TLA  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) 1996-2023, 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, and
      26                 :  * "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                 : } array_iter;
      46                 : 
      47                 : 
      48                 : static inline void
      49 CBC    11968372 : array_iter_setup(array_iter *it, AnyArrayType *a)
      50                 : {
      51        11968372 :     if (VARATT_IS_EXPANDED_HEADER(a))
      52                 :     {
      53            3624 :         if (a->xpn.dvalues)
      54                 :         {
      55            1359 :             it->datumptr = a->xpn.dvalues;
      56            1359 :             it->isnullptr = a->xpn.dnulls;
      57                 :             /* we must fill all fields to prevent compiler warnings */
      58            1359 :             it->dataptr = NULL;
      59            1359 :             it->bitmapptr = NULL;
      60                 :         }
      61                 :         else
      62                 :         {
      63                 :             /* Work with flat array embedded in the expanded datum */
      64            2265 :             it->datumptr = NULL;
      65            2265 :             it->isnullptr = NULL;
      66            2265 :             it->dataptr = ARR_DATA_PTR(a->xpn.fvalue);
      67            2265 :             it->bitmapptr = ARR_NULLBITMAP(a->xpn.fvalue);
      68                 :         }
      69                 :     }
      70                 :     else
      71                 :     {
      72        11964748 :         it->datumptr = NULL;
      73        11964748 :         it->isnullptr = NULL;
      74        11964748 :         it->dataptr = ARR_DATA_PTR((ArrayType *) a);
      75        11964748 :         it->bitmapptr = ARR_NULLBITMAP((ArrayType *) a);
      76                 :     }
      77        11968372 :     it->bitmask = 1;
      78        11968372 : }
      79                 : 
      80                 : static inline Datum
      81        21961854 : array_iter_next(array_iter *it, bool *isnull, int i,
      82                 :                 int elmlen, bool elmbyval, char elmalign)
      83                 : {
      84                 :     Datum       ret;
      85                 : 
      86        21961854 :     if (it->datumptr)
      87                 :     {
      88           91638 :         ret = it->datumptr[i];
      89           91638 :         *isnull = it->isnullptr ? it->isnullptr[i] : false;
      90                 :     }
      91                 :     else
      92                 :     {
      93        21870216 :         if (it->bitmapptr && (*(it->bitmapptr) & it->bitmask) == 0)
      94                 :         {
      95           17128 :             *isnull = true;
      96           17128 :             ret = (Datum) 0;
      97                 :         }
      98                 :         else
      99                 :         {
     100        21853088 :             *isnull = false;
     101        21853088 :             ret = fetch_att(it->dataptr, elmbyval, elmlen);
     102        21853088 :             it->dataptr = att_addlength_pointer(it->dataptr, elmlen,
     103                 :                                                 it->dataptr);
     104        21853088 :             it->dataptr = (char *) att_align_nominal(it->dataptr, elmalign);
     105                 :         }
     106        21870216 :         it->bitmask <<= 1;
     107        21870216 :         if (it->bitmask == 0x100)
     108                 :         {
     109           96277 :             if (it->bitmapptr)
     110            3861 :                 it->bitmapptr++;
     111           96277 :             it->bitmask = 1;
     112                 :         }
     113                 :     }
     114                 : 
     115        21961854 :     return ret;
     116                 : }
     117                 : 
     118                 : #endif                          /* ARRAYACCESS_H */