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btree_multiset.hpp
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1 /*******************************************************************************
2  * tlx/container/btree_multiset.hpp
3  *
4  * Part of tlx - http://panthema.net/tlx
5  *
6  * Copyright (C) 2008-2017 Timo Bingmann <[email protected]>
7  *
8  * All rights reserved. Published under the Boost Software License, Version 1.0
9  ******************************************************************************/
10 
11 #ifndef TLX_CONTAINER_BTREE_MULTISET_HEADER
12 #define TLX_CONTAINER_BTREE_MULTISET_HEADER
13 
14 #include <functional>
15 #include <memory>
16 #include <utility>
17 
18 #include <tlx/container/btree.hpp>
19 
20 namespace tlx {
21 
22 //! \addtogroup tlx_container_btree
23 //! \{
24 
25 /*!
26  * Specialized B+ tree template class implementing STL's multiset container.
27  *
28  * Implements the STL multiset using a B+ tree. It can be used as a drop-in
29  * replacement for std::multiset. Not all asymptotic time requirements are met
30  * in theory. The class has a traits class defining B+ tree properties like
31  * slots and self-verification. Furthermore an allocator can be specified for
32  * tree nodes.
33  *
34  * It is somewhat inefficient to implement a multiset using a B+ tree, a plain B
35  * tree would hold fewer copies of the keys.
36  */
37 template <typename Key_,
38  typename Compare_ = std::less<Key_>,
39  typename Traits_ = btree_default_traits<Key_, Key_>,
40  typename Alloc_ = std::allocator<Key_> >
42 {
43 public:
44  //! \name Template Parameter Types
45  //! \{
46 
47  //! First template parameter: The key type of the btree. This is stored in
48  //! inner nodes and leaves.
49  typedef Key_ key_type;
50 
51  //! Second template parameter: Key comparison function object
52  typedef Compare_ key_compare;
53 
54  //! Third template parameter: Traits object used to define more parameters
55  //! of the B+ tree
56  typedef Traits_ traits;
57 
58  //! Fourth template parameter: STL allocator
59  typedef Alloc_ allocator_type;
60 
61  //! \}
62 
63  // The macro TLX_BTREE_FRIENDS can be used by outside class to access the B+
64  // tree internals. This was added for wxBTreeDemo to be able to draw the
65  // tree.
67 
68 public:
69  //! \name Constructed Types
70  //! \{
71 
72  //! Construct the set value_type: the key_type.
74 
75  //! Typedef of our own type
77 
78  //! Key Extractor Struct
79  struct key_of_value {
80  //! pull first out of pair
81  static const key_type& get(const value_type& v) { return v; }
82  };
83 
84  //! Implementation type of the btree_base
85  typedef btree<key_type, value_type, key_of_value, key_compare,
87 
88  //! Function class comparing two value_type keys.
89  typedef typename btree_impl::value_compare value_compare;
90 
91  //! Size type used to count keys
92  typedef typename btree_impl::size_type size_type;
93 
94  //! Small structure containing statistics about the tree
95  typedef typename btree_impl::tree_stats tree_stats;
96 
97  //! \}
98 
99 public:
100  //! \name Static Constant Options and Values of the B+ Tree
101  //! \{
102 
103  //! Base B+ tree parameter: The number of key/data slots in each leaf
104  static const unsigned short leaf_slotmax = btree_impl::leaf_slotmax;
105 
106  //! Base B+ tree parameter: The number of key slots in each inner node,
107  //! this can differ from slots in each leaf.
108  static const unsigned short inner_slotmax = btree_impl::inner_slotmax;
109 
110  //! Computed B+ tree parameter: The minimum number of key slots used in a
111  //! leaf. If fewer slots are used, the leaf will be merged or slots shifted
112  //! from it's siblings.
113  static const unsigned short leaf_slotmin = btree_impl::leaf_slotmin;
114 
115  //! Computed B+ tree parameter: The minimum number of key slots used
116  //! in an inner node. If fewer slots are used, the inner node will be
117  //! merged or slots shifted from it's siblings.
118  static const unsigned short inner_slotmin = btree_impl::inner_slotmin;
119 
120  //! Debug parameter: Enables expensive and thorough checking of the B+ tree
121  //! invariants after each insert/erase operation.
123 
124  //! Debug parameter: Prints out lots of debug information about how the
125  //! algorithms change the tree. Requires the header file to be compiled with
126  //! TLX_BTREE_DEBUG and the key type must be std::ostream printable.
127  static const bool debug = btree_impl::debug;
128 
129  //! Operational parameter: Allow duplicate keys in the btree.
131 
132  //! \}
133 
134 public:
135  //! \name Iterators and Reverse Iterators
136  //! \{
137 
138  //! STL-like iterator object for B+ tree items. The iterator points to a
139  //! specific slot number in a leaf.
140  typedef typename btree_impl::iterator iterator;
141 
142  //! STL-like iterator object for B+ tree items. The iterator points to a
143  //! specific slot number in a leaf.
144  typedef typename btree_impl::const_iterator const_iterator;
145 
146  //! create mutable reverse iterator by using STL magic
147  typedef typename btree_impl::reverse_iterator reverse_iterator;
148 
149  //! create constant reverse iterator by using STL magic
150  typedef typename btree_impl::const_reverse_iterator const_reverse_iterator;
151 
152  //! \}
153 
154 private:
155  //! \name Tree Implementation Object
156  //! \{
157 
158  //! The contained implementation object
160 
161  //! \}
162 
163 public:
164  //! \name Constructors and Destructor
165  //! \{
166 
167  //! Default constructor initializing an empty B+ tree with the standard key
168  //! comparison function
169  explicit btree_multiset(const allocator_type& alloc = allocator_type())
170  : tree_(alloc)
171  { }
172 
173  //! Constructor initializing an empty B+ tree with a special key
174  //! comparison object
175  explicit btree_multiset(const key_compare& kcf,
176  const allocator_type& alloc = allocator_type())
177  : tree_(kcf, alloc)
178  { }
179 
180  //! Constructor initializing a B+ tree with the range [first,last)
181  template <class InputIterator>
182  btree_multiset(InputIterator first, InputIterator last,
183  const allocator_type& alloc = allocator_type())
184  : tree_(alloc) {
185  insert(first, last);
186  }
187 
188  //! Constructor initializing a B+ tree with the range [first,last) and a
189  //! special key comparison object
190  template <class InputIterator>
191  btree_multiset(InputIterator first, InputIterator last, const key_compare& kcf,
192  const allocator_type& alloc = allocator_type())
193  : tree_(kcf, alloc) {
194  insert(first, last);
195  }
196 
197  //! Frees up all used B+ tree memory pages
199  { }
200 
201  //! Fast swapping of two identical B+ tree objects.
202  void swap(btree_multiset& from) {
203  std::swap(tree_, from.tree_);
204  }
205 
206  //! \}
207 
208 public:
209  //! \name Key and Value Comparison Function Objects
210  //! \{
211 
212  //! Constant access to the key comparison object sorting the B+ tree
214  return tree_.key_comp();
215  }
216 
217  //! Constant access to a constructed value_type comparison object. Required
218  //! by the STL
220  return tree_.value_comp();
221  }
222 
223  //! \}
224 
225 public:
226  //! \name Allocators
227  //! \{
228 
229  //! Return the base node allocator provided during construction.
231  return tree_.get_allocator();
232  }
233 
234  //! \}
235 
236 public:
237  //! \name Fast Destruction of the B+ Tree
238  //! \{
239 
240  //! Frees all keys and all nodes of the tree
241  void clear() {
242  tree_.clear();
243  }
244 
245  //! \}
246 
247 public:
248  //! \name STL Iterator Construction Functions
249  //! \{
250 
251  //! Constructs a read/data-write iterator that points to the first slot in
252  //! the first leaf of the B+ tree.
254  return tree_.begin();
255  }
256 
257  //! Constructs a read/data-write iterator that points to the first invalid
258  //! slot in the last leaf of the B+ tree.
260  return tree_.end();
261  }
262 
263  //! Constructs a read-only constant iterator that points to the first slot
264  //! in the first leaf of the B+ tree.
266  return tree_.begin();
267  }
268 
269  //! Constructs a read-only constant iterator that points to the first
270  //! invalid slot in the last leaf of the B+ tree.
271  const_iterator end() const {
272  return tree_.end();
273  }
274 
275  //! Constructs a read/data-write reverse iterator that points to the first
276  //! invalid slot in the last leaf of the B+ tree. Uses STL magic.
278  return tree_.rbegin();
279  }
280 
281  //! Constructs a read/data-write reverse iterator that points to the first
282  //! slot in the first leaf of the B+ tree. Uses STL magic.
284  return tree_.rend();
285  }
286 
287  //! Constructs a read-only reverse iterator that points to the first
288  //! invalid slot in the last leaf of the B+ tree. Uses STL magic.
290  return tree_.rbegin();
291  }
292 
293  //! Constructs a read-only reverse iterator that points to the first slot
294  //! in the first leaf of the B+ tree. Uses STL magic.
296  return tree_.rend();
297  }
298 
299  //! \}
300 
301 public:
302  //! \name Access Functions to the Item Count
303  //! \{
304 
305  //! Return the number of keys in the B+ tree
306  size_type size() const {
307  return tree_.size();
308  }
309 
310  //! Returns true if there is at least one key in the B+ tree
311  bool empty() const {
312  return tree_.empty();
313  }
314 
315  //! Returns the largest possible size of the B+ Tree. This is just a
316  //! function required by the STL standard, the B+ Tree can hold more items.
317  size_type max_size() const {
318  return tree_.max_size();
319  }
320 
321  //! Return a const reference to the current statistics.
322  const tree_stats& get_stats() const {
323  return tree_.get_stats();
324  }
325 
326  //! \}
327 
328 public:
329  //! \name STL Access Functions Querying the Tree by Descending to a Leaf
330  //! \{
331 
332  //! Non-STL function checking whether a key is in the B+ tree. The same as
333  //! (find(k) != end()) or (count() != 0).
334  bool exists(const key_type& key) const {
335  return tree_.exists(key);
336  }
337 
338  //! Tries to locate a key in the B+ tree and returns an iterator to the key
339  //! slot if found. If unsuccessful it returns end().
340  iterator find(const key_type& key) {
341  return tree_.find(key);
342  }
343 
344  //! Tries to locate a key in the B+ tree and returns an constant iterator to
345  //! the key slot if found. If unsuccessful it returns end().
346  const_iterator find(const key_type& key) const {
347  return tree_.find(key);
348  }
349 
350  //! Tries to locate a key in the B+ tree and returns the number of identical
351  //! key entries found.
352  size_type count(const key_type& key) const {
353  return tree_.count(key);
354  }
355 
356  //! Searches the B+ tree and returns an iterator to the first pair equal to
357  //! or greater than key, or end() if all keys are smaller.
359  return tree_.lower_bound(key);
360  }
361 
362  //! Searches the B+ tree and returns a constant iterator to the first pair
363  //! equal to or greater than key, or end() if all keys are smaller.
364  const_iterator lower_bound(const key_type& key) const {
365  return tree_.lower_bound(key);
366  }
367 
368  //! Searches the B+ tree and returns an iterator to the first pair greater
369  //! than key, or end() if all keys are smaller or equal.
371  return tree_.upper_bound(key);
372  }
373 
374  //! Searches the B+ tree and returns a constant iterator to the first pair
375  //! greater than key, or end() if all keys are smaller or equal.
376  const_iterator upper_bound(const key_type& key) const {
377  return tree_.upper_bound(key);
378  }
379 
380  //! Searches the B+ tree and returns both lower_bound() and upper_bound().
381  std::pair<iterator, iterator> equal_range(const key_type& key) {
382  return tree_.equal_range(key);
383  }
384 
385  //! Searches the B+ tree and returns both lower_bound() and upper_bound().
386  std::pair<const_iterator, const_iterator> equal_range(const key_type& key) const {
387  return tree_.equal_range(key);
388  }
389 
390  //! \}
391 
392 public:
393  //! \name B+ Tree Object Comparison Functions
394  //! \{
395 
396  //! Equality relation of B+ trees of the same type. B+ trees of the same
397  //! size and equal key (counts) are considered equal.
398  bool operator == (const btree_multiset& other) const {
399  return (tree_ == other.tree_);
400  }
401 
402  //! Inequality relation. Based on operator==.
403  bool operator != (const btree_multiset& other) const {
404  return (tree_ != other.tree_);
405  }
406 
407  //! Total ordering relation of B+ trees of the same type. It uses
408  //! std::lexicographical_compare() for the actual comparison of elements.
409  bool operator < (const btree_multiset& other) const {
410  return (tree_ < other.tree_);
411  }
412 
413  //! Greater relation. Based on operator<.
414  bool operator > (const btree_multiset& other) const {
415  return (tree_ > other.tree_);
416  }
417 
418  //! Less-equal relation. Based on operator<.
419  bool operator <= (const btree_multiset& other) const {
420  return (tree_ <= other.tree_);
421  }
422 
423  //! Greater-equal relation. Based on operator<.
424  bool operator >= (const btree_multiset& other) const {
425  return (tree_ >= other.tree_);
426  }
427 
428  //! \}
429 
430 public:
431  //! \name Fast Copy: Assign Operator and Copy Constructors
432  //! \{
433 
434  //! Assignment operator. All the keys are copied
436  if (this != &other)
437  tree_ = other.tree_;
438  return *this;
439  }
440 
441  //! Copy constructor. The newly initialized B+ tree object will contain a
442  //! copy of all keys.
444  : tree_(other.tree_)
445  { }
446 
447  //! \}
448 
449 public:
450  //! \name Public Insertion Functions
451  //! \{
452 
453  //! Attempt to insert a key into the B+ tree. As this set allows duplicates,
454  //! this function never fails.
456  return tree_.insert(x).first;
457  }
458 
459  //! Attempt to insert a key into the B+ tree. The iterator hint is currently
460  //! ignored by the B+ tree insertion routine.
462  return tree_.insert(hint, x);
463  }
464 
465  //! Attempt to insert the range [first,last) of key_type into the B+
466  //! tree. Each key is inserted individually.
467  template <typename InputIterator>
468  void insert(InputIterator first, InputIterator last) {
469  InputIterator iter = first;
470  while (iter != last)
471  {
472  insert(*iter);
473  ++iter;
474  }
475  }
476 
477  //! Bulk load a sorted range [first,last). Loads items into leaves and
478  //! constructs a B-tree above them. The tree must be empty when calling this
479  //! function.
480  template <typename Iterator>
481  void bulk_load(Iterator first, Iterator last) {
482  return tree_.bulk_load(first, last);
483  }
484 
485  //! \}
486 
487 public:
488  //! \name Public Erase Functions
489  //! \{
490 
491  //! Erases one (the first) entry of the given key.
492  bool erase_one(const key_type& key) {
493  return tree_.erase_one(key);
494  }
495 
496  //! Erases all the entries of the given key. This is implemented using
497  //! erase_one() and thus not very efficient.
498  size_type erase(const key_type& key) {
499  return tree_.erase(key);
500  }
501 
502  //! Erase the key/data pair referenced by the iterator.
503  void erase(iterator iter) {
504  return tree_.erase(iter);
505  }
506 
507 #ifdef TLX_BTREE_TODO
508  //! Erase all keys in the range [first,last). This function is currently
509  //! not implemented by the B+ Tree.
510  void erase(iterator /* first */, iterator /* last */) {
511  abort();
512  }
513 #endif
514 
515  //! \}
516 
517 #ifdef TLX_BTREE_DEBUG
518 
519 public:
520  //! \name Debug Printing
521  //! \{
522 
523  //! Print out the B+ tree structure with keys onto the given ostream. This
524  //! function requires that the header is compiled with TLX_BTREE_DEBUG and
525  //! that key_type is printable via std::ostream.
526  void print(std::ostream& os) const {
527  tree_.print(os);
528  }
529 
530  //! Print out only the leaves via the double linked list.
531  void print_leaves(std::ostream& os) const {
532  tree_.print_leaves(os);
533  }
534 
535  //! \}
536 #endif
537 
538 public:
539  //! \name Verification of B+ Tree Invariants
540  //! \{
541 
542  //! Run a thorough verification of all B+ tree invariants. The program
543  //! aborts via TLX_BTREE_ASSERT() if something is wrong.
544  void verify() const {
545  tree_.verify();
546  }
547 
548  //! \}
549 };
550 
551 //! \}
552 
553 } // namespace tlx
554 
555 #endif // !TLX_CONTAINER_BTREE_MULTISET_HEADER
556 
557 /******************************************************************************/
Specialized B+ tree template class implementing STL's multiset container.
size_type max_size() const
bool operator>(const btree_multiset &other) const
Greater relation. Based on operator<.
const_iterator lower_bound(const key_type &key) const
static const unsigned short leaf_slotmax
Base B+ tree parameter: The number of key/data slots in each leaf.
void verify() const
Definition: btree.hpp:3367
Compare_ key_compare
Second template parameter: Key comparison function object.
iterator begin()
Definition: btree.hpp:1341
std::pair< iterator, iterator > equal_range(const key_type &key)
Searches the B+ tree and returns both lower_bound() and upper_bound().
Definition: btree.hpp:1695
const tree_stats & get_stats() const
Return a const reference to the current statistics.
allocator_type get_allocator() const
Return the base node allocator provided during construction.
Definition: btree.hpp:1232
bool operator<=(const btree_multiset &other) const
Less-equal relation. Based on operator<.
const_iterator begin() const
size_type size() const
Return the number of key/data pairs in the B+ tree.
Definition: btree.hpp:1494
btree_impl::tree_stats tree_stats
Small structure containing statistics about the tree.
bool exists(const key_type &key) const
Definition: btree.hpp:1522
key_compare key_comp() const
Constant access to the key comparison object sorting the B+ tree.
reverse_iterator rbegin()
btree_multiset(InputIterator first, InputIterator last, const key_compare &kcf, const allocator_type &alloc=allocator_type())
value_compare value_comp() const
Definition: btree.hpp:1189
iterator find(const key_type &key)
bool empty() const
Returns true if there is at least one key in the B+ tree.
btree_impl tree_
The contained implementation object.
bool erase_one(const key_type &key)
Definition: btree.hpp:2334
key_type value_type
Construct the set value_type: the key_type.
bool empty() const
Returns true if there is at least one key/data pair in the B+ tree.
Definition: btree.hpp:1499
btree_multiset(const key_compare &kcf, const allocator_type &alloc=allocator_type())
size_type count(const key_type &key) const
void clear()
Frees all key/data pairs and all nodes of the tree.
Definition: btree.hpp:1294
void bulk_load(Iterator ibegin, Iterator iend)
Definition: btree.hpp:2138
void bulk_load(Iterator first, Iterator last)
static const bool allow_duplicates
Operational parameter: Allow duplicate keys in the btree.
size_type size() const
Return the number of keys in the B+ tree.
btree_impl::value_compare value_compare
Function class comparing two value_type keys.
const_iterator find(const key_type &key) const
reverse_iterator rbegin()
Definition: btree.hpp:1365
Alloc_ allocator_type
Fourth template parameter: STL allocator.
const_reverse_iterator rbegin() const
static const bool debug
iterator insert(const key_type &x)
reverse_iterator rend()
Definition: btree.hpp:1371
static const unsigned short inner_slotmax
bool erase_one(const key_type &key)
Erases one (the first) entry of the given key.
iterator lower_bound(const key_type &key)
~btree_multiset()
Frees up all used B+ tree memory pages.
allocator_type get_allocator() const
Return the base node allocator provided during construction.
void swap(CountingPtr< A, D > &a1, CountingPtr< A, D > &a2) noexcept
size_type count(const key_type &key) const
Definition: btree.hpp:1584
list x
Definition: gen_data.py:39
static const unsigned short leaf_slotmax
Base B+ tree parameter: The number of key/data slots in each leaf.
Definition: btree.hpp:180
btree_multiset(InputIterator first, InputIterator last, const allocator_type &alloc=allocator_type())
Constructor initializing a B+ tree with the range [first,last)
btree_impl::iterator iterator
btree_impl::reverse_iterator reverse_iterator
create mutable reverse iterator by using STL magic
iterator end()
Definition: btree.hpp:1347
void clear()
Frees all keys and all nodes of the tree.
static const unsigned short leaf_slotmin
bool operator<(const btree_multiset &other) const
btree_multiset & operator=(const btree_multiset &other)
Assignment operator. All the keys are copied.
const struct tree_stats & get_stats() const
Return a const reference to the current statistics.
Definition: btree.hpp:1510
static const bool self_verify
btree_impl::size_type size_type
Size type used to count keys.
btree_impl::const_reverse_iterator const_reverse_iterator
create constant reverse iterator by using STL magic
btree_impl::const_iterator const_iterator
iterator upper_bound(const key_type &key)
Definition: btree.hpp:1656
std::pair< iterator, iterator > equal_range(const key_type &key)
Searches the B+ tree and returns both lower_bound() and upper_bound().
const_iterator upper_bound(const key_type &key) const
reverse_iterator rend()
btree_multiset(const allocator_type &alloc=allocator_type())
void erase(iterator iter)
Erase the key/data pair referenced by the iterator.
btree< key_type, value_type, key_of_value, key_compare, traits, true, allocator_type > btree_impl
Implementation type of the btree_base.
iterator lower_bound(const key_type &key)
Definition: btree.hpp:1616
std::pair< const_iterator, const_iterator > equal_range(const key_type &key) const
Searches the B+ tree and returns both lower_bound() and upper_bound().
static const unsigned short inner_slotmin
bool exists(const key_type &key) const
bool operator>=(const btree_multiset &other) const
Greater-equal relation. Based on operator<.
std::pair< iterator, bool > insert(const value_type &x)
Definition: btree.hpp:1846
Basic class implementing a B+ tree data structure in memory.
Definition: btree.hpp:124
size_type erase(const key_type &key)
Definition: btree.hpp:2356
key_compare key_comp() const
Constant access to the key comparison object sorting the B+ tree.
Definition: btree.hpp:1183
const_iterator end() const
iterator insert(iterator hint, const key_type &x)
bool operator!=(const btree_multiset &other) const
Inequality relation. Based on operator==.
const_reverse_iterator rend() const
void swap(btree_multiset &from)
Fast swapping of two identical B+ tree objects.
void insert(InputIterator first, InputIterator last)
value_compare value_comp() const
iterator find(const key_type &key)
Definition: btree.hpp:1542
iterator upper_bound(const key_type &key)
btree_multiset(const btree_multiset &other)
bool operator==(const btree_multiset &other) const
size_type erase(const key_type &key)
size_type max_size() const
Definition: btree.hpp:1505