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Fixed an assertion error...resize needs to account for starting with

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an empty array when considering legal ranges.
Some small housecleaning (renaming variables, moving asserts).


[SVN r62963]
This commit is contained in:
Ronald Garcia 2010-06-15 01:40:31 +00:00
parent f38af67708
commit 029dde4039
1 changed files with 36 additions and 13 deletions
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49
include/boost/multi_array/base.hpp
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@ -431,29 +431,52 @@ protected:
index offset = 0;
size_type dim = 0;
for (size_type n = 0; n != NumDims; ++n) {
// Use array specs and input specs to produce real specs.
const index default_start = index_bases[n];
const index default_finish = default_start+extents[n];
const index_range& current_range = indices.ranges_[n];
index start = current_range.get_start(default_start);
index finish = current_range.get_finish(default_finish);
index factor = current_range.stride();
index stride = current_range.stride();
BOOST_ASSERT(stride != 0);
// integral trick for ceiling((finish-start) / factor)
index shrinkage = factor > 0 ? 1 : -1;
index len = (finish - start + (factor - shrinkage)) / factor;
// An index range indicates a half-open strided interval
// [start,finish) (with stride) which faces upward when stride
// is positive and downward when stride is negative,
// RG: The following code for calculating length suffers from
// some representation issues: if finish-start cannot be represented as
// by type index, then overflow may result.
index len;
if ((finish - start) / stride < 0) {
// [start,finish) is empty according to the direction imposed by
// the stride.
len = 0;
} else {
// integral trick for ceiling((finish-start) / stride)
// taking into account signs.
index shrinkage = stride > 0 ? 1 : -1;
len = (finish - start + (stride - shrinkage)) / stride;
}
// start marks the closed side of the range, so it must lie
// exactly in the set of legal indices
// with a special case for empty arrays
BOOST_ASSERT(index_bases[n] <= start &&
start < index_bases[n]+index(extents[n]));
((start <= index_bases[n]+index(extents[n])) ||
(start == index_bases[n] && extents[n] == 0)));
#ifndef BOOST_DISABLE_ASSERTS
// The legal values of finish depends on the sign of the factor
index lb_adjustment = factor < 0 ? 1 : 0;
index ub_adjustment = factor > 0 ? 1 : 0;
BOOST_ASSERT(index_bases[n] - lb_adjustment <= finish &&
finish < index_bases[n]+index(extents[n]) + ub_adjustment);
// finish marks the open side of the range, so it can go one past
// the "far side" of the range (the top if stride is positive, the bottom
// if stride is negative).
index bound_adjustment = stride < 0 ? 1 : 0;
BOOST_ASSERT(((index_bases[n] - bound_adjustment) <= finish) &&
(finish <= (index_bases[n] + index(extents[n]) - bound_adjustment)));
#endif // BOOST_DISABLE_ASSERTS
BOOST_ASSERT(factor != 0);
// the array data pointer is modified to account for non-zero
// bases during slicing (see [Garcia] for the math involved)
@ -461,9 +484,9 @@ protected:
if (!current_range.is_degenerate()) {
// The factor for each dimension is included into the
// The stride for each dimension is included into the
// strides for the array_view (see [Garcia] for the math involved).
new_strides[dim] = factor * strides[n];
new_strides[dim] = stride * strides[n];
// calculate new extents
new_extents[dim] = len;