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[boost][range] - ticket 5544 - fix for termination of irange - done properly for negative step sizes.

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[SVN r72097]
This commit is contained in:
Neil Groves
2011-05-22 19:59:59 +00:00
parent df1a3a334f
commit 5ed6116490
2 changed files with 44 additions and 24 deletions
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19
include/boost/range/irange.hpp
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@ -124,13 +124,11 @@ namespace boost
typedef typename base_t::difference_type difference_type;
typedef typename base_t::reference reference;
integer_iterator_with_step(value_type first, value_type step, difference_type step_size)
integer_iterator_with_step(value_type first, difference_type step, value_type step_size)
: m_first(first)
, m_step(step)
, m_step_size(step_size)
{
BOOST_ASSERT( step >= 0 );
BOOST_ASSERT( step_size != 0 );
}
private:
@ -213,17 +211,18 @@ namespace boost
{
BOOST_ASSERT( step_size != 0 );
BOOST_ASSERT( (step_size > 0) ? (last >= first) : (last <= first) );
typedef typename range_detail::integer_iterator_with_step<Integer> iterator_t;
const std::ptrdiff_t l = static_cast<std::ptrdiff_t>(last);
const std::ptrdiff_t f = static_cast<std::ptrdiff_t>(first);
const std::ptrdiff_t sz = static_cast<std::ptrdiff_t>(step_size);
const std::ptrdiff_t last_step = (l + ((l-f) % sz) - f) / sz;
const std::ptrdiff_t sz = static_cast<std::ptrdiff_t>(step_size >= 0 ? step_size : -step_size);
const Integer l = step_size >= 0 ? last : first;
const Integer f = step_size >= 0 ? first : last;
const std::ptrdiff_t num_steps = (l + ((l-f) % sz) - f) / sz;
BOOST_ASSERT(num_steps >= 0);
return strided_integer_range<Integer>(
iterator_t(first, 0, step_size),
iterator_t(first, last_step, step_size));
iterator_t(first, num_steps, step_size));
}
} // namespace boost