/*******************************************************************************
 * tlx/container/btree_map.hpp
 *
 * Part of tlx - http://panthema.net/tlx
 *
 * Copyright (C) 2008-2017 Timo Bingmann <tb@panthema.net>
 *
 * All rights reserved. Published under the Boost Software License, Version 1.0
 ******************************************************************************/

#ifndef TLX_CONTAINER_BTREE_MAP_HEADER
#define TLX_CONTAINER_BTREE_MAP_HEADER

#include <functional>
#include <memory>
#include <utility>

#include "btree.hpp"

namespace tlx {

//! \addtogroup tlx_container_btree
//! \{

/*!
 * Specialized B+ tree template class implementing STL's map container.
 *
 * Implements the STL map using a B+ tree. It can be used as a drop-in
 * replacement for std::map. Not all asymptotic time requirements are met in
 * theory. The class has a traits class defining B+ tree properties like slots
 * and self-verification. Furthermore an allocator can be specified for tree
 * nodes.
 */
template <typename Key_, typename Data_, typename Compare_ = std::less<Key_>,
          typename Traits_ = btree_default_traits<Key_, std::pair<Key_, Data_>>,
          typename Alloc_ = std::allocator<std::pair<Key_, Data_>>>
class btree_map {
 public:
  //! \name Template Parameter Types
  //! \{

  //! First template parameter: The key type of the btree. This is stored in
  //! inner nodes.
  typedef Key_ key_type;

  //! Second template parameter: The value type associated with each key.
  //! Stored in the B+ tree's leaves
  typedef Data_ data_type;

  //! Third template parameter: Key comparison function object
  typedef Compare_ key_compare;

  //! Fourth template parameter: Traits object used to define more parameters
  //! of the B+ tree
  typedef Traits_ traits;

  //! Fifth template parameter: STL allocator
  typedef Alloc_ allocator_type;

  //! \}

  // The macro TLX_BTREE_FRIENDS can be used by outside class to access the B+
  // tree internals. This was added for wxBTreeDemo to be able to draw the
  // tree.
  TLX_BTREE_FRIENDS;

 public:
  //! \name Constructed Types
  //! \{

  //! Typedef of our own type
  typedef btree_map<key_type, data_type, key_compare, traits, allocator_type> self;

  //! Construct the STL-required value_type as a composition pair of key and
  //! data types
  typedef std::pair<key_type, data_type> value_type;

  //! Key Extractor Struct
  struct key_of_value {
    //! pull first out of pair
    static const key_type &get(const value_type &v) { return v.first; }
  };

  //! Implementation type of the btree_base
  typedef BTree<key_type, value_type, key_of_value, key_compare, traits, false, allocator_type> btree_impl;

  //! Function class comparing two value_type pairs.
  typedef typename btree_impl::value_compare value_compare;

  //! Size type used to count keys
  typedef typename btree_impl::size_type size_type;

  //! Small structure containing statistics about the tree
  typedef typename btree_impl::tree_stats tree_stats;

  //! \}

 public:
  //! \name Static Constant Options and Values of the B+ Tree
  //! \{

  //! Base B+ tree parameter: The number of key/data slots in each leaf
  static const unsigned short leaf_slotmax = btree_impl::leaf_slotmax;

  //! Base B+ tree parameter: The number of key slots in each inner node,
  //! this can differ from slots in each leaf.
  static const unsigned short inner_slotmax = btree_impl::inner_slotmax;

  //! Computed B+ tree parameter: The minimum number of key/data slots used
  //! in a leaf. If fewer slots are used, the leaf will be merged or slots
  //! shifted from it's siblings.
  static const unsigned short leaf_slotmin = btree_impl::leaf_slotmin;

  //! Computed B+ tree parameter: The minimum number of key slots used
  //! in an inner node. If fewer slots are used, the inner node will be
  //! merged or slots shifted from it's siblings.
  static const unsigned short inner_slotmin = btree_impl::inner_slotmin;

  //! Debug parameter: Enables expensive and thorough checking of the B+ tree
  //! invariants after each insert/erase operation.
  static const bool self_verify = btree_impl::self_verify;

  //! Debug parameter: Prints out lots of debug information about how the
  //! algorithms change the tree. Requires the header file to be compiled
  //! with TLX_BTREE_DEBUG and the key type must be std::ostream printable.
  static const bool debug = btree_impl::debug;

  //! Operational parameter: Allow duplicate keys in the btree.
  static const bool allow_duplicates = btree_impl::allow_duplicates;

  //! \}

 public:
  //! \name Iterators and Reverse Iterators
  //! \{

  //! STL-like iterator object for B+ tree items. The iterator points to a
  //! specific slot number in a leaf.
  typedef typename btree_impl::iterator iterator;

  //! STL-like iterator object for B+ tree items. The iterator points to a
  //! specific slot number in a leaf.
  typedef typename btree_impl::const_iterator const_iterator;

  //! create mutable reverse iterator by using STL magic
  typedef typename btree_impl::reverse_iterator reverse_iterator;

  //! create constant reverse iterator by using STL magic
  typedef typename btree_impl::const_reverse_iterator const_reverse_iterator;

  //! \}

 private:
  //! \name Tree Implementation Object
  //! \{

  //! The contained implementation object
  btree_impl tree_;

  //! \}

 public:
  //! \name Constructors and Destructor
  //! \{

  //! Default constructor initializing an empty B+ tree with the standard key
  //! comparison function
  explicit btree_map(const allocator_type &alloc = allocator_type()) : tree_(alloc) {}

  //! Constructor initializing an empty B+ tree with a special key
  //! comparison object
  explicit btree_map(const key_compare &kcf, const allocator_type &alloc = allocator_type()) : tree_(kcf, alloc) {}

  //! Constructor initializing a B+ tree with the range [first,last)
  template <class InputIterator>
  btree_map(InputIterator first, InputIterator last, const allocator_type &alloc = allocator_type())
      : tree_(first, last, alloc) {}

  //! Constructor initializing a B+ tree with the range [first,last) and a
  //! special key comparison object
  template <class InputIterator>
  btree_map(InputIterator first, InputIterator last, const key_compare &kcf,
            const allocator_type &alloc = allocator_type())
      : tree_(first, last, kcf, alloc) {}

  //! Frees up all used B+ tree memory pages
  ~btree_map() {}

  //! Fast swapping of two identical B+ tree objects.
  void swap(btree_map &from) { std::swap(tree_, from.tree_); }

  //! \}

 public:
  //! \name Key and Value Comparison Function Objects
  //! \{

  //! Constant access to the key comparison object sorting the B+ tree
  key_compare key_comp() const { return tree_.key_comp(); }

  //! Constant access to a constructed value_type comparison object. required
  //! by the STL
  value_compare value_comp() const { return tree_.value_comp(); }

  //! \}

 public:
  //! \name Allocators
  //! \{

  //! Return the base node allocator provided during construction.
  allocator_type get_allocator() const { return tree_.get_allocator(); }

  //! \}

 public:
  //! \name Fast Destruction of the B+ Tree
  //! \{

  //! Frees all key/data pairs and all nodes of the tree
  void clear() { tree_.clear(); }

  //! \}

 public:
  //! \name STL Iterator Construction Functions
  //! \{

  //! Constructs a read/data-write iterator that points to the first slot in
  //! the first leaf of the B+ tree.
  iterator begin() { return tree_.begin(); }

  //! Constructs a read/data-write iterator that points to the first invalid
  //! slot in the last leaf of the B+ tree.
  iterator end() { return tree_.end(); }

  //! Constructs a read-only constant iterator that points to the first slot
  //! in the first leaf of the B+ tree.
  const_iterator begin() const { return tree_.begin(); }

  //! Constructs a read-only constant iterator that points to the first
  //! invalid slot in the last leaf of the B+ tree.
  const_iterator end() const { return tree_.end(); }

  //! Constructs a read/data-write reverse iterator that points to the first
  //! invalid slot in the last leaf of the B+ tree. Uses STL magic.
  reverse_iterator rbegin() { return tree_.rbegin(); }

  //! Constructs a read/data-write reverse iterator that points to the first
  //! slot in the first leaf of the B+ tree. Uses STL magic.
  reverse_iterator rend() { return tree_.rend(); }

  //! Constructs a read-only reverse iterator that points to the first
  //! invalid slot in the last leaf of the B+ tree. Uses STL magic.
  const_reverse_iterator rbegin() const { return tree_.rbegin(); }

  //! Constructs a read-only reverse iterator that points to the first slot
  //! in the first leaf of the B+ tree. Uses STL magic.
  const_reverse_iterator rend() const { return tree_.rend(); }

  //! \}

 public:
  //! \name Access Functions to the Item Count
  //! \{

  //! Return the number of key/data pairs in the B+ tree
  size_type size() const { return tree_.size(); }

  //! Returns true if there is at least one key/data pair in the B+ tree
  bool empty() const { return tree_.empty(); }

  //! Returns the largest possible size of the B+ Tree. This is just a
  //! function required by the STL standard, the B+ Tree can hold more items.
  size_type max_size() const { return tree_.max_size(); }

  //! Return a const reference to the current statistics.
  const tree_stats &get_stats() const { return tree_.get_stats(); }

  //! \}

 public:
  //! \name STL Access Functions Querying the Tree by Descending to a Leaf
  //! \{

  //! Non-STL function checking whether a key is in the B+ tree. The same as
  //! (find(k) != end()) or (count() != 0).
  bool exists(const key_type &key) const { return tree_.exists(key); }

  //! Tries to locate a key in the B+ tree and returns an iterator to the
  //! key/data slot if found. If unsuccessful it returns end().
  iterator find(const key_type &key) { return tree_.find(key); }

  //! Tries to locate a key in the B+ tree and returns an constant iterator to
  //! the key/data slot if found. If unsuccessful it returns end().
  const_iterator find(const key_type &key) const { return tree_.find(key); }

  //! Tries to locate a key in the B+ tree and returns the number of identical
  //! key entries found. Since this is a unique map, count() returns either 0
  //! or 1.
  size_type count(const key_type &key) const { return tree_.count(key); }

  //! Searches the B+ tree and returns an iterator to the first pair equal to
  //! or greater than key, or end() if all keys are smaller.
  iterator lower_bound(const key_type &key) { return tree_.lower_bound(key); }

  //! Searches the B+ tree and returns a constant iterator to the first pair
  //! equal to or greater than key, or end() if all keys are smaller.
  const_iterator lower_bound(const key_type &key) const { return tree_.lower_bound(key); }

  //! Searches the B+ tree and returns an iterator to the first pair greater
  //! than key, or end() if all keys are smaller or equal.
  iterator upper_bound(const key_type &key) { return tree_.upper_bound(key); }

  //! Searches the B+ tree and returns a constant iterator to the first pair
  //! greater than key, or end() if all keys are smaller or equal.
  const_iterator upper_bound(const key_type &key) const { return tree_.upper_bound(key); }

  //! Searches the B+ tree and returns both lower_bound() and upper_bound().
  std::pair<iterator, iterator> equal_range(const key_type &key) { return tree_.equal_range(key); }

  //! Searches the B+ tree and returns both lower_bound() and upper_bound().
  std::pair<const_iterator, const_iterator> equal_range(const key_type &key) const { return tree_.equal_range(key); }

  //! \}

 public:
  //! \name B+ Tree Object Comparison Functions
  //! \{

  //! Equality relation of B+ trees of the same type. B+ trees of the same
  //! size and equal elements (both key and data) are considered equal.
  bool operator==(const btree_map &other) const { return (tree_ == other.tree_); }

  //! Inequality relation. Based on operator==.
  bool operator!=(const btree_map &other) const { return (tree_ != other.tree_); }

  //! Total ordering relation of B+ trees of the same type. It uses
  //! std::lexicographical_compare() for the actual comparison of elements.
  bool operator<(const btree_map &other) const { return (tree_ < other.tree_); }

  //! Greater relation. Based on operator<.
  bool operator>(const btree_map &other) const { return (tree_ > other.tree_); }

  //! Less-equal relation. Based on operator<.
  bool operator<=(const btree_map &other) const { return (tree_ <= other.tree_); }

  //! Greater-equal relation. Based on operator<.
  bool operator>=(const btree_map &other) const { return (tree_ >= other.tree_); }

  //! \}

 public:
  //! \name Fast Copy: Assign Operator and Copy Constructors
  //! \{

  //! Assignment operator. All the key/data pairs are copied
  btree_map &operator=(const btree_map &other) {
    if (this != &other) tree_ = other.tree_;
    return *this;
  }

  //! Copy constructor. The newly initialized B+ tree object will contain a
  //! copy of all key/data pairs.
  btree_map(const btree_map &other) : tree_(other.tree_) {}

  //! \}

 public:
  //! \name Public Insertion Functions
  //! \{

  //! Attempt to insert a key/data pair into the B+ tree. Fails if the pair is
  //! already present.
  std::pair<iterator, bool> insert(const value_type &x) { return tree_.insert(x); }

  //! Attempt to insert a key/data pair into the B+ tree. This function is the
  //! same as the other insert. Fails if the inserted pair is already present.
  std::pair<iterator, bool> insert2(const key_type &key, const data_type &data) {
    return tree_.insert(value_type(key, data));
  }

  //! Attempt to insert a key/data pair into the B+ tree. The iterator hint is
  //! currently ignored by the B+ tree insertion routine.
  iterator insert(iterator hint, const value_type &x) { return tree_.insert(hint, x); }

  //! Attempt to insert a key/data pair into the B+ tree. The iterator hint is
  //! currently ignored by the B+ tree insertion routine.
  iterator insert2(iterator hint, const key_type &key, const data_type &data) {
    return tree_.insert(hint, value_type(key, data));
  }

  //! Returns a reference to the object that is associated with a particular
  //! key. If the map does not already contain such an object, operator[]
  //! inserts the default object data_type().
  data_type &operator[](const key_type &key) {
    iterator i = insert(value_type(key, data_type())).first;
    return i->second;
  }

  //! Attempt to insert the range [first,last) of value_type pairs into the B+
  //! tree. Each key/data pair is inserted individually.
  template <typename InputIterator>
  void insert(InputIterator first, InputIterator last) {
    return tree_.insert(first, last);
  }

  //! Bulk load a sorted range [first,last). Loads items into leaves and
  //! constructs a B-tree above them. The tree must be empty when calling this
  //! function.
  template <typename Iterator>
  void bulk_load(Iterator first, Iterator last) {
    return tree_.bulk_load(first, last);
  }

  //! \}

 public:
  //! \name Public Erase Functions
  //! \{

  //! Erases the key/data pairs associated with the given key. For this
  //! unique-associative map there is no difference to erase().
  bool erase_one(const key_type &key) { return tree_.erase_one(key); }

  //! Erases all the key/data pairs associated with the given key. This is
  //! implemented using erase_one().
  size_type erase(const key_type &key) { return tree_.erase(key); }

  //! Erase the key/data pair referenced by the iterator.
  void erase(iterator iter) { return tree_.erase(iter); }

#ifdef TLX_BTREE_TODO
  //! Erase all key/data pairs in the range [first,last). This function is
  //! currently not implemented by the B+ Tree.
  void erase(iterator /* first */, iterator /* last */) { abort(); }
#endif

  //! \}

#ifdef TLX_BTREE_DEBUG

 public:
  //! \name Debug Printing
  //! \{

  //! Print out the B+ tree structure with keys onto the given ostream. This
  //! function requires that the header is compiled with TLX_BTREE_DEBUG and
  //! that key_type is printable via std::ostream.
  void print(std::ostream &os) const { tree_.print(os); }

  //! Print out only the leaves via the double linked list.
  void print_leaves(std::ostream &os) const { tree_.print_leaves(os); }

  //! \}
#endif

 public:
  //! \name Verification of B+ Tree Invariants
  //! \{

  //! Run a thorough verification of all B+ tree invariants. The program
  //! aborts via TLX_BTREE_ASSERT() if something is wrong.
  void verify() const { tree_.verify(); }

  //! \}
};

//! \}

}  // namespace tlx

#endif  // !TLX_CONTAINER_BTREE_MAP_HEADER

/******************************************************************************/