ConcurrentStrToValMap.icc

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/*
 * Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration.
 */
/**
 * @file CxxUtils/ConcurrentStrToValMap.icc
 * @author scott snyder <snyder@bnl.gov>
 * @date Jul, 2023
 * @brief Hash map from strings to arbitrary objects allowing
 *        concurrent, lockless reads.
 */
 
 
namespace CxxUtils {
 
 
#define T_CONCURRENTSTRTOVALMAP template <class VALUE,                  \
                                          template <class> class UPDATER> \
  requires (detail::IsUpdater<UPDATER>)
 
#define CONCURRENTSTRTOVALMAP ConcurrentStrToValMap<VALUE, UPDATER>
 
 
/**
 * @brief Constructor.
 * @param updater Object used to manage memory
 *                (see comments at the start of the class).
 * @param capacity The initial table capacity.
 *                 (Will be rounded up to a power of two.)
 * @param ctx Execution context.
 */
T_CONCURRENTSTRTOVALMAP
CONCURRENTSTRTOVALMAP::ConcurrentStrToValMap (Updater_t&& updater,
                                              size_type capacity /*= 64*/,
                                              const Context_t& ctx
                                                /* = Updater_t::defaultContext()*/) 
  : m_impl (std::move (updater),
            capacity,
            Hasher(),
            Matcher(),
            ctx)
{
}
 
 
/** 
 * @brief Constructor from another map.
 * @param updater Object used to manage memory
 *                (see comments at the start of the class).
 * @param capacity The initial table capacity of the new table.
 *                 (Will be rounded up to a power of two.)
 * @param ctx Execution context.
 *
 * (Not really a copy constructor since we need to pass @c updater.)
 */
T_CONCURRENTSTRTOVALMAP
CONCURRENTSTRTOVALMAP::ConcurrentStrToValMap (const ConcurrentStrToValMap& other,
                                              Updater_t&& updater,
                                              size_type capacity /*= 64*/,
                                              const Context_t& ctx
                                                /*= Updater_t::defaultContext()*/)
  : m_impl (std::move (updater),
            capacity,
            Hasher(),
            Matcher(),
            ctx)
{
  // not using reference, because our iterator doesn't return a reference
  for (const auto p : other) {
    this->put (std::make_unique<key_type> (p.first),
               std::make_unique<mapped_type> (p.second),
               ctx);
  }
}
 
 
/** 
 * @brief Constructor from a range.
 * @param f Start iterator for the range.
 * @param l End iterator for the range.
 * @param updater Object used to manage memory
 *                (see comments at the start of the class).
 * @param capacity The initial table capacity of the new table.
 *                 (Will be rounded up to a power of two.)
 * @param ctx Execution context.
 *
 * Constructor from a range of pairs.
 */
T_CONCURRENTSTRTOVALMAP
template <class InputIterator>
CONCURRENTSTRTOVALMAP::ConcurrentStrToValMap (InputIterator f,
                                              InputIterator l,
                                              Updater_t&& updater,
                                              size_t capacity /*= 64*/,
                                              const Context_t& ctx
                                                /*= Updater_t::defaultContext()*/)
  : m_impl (std::move (updater),
            capacity,
            Hasher(),
            Matcher(),
            ctx)
{
  if constexpr (std::is_rvalue_reference_v<typename InputIterator::reference>)
  {
    for (; f != l; ++f) {
      emplace (std::move (f->first), std::move (f->second), ctx);
    }
  }
  else {
    for (; f != l; ++f) {
      emplace (f->first, f->second, ctx);
    }
  }
}
 
 
/**
 * @brief Destructor.
 */
T_CONCURRENTSTRTOVALMAP
CONCURRENTSTRTOVALMAP::~ConcurrentStrToValMap()
{
  // Need to delete the strings and values that we've stored.
  auto [begin, end] = m_impl.range();
  while (begin != end) {
    if (begin.key() != Impl_t::nullval) {
      delete keyAsString (begin.key());
      delete mappedAsMapped (begin.value());
    }
    begin.next();
  }
}
 
 
/**
 * @brief Return the number of items currently in the map.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::size() const -> size_type
{
  return m_impl.size();
}
 
 
/**
 * @brief Test if the map is currently empty.
 */
T_CONCURRENTSTRTOVALMAP
inline
bool CONCURRENTSTRTOVALMAP::empty() const
{
  return !m_impl.size();
}
 
 
/**
 * @brief Return the current size (capacity) of the hash table.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::capacity() const -> size_t
{
  return m_impl.capacity();
}
 
 
/**
 * @brief Constructor.
 * @param it Iterator of the underlying table.
 */
T_CONCURRENTSTRTOVALMAP
inline
CONCURRENTSTRTOVALMAP::const_iterator::const_iterator (typename Impl_t::const_iterator it)
  : m_impl (it)
{
}
 
 
/**
 * @brief Conversion from non-const iterator (for interoperability).
 * @param other The other iterator.
 */
T_CONCURRENTSTRTOVALMAP
inline
CONCURRENTSTRTOVALMAP::const_iterator::const_iterator (const iterator& other)
  : m_impl (other.m_impl)
{
}
 
 
/**
 * @brief Test if this iterator is valid.
 *
 * This should be the same as testing for != end().
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::const_iterator::valid() const -> bool
{
  return m_impl.valid();
}
 
 
/**
 * @brief iterator_facade requirement: Increment the iterator.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::const_iterator::increment() -> void
{
  m_impl.next();
}
 
 
/**
 * @brief iterator_facade requirement: Decrement the iterator.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::const_iterator::decrement() -> void
{
  m_impl.prev();
}
 
 
/**
 * @brief iterator_facade requirement: Dereference the iterator.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::const_iterator::dereference() const
  -> const const_iterator_value
{
  return const_iterator_value (*keyAsString (m_impl.key()),
                               *mappedAsMapped (m_impl.value()));
}
 
 
/**
 * @brief iterator_facade requirement: Equality test.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::const_iterator::equal (const const_iterator& other) const
  -> bool
{
  return !(m_impl != other.m_impl);
}
 
 
/**
 * @brief iterator_facade requirement: Equality test.  (Interoperability.)
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::const_iterator::equal (const iterator& other) const
  -> bool
{
  return !(m_impl != other.m_impl);
}
 
 
/**
 * @brief Constructor.
 * @param it Iterator of the underlying table.
 */
T_CONCURRENTSTRTOVALMAP
inline
CONCURRENTSTRTOVALMAP::iterator::iterator (typename Impl_t::const_iterator it)
  : m_impl (it)
{
}
 
 
/**
 * @brief Test if this iterator is valid.
 *
 * This should be the same as testing for != end().
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::iterator::valid() const -> bool
{
  return m_impl.valid();
}
 
 
/**
 * @brief iterator_facade requirement: Increment the iterator.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::iterator::increment() -> void
{
  m_impl.next();
}
 
 
/**
 * @brief iterator_facade requirement: Decrement the iterator.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::iterator::decrement() -> void
{
  m_impl.prev();
}
 
 
/**
 * @brief iterator_facade requirement: Dereference the iterator.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::iterator::dereference() const
  -> const iterator_value
{
  return iterator_value (*keyAsString (m_impl.key()),
                         *mappedAsMapped (m_impl.value()));
}
 
 
/**
 * @brief iterator_facade requirement: Equality test.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::iterator::equal (const iterator& other) const
  -> bool
{
  return !(m_impl != other.m_impl);
}
 
 
/**
 * @brief iterator_facade requirement: Equality test.  (Interoperability.)
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::iterator::equal (const const_iterator& other) const
  -> bool
{
  return !(m_impl != other.m_impl);
}
 
 
/**
 * @brief Return an iterator range covering the entire map.
 */
T_CONCURRENTSTRTOVALMAP
auto CONCURRENTSTRTOVALMAP::range() const -> const_iterator_range
{
  auto [begin, end] = m_impl.range();
  return const_iterator_range (begin, end);
}
 
 
/**
 * @brief Return an iterator range covering the entire map.
 *
 * The mapped objects must themselves be thread-safe in order to make
 * any changes to them through the returned iterators.
 */
T_CONCURRENTSTRTOVALMAP
auto CONCURRENTSTRTOVALMAP::range() -> iterator_range
{
  auto [begin, end] = m_impl.range();
  return iterator_range (begin, end);
}
 
 
/**
 * @brief Iterator at the start of the map.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::begin() const -> const_iterator
{
  return const_iterator (m_impl.begin());
}
 
 
/**
 * @brief Iterator at the end of the map.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::end() const -> const_iterator
{
  return const_iterator (m_impl.end());
}
 
 
/**
 * @brief Iterator at the start of the map.
 *
 * The mapped objects must themselves be thread-safe in order to make
 * any changes to them through the returned iterators.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::begin() -> iterator
{
  return iterator (m_impl.begin());
}
 
 
/**
 * @brief Iterator at the end of the map.
 *
 * The mapped objects must themselves be thread-safe in order to make
 * any changes to them through the returned iterators.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::end() -> iterator
{
  return iterator (m_impl.end());
}
 
 
/**
 * @brief Iterator at the start of the map.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::cbegin() const -> const_iterator
{
  return begin();
}
 
 
/**
 * @brief Iterator at the end of the map.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::cend() const -> const_iterator
{
  return end();
}
 
 
/**
 * @brief Test if a key is in the container.
 * @param key The key to test.
 */
T_CONCURRENTSTRTOVALMAP
inline
bool CONCURRENTSTRTOVALMAP::contains (const key_type& key) const
{
  return get(key).valid();
}
 
 
/**
 * @brief Return the number of times a given key is in the container.
 * @param key The key to test.
 *
 * Returns either 0 or 1, depending on whether or not the key is in the map.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::count (const key_type& key) const -> size_type
{
  return contains (key) ? 1 : 0;
}
 
 
/**
 * @brief Look up an element in the map.
 * @param key The element to find.
 *
 * Returns either an iterator referencing the found element or end().
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::find (const key_type& key) const -> const_iterator
{
  return const_iterator (this->get (key));
}
 
 
/**
 * @brief Look up an element in the map.
 * @param key The element to find.
 *
 * Returns either an iterator referencing the found element or end().
 *
 * The mapped object must itself be thread-safe in order to make
 * any changes to it through the returned iterator.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::find (const key_type& key) -> iterator
{
  return iterator (this->get (key));
}
 
 
/**
 * @brief Look up an element in the map.
 * @param key The element to find.
 *
 * Returns the value associated with the key.
 * Throws @c std::out_of_range if the key does not exist in the map.
 */
T_CONCURRENTSTRTOVALMAP
auto CONCURRENTSTRTOVALMAP::at (const key_type& key) const -> const mapped_type&
{
  typename Impl_t::const_iterator it = this->get (key);
  if (!it.valid()) {
    throw std::out_of_range ("ConcurrentToValMap::at");
  }
  return *mappedAsMapped (it.value());
}
 
 
/**
 * @brief Look up an element in the map.
 * @param key The element to find.
 *
 * Returns the value associated with the key.
 * Throws @c std::out_of_range if the key does not exist in the map.
 *
 * This returns a non-const reference to the mapped object.
 * The mapped object must be thread-safe itself in order to safely
 * make any changes to it.
 */
T_CONCURRENTSTRTOVALMAP
auto CONCURRENTSTRTOVALMAP::at (const key_type& key) -> mapped_type&
{
  typename Impl_t::const_iterator it = this->get (key);
  if (!it.valid()) {
    throw std::out_of_range ("ConcurrentToValMap::at");
  }
  return *mappedAsMapped (it.value());
}
 
 
/**
 * @brief Return a range of iterators with entries matching @c key.
 * @param key The element to find.
 *
 * As keys are unique in this container, this is either a single-element
 * range, or both iterators are equal to end().
 */
T_CONCURRENTSTRTOVALMAP
auto CONCURRENTSTRTOVALMAP::equal_range (const key_type& key) const
  -> std::pair<const_iterator, const_iterator>
{
  const_iterator i1 = find (key);
  const_iterator i2 = i1;
  if (i2.valid()) {
    ++i2;
  }
  return std::make_pair (i1, i2);
}
 
 
/**
 * @brief Return a range of iterators with entries matching @c key.
 * @param key The element to find.
 *
 * As keys are unique in this container, this is either a single-element
 * range, or both iterators are equal to end().
 *
 * The mapped objects must themselves be thread-safe in order to make
 * any changes to them through the returned iterators.
 */
T_CONCURRENTSTRTOVALMAP
auto CONCURRENTSTRTOVALMAP::equal_range (const key_type& key)
  -> std::pair<iterator, iterator>
{
  iterator i1 = find (key);
  iterator i2 = i1;
  if (i2.valid()) {
    ++i2;
  }
  return std::make_pair (i1, i2);
}
 
 
/**
 * @brief Add an element to the map.
 * @param key The key of the new item to add.
 * @param val The value of the new item to add.
 * @param ctx Execution context.
 *
 * This will not overwrite an existing entry.
 * The first element in the returned pair is an iterator referencing
 * the added item.  The second is a flag that is true if a new element
 * was added.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::emplace (const key_type& key,
                                     const mapped_type& val,
                                     const Context_t& ctx
                                       /*= Updater_t::defaultContext()*/)
  -> std::pair<const_iterator, bool>
{
  return put (std::make_unique<key_type> (key),
              std::make_unique<mapped_type> (val),
              ctx);
}
 
 
/**
 * @brief Add an element to the map.
 * @param key The key of the new item to add.
 * @param val The value of the new item to add.
 * @param ctx Execution context.
 *
 * This will not overwrite an existing entry.
 * The first element in the returned pair is an iterator referencing
 * the added item.  The second is a flag that is true if a new element
 * was added.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::emplace (key_type&& key,
                                     const mapped_type& val,
                                     const Context_t& ctx
                                       /*= Updater_t::defaultContext()*/)
  -> std::pair<const_iterator, bool>
{
  return put (std::make_unique<key_type> (std::move (key)),
              std::make_unique<mapped_type> (val),
              ctx);
}
 
 
/**
 * @brief Add an element to the map.
 * @param key The key of the new item to add.
 * @param val The value of the new item to add.
 * @param ctx Execution context.
 *
 * This will not overwrite an existing entry.
 * The first element in the returned pair is an iterator referencing
 * the added item.  The second is a flag that is true if a new element
 * was added.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::emplace (const key_type& key,
                                     mapped_type&& val,
                                     const Context_t& ctx
                                       /*= Updater_t::defaultContext()*/)
  -> std::pair<const_iterator, bool>
{
  return put (std::make_unique<key_type> (key),
              std::make_unique<mapped_type> (std::move (val)),
              ctx);
}
 
 
/**
 * @brief Add an element to the map.
 * @param key The key of the new item to add.
 * @param val The value of the new item to add.
 * @param ctx Execution context.
 *
 * This will not overwrite an existing entry.
 * The first element in the returned pair is an iterator referencing
 * the added item.  The second is a flag that is true if a new element
 * was added.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::emplace (key_type&& key,
                                     mapped_type&& val,
                                     const Context_t& ctx
                                       /*= Updater_t::defaultContext()*/)
  -> std::pair<const_iterator, bool>
{
  return put (std::make_unique<key_type> (std::move (key)),
              std::make_unique<mapped_type> (std::move (val)),
              ctx);
}
 
 
/**
 * @brief Add an element to the map.
 * @param key The key of the new item to add.
 * @param val The value of the new item to add.
 * @param ctx Execution context.
 *
 * This will not overwrite an existing entry.
 * The first element in the returned pair is an iterator referencing
 * the added item.  The second is a flag that is true if a new element
 * was added.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::emplace (const key_type& key,
                                     std::unique_ptr<mapped_type> val,
                                     const Context_t& ctx
                                      /*= Updater_t::defaultContext()*/)
  -> std::pair<const_iterator, bool>
{
  return put (std::make_unique<key_type> (key),
              std::move (val),
              ctx);
}
 
 
/**
 * @brief Add an element to the map.
 * @param key The key of the new item to add.
 * @param val The value of the new item to add.
 * @param ctx Execution context.
 *
 * This will not overwrite an existing entry.
 * The first element in the returned pair is an iterator referencing
 * the added item.  The second is a flag that is true if a new element
 * was added.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::emplace (key_type&& key,
                                     std::unique_ptr<mapped_type> val,
                                     const Context_t& ctx
                                      /*= Updater_t::defaultContext()*/)
  -> std::pair<const_iterator, bool>
{
  return put (std::make_unique<key_type> (std::move (key)),
              std::move (val),
              ctx);
}
 
 
/**
 * @brief Add an element to the map.
 * @param p The item to add.
 *          Should be a pair where first is the string key
 *          and second is the integer value.
 * @param ctx Execution context.
 *
 * This will not overwrite an existing entry.
 * The first element in the returned pair is an iterator referencing
 * the added item.  The second is a flag that is true if a new element
 * was added.
 */
T_CONCURRENTSTRTOVALMAP
template <class PAIR>
inline
auto CONCURRENTSTRTOVALMAP::insert (const PAIR& p,
                                    const Context_t& ctx /*= Updater_t::defaultContext()*/)
  -> std::pair<const_iterator, bool>
{
  return emplace (p.first, p.second, ctx);
}
 
 
/**
 * @brief Add an element to the map.
 * @param p The item to add.
 *          Should be a pair where first is the string key
 *          and second is the integer value.
 * @param ctx Execution context.
 *
 * This will not overwrite an existing entry.
 * The first element in the returned pair is an iterator referencing
 * the added item.  The second is a flag that is true if a new element
 * was added.
 */
T_CONCURRENTSTRTOVALMAP
template <class PAIR>
inline
auto CONCURRENTSTRTOVALMAP::insert (PAIR&& p,
                                    const Context_t& ctx /*= Updater_t::defaultContext()*/)
  -> std::pair<const_iterator, bool>
{
  return emplace (std::move (p.first), std::move (p.second), ctx);
}
 
 
/**
 * @brief Insert a range of elements to the map.
 * @param first Start of the range.
 * @param last End of the range.
 * @param ctx Execution context.
 *
 * The range should be a sequence of pairs where first is the string key
 *  and second is the integer value.
 */
T_CONCURRENTSTRTOVALMAP
template <class InputIterator>
void CONCURRENTSTRTOVALMAP::insert (InputIterator first, InputIterator last,
                                 const Context_t& ctx /*= Updater_t::defaultContext()*/)
{
  if constexpr (std::is_rvalue_reference_v<typename InputIterator::reference>)
  {
    for (; first != last; ++first) {
      emplace (std::move (first->first), std::move (first->second), ctx);
    }
  }
  else {
    for (; first != last; ++first) {
      emplace (first->first, first->second, ctx);
    }
  }
}
 
 
/**
 * @brief Increase the table capacity.
 * @param capacity The new table capacity.
 * @param ctx Execution context.
 *
 * No action will be taken if @c capacity is smaller
 * than the current capacity.
 */
T_CONCURRENTSTRTOVALMAP
inline
void CONCURRENTSTRTOVALMAP::reserve (size_type capacity,
                                  const Context_t& ctx
                                    /*= Updater_t::defaultContext()*/)
{
  return m_impl.reserve (capacity, ctx);
}
 
 
/**
 * @brief Increase the table capacity.
 * @param capacity The new table capacity.
 *
 * No action will be taken if @c capacity is smaller
 * than the current capacity.
 */
T_CONCURRENTSTRTOVALMAP
inline
void CONCURRENTSTRTOVALMAP::rehash (size_type capacity)
{
  return reserve (capacity);
}
 
 
/**
 * @brief Called when this thread is no longer referencing anything
 *        from this container.
 * @param ctx Execution context.
 */
T_CONCURRENTSTRTOVALMAP
inline
void CONCURRENTSTRTOVALMAP::quiescent (const Context_t& ctx)
{
  return m_impl.quiescent (ctx);
}
 
 
/**
 * @brief Swap this container with another.
 * @param other The container with which to swap.
 *
 * This will also call swap on the Updater object; hence, the Updater
 * object must also support swap.
 *
 * This operation is NOT thread-safe.  No other threads may be accessing
 * either container during this operation.
 */
T_CONCURRENTSTRTOVALMAP
void CONCURRENTSTRTOVALMAP::swap (ConcurrentStrToValMap& other)
{
  m_impl.swap (other.m_impl);
}
 
 
/**
 * @brief Access the Updater instance.
 */
T_CONCURRENTSTRTOVALMAP
auto CONCURRENTSTRTOVALMAP::updater() -> Updater_t&
{
  return m_impl.updater();
}
 
 
/**
 * @brief Convert an underlying key value to a string pointer.
 * @param val The underlying key value.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::keyAsString (val_t val) -> const std::string*
{
  return reinterpret_cast<std::string*> (val);
}
 
 
/**
 * @brief Convert a string pointer to an underlying key value.
 * @param s The string pointer.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::keyAsVal (const std::string* s) -> val_t
{
  return reinterpret_cast<val_t> (s);
}
 
 
/**
 * @brief Convert an underlying mapped value a pointer to
 *        this type's mapped value.
 * @param val The underlying mapped value.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::mappedAsMapped (val_t val) -> mapped_type*
{
  return CxxUtils::detail::UIntConv<mapped_type*>::uintToVal (val);
}
 
 
/**
 * @brief Convert this type's mapped value to an underlying mapped value.
 * @param val The mapped value.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::mappedAsVal (mapped_type* val) -> val_t
{
  return CxxUtils::detail::UIntConv<mapped_type*>::valToUInt (val);
}
 
 
/**
 * @brief Do a lookup in the table.
 * @param key The key to look up.
 *
 * Returns an iterator of the underlying map pointing at the found
 * entry or end();
 */
T_CONCURRENTSTRTOVALMAP
auto CONCURRENTSTRTOVALMAP::get (const key_type& key) const
  -> typename Impl_t::const_iterator
{
  size_t hash = m_impl.hasher() (key);
  return m_impl.get (keyAsVal(&key), hash);
}
 
 
/**
 * @brief Insert an entry in the table.
 * @param key The key of the new item to add.
 * @param val The new mapped value to add.
 * @param ctx Execution context.
 *
 * The first element in the returned pair is an iterator referencing
 * the added item.  The second is a flag that is true if a new element
 * was added.
 */
T_CONCURRENTSTRTOVALMAP
auto CONCURRENTSTRTOVALMAP::put (std::unique_ptr<key_type> key,
                                 std::unique_ptr<mapped_type> val,
                                 const Context_t& ctx /*= Updater_t::defaultContext()*/)
  -> std::pair<const_iterator, bool>
{
  size_t hash = m_impl.hasher() (*key);
  auto [it, flag] = m_impl.put (keyAsVal(key.get()), hash,
                                mappedAsVal (val.get()),
                                false, ctx);
  if (flag) {
    key.release();
    val.release();
  }
 
  return std::make_pair (const_iterator (it), flag);
}
 
 
/**
 * @brief Hash function from the underlying representation type.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::Hasher::operator() (const val_t p) const -> size_t
{
  return m_hash (*keyAsString(p));
}
 
 
/**
 * @brief Hash function from a std::string.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::Hasher::operator() (const std::string& s) const -> size_t
{
  return m_hash (s);
}
 
 
/**
 * @brief Compare two keys (as the underlying representation type) for equality.
 */
T_CONCURRENTSTRTOVALMAP
inline
auto CONCURRENTSTRTOVALMAP::Matcher::operator() (const val_t a, const val_t b) const -> bool
{
  // First test if the keys (pointers) themselves are equal.
  if (a == b) return true;
  // Otherwise, need to test the strings to which they point.
  return *keyAsString(a) == *keyAsString(b);
}
 
 
#undef T_CONCURRENTSTRTOVALMAP
#undef CONCURRENTSTRTOVALMAP
 
 
} // namespace CxxUtils