1 // Iterators -*- C++ -*-
3 // Copyright (C) 2001, 2002 Free Software Foundation, Inc.
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 2, or (at your option)
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
16 // You should have received a copy of the GNU General Public License along
17 // with this library; see the file COPYING. If not, write to the Free
18 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
21 // As a special exception, you may use this file as part of a free software
22 // library without restriction. Specifically, if other files instantiate
23 // templates or use macros or inline functions from this file, or you compile
24 // this file and link it with other files to produce an executable, this
25 // file does not by itself cause the resulting executable to be covered by
26 // the GNU General Public License. This exception does not however
27 // invalidate any other reasons why the executable file might be covered by
28 // the GNU General Public License.
33 * Hewlett-Packard Company
35 * Permission to use, copy, modify, distribute and sell this software
36 * and its documentation for any purpose is hereby granted without fee,
37 * provided that the above copyright notice appear in all copies and
38 * that both that copyright notice and this permission notice appear
39 * in supporting documentation. Hewlett-Packard Company makes no
40 * representations about the suitability of this software for any
41 * purpose. It is provided "as is" without express or implied warranty.
44 * Copyright (c) 1996-1998
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
50 * that both that copyright notice and this permission notice appear
51 * in supporting documentation. Silicon Graphics makes no
52 * representations about the suitability of this software for any
53 * purpose. It is provided "as is" without express or implied warranty.
56 /** @file stl_iterator.h
57 * This is an internal header file, included by other library headers.
58 * You should not attempt to use it directly.
60 * This file implements reverse_iterator, back_insert_iterator,
61 * front_insert_iterator, insert_iterator, __normal_iterator, and their
62 * supporting functions and overloaded operators.
65 #ifndef __GLIBCPP_INTERNAL_ITERATOR_H
66 #define __GLIBCPP_INTERNAL_ITERATOR_H
70 // 24.4.1 Reverse iterators
72 * "Bidirectional and random access iterators have corresponding reverse
73 * %iterator adaptors that iterate through the data structure in the
74 * opposite direction. They have the same signatures as the corresponding
75 * iterators. The fundamental relation between a reverse %iterator and its
76 * corresponding %iterator @c i is established by the identity:
78 * &*(reverse_iterator(i)) == &*(i - 1)
81 * This mapping is dictated by the fact that while there is always a
82 * pointer past the end of an array, there might not be a valid pointer
83 * before the beginning of an array." [24.4.1]/1,2
85 * Reverse iterators can be tricky and surprising at first. Their
86 * semantics make sense, however, and the trickiness is a side effect of
87 * the requirement that the iterators must be safe.
89 template<typename _Iterator>
90 class reverse_iterator
91 : public iterator<typename iterator_traits<_Iterator>::iterator_category,
92 typename iterator_traits<_Iterator>::value_type,
93 typename iterator_traits<_Iterator>::difference_type,
94 typename iterator_traits<_Iterator>::pointer,
95 typename iterator_traits<_Iterator>::reference>
101 typedef _Iterator iterator_type;
102 typedef typename iterator_traits<_Iterator>::difference_type
104 typedef typename iterator_traits<_Iterator>::reference reference;
105 typedef typename iterator_traits<_Iterator>::pointer pointer;
109 * The default constructor gives an undefined state to this %iterator.
111 reverse_iterator() { }
114 * This %iterator will move in the opposite direction that @p x does.
117 reverse_iterator(iterator_type __x) : current(__x) { }
120 * The copy constructor is normal.
122 reverse_iterator(const reverse_iterator& __x)
123 : current(__x.current) { }
126 * A reverse_iterator across other types can be copied in the normal
129 template<typename _Iter>
130 reverse_iterator(const reverse_iterator<_Iter>& __x)
131 : current(__x.base()) { }
134 * @return @c current, the %iterator used for underlying work.
137 base() const { return current; }
147 _Iterator __tmp = current;
157 operator->() const { return &(operator*()); }
179 reverse_iterator __tmp = *this;
201 reverse_iterator operator--(int)
203 reverse_iterator __tmp = *this;
214 operator+(difference_type __n) const
215 { return reverse_iterator(current - __n); }
223 operator+=(difference_type __n)
235 operator-(difference_type __n) const
236 { return reverse_iterator(current + __n); }
244 operator-=(difference_type __n)
256 operator[](difference_type __n) const { return *(*this + __n); }
261 * @param x A %reverse_iterator.
262 * @param y A %reverse_iterator.
263 * @return A simple bool.
265 * Reverse iterators forward many operations to their underlying base()
266 * iterators. Others are implemented in terms of one another.
269 template<typename _Iterator>
271 operator==(const reverse_iterator<_Iterator>& __x,
272 const reverse_iterator<_Iterator>& __y)
273 { return __x.base() == __y.base(); }
275 template<typename _Iterator>
277 operator<(const reverse_iterator<_Iterator>& __x,
278 const reverse_iterator<_Iterator>& __y)
279 { return __y.base() < __x.base(); }
281 template<typename _Iterator>
283 operator!=(const reverse_iterator<_Iterator>& __x,
284 const reverse_iterator<_Iterator>& __y)
285 { return !(__x == __y); }
287 template<typename _Iterator>
289 operator>(const reverse_iterator<_Iterator>& __x,
290 const reverse_iterator<_Iterator>& __y)
291 { return __y < __x; }
293 template<typename _Iterator>
295 operator<=(const reverse_iterator<_Iterator>& __x,
296 const reverse_iterator<_Iterator>& __y)
297 { return !(__y < __x); }
299 template<typename _Iterator>
301 operator>=(const reverse_iterator<_Iterator>& __x,
302 const reverse_iterator<_Iterator>& __y)
303 { return !(__x < __y); }
305 template<typename _Iterator>
306 inline typename reverse_iterator<_Iterator>::difference_type
307 operator-(const reverse_iterator<_Iterator>& __x,
308 const reverse_iterator<_Iterator>& __y)
309 { return __y.base() - __x.base(); }
311 template<typename _Iterator>
312 inline reverse_iterator<_Iterator>
313 operator+(typename reverse_iterator<_Iterator>::difference_type __n,
314 const reverse_iterator<_Iterator>& __x)
315 { return reverse_iterator<_Iterator>(__x.base() - __n); }
318 // 24.4.2.2.1 back_insert_iterator
320 * These are output iterators, constructed from a container-of-T.
321 * Assigning a T to the iterator appends it to the container using
324 * Tip: Using the back_inserter function to create these iterators can
327 template<typename _Container>
328 class back_insert_iterator
329 : public iterator<output_iterator_tag, void, void, void, void>
332 _Container* container;
335 /// A nested typedef for the type of whatever container you used.
336 typedef _Container container_type;
338 /// The only way to create this %iterator is with a container.
340 back_insert_iterator(_Container& __x) : container(&__x) { }
343 * @param value An instance of whatever type
344 * container_type::const_reference is; presumably a
345 * reference-to-const T for container<T>.
346 * @return This %iterator, for chained operations.
348 * This kind of %iterator doesn't really have a "position" in the
349 * container (you can think of the position as being permanently at
350 * the end, if you like). Assigning a value to the %iterator will
351 * always append the value to the end of the container.
353 back_insert_iterator&
354 operator=(typename _Container::const_reference __value)
356 container->push_back(__value);
360 /// Simply returns *this.
361 back_insert_iterator&
362 operator*() { return *this; }
364 /// Simply returns *this. (This %iterator does not "move".)
365 back_insert_iterator&
366 operator++() { return *this; }
368 /// Simply returns *this. (This %iterator does not "move".)
370 operator++(int) { return *this; }
374 * @param x A container of arbitrary type.
375 * @return An instance of back_insert_iterator working on @p x.
377 * This wrapper function helps in creating back_insert_iterator instances.
378 * Typing the name of the %iterator requires knowing the precise full
379 * type of the container, which can be tedious and impedes generic
380 * programming. Using this function lets you take advantage of automatic
381 * template parameter deduction, making the compiler match the correct
384 template<typename _Container>
385 inline back_insert_iterator<_Container>
386 back_inserter(_Container& __x)
387 { return back_insert_iterator<_Container>(__x); }
390 * These are output iterators, constructed from a container-of-T.
391 * Assigning a T to the iterator prepends it to the container using
394 * Tip: Using the front_inserter function to create these iterators can
397 template<typename _Container>
398 class front_insert_iterator
399 : public iterator<output_iterator_tag, void, void, void, void>
402 _Container* container;
405 /// A nested typedef for the type of whatever container you used.
406 typedef _Container container_type;
408 /// The only way to create this %iterator is with a container.
409 explicit front_insert_iterator(_Container& __x) : container(&__x) { }
412 * @param value An instance of whatever type
413 * container_type::const_reference is; presumably a
414 * reference-to-const T for container<T>.
415 * @return This %iterator, for chained operations.
417 * This kind of %iterator doesn't really have a "position" in the
418 * container (you can think of the position as being permanently at
419 * the front, if you like). Assigning a value to the %iterator will
420 * always prepend the value to the front of the container.
422 front_insert_iterator&
423 operator=(typename _Container::const_reference __value)
425 container->push_front(__value);
429 /// Simply returns *this.
430 front_insert_iterator&
431 operator*() { return *this; }
433 /// Simply returns *this. (This %iterator does not "move".)
434 front_insert_iterator&
435 operator++() { return *this; }
437 /// Simply returns *this. (This %iterator does not "move".)
438 front_insert_iterator
439 operator++(int) { return *this; }
443 * @param x A container of arbitrary type.
444 * @return An instance of front_insert_iterator working on @p x.
446 * This wrapper function helps in creating front_insert_iterator instances.
447 * Typing the name of the %iterator requires knowing the precise full
448 * type of the container, which can be tedious and impedes generic
449 * programming. Using this function lets you take advantage of automatic
450 * template parameter deduction, making the compiler match the correct
453 template<typename _Container>
454 inline front_insert_iterator<_Container>
455 front_inserter(_Container& __x)
456 { return front_insert_iterator<_Container>(__x); }
459 * These are output iterators, constructed from a container-of-T.
460 * Assigning a T to the iterator inserts it in the container at the
461 * %iterator's position, rather than overwriting the value at that
464 * (Sequences will actually insert a @e copy of the value before the
465 * %iterator's position.)
467 * Tip: Using the inserter function to create these iterators can
470 template<typename _Container>
471 class insert_iterator
472 : public iterator<output_iterator_tag, void, void, void, void>
475 _Container* container;
476 typename _Container::iterator iter;
479 /// A nested typedef for the type of whatever container you used.
480 typedef _Container container_type;
483 * The only way to create this %iterator is with a container and an
484 * initial position (a normal %iterator into the container).
486 insert_iterator(_Container& __x, typename _Container::iterator __i)
487 : container(&__x), iter(__i) {}
490 * @param value An instance of whatever type
491 * container_type::const_reference is; presumably a
492 * reference-to-const T for container<T>.
493 * @return This %iterator, for chained operations.
495 * This kind of %iterator maintains its own position in the
496 * container. Assigning a value to the %iterator will insert the
497 * value into the container at the place before the %iterator.
499 * The position is maintained such that subsequent assignments will
500 * insert values immediately after one another. For example,
502 * // vector v contains A and Z
504 * insert_iterator i (v, ++v.begin());
509 * // vector v contains A, 1, 2, 3, and Z
513 operator=(const typename _Container::const_reference __value)
515 iter = container->insert(iter, __value);
520 /// Simply returns *this.
522 operator*() { return *this; }
524 /// Simply returns *this. (This %iterator does not "move".)
526 operator++() { return *this; }
528 /// Simply returns *this. (This %iterator does not "move".)
530 operator++(int) { return *this; }
534 * @param x A container of arbitrary type.
535 * @return An instance of insert_iterator working on @p x.
537 * This wrapper function helps in creating insert_iterator instances.
538 * Typing the name of the %iterator requires knowing the precise full
539 * type of the container, which can be tedious and impedes generic
540 * programming. Using this function lets you take advantage of automatic
541 * template parameter deduction, making the compiler match the correct
544 template<typename _Container, typename _Iterator>
545 inline insert_iterator<_Container>
546 inserter(_Container& __x, _Iterator __i)
548 return insert_iterator<_Container>(__x,
549 typename _Container::iterator(__i));
552 // This iterator adapter is 'normal' in the sense that it does not
553 // change the semantics of any of the operators of its iterator
554 // parameter. Its primary purpose is to convert an iterator that is
555 // not a class, e.g. a pointer, into an iterator that is a class.
556 // The _Container parameter exists solely so that different containers
557 // using this template can instantiate different types, even if the
558 // _Iterator parameter is the same.
559 template<typename _Iterator, typename _Container>
560 class __normal_iterator
561 : public iterator<typename iterator_traits<_Iterator>::iterator_category,
562 typename iterator_traits<_Iterator>::value_type,
563 typename iterator_traits<_Iterator>::difference_type,
564 typename iterator_traits<_Iterator>::pointer,
565 typename iterator_traits<_Iterator>::reference>
568 _Iterator _M_current;
571 typedef typename iterator_traits<_Iterator>::difference_type
573 typedef typename iterator_traits<_Iterator>::reference reference;
574 typedef typename iterator_traits<_Iterator>::pointer pointer;
576 __normal_iterator() : _M_current(_Iterator()) { }
579 __normal_iterator(const _Iterator& __i) : _M_current(__i) { }
581 // Allow iterator to const_iterator conversion
582 template<typename _Iter>
583 inline __normal_iterator(const __normal_iterator<_Iter, _Container>& __i)
584 : _M_current(__i.base()) { }
586 // Forward iterator requirements
588 operator*() const { return *_M_current; }
591 operator->() const { return _M_current; }
594 operator++() { ++_M_current; return *this; }
597 operator++(int) { return __normal_iterator(_M_current++); }
599 // Bidirectional iterator requirements
601 operator--() { --_M_current; return *this; }
604 operator--(int) { return __normal_iterator(_M_current--); }
606 // Random access iterator requirements
608 operator[](const difference_type& __n) const
609 { return _M_current[__n]; }
612 operator+=(const difference_type& __n)
613 { _M_current += __n; return *this; }
616 operator+(const difference_type& __n) const
617 { return __normal_iterator(_M_current + __n); }
620 operator-=(const difference_type& __n)
621 { _M_current -= __n; return *this; }
624 operator-(const difference_type& __n) const
625 { return __normal_iterator(_M_current - __n); }
628 operator-(const __normal_iterator& __i) const
629 { return _M_current - __i._M_current; }
632 base() const { return _M_current; }
635 // Forward iterator requirements
636 template<typename _IteratorL, typename _IteratorR, typename _Container>
638 operator==(const __normal_iterator<_IteratorL, _Container>& __lhs,
639 const __normal_iterator<_IteratorR, _Container>& __rhs)
640 { return __lhs.base() == __rhs.base(); }
642 template<typename _IteratorL, typename _IteratorR, typename _Container>
644 operator!=(const __normal_iterator<_IteratorL, _Container>& __lhs,
645 const __normal_iterator<_IteratorR, _Container>& __rhs)
646 { return !(__lhs == __rhs); }
648 // Random access iterator requirements
649 template<typename _IteratorL, typename _IteratorR, typename _Container>
651 operator<(const __normal_iterator<_IteratorL, _Container>& __lhs,
652 const __normal_iterator<_IteratorR, _Container>& __rhs)
653 { return __lhs.base() < __rhs.base(); }
655 template<typename _IteratorL, typename _IteratorR, typename _Container>
657 operator>(const __normal_iterator<_IteratorL, _Container>& __lhs,
658 const __normal_iterator<_IteratorR, _Container>& __rhs)
659 { return __rhs < __lhs; }
661 template<typename _IteratorL, typename _IteratorR, typename _Container>
663 operator<=(const __normal_iterator<_IteratorL, _Container>& __lhs,
664 const __normal_iterator<_IteratorR, _Container>& __rhs)
665 { return !(__rhs < __lhs); }
667 template<typename _IteratorL, typename _IteratorR, typename _Container>
669 operator>=(const __normal_iterator<_IteratorL, _Container>& __lhs,
670 const __normal_iterator<_IteratorR, _Container>& __rhs)
671 { return !(__lhs < __rhs); }
673 template<typename _Iterator, typename _Container>
674 inline __normal_iterator<_Iterator, _Container>
675 operator+(typename __normal_iterator<_Iterator, _Container>::difference_type __n,
676 const __normal_iterator<_Iterator, _Container>& __i)
677 { return __normal_iterator<_Iterator, _Container>(__i.base() + __n); }