text: /* -------------------------------------------------------------------------
   *
   * arrayutils.c
   *	  This file contains some support routines required for array functions.
   *
   * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
   *
   * IDENTIFICATION
   *	  src/backend/utils/adt/arrayutils.c
   *
   * -------------------------------------------------------------------------
   */
  
  #include "postgres.h"
  #include "knl/knl_variable.h"
  
  #include "catalog/pg_type.h"
  #include "utils/array.h"
  #include "utils/builtins.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 ArrayGetOffset(int n, const int* dim, const int* lb, const int* indx)
  {
      int i;
      int scale = 1;
      int offset = 0;
  
      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 ArrayGetOffset0(int n, const int* tup, const int* scale)
  {
      int i;
      int lin = 0;
  
      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 ArrayGetNItems(int ndim, const int* dims)
  {
      int32 ret;
      int i;
  
  #define MaxArraySize ((Size)(MaxAllocSize / sizeof(Datum)))
  
      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, const int* st, const int* endp)
  {
      int i;
  
      for (i = 0; i < n; 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, const int* range, int* prod)
  {
      int i;
  
      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 mda_get_offset_values(int n, int* dist, const int* prod, const int* span)
  {
      int i, j;
  
      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 -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 mda_next_tuple(int n, int* curr, const int* span)
  {
      int i;
  
      if (n <= 0) {
          return -1;
      }
  
  
      curr[n - 1] = (curr[n - 1] + 1) % span[n - 1];
      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;
  }
  
  /*
   * ArrayGetIntegerTypmods: verify that argument is a 1-D cstring array,
   * and get the contents converted to integers.	Returns a palloc'd array
   * and places the length at *n.
   */
  int32* ArrayGetIntegerTypmods(ArrayType* arr, int* n)
  {
      int32* result = NULL;
      Datum* elem_values = NULL;
      int i;
  
      if (ARR_ELEMTYPE(arr) != CSTRINGOID) {
          ereport(ERROR, (errcode(ERRCODE_ARRAY_ELEMENT_ERROR), errmsg("typmod array must be type cstring[]")));
      }
  
  
      if (ARR_NDIM(arr) != 1) {
          ereport(ERROR, (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR), errmsg("typmod array must be one-dimensional")));
      }
  
  
      if (array_contains_nulls(arr)) {
          ereport(ERROR, (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED), errmsg("typmod array must not contain nulls")));
      }
  
  
      /* hardwired knowledge about cstring's representation details here */
      deconstruct_array(arr, CSTRINGOID, -2, false, 'c', &elem_values, NULL, n);
  
      result = (int32*)palloc(*n * sizeof(int32));
  
      for (i = 0; i < *n; i++) {
          result[i] = pg_strtoint32(DatumGetCString(elem_values[i]));
      }
  
  
      pfree_ext(elem_values);
  
      return result;
  }
  