collection.h

/* Copyright (c) 2014, 2025, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

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   as designated in a particular file or component or in included license
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   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#ifndef DD__COLLECTION_IMPL_INCLUDED
#define DD__COLLECTION_IMPL_INCLUDED

#include <assert.h>
#include <stddef.h>
#include <sys/types.h>
#include <algorithm>
#include <iterator>
#include <type_traits>
#include <vector>

namespace dd {

///////////////////////////////////////////////////////////////////////////

class Object_key;
class Open_dictionary_tables_ctx;
class Raw_table;

template <typename T>
class Collection {
 public:
  // Pointer to abstract type. Template argument.
  typedef T value_type;
  // Abstract type.
  typedef typename std::remove_pointer<T>::type abstract_type;
  // Implementation type. Pointer to this type is actually stored in the vector.
  typedef typename abstract_type::Impl impl_type;
  typedef std::vector<impl_type *> Array;

 private:
  Array m_items;
  Array m_removed_items;

  void clear_all_items();

  void renumerate_items() {
    for (size_t i = 0; i < m_items.size(); ++i)
      m_items[i]->set_ordinal_position(static_cast<unsigned int>(i + 1));
  }

  class Collection_iterator {
   public:
    using iterator_category = std::forward_iterator_tag;
    using value_type = T;
    using difference_type = std::ptrdiff_t;
    using pointer = value_type *;
    using reference = value_type &;

    Collection_iterator(Array *array)
        : m_array(array), m_current(array->begin()), m_current_obj(nullptr) {}

    Collection_iterator(Array *array, typename Array::iterator it)
        : m_array(array), m_current(it), m_current_obj(nullptr) {}

    bool operator==(const Collection_iterator &iter) const {
      return (m_array == iter.m_array && m_current == iter.m_current);
    }

    bool operator!=(const Collection_iterator &iter) const {
      return (m_array != iter.m_array || m_current != iter.m_current);
    }

    Collection_iterator &operator++() {
      if (m_current != m_array->end()) ++m_current;
      return *this;
    }

    T &operator*();

    Collection_iterator &end() {
      m_current = m_array->end();
      return *this;
    }

    typename Array::iterator current() { return m_current; }

   private:
    Array *m_array;
    typename Array::iterator m_current;
    T m_current_obj;
  };

  class Collection_const_iterator {
   public:
    using iterator_category = std::forward_iterator_tag;
    using value_type = const abstract_type *;
    using difference_type = std::ptrdiff_t;
    using pointer = value_type *;
    using reference = value_type &;

    Collection_const_iterator(const Array *array)
        : m_array(array), m_current(array->begin()), m_current_obj(nullptr) {}

    Collection_const_iterator(const Array *array,
                              typename Array::const_iterator it)
        : m_array(array), m_current(it), m_current_obj(nullptr) {}

    bool operator==(const Collection_const_iterator &iter) const {
      return (m_array == iter.m_array && m_current == iter.m_current);
    }

    bool operator!=(const Collection_const_iterator &iter) const {
      return (m_array != iter.m_array || m_current != iter.m_current);
    }

    Collection_const_iterator &operator++() {
      if (m_current != m_array->end()) ++m_current;
      return *this;
    }

    const abstract_type *&operator*();

    Collection_const_iterator &end() {
      m_current = m_array->end();
      return *this;
    }

    typename Array::const_iterator current() const { return m_current; }

   private:
    const Array *m_array;
    typename Array::const_iterator m_current;
    const abstract_type *m_current_obj;
  };

 public:
  Collection() = default;

  ~Collection() { clear_all_items(); }

  /**
    Remove elements from m_removed_items.  This is used only in case of
    dropping triggers for now.  See comments in
    Table_impl::store_children() for more details.
  */
  void clear_removed_items();

  Collection(const Collection &) = delete;
  void operator=(Collection &) = delete;

  typedef Collection_iterator iterator;
  typedef Collection_const_iterator const_iterator;

  void push_back(impl_type *item) {
    item->set_ordinal_position(static_cast<unsigned int>(m_items.size() + 1));
    m_items.push_back(item);
  }

  void push_front(impl_type *item) {
    m_items.insert(m_items.begin(), item);
    renumerate_items();
  }

  void insert(iterator it, impl_type *item) {
    m_items.insert(it.current(), item);
    renumerate_items();
  }

  void remove(impl_type *item);

  /**
    Remove all items and move it to m_removed_items items.
  */

  void remove_all() { m_removed_items = std::move(m_items); }

  /**
    Find item and return the position.

    @returns iterator pointing to found element.
  */

  iterator find(const impl_type *item);

  iterator begin() { return iterator(&m_items); }

  const_iterator begin() const { return const_iterator(&m_items); }

  iterator end() {
    iterator it(&m_items);
    it.end();
    return it;
  }

  const_iterator end() const {
    const_iterator it(&m_items);
    it.end();
    return it;
  }

  const_iterator cbegin() const { return begin(); }

  const_iterator cend() const { return end(); }

  bool empty() const { return m_items.empty() && m_removed_items.empty(); }

  /**
    Check if some of collection elements are removed.

    @returns void.
  */

  bool has_removed_items() const { return !m_removed_items.empty(); }

  size_t size() const { return m_items.size(); }

  const abstract_type *at(size_t n) const;

  T at(size_t n) {
    assert(n < size());
    return m_items[n];
  }

  const abstract_type *front() const { return at(0); }
  T front() { return at(0); }

  const abstract_type *back() const { return at(size() - 1); }
  T back() { return at(size() - 1); }

  const abstract_type *operator[](size_t n) const { return at(n); }
  T operator[](size_t n) { return at(n); }

  /**
    @brief
    Populate collection with items read from DD table.

    @details
    Iterate through DD tables to find rows that match the 'Object_key'
    supplied. Create collection item for each row we find and populate
    the item with data read from DD. Sort items in collection by their
    ordinal position property.

    @param parent - Object owning the restored object.
    @param otx - Context with information about open tables.
    @param table - The DD table from which read rows for items.
    @param key - The search key to be used to find rows.

    @return true - on failure and error is reported.
    @return false - on success.
  */
  template <typename Parent_item>
  bool restore_items(Parent_item *parent, Open_dictionary_tables_ctx *otx,
                     Raw_table *table, Object_key *key);

  /**
    Populate collection with items read from DD table.

    @details
    Iterate through DD tables to find rows that match the 'Object_key'
    supplied. Create collection item for each row we find and populate
    the item with data read from DD. Sort items in collection using
    comparator provided.

    @param parent   Object owning the restored object.
    @param otx      Context with information about open tables.
    @param table    The DD table from which read rows for items.
    @param key      The search key to be used to find rows.
    @param comp     Comparator to be used for sorting items.

    @retval True    on failure and error is reported.
    @retval False   on success.
  */
  template <typename Parent_item, typename Compare>
  bool restore_items(Parent_item *parent, Open_dictionary_tables_ctx *otx,
                     Raw_table *table, Object_key *key, Compare comp);

  /**
    @brief
    store items in collection on to DD table.

    @details
    Iterate through collection and stores them in DD tables.

    @param otx - Context with information about open tables.

    @return true - on failure and error is reported.
    @return false - on success.
  */
  bool store_items(Open_dictionary_tables_ctx *otx);

  /**
    @brief
    Remove all items details from DD table.

    @details
    Iterate through the collection and remove respective rows
    from DD tables.

    @param otx - Context with information about open tables.
    @param table - The DD table from which rows are removed.
    @param key - The search key to use to find rows.

    @return true - on failure and error is reported.
    @return false - on success.
  */
  bool drop_items(Open_dictionary_tables_ctx *otx, Raw_table *table,
                  Object_key *key) const;

  /**
    @brief
    Do a deep copy of a given collection.

    @details
    Calls clone() on the items in the given collection and
    stores the result in this collection.

    @param src - Collection to do a deep copy of.
    @param parent - Object "owning" the items in the collection.
                    E.g. Columns are owned by Table.
  */
  template <typename Parent_item>
  void deep_copy(const Collection<T> &src, Parent_item *parent);
};

///////////////////////////////////////////////////////////////////////////

}  // namespace dd

#endif  // DD__COLLECTION_PARENT_INCLUDED