Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * arrayaccess.h
       4             :  *    Declarations for element-by-element access to Postgres arrays.
       5             :  *
       6             :  *
       7             :  * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
       8             :  * Portions Copyright (c) 1994, Regents of the University of California
       9             :  *
      10             :  * src/include/utils/arrayaccess.h
      11             :  *
      12             :  *-------------------------------------------------------------------------
      13             :  */
      14             : #ifndef ARRAYACCESS_H
      15             : #define ARRAYACCESS_H
      16             : 
      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,
      26             :  * and "datumvar = array_iter_next(&iter, &isnullvar, index);" to fetch
      27             :  * the next element into datumvar/isnullvar.
      28             :  * "index" must be the zero-origin element number; we make caller provide
      29             :  * this since caller is generally counting the elements anyway.  Despite
      30             :  * that, these functions can only fetch elements sequentially.
      31             :  */
      32             : 
      33             : typedef struct array_iter
      34             : {
      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             : 
      46             :     /* Fields used in both cases: data about array's element type */
      47             :     int         elmlen;
      48             :     bool        elmbyval;
      49             :     uint8       elmalignby;
      50             : } array_iter;
      51             : 
      52             : 
      53             : static inline void
      54    18175994 : array_iter_setup(array_iter *it, AnyArrayType *a,
      55             :                  int elmlen, bool elmbyval, char elmalign)
      56             : {
      57    18175994 :     if (VARATT_IS_EXPANDED_HEADER(a))
      58             :     {
      59        7292 :         if (a->xpn.dvalues)
      60             :         {
      61        2730 :             it->datumptr = a->xpn.dvalues;
      62        2730 :             it->isnullptr = a->xpn.dnulls;
      63             :             /* we must fill all fields to prevent compiler warnings */
      64        2730 :             it->dataptr = NULL;
      65        2730 :             it->bitmapptr = NULL;
      66             :         }
      67             :         else
      68             :         {
      69             :             /* Work with flat array embedded in the expanded datum */
      70        4562 :             it->datumptr = NULL;
      71        4562 :             it->isnullptr = NULL;
      72        4562 :             it->dataptr = ARR_DATA_PTR(a->xpn.fvalue);
      73        4562 :             it->bitmapptr = ARR_NULLBITMAP(a->xpn.fvalue);
      74             :         }
      75             :     }
      76             :     else
      77             :     {
      78    18168702 :         it->datumptr = NULL;
      79    18168702 :         it->isnullptr = NULL;
      80    18168702 :         it->dataptr = ARR_DATA_PTR((ArrayType *) a);
      81    18168702 :         it->bitmapptr = ARR_NULLBITMAP((ArrayType *) a);
      82             :     }
      83    18175994 :     it->bitmask = 1;
      84    18175994 :     it->elmlen = elmlen;
      85    18175994 :     it->elmbyval = elmbyval;
      86    18175994 :     it->elmalignby = typalign_to_alignby(elmalign);
      87    18175994 : }
      88             : 
      89             : static inline Datum
      90    34092744 : array_iter_next(array_iter *it, bool *isnull, int i)
      91             : {
      92             :     Datum       ret;
      93             : 
      94    34092744 :     if (it->datumptr)
      95             :     {
      96      183324 :         ret = it->datumptr[i];
      97      183324 :         *isnull = it->isnullptr ? it->isnullptr[i] : false;
      98             :     }
      99             :     else
     100             :     {
     101    33909420 :         if (it->bitmapptr && (*(it->bitmapptr) & it->bitmask) == 0)
     102             :         {
     103       34556 :             *isnull = true;
     104       34556 :             ret = (Datum) 0;
     105             :         }
     106             :         else
     107             :         {
     108    33874864 :             *isnull = false;
     109    33874864 :             ret = fetch_att(it->dataptr, it->elmbyval, it->elmlen);
     110    33874864 :             it->dataptr = att_addlength_pointer(it->dataptr, it->elmlen,
     111             :                                                 it->dataptr);
     112    33874864 :             it->dataptr = (char *) att_nominal_alignby(it->dataptr,
     113             :                                                        it->elmalignby);
     114             :         }
     115    33909420 :         it->bitmask <<= 1;
     116    33909420 :         if (it->bitmask == 0x100)
     117             :         {
     118      199554 :             if (it->bitmapptr)
     119        7782 :                 it->bitmapptr++;
     120      199554 :             it->bitmask = 1;
     121             :         }
     122             :     }
     123             : 
     124    34092744 :     return ret;
     125             : }
     126             : 
     127             : #endif                          /* ARRAYACCESS_H */