/*-------------------------------------------------------------------------
*
- * arrayutils.c--
+ * arrayutils.c
* This file contains some support routines required for array functions.
*
- * Copyright (c) 1994, Regents of the University of California
+ * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/arrayutils.c,v 1.6 1998/09/01 03:25:47 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/arrayutils.c,v 1.21 2006/03/05 15:58:41 momjian Exp $
*
*-------------------------------------------------------------------------
*/
-#define WEAK_C_OPTIMIZER
-
#include "postgres.h"
#include "utils/array.h"
+#include "utils/memutils.h"
+
+/*
+ * Convert subscript list into linear element number (from 0)
+ *
+ * We assume caller has already range-checked the dimensions and subscripts,
+ * so no overflow is possible.
+ */
int
-GetOffset(int n, int *dim, int *lb, int *indx)
+ArrayGetOffset(int n, const int *dim, const int *lb, const int *indx)
{
int i,
- scale,
- offset;
+ scale = 1,
+ offset = 0;
- for (i = n - 1, scale = 1, offset = 0; i >= 0; scale *= dim[i--])
+ for (i = n - 1; i >= 0; i--)
+ {
offset += (indx[i] - lb[i]) * scale;
+ scale *= dim[i];
+ }
return offset;
}
+/*
+ * Same, but subscripts are assumed 0-based, and use a scale array
+ * instead of raw dimension data (see mda_get_prod to create scale array)
+ */
int
-getNitems(int n, int *a)
+ArrayGetOffset0(int n, const int *tup, const int *scale)
{
int i,
- ret;
+ lin = 0;
- for (i = 0, ret = 1; i < n; ret *= a[i++]);
- if (n == 0)
- ret = 0;
- return ret;
+ for (i = 0; i < n; i++)
+ lin += tup[i] * scale[i];
+ return lin;
}
+/*
+ * Convert array dimensions into number of elements
+ *
+ * This must do overflow checking, since it is used to validate that a user
+ * dimensionality request doesn't overflow what we can handle.
+ *
+ * We limit array sizes to at most about a quarter billion elements,
+ * so that it's not necessary to check for overflow in quite so many
+ * places --- for instance when palloc'ing Datum arrays.
+ *
+ * The multiplication overflow check only works on machines that have int64
+ * arithmetic, but that is nearly all platforms these days, and doing check
+ * divides for those that don't seems way too expensive.
+ */
int
-compute_size(int *st, int *endp, int n, int base)
+ArrayGetNItems(int ndim, const int *dims)
{
- int i,
- ret;
+ int32 ret;
+ int i;
- for (i = 0, ret = base; i < n; i++)
- ret *= (endp[i] - st[i] + 1);
- return ret;
-}
+#define MaxArraySize ((Size) (MaxAllocSize / sizeof(Datum)))
-void
-mda_get_offset_values(int n, int *dist, int *PC, int *span)
-{
- int i,
- j;
-
- for (j = n - 2, dist[n - 1] = 0; j >= 0; j--)
- for (i = j + 1, dist[j] = PC[j] - 1; i < n;
- dist[j] -= (span[i] - 1) * PC[i], i++);
+ if (ndim <= 0)
+ return 0;
+ ret = 1;
+ for (i = 0; i < ndim; i++)
+ {
+ int64 prod;
+
+ /* A negative dimension implies that UB-LB overflowed ... */
+ if (dims[i] < 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+ errmsg("array size exceeds the maximum allowed (%d)",
+ (int) MaxArraySize)));
+
+ prod = (int64) ret *(int64) dims[i];
+
+ ret = (int32) prod;
+ if ((int64) ret != prod)
+ ereport(ERROR,
+ (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+ errmsg("array size exceeds the maximum allowed (%d)",
+ (int) MaxArraySize)));
+ }
+ Assert(ret >= 0);
+ if ((Size) ret > MaxArraySize)
+ ereport(ERROR,
+ (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+ errmsg("array size exceeds the maximum allowed (%d)",
+ (int) MaxArraySize)));
+ return (int) ret;
}
+/*
+ * Compute ranges (sub-array dimensions) for an array slice
+ *
+ * We assume caller has validated slice endpoints, so overflow is impossible
+ */
void
-mda_get_range(int n, int *span, int *st, int *endp)
+mda_get_range(int n, int *span, const int *st, const int *endp)
{
int i;
span[i] = endp[i] - st[i] + 1;
}
+/*
+ * Compute products of array dimensions, ie, scale factors for subscripts
+ *
+ * We assume caller has validated dimensions, so overflow is impossible
+ */
void
-mda_get_prod(int n, int *range, int *P)
+mda_get_prod(int n, const int *range, int *prod)
{
int i;
- for (i = n - 2, P[n - 1] = 1; i >= 0; i--)
- P[i] = P[i + 1] * range[i + 1];
-}
-
-int
-tuple2linear(int n, int *tup, int *scale)
-{
- int i,
- lin;
-
- for (i = lin = 0; i < n; i++)
- lin += tup[i] * scale[i];
- return lin;
+ prod[n - 1] = 1;
+ for (i = n - 2; i >= 0; i--)
+ prod[i] = prod[i + 1] * range[i + 1];
}
+/*
+ * From products of whole-array dimensions and spans of a sub-array,
+ * compute offset distances needed to step through subarray within array
+ *
+ * We assume caller has validated dimensions, so overflow is impossible
+ */
void
-array2chunk_coord(int n, int *C, int *a_coord, int *c_coord)
+mda_get_offset_values(int n, int *dist, const int *prod, const int *span)
{
- int i;
+ int i,
+ j;
- for (i = 0; i < n; i++)
- c_coord[i] = a_coord[i] / C[i];
+ dist[n - 1] = 0;
+ for (j = n - 2; j >= 0; j--)
+ {
+ dist[j] = prod[j] - 1;
+ for (i = j + 1; i < n; i++)
+ dist[j] -= (span[i] - 1) * prod[i];
+ }
}
-/*-----------------------------------------------------------------------------
- generates the tuple that is lexicographically one greater than the current
- n-tuple in "curr", with the restriction that the i-th element of "curr" is
- less than the i-th element of "span".
- RETURNS 0 if no next tuple exists
- 1 otherwise
- -----------------------------------------------------------------------------*/
+/*
+ * Generates the tuple that is lexicographically one greater than the current
+ * n-tuple in "curr", with the restriction that the i-th element of "curr" is
+ * less than the i-th element of "span".
+ *
+ * Returns -1 if no next tuple exists, else the subscript position (0..n-1)
+ * corresponding to the dimension to advance along.
+ *
+ * We assume caller has validated dimensions, so overflow is impossible
+ */
int
-next_tuple(int n, int *curr, int *span)
+mda_next_tuple(int n, int *curr, const int *span)
{
int i;
- if (!n)
+ if (n <= 0)
return -1;
+
curr[n - 1] = (curr[n - 1] + 1) % span[n - 1];
- for (i = n - 1; i * (!curr[i]); i--)
+ for (i = n - 1; i && curr[i] == 0; i--)
curr[i - 1] = (curr[i - 1] + 1) % span[i - 1];
if (i)
return i;
if (curr[0])
return 0;
+
return -1;
}
projects / postgresql / blobdiff