, void *))
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ArrayQuickSort(array, 0, array->size - 1, compare);
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}
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Array *
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ArrayUnique(Array * array, int (*compare) (void *, void *))
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{
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Array *ret;
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size_t i;
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if (!array)
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{
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return NULL;
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}
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ret = ArrayDuplicate(array);
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if (!ret)
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{
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return NULL;
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}
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if (ArraySize(ret) == 1)
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{
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/* There can't be any duplicates when there's only 1 value */
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return ret;
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}
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ArraySort(ret, compare);
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for (i = 1; i < ArraySize(ret); i++)
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{
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void *cur = ret->entries[i];
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void *prev = ret->entries[i - 1];
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if (compare(cur, prev) == 0)
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{
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/* Remove the duplicate, and put i back where it was. */
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ArrayDelete(ret, i--);
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}
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}
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ArrayTrim(ret);
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return ret;
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}
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/* Even though the following operations could be done using only the
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* public Array API defined above, I opted for low-level struct
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* manipulation because it allows much more efficient copying; we only
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@ -136,6 +136,21 @@ extern void * ArrayDelete(Array *, size_t);
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*/
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extern void ArraySort(Array *, int (*) (void *, void *));
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/**
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* Remove all duplicates from an array by using the given comparison
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* function to sort the array, then remove matching values. This
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* function returns a new array with all duplicates removed. The
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* original array is unaffected. Note that arrays only store pointers
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* to values, usually values on the heap. Thus, it is possible to lose
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* pointers to duplicate values and have them leak.
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* .P
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* This is a relatively expensive operation. The array must first be
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* duplicated. Then it is sorted, then it is iterated from beginning
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* to end to remove duplicate entires. Note that the comparison
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* function is executed on each element at least twice.
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*/
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extern Array *ArrayUnique(Array *, int (*) (void *, void *));
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/**
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* If possible, reduce the amount of memory allocated to this array
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* by calling
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