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) 1996-2017, 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       38096 : array_iter_setup(array_iter *it, AnyArrayType *a)
      50             : {
      51       38096 :     if (VARATT_IS_EXPANDED_HEADER(a))
      52             :     {
      53         806 :         if (a->xpn.dvalues)
      54             :         {
      55         254 :             it->datumptr = a->xpn.dvalues;
      56         254 :             it->isnullptr = a->xpn.dnulls;
      57             :             /* we must fill all fields to prevent compiler warnings */
      58         254 :             it->dataptr = NULL;
      59         254 :             it->bitmapptr = NULL;
      60             :         }
      61             :         else
      62             :         {
      63             :             /* Work with flat array embedded in the expanded datum */
      64         552 :             it->datumptr = NULL;
      65         552 :             it->isnullptr = NULL;
      66         552 :             it->dataptr = ARR_DATA_PTR(a->xpn.fvalue);
      67         552 :             it->bitmapptr = ARR_NULLBITMAP(a->xpn.fvalue);
      68             :         }
      69             :     }
      70             :     else
      71             :     {
      72       37290 :         it->datumptr = NULL;
      73       37290 :         it->isnullptr = NULL;
      74       37290 :         it->dataptr = ARR_DATA_PTR(&a->flt);
      75       37290 :         it->bitmapptr = ARR_NULLBITMAP(&a->flt);
      76             :     }
      77       38096 :     it->bitmask = 1;
      78       38096 : }
      79             : 
      80             : static inline Datum
      81      103393 : array_iter_next(array_iter *it, bool *isnull, int i,
      82             :                 int elmlen, bool elmbyval, char elmalign)
      83             : {
      84             :     Datum       ret;
      85             : 
      86      103393 :     if (it->datumptr)
      87             :     {
      88       18300 :         ret = it->datumptr[i];
      89       18300 :         *isnull = it->isnullptr ? it->isnullptr[i] : false;
      90             :     }
      91             :     else
      92             :     {
      93       85093 :         if (it->bitmapptr && (*(it->bitmapptr) & it->bitmask) == 0)
      94             :         {
      95         595 :             *isnull = true;
      96         595 :             ret = (Datum) 0;
      97             :         }
      98             :         else
      99             :         {
     100       84498 :             *isnull = false;
     101       84498 :             ret = fetch_att(it->dataptr, elmbyval, elmlen);
     102       84498 :             it->dataptr = att_addlength_pointer(it->dataptr, elmlen,
     103             :                                                 it->dataptr);
     104       84498 :             it->dataptr = (char *) att_align_nominal(it->dataptr, elmalign);
     105             :         }
     106       85093 :         it->bitmask <<= 1;
     107       85093 :         if (it->bitmask == 0x100)
     108             :         {
     109        3011 :             if (it->bitmapptr)
     110          42 :                 it->bitmapptr++;
     111        3011 :             it->bitmask = 1;
     112             :         }
     113             :     }
     114             : 
     115      103393 :     return ret;
     116             : }
     117             : 
     118             : #endif                          /* ARRAYACCESS_H */