codekingpro/portable-devtools

1/*-------------------------------------------------------------------------2 *3 * arrayaccess.h4 *	  Declarations for element-by-element access to Postgres arrays.5 *6 *7 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group8 * Portions Copyright (c) 1994, Regents of the University of California9 *10 * src/include/utils/arrayaccess.h11 *12 *-------------------------------------------------------------------------13 */14#ifndef ARRAYACCESS_H15#define ARRAYACCESS_H16 17#include "access/tupmacs.h"18#include "utils/array.h"19 20 21/*22 * Functions for iterating through elements of a flat or expanded array.23 * These require a state struct "array_iter iter".24 *25 * Use "array_iter_setup(&iter, arrayptr);" to prepare to iterate, and26 * "datumvar = array_iter_next(&iter, &isnullvar, index, ...);" to fetch27 * the next element into datumvar/isnullvar.28 * "index" must be the zero-origin element number; we make caller provide29 * this since caller is generally counting the elements anyway.  Despite30 * that, these functions can only fetch elements sequentially.31 */32 33typedef struct array_iter34{35	/* datumptr being NULL or not tells if we have flat or expanded array */36 37	/* Fields used when we have an expanded array */38	Datum	   *datumptr;		/* Pointer to Datum array */39	bool	   *isnullptr;		/* Pointer to isnull array */40 41	/* Fields used when we have a flat array */42	char	   *dataptr;		/* Current spot in the data area */43	bits8	   *bitmapptr;		/* Current byte of the nulls bitmap, or NULL */44	int			bitmask;		/* mask for current bit in nulls bitmap */45} array_iter;46 47 48static inline void49array_iter_setup(array_iter *it, AnyArrayType *a)50{51	if (VARATT_IS_EXPANDED_HEADER(a))52	{53		if (a->xpn.dvalues)54		{55			it->datumptr = a->xpn.dvalues;56			it->isnullptr = a->xpn.dnulls;57			/* we must fill all fields to prevent compiler warnings */58			it->dataptr = NULL;59			it->bitmapptr = NULL;60		}61		else62		{63			/* Work with flat array embedded in the expanded datum */64			it->datumptr = NULL;65			it->isnullptr = NULL;66			it->dataptr = ARR_DATA_PTR(a->xpn.fvalue);67			it->bitmapptr = ARR_NULLBITMAP(a->xpn.fvalue);68		}69	}70	else71	{72		it->datumptr = NULL;73		it->isnullptr = NULL;74		it->dataptr = ARR_DATA_PTR((ArrayType *) a);75		it->bitmapptr = ARR_NULLBITMAP((ArrayType *) a);76	}77	it->bitmask = 1;78}79 80static inline Datum81array_iter_next(array_iter *it, bool *isnull, int i,82				int elmlen, bool elmbyval, char elmalign)83{84	Datum		ret;85 86	if (it->datumptr)87	{88		ret = it->datumptr[i];89		*isnull = it->isnullptr ? it->isnullptr[i] : false;90	}91	else92	{93		if (it->bitmapptr && (*(it->bitmapptr) & it->bitmask) == 0)94		{95			*isnull = true;96			ret = (Datum) 0;97		}98		else99		{100			*isnull = false;101			ret = fetch_att(it->dataptr, elmbyval, elmlen);102			it->dataptr = att_addlength_pointer(it->dataptr, elmlen,103												it->dataptr);104			it->dataptr = (char *) att_align_nominal(it->dataptr, elmalign);105		}106		it->bitmask <<= 1;107		if (it->bitmask == 0x100)108		{109			if (it->bitmapptr)110				it->bitmapptr++;111			it->bitmask = 1;112		}113	}114 115	return ret;116}117 118#endif							/* ARRAYACCESS_H */119