New cpp folder structure

Signed-off-by: Alexander Borsuk <me@alex.bio>

libs/indexer/string_slice.cpp

@@ -0,0 +1,74 @@
+#include "indexer/string_slice.hpp"
+
+namespace search
+{
+JoinIterator::JoinIterator(StringSliceBase const & slice, Position position) : m_slice(slice)
+{
+  if (position == Position::Begin)
+  {
+    m_string = 0;
+    m_offset = 0;
+    Normalize();
+  }
+  else
+  {
+    m_string = GetMaxSize();
+    m_offset = 0;
+  }
+}
+
+// static
+JoinIterator JoinIterator::Begin(StringSliceBase const & slice)
+{
+  return JoinIterator(slice, Position::Begin);
+}
+
+// static
+JoinIterator JoinIterator::End(StringSliceBase const & slice)
+{
+  return JoinIterator(slice, Position::End);
+}
+
+JoinIterator & JoinIterator::operator++()
+{
+  ++m_offset;
+  Normalize();
+  return *this;
+}
+
+void JoinIterator::Normalize()
+{
+  while (m_string != GetMaxSize() && m_offset >= GetSize(m_string))
+  {
+    ++m_string;
+    m_offset = 0;
+  }
+}
+
+size_t JoinIterator::GetSize(size_t string) const
+{
+  if (string >= GetMaxSize())
+    return 0;
+
+  if (string & 1)
+    return 1;
+
+  return m_slice.Get(string >> 1).size();
+}
+
+JoinIterator::value_type JoinIterator::GetChar(size_t string, size_t offset) const
+{
+  if (string >= GetMaxSize())
+    return 0;
+
+  if (string & 1)
+  {
+    ASSERT_EQUAL(offset, 0, ());
+    return ' ';
+  }
+
+  auto const & s = m_slice.Get(string >> 1);
+  ASSERT_LESS(offset, s.size(), ());
+  return s[offset];
+}
+}  // namespace search