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Implement partial "operator-" for local iterators.

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This commit is contained in:
Ion Gaztañaga
2026-03-17 23:26:06 +01:00
parent ba853bbd0d
commit 384bb236c4
1 changed files with 30 additions and 20 deletions
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include/boost/container/experimental/nest.hpp
+30 -20
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@@ -232,7 +232,7 @@ struct pointer_rebind
//
//////////////////////////////////////////////
inline int unchecked_countr_zero(boost::uint64_t x)
BOOST_CONTAINER_FORCEINLINE int unchecked_countr_zero(boost::uint64_t x)
{
#if defined(BOOST_MSVC) && (defined(_M_X64) || defined(_M_ARM64))
unsigned long r;
@@ -265,20 +265,6 @@ BOOST_CONTAINER_FORCEINLINE int unchecked_countl_zero(boost::uint64_t x)
#endif
}
inline int countr_zero(boost::uint64_t x)
{
return (int)boost::core::countr_zero(x);
}
BOOST_CONTAINER_FORCEINLINE int countr_one(boost::uint64_t x)
{
return unchecked_countr_zero(~x);
}
BOOST_CONTAINER_FORCEINLINE int countl_zero(boost::uint64_t x)
{
return (int)boost::core::countl_zero(x);
}
@@ -715,7 +701,7 @@ private:
//
//////////////////////////////////////////////
//#define NEST_LOCAL_ITERATOR_FULL
#define NEST_LOCAL_ITERATOR_FULL
#if defined(NEST_LOCAL_ITERATOR_FULL)
template<class ValuePointer, bool StoreDataInBlock>
@@ -759,8 +745,9 @@ public:
BOOST_CONTAINER_FORCEINLINE nest_local_iterator& operator++() BOOST_NOEXCEPT
{
BOOST_CONTAINER_NEST_ASSUME(n != (int)N); // Undefined behavior otherwise
const mask_type m = pbb->mask & (full_l << std::size_t(n));
n = nest_detail::countr_zero(m);
n = m ? nest_detail::unchecked_countr_zero(m) : (int)N;
return *this;
}
@@ -769,6 +756,7 @@ public:
BOOST_CONTAINER_FORCEINLINE nest_local_iterator& operator--() BOOST_NOEXCEPT
{
BOOST_CONTAINER_NEST_ASSUME(n != 0); // Undefined behavior otherwise
const mask_type m = pbb->mask & (full >> (N - std::size_t(n)));
n = int((N - 1) - (std::size_t)nest_detail::unchecked_countl_zero(m));
return *this;
@@ -785,6 +773,16 @@ public:
friend bool operator!=(const nest_local_iterator& x, const nest_local_iterator& y) BOOST_NOEXCEPT
{ return x.n != y.n; }
BOOST_CONTAINER_FORCEINLINE
friend difference_type operator-(const nest_local_iterator& x, const nest_local_iterator& y) BOOST_NOEXCEPT
{
BOOST_CONTAINER_NEST_ASSUME(x.pbb == y.pbb); // Undefined behavior otherwise
const mask_type lo_x = (x.n == int(N)) ? full : ((mask_type(1) << x.n) - 1);
const mask_type lo_y = (y.n == int(N)) ? full : ((mask_type(1) << y.n) - 1);
const mask_type m = x.pbb->mask;
return boost::core::popcount(m & lo_x & (~lo_y));
}
BOOST_CONTAINER_FORCEINLINE block_base_pointer get_block() const BOOST_NOEXCEPT { return pbb; }
BOOST_CONTAINER_FORCEINLINE int get_slot() const BOOST_NOEXCEPT { return n; }
@@ -840,10 +838,10 @@ public:
BOOST_CONTAINER_FORCEINLINE nest_local_iterator& operator++() BOOST_NOEXCEPT
{
BOOST_ASSERT(n != N);
BOOST_CONTAINER_NEST_ASSUME(n != N);
const mask_type m = mask & (full_l << std::size_t(n));
const int old_n = n;
n = nest_detail::countr_zero(m);
n = m ? nest_detail::unchecked_countr_zero(m) : (int)N;
pos += (n - old_n);
return *this;
}
@@ -853,7 +851,7 @@ public:
BOOST_CONTAINER_FORCEINLINE nest_local_iterator& operator--() BOOST_NOEXCEPT
{
BOOST_ASSERT(n != 0);
BOOST_CONTAINER_NEST_ASSUME(n != 0);
const mask_type m = mask & (full >> (N - std::size_t(n)));
const int old_n = n;
n = int((N - 1) - (std::size_t)nest_detail::unchecked_countl_zero(m));
@@ -876,6 +874,18 @@ public:
return x.n != y.n;
}
BOOST_CONTAINER_FORCEINLINE
friend difference_type operator-(const nest_local_iterator& x, const nest_local_iterator& y) BOOST_NOEXCEPT
{
BOOST_CONTAINER_NEST_ASSUME(x.mask == y.mask); // Undefined behavior otherwise
BOOST_CONTAINER_NEST_ASSUME(x.n >= y.n); // Undefined behavior otherwise
const mask_type m = x.mask;
const mask_type lo_x = (x.n == int(N)) ? full : ((mask_type(1) << x.n) - 1);
const mask_type lo_y = (y.n == int(N)) ? full : ((mask_type(1) << y.n) - 1);
return boost::core::popcount(m & lo_x & (~lo_y));
}
//BOOST_CONTAINER_FORCEINLINE block_base_pointer get_block() const BOOST_NOEXCEPT { return pbb; }
BOOST_CONTAINER_FORCEINLINE int get_slot() const BOOST_NOEXCEPT { return n; }