68 lines
1.6 KiB
C
68 lines
1.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* qunique.h
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* inline array unique functions
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* Portions Copyright (c) 2019-2024, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* src/include/lib/qunique.h
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*-------------------------------------------------------------------------
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*/
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#ifndef QUNIQUE_H
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#define QUNIQUE_H
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/*
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* Remove duplicates from a pre-sorted array, according to a user-supplied
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* comparator. Usually the array should have been sorted with qsort() using
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* the same arguments. Return the new size.
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*/
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static inline size_t
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qunique(void *array, size_t elements, size_t width,
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int (*compare) (const void *, const void *))
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{
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char *bytes = (char *) array;
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size_t i,
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j;
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if (elements <= 1)
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return elements;
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for (i = 1, j = 0; i < elements; ++i)
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{
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if (compare(bytes + i * width, bytes + j * width) != 0 &&
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++j != i)
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memcpy(bytes + j * width, bytes + i * width, width);
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}
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return j + 1;
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}
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/*
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* Like qunique(), but takes a comparator with an extra user data argument
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* which is passed through, for compatibility with qsort_arg().
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*/
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static inline size_t
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qunique_arg(void *array, size_t elements, size_t width,
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int (*compare) (const void *, const void *, void *),
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void *arg)
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{
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char *bytes = (char *) array;
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size_t i,
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j;
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if (elements <= 1)
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return elements;
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for (i = 1, j = 0; i < elements; ++i)
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{
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if (compare(bytes + i * width, bytes + j * width, arg) != 0 &&
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++j != i)
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memcpy(bytes + j * width, bytes + i * width, width);
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}
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return j + 1;
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}
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#endif /* QUNIQUE_H */
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