119 lines
3.0 KiB
C
119 lines
3.0 KiB
C
/*-------------------------------------------------------------------------
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*
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* arrayaccess.h
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* Declarations for element-by-element access to Postgres arrays.
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*
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*
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* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/utils/arrayaccess.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef ARRAYACCESS_H
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#define ARRAYACCESS_H
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#include "access/tupmacs.h"
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#include "utils/array.h"
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/*
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* Functions for iterating through elements of a flat or expanded array.
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* These require a state struct "array_iter iter".
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*
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* Use "array_iter_setup(&iter, arrayptr);" to prepare to iterate, and
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* "datumvar = array_iter_next(&iter, &isnullvar, index, ...);" to fetch
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* the next element into datumvar/isnullvar.
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* "index" must be the zero-origin element number; we make caller provide
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* this since caller is generally counting the elements anyway. Despite
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* that, these functions can only fetch elements sequentially.
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*/
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typedef struct array_iter
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{
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/* datumptr being NULL or not tells if we have flat or expanded array */
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/* Fields used when we have an expanded array */
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Datum *datumptr; /* Pointer to Datum array */
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bool *isnullptr; /* Pointer to isnull array */
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/* Fields used when we have a flat array */
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char *dataptr; /* Current spot in the data area */
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bits8 *bitmapptr; /* Current byte of the nulls bitmap, or NULL */
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int bitmask; /* mask for current bit in nulls bitmap */
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} array_iter;
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static inline void
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array_iter_setup(array_iter *it, AnyArrayType *a)
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{
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if (VARATT_IS_EXPANDED_HEADER(a))
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{
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if (a->xpn.dvalues)
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{
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it->datumptr = a->xpn.dvalues;
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it->isnullptr = a->xpn.dnulls;
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/* we must fill all fields to prevent compiler warnings */
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it->dataptr = NULL;
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it->bitmapptr = NULL;
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}
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else
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{
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/* Work with flat array embedded in the expanded datum */
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it->datumptr = NULL;
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it->isnullptr = NULL;
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it->dataptr = ARR_DATA_PTR(a->xpn.fvalue);
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it->bitmapptr = ARR_NULLBITMAP(a->xpn.fvalue);
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}
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}
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else
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{
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it->datumptr = NULL;
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it->isnullptr = NULL;
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it->dataptr = ARR_DATA_PTR((ArrayType *) a);
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it->bitmapptr = ARR_NULLBITMAP((ArrayType *) a);
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}
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it->bitmask = 1;
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}
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static inline Datum
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array_iter_next(array_iter *it, bool *isnull, int i,
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int elmlen, bool elmbyval, char elmalign)
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{
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Datum ret;
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if (it->datumptr)
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{
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ret = it->datumptr[i];
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*isnull = it->isnullptr ? it->isnullptr[i] : false;
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}
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else
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{
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if (it->bitmapptr && (*(it->bitmapptr) & it->bitmask) == 0)
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{
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*isnull = true;
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ret = (Datum) 0;
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}
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else
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{
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*isnull = false;
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ret = fetch_att(it->dataptr, elmbyval, elmlen);
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it->dataptr = att_addlength_pointer(it->dataptr, elmlen,
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it->dataptr);
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it->dataptr = (char *) att_align_nominal(it->dataptr, elmalign);
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}
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it->bitmask <<= 1;
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if (it->bitmask == 0x100)
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{
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if (it->bitmapptr)
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it->bitmapptr++;
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it->bitmask = 1;
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}
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}
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return ret;
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}
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#endif /* ARRAYACCESS_H */
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