1 // Map implementation -*- C++ -*-
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44 * Copyright (c) 1996,1997
45 * Silicon Graphics Computer Systems, Inc.
47 * Permission to use, copy, modify, distribute and sell this software
48 * and its documentation for any purpose is hereby granted without fee,
49 * provided that the above copyright notice appear in all copies and
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53 * purpose. It is provided "as is" without express or implied warranty.
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
= less
<_Key
>,
90 typename _Alloc
= allocator
<pair
<const _Key
, _Tp
> > >
93 // concept requirements
94 __glibcxx_class_requires(_Tp
, _SGIAssignableConcept
)
95 __glibcxx_class_requires4(_Compare
, bool, _Key
, _Key
,
96 _BinaryFunctionConcept
)
99 typedef _Key key_type
;
100 typedef _Tp mapped_type
;
101 typedef pair
<const _Key
, _Tp
> value_type
;
102 typedef _Compare key_compare
;
105 : public binary_function
<value_type
, value_type
, bool>
107 friend class map
<_Key
,_Tp
,_Compare
,_Alloc
>;
111 value_compare(_Compare __c
)
115 bool operator()(const value_type
& __x
, const value_type
& __y
) const
116 { return comp(__x
.first
, __y
.first
); }
120 /// @if maint This turns a red-black tree into a [multi]map. @endif
121 typedef _Rb_tree
<key_type
, value_type
,
122 _Select1st
<value_type
>, key_compare
, _Alloc
> _Rep_type
;
123 /// @if maint The actual tree structure. @endif
127 // many of these are specified differently in ISO, but the following are
128 // "functionally equivalent"
129 typedef typename
_Alloc::pointer pointer
;
130 typedef typename
_Alloc::const_pointer const_pointer
;
131 typedef typename
_Alloc::reference reference
;
132 typedef typename
_Alloc::const_reference const_reference
;
133 typedef typename
_Rep_type::allocator_type allocator_type
;
134 typedef typename
_Rep_type::iterator iterator
;
135 typedef typename
_Rep_type::const_iterator const_iterator
;
136 typedef typename
_Rep_type::size_type size_type
;
137 typedef typename
_Rep_type::difference_type difference_type
;
138 typedef typename
_Rep_type::reverse_iterator reverse_iterator
;
139 typedef typename
_Rep_type::const_reverse_iterator const_reverse_iterator
;
141 // [23.3.1.1] construct/copy/destroy
142 // (get_allocator() is normally listed in this section, but seems to have
143 // been accidentally omitted in the printed standard)
145 * @brief Default constructor creates no elements.
148 : _M_t(_Compare(), allocator_type()) { }
150 // for some reason this was made a separate function
152 * @brief Default constructor creates no elements.
155 map(const _Compare
& __comp
, const allocator_type
& __a
= allocator_type())
156 : _M_t(__comp
, __a
) { }
159 * @brief Map copy constructor.
160 * @param x A %map of identical element and allocator types.
162 * The newly-created %map uses a copy of the allocation object used
169 * @brief Builds a %map from a range.
170 * @param first An input iterator.
171 * @param last An input iterator.
173 * Create a %map consisting of copies of the elements from [first,last).
174 * This is linear in N if the range is already sorted, and NlogN
175 * otherwise (where N is distance(first,last)).
177 template <typename _InputIterator
>
178 map(_InputIterator __first
, _InputIterator __last
)
179 : _M_t(_Compare(), allocator_type())
180 { _M_t
.insert_unique(__first
, __last
); }
183 * @brief Builds a %map from a range.
184 * @param first An input iterator.
185 * @param last An input iterator.
186 * @param comp A comparison functor.
187 * @param a An allocator object.
189 * Create a %map consisting of copies of the elements from [first,last).
190 * This is linear in N if the range is already sorted, and NlogN
191 * otherwise (where N is distance(first,last)).
193 template <typename _InputIterator
>
194 map(_InputIterator __first
, _InputIterator __last
,
195 const _Compare
& __comp
, const allocator_type
& __a
= allocator_type())
197 { _M_t
.insert_unique(__first
, __last
); }
199 // FIXME There is no dtor declared, but we should have something generated
200 // by Doxygen. I don't know what tags to add to this paragraph to make
203 * The dtor only erases the elements, and note that if the elements
204 * themselves are pointers, the pointed-to memory is not touched in any
205 * way. Managing the pointer is the user's responsibilty.
209 * @brief Map assignment operator.
210 * @param x A %map of identical element and allocator types.
212 * All the elements of @a x are copied, but unlike the copy constructor,
213 * the allocator object is not copied.
216 operator=(const map
& __x
)
222 /// Get a copy of the memory allocation object.
224 get_allocator() const
225 { return _M_t
.get_allocator(); }
229 * Returns a read/write iterator that points to the first pair in the
231 * Iteration is done in ascending order according to the keys.
235 { return _M_t
.begin(); }
238 * Returns a read-only (constant) iterator that points to the first pair
239 * in the %map. Iteration is done in ascending order according to the
244 { return _M_t
.begin(); }
247 * Returns a read/write iterator that points one past the last pair in
248 * the %map. Iteration is done in ascending order according to the keys.
252 { return _M_t
.end(); }
255 * Returns a read-only (constant) iterator that points one past the last
256 * pair in the %map. Iteration is done in ascending order according to
261 { return _M_t
.end(); }
264 * Returns a read/write reverse iterator that points to the last pair in
265 * the %map. Iteration is done in descending order according to the
270 { return _M_t
.rbegin(); }
273 * Returns a read-only (constant) reverse iterator that points to the
274 * last pair in the %map. Iteration is done in descending order
275 * according to the keys.
277 const_reverse_iterator
279 { return _M_t
.rbegin(); }
282 * Returns a read/write reverse iterator that points to one before the
283 * first pair in the %map. Iteration is done in descending order
284 * according to the keys.
288 { return _M_t
.rend(); }
291 * Returns a read-only (constant) reverse iterator that points to one
292 * before the first pair in the %map. Iteration is done in descending
293 * order according to the keys.
295 const_reverse_iterator
297 { return _M_t
.rend(); }
300 /** Returns true if the %map is empty. (Thus begin() would equal
305 { return _M_t
.empty(); }
307 /** Returns the size of the %map. */
310 { return _M_t
.size(); }
312 /** Returns the maximum size of the %map. */
315 { return _M_t
.max_size(); }
317 // [23.3.1.2] element access
319 * @brief Subscript ( @c [] ) access to %map data.
320 * @param k The key for which data should be retrieved.
321 * @return A reference to the data of the (key,data) %pair.
323 * Allows for easy lookup with the subscript ( @c [] ) operator. Returns
324 * data associated with the key specified in subscript. If the key does
325 * not exist, a pair with that key is created using default values, which
328 * Lookup requires logarithmic time.
331 operator[](const key_type
& __k
)
333 // concept requirements
334 __glibcxx_function_requires(_DefaultConstructibleConcept
<mapped_type
>)
336 iterator __i
= lower_bound(__k
);
337 // __i->first is greater than or equivalent to __k.
338 if (__i
== end() || key_comp()(__k
, (*__i
).first
))
339 __i
= insert(__i
, value_type(__k
, mapped_type()));
340 return (*__i
).second
;
345 * @brief Attempts to insert a std::pair into the %map.
346 * @param x Pair to be inserted (see std::make_pair for easy creation of
348 * @return A pair, of which the first element is an iterator that points
349 * to the possibly inserted pair, and the second is a bool that
350 * is true if the pair was actually inserted.
352 * This function attempts to insert a (key, value) %pair into the %map.
353 * A %map relies on unique keys and thus a %pair is only inserted if its
354 * first element (the key) is not already present in the %map.
356 * Insertion requires logarithmic time.
359 insert(const value_type
& __x
)
360 { return _M_t
.insert_unique(__x
); }
363 * @brief Attempts to insert a std::pair into the %map.
364 * @param position An iterator that serves as a hint as to where the
365 * pair should be inserted.
366 * @param x Pair to be inserted (see std::make_pair for easy creation of
368 * @return An iterator that points to the element with key of @a x (may
369 * or may not be the %pair passed in).
371 * This function is not concerned about whether the insertion took place,
372 * and thus does not return a boolean like the single-argument
373 * insert() does. Note that the first parameter is only a hint and can
374 * potentially improve the performance of the insertion process. A bad
375 * hint would cause no gains in efficiency.
377 * See http://gcc.gnu.org/onlinedocs/libstdc++/23_containers/howto.html#4
378 * for more on "hinting".
380 * Insertion requires logarithmic time (if the hint is not taken).
383 insert(iterator position
, const value_type
& __x
)
384 { return _M_t
.insert_unique(position
, __x
); }
387 * @brief A template function that attemps to insert a range of elements.
388 * @param first Iterator pointing to the start of the range to be
390 * @param last Iterator pointing to the end of the range.
392 * Complexity similar to that of the range constructor.
394 template <typename _InputIterator
>
396 insert(_InputIterator __first
, _InputIterator __last
)
397 { _M_t
.insert_unique(__first
, __last
); }
400 * @brief Erases an element from a %map.
401 * @param position An iterator pointing to the element to be erased.
403 * This function erases an element, pointed to by the given iterator,
404 * from a %map. Note that this function only erases the element, and
405 * that if the element is itself a pointer, the pointed-to memory is not
406 * touched in any way. Managing the pointer is the user's responsibilty.
409 erase(iterator __position
)
410 { _M_t
.erase(__position
); }
413 * @brief Erases elements according to the provided key.
414 * @param x Key of element to be erased.
415 * @return The number of elements erased.
417 * This function erases all the elements located by the given key from
419 * Note that this function only erases the element, and that if
420 * the element is itself a pointer, the pointed-to memory is not touched
421 * in any way. Managing the pointer is the user's responsibilty.
424 erase(const key_type
& __x
)
425 { return _M_t
.erase(__x
); }
428 * @brief Erases a [first,last) range of elements from a %map.
429 * @param first Iterator pointing to the start of the range to be
431 * @param last Iterator pointing to the end of the range to be erased.
433 * This function erases a sequence of elements from a %map.
434 * Note that this function only erases the element, and that if
435 * the element is itself a pointer, the pointed-to memory is not touched
436 * in any way. Managing the pointer is the user's responsibilty.
439 erase(iterator __first
, iterator __last
)
440 { _M_t
.erase(__first
, __last
); }
443 * @brief Swaps data with another %map.
444 * @param x A %map of the same element and allocator types.
446 * This exchanges the elements between two maps in constant time.
447 * (It is only swapping a pointer, an integer, and an instance of
448 * the @c Compare type (which itself is often stateless and empty), so it
449 * should be quite fast.)
450 * Note that the global std::swap() function is specialized such that
451 * std::swap(m1,m2) will feed to this function.
455 { _M_t
.swap(__x
._M_t
); }
458 * Erases all elements in a %map. Note that this function only erases
459 * the elements, and that if the elements themselves are pointers, the
460 * pointed-to memory is not touched in any way. Managing the pointer is
461 * the user's responsibilty.
469 * Returns the key comparison object out of which the %map was
474 { return _M_t
.key_comp(); }
477 * Returns a value comparison object, built from the key comparison
478 * object out of which the %map was constructed.
482 { return value_compare(_M_t
.key_comp()); }
484 // [23.3.1.3] map operations
486 * @brief Tries to locate an element in a %map.
487 * @param x Key of (key, value) %pair to be located.
488 * @return Iterator pointing to sought-after element, or end() if not
491 * This function takes a key and tries to locate the element with which
492 * the key matches. If successful the function returns an iterator
493 * pointing to the sought after %pair. If unsuccessful it returns the
494 * past-the-end ( @c end() ) iterator.
497 find(const key_type
& __x
)
498 { return _M_t
.find(__x
); }
501 * @brief Tries to locate an element in a %map.
502 * @param x Key of (key, value) %pair to be located.
503 * @return Read-only (constant) iterator pointing to sought-after
504 * element, or end() if not found.
506 * This function takes a key and tries to locate the element with which
507 * the key matches. If successful the function returns a constant
508 * iterator pointing to the sought after %pair. If unsuccessful it
509 * returns the past-the-end ( @c end() ) iterator.
512 find(const key_type
& __x
) const
513 { return _M_t
.find(__x
); }
516 * @brief Finds the number of elements with given key.
517 * @param x Key of (key, value) pairs to be located.
518 * @return Number of elements with specified key.
520 * This function only makes sense for multimaps; for map the result will
521 * either be 0 (not present) or 1 (present).
524 count(const key_type
& __x
) const
525 { return _M_t
.find(__x
) == _M_t
.end() ? 0 : 1; }
528 * @brief Finds the beginning of a subsequence matching given key.
529 * @param x Key of (key, value) pair to be located.
530 * @return Iterator pointing to first element equal to or greater
531 * than key, or end().
533 * This function returns the first element of a subsequence of elements
534 * that matches the given key. If unsuccessful it returns an iterator
535 * pointing to the first element that has a greater value than given key
536 * or end() if no such element exists.
539 lower_bound(const key_type
& __x
)
540 { return _M_t
.lower_bound(__x
); }
543 * @brief Finds the beginning of a subsequence matching given key.
544 * @param x Key of (key, value) pair to be located.
545 * @return Read-only (constant) iterator pointing to first element
546 * equal to or greater than key, or end().
548 * This function returns the first element of a subsequence of elements
549 * that matches the given key. If unsuccessful it returns an iterator
550 * pointing to the first element that has a greater value than given key
551 * or end() if no such element exists.
554 lower_bound(const key_type
& __x
) const
555 { return _M_t
.lower_bound(__x
); }
558 * @brief Finds the end of a subsequence matching given key.
559 * @param x Key of (key, value) pair to be located.
560 * @return Iterator pointing to the first element
561 * greater than key, or end().
564 upper_bound(const key_type
& __x
)
565 { return _M_t
.upper_bound(__x
); }
568 * @brief Finds the end of a subsequence matching given key.
569 * @param x Key of (key, value) pair to be located.
570 * @return Read-only (constant) iterator pointing to first iterator
571 * greater than key, or end().
574 upper_bound(const key_type
& __x
) const
575 { return _M_t
.upper_bound(__x
); }
578 * @brief Finds a subsequence matching given key.
579 * @param x Key of (key, value) pairs to be located.
580 * @return Pair of iterators that possibly points to the subsequence
581 * matching given key.
583 * This function is equivalent to
585 * std::make_pair(c.lower_bound(val),
586 * c.upper_bound(val))
588 * (but is faster than making the calls separately).
590 * This function probably only makes sense for multimaps.
592 pair
<iterator
,iterator
>
593 equal_range(const key_type
& __x
)
594 { return _M_t
.equal_range(__x
); }
597 * @brief Finds a subsequence matching given key.
598 * @param x Key of (key, value) pairs to be located.
599 * @return Pair of read-only (constant) iterators that possibly points
600 * to the subsequence matching given key.
602 * This function is equivalent to
604 * std::make_pair(c.lower_bound(val),
605 * c.upper_bound(val))
607 * (but is faster than making the calls separately).
609 * This function probably only makes sense for multimaps.
611 pair
<const_iterator
,const_iterator
>
612 equal_range(const key_type
& __x
) const
613 { return _M_t
.equal_range(__x
); }
615 template <typename _K1
, typename _T1
, typename _C1
, typename _A1
>
617 operator== (const map
<_K1
,_T1
,_C1
,_A1
>&,
618 const map
<_K1
,_T1
,_C1
,_A1
>&);
620 template <typename _K1
, typename _T1
, typename _C1
, typename _A1
>
622 operator< (const map
<_K1
,_T1
,_C1
,_A1
>&,
623 const map
<_K1
,_T1
,_C1
,_A1
>&);
627 * @brief Map equality comparison.
629 * @param y A %map of the same type as @a x.
630 * @return True iff the size and elements of the maps are equal.
632 * This is an equivalence relation. It is linear in the size of the
633 * maps. Maps are considered equivalent if their sizes are equal,
634 * and if corresponding elements compare equal.
636 template <typename _Key
, typename _Tp
, typename _Compare
, typename _Alloc
>
638 operator==(const map
<_Key
,_Tp
,_Compare
,_Alloc
>& __x
,
639 const map
<_Key
,_Tp
,_Compare
,_Alloc
>& __y
)
640 { return __x
._M_t
== __y
._M_t
; }
643 * @brief Map ordering relation.
645 * @param y A %map of the same type as @a x.
646 * @return True iff @a x is lexicographically less than @a y.
648 * This is a total ordering relation. It is linear in the size of the
649 * maps. The elements must be comparable with @c <.
651 * See std::lexicographical_compare() for how the determination is made.
653 template <typename _Key
, typename _Tp
, typename _Compare
, typename _Alloc
>
655 operator<(const map
<_Key
,_Tp
,_Compare
,_Alloc
>& __x
,
656 const map
<_Key
,_Tp
,_Compare
,_Alloc
>& __y
)
657 { return __x
._M_t
< __y
._M_t
; }
659 /// Based on operator==
660 template <typename _Key
, typename _Tp
, typename _Compare
, typename _Alloc
>
662 operator!=(const map
<_Key
,_Tp
,_Compare
,_Alloc
>& __x
,
663 const map
<_Key
,_Tp
,_Compare
,_Alloc
>& __y
)
664 { return !(__x
== __y
); }
666 /// Based on operator<
667 template <typename _Key
, typename _Tp
, typename _Compare
, typename _Alloc
>
669 operator>(const map
<_Key
,_Tp
,_Compare
,_Alloc
>& __x
,
670 const map
<_Key
,_Tp
,_Compare
,_Alloc
>& __y
)
671 { return __y
< __x
; }
673 /// Based on operator<
674 template <typename _Key
, typename _Tp
, typename _Compare
, typename _Alloc
>
676 operator<=(const map
<_Key
,_Tp
,_Compare
,_Alloc
>& __x
,
677 const map
<_Key
,_Tp
,_Compare
,_Alloc
>& __y
)
678 { return !(__y
< __x
); }
680 /// Based on operator<
681 template <typename _Key
, typename _Tp
, typename _Compare
, typename _Alloc
>
683 operator>=(const map
<_Key
,_Tp
,_Compare
,_Alloc
>& __x
,
684 const map
<_Key
,_Tp
,_Compare
,_Alloc
>& __y
)
685 { return !(__x
< __y
); }
687 /// See std::map::swap().
688 template <typename _Key
, typename _Tp
, typename _Compare
, typename _Alloc
>
690 swap(map
<_Key
,_Tp
,_Compare
,_Alloc
>& __x
, map
<_Key
,_Tp
,_Compare
,_Alloc
>& __y
)