container/experimental/segmented_fill_test.cpp

//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2025-2026. Distributed under the Boost
// Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/libs/container for documentation.
//
//////////////////////////////////////////////////////////////////////////////

#include <boost/container/experimental/segmented_fill.hpp>
#include <boost/core/lightweight_test.hpp>
#include "segmented_test_helper.hpp"
#include <boost/container/vector.hpp>

using namespace boost::container;

void test_fill_full_range()
{
   test_detail::seg_vector<int> sv;
   sv.add_segment(3, 0);
   sv.add_segment(4, 0);
   sv.add_segment(2, 0);

   segmented_fill(sv.begin(), sv.end(), 42);

   test_detail::seg_vector<int>::iterator it = sv.begin();
   for(; it != sv.end(); ++it)
      BOOST_TEST_EQ(*it, 42);
}

void test_fill_empty_range()
{
   test_detail::seg_vector<int> sv;
   segmented_fill(sv.begin(), sv.end(), 42);
   BOOST_TEST_EQ(sv.total_size(), 0u);
}

void test_fill_partial_range()
{
   test_detail::seg_vector<int> sv;
   int a1[] = {1, 2, 3};
   int a2[] = {4, 5, 6, 7};
   int a3[] = {8, 9};
   sv.add_segment_range(a1, a1 + 3);
   sv.add_segment_range(a2, a2 + 4);
   sv.add_segment_range(a3, a3 + 2);

   // Fill only the middle segment by constructing sub-range iterators
   typedef test_detail::seg_vector<int>::iterator iter_t;
   typedef segmented_iterator_traits<iter_t> traits;
   traits::segment_iterator seg_begin = traits::segment(sv.begin());
   ++seg_begin; // second segment
   iter_t mid_begin = traits::compose(seg_begin, traits::begin(seg_begin));
   iter_t mid_end   = traits::compose(seg_begin, traits::end(seg_begin));

   segmented_fill(mid_begin, mid_end, 0);

   // Verify: first segment unchanged, second zeroed, third unchanged
   iter_t it = sv.begin();
   BOOST_TEST_EQ(*it, 1); ++it;
   BOOST_TEST_EQ(*it, 2); ++it;
   BOOST_TEST_EQ(*it, 3); ++it;
   BOOST_TEST_EQ(*it, 0); ++it;
   BOOST_TEST_EQ(*it, 0); ++it;
   BOOST_TEST_EQ(*it, 0); ++it;
   BOOST_TEST_EQ(*it, 0); ++it;
   BOOST_TEST_EQ(*it, 8); ++it;
   BOOST_TEST_EQ(*it, 9);
}

void test_fill_non_segmented()
{
   boost::container::vector<int> v(5, 0);
   segmented_fill(v.begin(), v.end(), 7);
   for(std::size_t i = 0; i < v.size(); ++i)
      BOOST_TEST_EQ(v[i], 7);
}

void test_fill_sentinel_segmented()
{
   test_detail::seg_vector<int> sv;
   sv.add_segment(3, 0);
   sv.add_segment(4, 0);
   sv.add_segment(2, 0);

   segmented_fill(sv.begin(), test_detail::make_sentinel(sv.end()), 42);

   test_detail::seg_vector<int>::iterator it = sv.begin();
   for(; it != sv.end(); ++it)
      BOOST_TEST_EQ(*it, 42);
}

void test_fill_sentinel_non_segmented()
{
   boost::container::vector<int> v(5, 0);
   segmented_fill(v.begin(), test_detail::make_sentinel(v.end()), 7);
   for(std::size_t i = 0; i < v.size(); ++i)
      BOOST_TEST_EQ(v[i], 7);
}

void test_fill_seg2()
{
   test_detail::seg2_vector<int> sv2;
   int a1[] = {0, 0, 0};
   int a2[] = {0, 0, 0};
   int a3[] = {0, 0, 0};
   sv2.add_flat_segment_range(a1, a1 + 3);
   sv2.add_flat_segment_range(a2, a2 + 3);
   sv2.add_flat_segment_range(a3, a3 + 3);

   segmented_fill(sv2.begin(), sv2.end(), 42);

   test_detail::seg2_vector<int>::iterator it = sv2.begin();
   for(; it != sv2.end(); ++it)
      BOOST_TEST_EQ(*it, 42);
}

// Fills a sub-range whose segmentation shape is dictated by a branch spec, so
// that every level of the recursive dispatch is exercised on its
// single-segment path, on its multi-segment path and on the multi-segment path
// with empty segments interleaved.  The guard just past the end must survive
// untouched: fill writes, so an overrun corrupts the container rather than
// merely misreading it.
struct fill_shape_check
{
   template<class Cont>
   void operator()(Cont& c, std::size_t n, const char* spec) const
   {
      typedef typename Cont::iterator iter_t;
      const iter_t first = c.begin();
      const iter_t last  = test_detail::iter_at(c, n);

      segmented_fill(first, last, 42);

      const boost::container::vector<int> after = test_detail::flatten_n_ints(c, n);
      BOOST_TEST_EQ(after.size(), n);
      for(std::size_t i = 0; i != after.size(); ++i)
         BOOST_TEST_EQ(after[i], 42);

      BOOST_TEST(test_detail::filler_intact(c, n, -999));
      BOOST_TEST(spec != 0);
   }
};

void test_fill_shape_matrix()
{
   int vals[16];
   for(int i = 0; i != 16; ++i)
      vals[i] = i + 1;

   const std::size_t sizes[] = { 0u, 1u, 2u, 5u, 12u };
   for(std::size_t s = 0; s != sizeof(sizes)/sizeof(sizes[0]); ++s)
      test_detail::for_each_shape_all<int>(vals, sizes[s], -999, fill_shape_check());
}

void test_fill_single_segment_sentinel()
{
   test_detail::seg_vector<int> sv;
   int a[] = {1, 2, 3, 4, 5, 6, 7};
   sv.add_segment_range(a, a + 7);

   typedef test_detail::seg_vector<int>::iterator iter_t;
   segmented_fill(test_detail::iter_at(sv, 1),
                  test_detail::make_sentinel(test_detail::iter_at(sv, 6)), 42);

   int expected[] = {1, 42, 42, 42, 42, 42, 7};
   iter_t it = sv.begin();
   for(int i = 0; i < 7; ++i, ++it)
      BOOST_TEST_EQ(*it, expected[i]);
}

//////////////////////////////////////////////////////////////////////////////
// Assignment count.
//
// [alg.fill] mandates "Exactly last - first assignments", so a slot written
// twice at a segment boundary is a conformance failure.  The count is taken
// from the value type, fill having no functor to instrument.
//////////////////////////////////////////////////////////////////////////////

struct fill_assignment_check
{
   template<class Cont>
   void operator()(Cont& c, std::size_t n, const char* spec) const
   {
      const test_detail::counted_int value(42);

      test_detail::counted_int_ops().reset();
      segmented_fill(c.begin(), test_detail::iter_at(c, n), value);
      const std::size_t applied = test_detail::counted_int_ops().assign;

      BOOST_TEST_EQ(applied, n);
      BOOST_TEST(spec != 0);
   }
};

void test_fill_assignment_count()
{
   int vals[16];
   for(int i = 0; i != 16; ++i)
      vals[i] = i + 1;

   const std::size_t sizes[] = { 0u, 1u, 2u, 5u, 12u };
   for(std::size_t s = 0; s != sizeof(sizes)/sizeof(sizes[0]); ++s)
      test_detail::for_each_shape_all<test_detail::counted_int>
         (vals, sizes[s], -999, fill_assignment_check());
}

int main()
{
   test_fill_shape_matrix();
   test_fill_full_range();
   test_fill_empty_range();
   test_fill_partial_range();
   test_fill_non_segmented();
   test_fill_sentinel_segmented();
   test_fill_sentinel_non_segmented();
   test_fill_seg2();
   test_fill_single_segment_sentinel();
   test_fill_assignment_count();
   return boost::report_errors();
}