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Apply #71: Add ArrayUnique() function.

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This commit is contained in:
Jordan Bancino 2023-07-15 22:27:24 +00:00
parent c96ac30f28
commit a958c4a529
2 changed files with 64 additions and 6 deletions
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43
Cytoplasm/src/Array.c
View file

@ -274,6 +274,49 @@ ArraySort(Array * array, int (*compare) (void *, void *))
ArrayQuickSort(array, 0, array->size - 1, compare);
}
Array *
ArrayUnique(Array * array, int (*compare) (void *, void *))
{
Array *ret;
size_t i;
if (!array)
{
return NULL;
}
ret = ArrayDuplicate(array);
if (!ret)
{
return NULL;
}
if (ArraySize(ret) == 1)
{
/* There can't be any duplicates when there's only 1 value */
return ret;
}
ArraySort(ret, compare);
for (i = 1; i < ArraySize(ret); i++)
{
void *cur = ret->entries[i];
void *prev = ret->entries[i - 1];
if (compare(cur, prev) == 0)
{
/* Remove the duplicate, and put i back where it was. */
ArrayDelete(ret, i--);
}
}
ArrayTrim(ret);
return ret;
}
/* Even though the following operations could be done using only the
* public Array API defined above, I opted for low-level struct
* manipulation because it allows much more efficient copying; we only

27
Cytoplasm/src/include/Array.h
View file

@ -64,7 +64,7 @@ typedef struct Array Array;
* used with the other functions in this API, or NULL if there was an
* error allocating memory for the array.
*/
extern Array * ArrayCreate(void);
extern Array *ArrayCreate(void);
/**
* Deallocate an array. Note that this function does not free any of
@ -88,7 +88,7 @@ extern size_t ArraySize(Array *);
* or
* .Fn ArraySet .
*/
extern void * ArrayGet(Array *, size_t);
extern void *ArrayGet(Array *, size_t);
/**
* Insert the specified element at the specified index in the specified
@ -105,7 +105,7 @@ extern int ArrayInsert(Array *, size_t, void *);
* specified value. This function will return the old value at that
* index, if any.
*/
extern void * ArraySet(Array *, size_t, void *);
extern void *ArraySet(Array *, size_t, void *);
/**
* Append the specified element to the end of the specified array. This
@ -121,7 +121,7 @@ extern int ArrayAdd(Array *, void *);
* Remove the element at the specified index from the specified array.
* This function returns the element removed, if any.
*/
extern void * ArrayDelete(Array *, size_t);
extern void *ArrayDelete(Array *, size_t);
/**
* Sort the specified array using the specified sort function. The
@ -136,6 +136,21 @@ extern void * ArrayDelete(Array *, size_t);
*/
extern void ArraySort(Array *, int (*) (void *, void *));
/**
* Remove all duplicates from an array by using the given comparison
* function to sort the array, then remove matching values. This
* function returns a new array with all duplicates removed. The
* original array is unaffected. Note that arrays only store pointers
* to values, usually values on the heap. Thus, it is possible to lose
* pointers to duplicate values and have them leak.
* .P
* This is a relatively expensive operation. The array must first be
* duplicated. Then it is sorted, then it is iterated from beginning
* to end to remove duplicate entires. Note that the comparison
* function is executed on each element at least twice.
*/
extern Array *ArrayUnique(Array *, int (*) (void *, void *));
/**
* If possible, reduce the amount of memory allocated to this array
* by calling
@ -152,13 +167,13 @@ extern int ArrayTrim(Array *);
* .Fn va_arg
* and friends.
*/
extern Array * ArrayFromVarArgs(size_t, va_list);
extern Array *ArrayFromVarArgs(size_t, va_list);
/**
* Duplicate an existing array. Note that arrays only hold pointers to
* their data, not the data itself, so the duplicated array will point
* to the same places in memory as the original array.
*/
extern Array * ArrayDuplicate(Array *);
extern Array *ArrayDuplicate(Array *);
#endif /* CYTOPLASM_ARRAY_H */