1 // Map implementation -*- C++ -*-
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44 * Copyright (c) 1996,1997
45 * Silicon Graphics Computer Systems, Inc.
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48 * and its documentation for any purpose is hereby granted without fee,
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57 * This is an internal header file, included by other library headers.
58 * You should not attempt to use it directly.
64 #include <bits/concept_check.h>
66 namespace _GLIBCXX_STD
69 * @brief A standard container made up of (key,value) pairs, which can be
70 * retrieved based on a key, in logarithmic time.
73 * @ingroup Assoc_containers
75 * Meets the requirements of a <a href="tables.html#65">container</a>, a
76 * <a href="tables.html#66">reversible container</a>, and an
77 * <a href="tables.html#69">associative container</a> (using unique keys).
78 * For a @c map<Key,T> the key_type is Key, the mapped_type is T, and the
79 * value_type is std::pair<const Key,T>.
81 * Maps support bidirectional iterators.
84 * The private tree data is declared exactly the same way for map and
85 * multimap; the distinction is made entirely in how the tree functions are
86 * called (*_unique versus *_equal, same as the standard).
89 template <typename _Key, typename _Tp, typename _Compare = std::less<_Key>,
90 typename _Alloc = std::allocator<std::pair<const _Key, _Tp> > >
94 typedef _Key key_type;
95 typedef _Tp mapped_type;
96 typedef std::pair<const _Key, _Tp> value_type;
97 typedef _Compare key_compare;
98 typedef _Alloc allocator_type;
101 // concept requirements
102 typedef typename _Alloc::value_type _Alloc_value_type;
103 __glibcxx_class_requires(_Tp, _SGIAssignableConcept)
104 __glibcxx_class_requires4(_Compare, bool, _Key, _Key,
105 _BinaryFunctionConcept)
106 __glibcxx_class_requires2(value_type, _Alloc_value_type, _SameTypeConcept)
110 : public std::binary_function<value_type, value_type, bool>
112 friend class map<_Key, _Tp, _Compare, _Alloc>;
116 value_compare(_Compare __c)
120 bool operator()(const value_type& __x, const value_type& __y) const
121 { return comp(__x.first, __y.first); }
125 /// @if maint This turns a red-black tree into a [multi]map. @endif
126 typedef typename _Alloc::template rebind<value_type>::other
129 typedef _Rb_tree<key_type, value_type, _Select1st<value_type>,
130 key_compare, _Pair_alloc_type> _Rep_type;
132 /// @if maint The actual tree structure. @endif
136 // many of these are specified differently in ISO, but the following are
137 // "functionally equivalent"
138 typedef typename _Pair_alloc_type::pointer pointer;
139 typedef typename _Pair_alloc_type::const_pointer const_pointer;
140 typedef typename _Pair_alloc_type::reference reference;
141 typedef typename _Pair_alloc_type::const_reference const_reference;
142 typedef typename _Rep_type::iterator iterator;
143 typedef typename _Rep_type::const_iterator const_iterator;
144 typedef typename _Rep_type::size_type size_type;
145 typedef typename _Rep_type::difference_type difference_type;
146 typedef typename _Rep_type::reverse_iterator reverse_iterator;
147 typedef typename _Rep_type::const_reverse_iterator const_reverse_iterator;
149 // [23.3.1.1] construct/copy/destroy
150 // (get_allocator() is normally listed in this section, but seems to have
151 // been accidentally omitted in the printed standard)
153 * @brief Default constructor creates no elements.
156 : _M_t(_Compare(), allocator_type()) { }
158 // for some reason this was made a separate function
160 * @brief Default constructor creates no elements.
163 map(const _Compare& __comp, const allocator_type& __a = allocator_type())
164 : _M_t(__comp, __a) { }
167 * @brief Map copy constructor.
168 * @param x A %map of identical element and allocator types.
170 * The newly-created %map uses a copy of the allocation object used
177 * @brief Builds a %map from a range.
178 * @param first An input iterator.
179 * @param last An input iterator.
181 * Create a %map consisting of copies of the elements from [first,last).
182 * This is linear in N if the range is already sorted, and NlogN
183 * otherwise (where N is distance(first,last)).
185 template <typename _InputIterator>
186 map(_InputIterator __first, _InputIterator __last)
187 : _M_t(_Compare(), allocator_type())
188 { _M_t.insert_unique(__first, __last); }
191 * @brief Builds a %map from a range.
192 * @param first An input iterator.
193 * @param last An input iterator.
194 * @param comp A comparison functor.
195 * @param a An allocator object.
197 * Create a %map consisting of copies of the elements from [first,last).
198 * This is linear in N if the range is already sorted, and NlogN
199 * otherwise (where N is distance(first,last)).
201 template <typename _InputIterator>
202 map(_InputIterator __first, _InputIterator __last,
203 const _Compare& __comp, const allocator_type& __a = allocator_type())
205 { _M_t.insert_unique(__first, __last); }
207 // FIXME There is no dtor declared, but we should have something generated
208 // by Doxygen. I don't know what tags to add to this paragraph to make
211 * The dtor only erases the elements, and note that if the elements
212 * themselves are pointers, the pointed-to memory is not touched in any
213 * way. Managing the pointer is the user's responsibilty.
217 * @brief Map assignment operator.
218 * @param x A %map of identical element and allocator types.
220 * All the elements of @a x are copied, but unlike the copy constructor,
221 * the allocator object is not copied.
224 operator=(const map& __x)
230 /// Get a copy of the memory allocation object.
232 get_allocator() const
233 { return _M_t.get_allocator(); }
237 * Returns a read/write iterator that points to the first pair in the
239 * Iteration is done in ascending order according to the keys.
243 { return _M_t.begin(); }
246 * Returns a read-only (constant) iterator that points to the first pair
247 * in the %map. Iteration is done in ascending order according to the
252 { return _M_t.begin(); }
255 * Returns a read/write iterator that points one past the last pair in
256 * the %map. Iteration is done in ascending order according to the keys.
260 { return _M_t.end(); }
263 * Returns a read-only (constant) iterator that points one past the last
264 * pair in the %map. Iteration is done in ascending order according to
269 { return _M_t.end(); }
272 * Returns a read/write reverse iterator that points to the last pair in
273 * the %map. Iteration is done in descending order according to the
278 { return _M_t.rbegin(); }
281 * Returns a read-only (constant) reverse iterator that points to the
282 * last pair in the %map. Iteration is done in descending order
283 * according to the keys.
285 const_reverse_iterator
287 { return _M_t.rbegin(); }
290 * Returns a read/write reverse iterator that points to one before the
291 * first pair in the %map. Iteration is done in descending order
292 * according to the keys.
296 { return _M_t.rend(); }
299 * Returns a read-only (constant) reverse iterator that points to one
300 * before the first pair in the %map. Iteration is done in descending
301 * order according to the keys.
303 const_reverse_iterator
305 { return _M_t.rend(); }
308 /** Returns true if the %map is empty. (Thus begin() would equal
313 { return _M_t.empty(); }
315 /** Returns the size of the %map. */
318 { return _M_t.size(); }
320 /** Returns the maximum size of the %map. */
323 { return _M_t.max_size(); }
325 // [23.3.1.2] element access
327 * @brief Subscript ( @c [] ) access to %map data.
328 * @param k The key for which data should be retrieved.
329 * @return A reference to the data of the (key,data) %pair.
331 * Allows for easy lookup with the subscript ( @c [] ) operator. Returns
332 * data associated with the key specified in subscript. If the key does
333 * not exist, a pair with that key is created using default values, which
336 * Lookup requires logarithmic time.
339 operator[](const key_type& __k)
341 // concept requirements
342 __glibcxx_function_requires(_DefaultConstructibleConcept<mapped_type>)
344 iterator __i = lower_bound(__k);
345 // __i->first is greater than or equivalent to __k.
346 if (__i == end() || key_comp()(__k, (*__i).first))
347 __i = insert(__i, value_type(__k, mapped_type()));
348 return (*__i).second;
353 * @brief Attempts to insert a std::pair into the %map.
354 * @param x Pair to be inserted (see std::make_pair for easy creation of
356 * @return A pair, of which the first element is an iterator that points
357 * to the possibly inserted pair, and the second is a bool that
358 * is true if the pair was actually inserted.
360 * This function attempts to insert a (key, value) %pair into the %map.
361 * A %map relies on unique keys and thus a %pair is only inserted if its
362 * first element (the key) is not already present in the %map.
364 * Insertion requires logarithmic time.
366 std::pair<iterator,bool>
367 insert(const value_type& __x)
368 { return _M_t.insert_unique(__x); }
371 * @brief Attempts to insert a std::pair into the %map.
372 * @param position An iterator that serves as a hint as to where the
373 * pair should be inserted.
374 * @param x Pair to be inserted (see std::make_pair for easy creation of
376 * @return An iterator that points to the element with key of @a x (may
377 * or may not be the %pair passed in).
379 * This function is not concerned about whether the insertion took place,
380 * and thus does not return a boolean like the single-argument
381 * insert() does. Note that the first parameter is only a hint and can
382 * potentially improve the performance of the insertion process. A bad
383 * hint would cause no gains in efficiency.
385 * See http://gcc.gnu.org/onlinedocs/libstdc++/23_containers/howto.html#4
386 * for more on "hinting".
388 * Insertion requires logarithmic time (if the hint is not taken).
391 insert(iterator position, const value_type& __x)
392 { return _M_t.insert_unique(position, __x); }
395 * @brief A template function that attemps to insert a range of elements.
396 * @param first Iterator pointing to the start of the range to be
398 * @param last Iterator pointing to the end of the range.
400 * Complexity similar to that of the range constructor.
402 template <typename _InputIterator>
404 insert(_InputIterator __first, _InputIterator __last)
405 { _M_t.insert_unique(__first, __last); }
408 * @brief Erases an element from a %map.
409 * @param position An iterator pointing to the element to be erased.
411 * This function erases an element, pointed to by the given iterator,
412 * from a %map. Note that this function only erases the element, and
413 * that if the element is itself a pointer, the pointed-to memory is not
414 * touched in any way. Managing the pointer is the user's responsibilty.
417 erase(iterator __position)
418 { _M_t.erase(__position); }
421 * @brief Erases elements according to the provided key.
422 * @param x Key of element to be erased.
423 * @return The number of elements erased.
425 * This function erases all the elements located by the given key from
427 * Note that this function only erases the element, and that if
428 * the element is itself a pointer, the pointed-to memory is not touched
429 * in any way. Managing the pointer is the user's responsibilty.
432 erase(const key_type& __x)
433 { return _M_t.erase(__x); }
436 * @brief Erases a [first,last) range of elements from a %map.
437 * @param first Iterator pointing to the start of the range to be
439 * @param last Iterator pointing to the end of the range to be erased.
441 * This function erases a sequence of elements from a %map.
442 * Note that this function only erases the element, and that if
443 * the element is itself a pointer, the pointed-to memory is not touched
444 * in any way. Managing the pointer is the user's responsibilty.
447 erase(iterator __first, iterator __last)
448 { _M_t.erase(__first, __last); }
451 * @brief Swaps data with another %map.
452 * @param x A %map of the same element and allocator types.
454 * This exchanges the elements between two maps in constant time.
455 * (It is only swapping a pointer, an integer, and an instance of
456 * the @c Compare type (which itself is often stateless and empty), so it
457 * should be quite fast.)
458 * Note that the global std::swap() function is specialized such that
459 * std::swap(m1,m2) will feed to this function.
463 { _M_t.swap(__x._M_t); }
466 * Erases all elements in a %map. Note that this function only erases
467 * the elements, and that if the elements themselves are pointers, the
468 * pointed-to memory is not touched in any way. Managing the pointer is
469 * the user's responsibilty.
477 * Returns the key comparison object out of which the %map was
482 { return _M_t.key_comp(); }
485 * Returns a value comparison object, built from the key comparison
486 * object out of which the %map was constructed.
490 { return value_compare(_M_t.key_comp()); }
492 // [23.3.1.3] map operations
494 * @brief Tries to locate an element in a %map.
495 * @param x Key of (key, value) %pair to be located.
496 * @return Iterator pointing to sought-after element, or end() if not
499 * This function takes a key and tries to locate the element with which
500 * the key matches. If successful the function returns an iterator
501 * pointing to the sought after %pair. If unsuccessful it returns the
502 * past-the-end ( @c end() ) iterator.
505 find(const key_type& __x)
506 { return _M_t.find(__x); }
509 * @brief Tries to locate an element in a %map.
510 * @param x Key of (key, value) %pair to be located.
511 * @return Read-only (constant) iterator pointing to sought-after
512 * element, or end() if not found.
514 * This function takes a key and tries to locate the element with which
515 * the key matches. If successful the function returns a constant
516 * iterator pointing to the sought after %pair. If unsuccessful it
517 * returns the past-the-end ( @c end() ) iterator.
520 find(const key_type& __x) const
521 { return _M_t.find(__x); }
524 * @brief Finds the number of elements with given key.
525 * @param x Key of (key, value) pairs to be located.
526 * @return Number of elements with specified key.
528 * This function only makes sense for multimaps; for map the result will
529 * either be 0 (not present) or 1 (present).
532 count(const key_type& __x) const
533 { return _M_t.find(__x) == _M_t.end() ? 0 : 1; }
536 * @brief Finds the beginning of a subsequence matching given key.
537 * @param x Key of (key, value) pair to be located.
538 * @return Iterator pointing to first element equal to or greater
539 * than key, or end().
541 * This function returns the first element of a subsequence of elements
542 * that matches the given key. If unsuccessful it returns an iterator
543 * pointing to the first element that has a greater value than given key
544 * or end() if no such element exists.
547 lower_bound(const key_type& __x)
548 { return _M_t.lower_bound(__x); }
551 * @brief Finds the beginning of a subsequence matching given key.
552 * @param x Key of (key, value) pair to be located.
553 * @return Read-only (constant) iterator pointing to first element
554 * equal to or greater than key, or end().
556 * This function returns the first element of a subsequence of elements
557 * that matches the given key. If unsuccessful it returns an iterator
558 * pointing to the first element that has a greater value than given key
559 * or end() if no such element exists.
562 lower_bound(const key_type& __x) const
563 { return _M_t.lower_bound(__x); }
566 * @brief Finds the end of a subsequence matching given key.
567 * @param x Key of (key, value) pair to be located.
568 * @return Iterator pointing to the first element
569 * greater than key, or end().
572 upper_bound(const key_type& __x)
573 { return _M_t.upper_bound(__x); }
576 * @brief Finds the end of a subsequence matching given key.
577 * @param x Key of (key, value) pair to be located.
578 * @return Read-only (constant) iterator pointing to first iterator
579 * greater than key, or end().
582 upper_bound(const key_type& __x) const
583 { return _M_t.upper_bound(__x); }
586 * @brief Finds a subsequence matching given key.
587 * @param x Key of (key, value) pairs to be located.
588 * @return Pair of iterators that possibly points to the subsequence
589 * matching given key.
591 * This function is equivalent to
593 * std::make_pair(c.lower_bound(val),
594 * c.upper_bound(val))
596 * (but is faster than making the calls separately).
598 * This function probably only makes sense for multimaps.
600 std::pair<iterator, iterator>
601 equal_range(const key_type& __x)
602 { return _M_t.equal_range(__x); }
605 * @brief Finds a subsequence matching given key.
606 * @param x Key of (key, value) pairs to be located.
607 * @return Pair of read-only (constant) iterators that possibly points
608 * to the subsequence matching given key.
610 * This function is equivalent to
612 * std::make_pair(c.lower_bound(val),
613 * c.upper_bound(val))
615 * (but is faster than making the calls separately).
617 * This function probably only makes sense for multimaps.
619 std::pair<const_iterator, const_iterator>
620 equal_range(const key_type& __x) const
621 { return _M_t.equal_range(__x); }
623 template <typename _K1, typename _T1, typename _C1, typename _A1>
625 operator== (const map<_K1, _T1, _C1, _A1>&,
626 const map<_K1, _T1, _C1, _A1>&);
628 template <typename _K1, typename _T1, typename _C1, typename _A1>
630 operator< (const map<_K1, _T1, _C1, _A1>&,
631 const map<_K1, _T1, _C1, _A1>&);
635 * @brief Map equality comparison.
637 * @param y A %map of the same type as @a x.
638 * @return True iff the size and elements of the maps are equal.
640 * This is an equivalence relation. It is linear in the size of the
641 * maps. Maps are considered equivalent if their sizes are equal,
642 * and if corresponding elements compare equal.
644 template <typename _Key, typename _Tp, typename _Compare, typename _Alloc>
646 operator==(const map<_Key, _Tp, _Compare, _Alloc>& __x,
647 const map<_Key, _Tp, _Compare, _Alloc>& __y)
648 { return __x._M_t == __y._M_t; }
651 * @brief Map ordering relation.
653 * @param y A %map of the same type as @a x.
654 * @return True iff @a x is lexicographically less than @a y.
656 * This is a total ordering relation. It is linear in the size of the
657 * maps. The elements must be comparable with @c <.
659 * See std::lexicographical_compare() for how the determination is made.
661 template <typename _Key, typename _Tp, typename _Compare, typename _Alloc>
663 operator<(const map<_Key, _Tp, _Compare, _Alloc>& __x,
664 const map<_Key, _Tp, _Compare, _Alloc>& __y)
665 { return __x._M_t < __y._M_t; }
667 /// Based on operator==
668 template <typename _Key, typename _Tp, typename _Compare, typename _Alloc>
670 operator!=(const map<_Key, _Tp, _Compare, _Alloc>& __x,
671 const map<_Key, _Tp, _Compare, _Alloc>& __y)
672 { return !(__x == __y); }
674 /// Based on operator<
675 template <typename _Key, typename _Tp, typename _Compare, typename _Alloc>
677 operator>(const map<_Key, _Tp, _Compare, _Alloc>& __x,
678 const map<_Key, _Tp, _Compare, _Alloc>& __y)
679 { return __y < __x; }
681 /// Based on operator<
682 template <typename _Key, typename _Tp, typename _Compare, typename _Alloc>
684 operator<=(const map<_Key, _Tp, _Compare, _Alloc>& __x,
685 const map<_Key, _Tp, _Compare, _Alloc>& __y)
686 { return !(__y < __x); }
688 /// Based on operator<
689 template <typename _Key, typename _Tp, typename _Compare, typename _Alloc>
691 operator>=(const map<_Key, _Tp, _Compare, _Alloc>& __x,
692 const map<_Key, _Tp, _Compare, _Alloc>& __y)
693 { return !(__x < __y); }
695 /// See std::map::swap().
696 template <typename _Key, typename _Tp, typename _Compare, typename _Alloc>
698 swap(map<_Key, _Tp, _Compare, _Alloc>& __x,
699 map<_Key, _Tp, _Compare, _Alloc>& __y)