deque.h

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/*
 *
 * Copyright (c) 1994
 * Hewlett-Packard Company
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies and
 * that both that copyright notice and this permission notice appear
 * in supporting documentation.  Hewlett-Packard Company makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 *
 */

#ifndef DEQUE_H
#define DEQUE_H

#include <function.h>
#include <algobase.h>
#include <iterator.h>
#include <bool.h>

#ifndef Allocator
#define Allocator allocator
#include <defalloc.h>
#endif

#ifndef deque 
#define deque deque
#endif

template <class T> 
class deque {
public:
    class iterator;
    class const_iterator;
    friend class iterator;
    friend class const_iterator;
public:
    typedef T value_type;
    typedef Allocator<T> data_allocator_type;
    typedef Allocator<T>::pointer pointer;
    typedef Allocator<T>::reference reference;
    typedef Allocator<T>::const_reference const_reference;
    typedef Allocator<T>::size_type size_type;
    typedef Allocator<T>::difference_type difference_type;
    typedef Allocator<pointer> map_allocator_type;   
protected:
    static data_allocator_type data_allocator;
    static size_type buffer_size;
    static map_allocator_type map_allocator;
    typedef Allocator<pointer>::pointer map_pointer;
public:
    class iterator : public random_access_iterator<T, difference_type> {
    friend class deque<T>;
    friend class const_iterator;
    protected:
        pointer current;
        pointer first;
        pointer last;
        map_pointer node;
        iterator(pointer x, map_pointer y) 
            : current(x), first(*y), last(*y + buffer_size), node(y) {}
    public:
        iterator() : current(0), first(0), last(0), node(0) {}
        reference operator*() const { return *current; }
        difference_type operator-(const iterator& x) const {
            return node == x.node 
                ? current - x.current 
                : difference_type(buffer_size * (node - x.node - 1) +
                                  (current - first) + (x.last - x.current));
        }
        iterator& operator++() {
            if (++current == last) {
                first = *(++node);
                current = first;
                last = first + buffer_size;
            }
            return *this; 
        }
        iterator operator++(int)  {
            iterator tmp = *this;
            ++*this;
            return tmp;
        }
        iterator& operator--() {
            if (current == first) {
                first = *(--node);
                last = first + buffer_size;
                current = last;
            }
            --current;
            return *this;
        }
        iterator operator--(int) {
            iterator tmp = *this;
            --*this;
            return tmp;
        }
        iterator& operator+=(difference_type n) {
            difference_type offset = n + (current - first);
            difference_type num_node_to_jump = offset >= 0
                ? offset / buffer_size
                : -((-offset + buffer_size - 1) / buffer_size);
            if (num_node_to_jump == 0)
                current += n;
            else {
                node = node + num_node_to_jump;
                first = *node;
                last = first + buffer_size;
                current = first + (offset - num_node_to_jump * buffer_size);
            }
            return *this;
        }
        iterator& operator-=(difference_type n) { return *this += -n; }
        iterator operator+(difference_type n) const {
            iterator tmp = *this;
            return tmp += n;
        }
        iterator operator-(difference_type n) const {
            iterator tmp = *this;
            return tmp -= n;
        }
        reference operator[](difference_type n) { return *(*this + n); }
        bool operator==(const iterator& x) const {      
            return current == x.current || 
                ((current == first || x.current == x.first) && 
                 *this - x == 0);
        }
        bool operator<(const iterator& x) const {
            return (node == x.node) ? (current < x.current) : (node < x.node);
        }
    };
    class const_iterator : public random_access_iterator<T, difference_type> {
    friend class deque<T>;
    protected:
        pointer current;
        pointer first;
        pointer last;
        map_pointer node;
        const_iterator(pointer x, map_pointer y) 
            : current(x), first(*y), last(*y + buffer_size), node(y) {}
    public:
        const_iterator() : current(0), first(0), last(0), node(0) {}
        const_iterator(const iterator& x) 
            : current(x.current), first(x.first), last(x.last), node(x.node) {}     
        const_reference operator*() const { return *current; }
        difference_type operator-(const const_iterator& x) const {
            return node == x.node 
                ? current - x.current 
                : difference_type(buffer_size * (node - x.node - 1) +
                                  (current - first) + (x.last - x.current));
        }
        const_iterator& operator++() {
            if (++current == last) {
                first = *(++node);
                current = first;
                last = first + buffer_size;
            }
            return *this; 
        }
        const_iterator operator++(int)  {
            const_iterator tmp = *this;
            ++*this;
            return tmp;
        }
        const_iterator& operator--() {
            if (current == first) {
                first = *(--node);
                last = first + buffer_size;
                current = last;
            }
            --current;
            return *this;
        }
        const_iterator operator--(int) {
            const_iterator tmp = *this;
            --*this;
            return tmp;
        }
        const_iterator& operator+=(difference_type n) {
            difference_type offset = n + (current - first);
            difference_type num_node_to_jump = offset >= 0
                ? offset / buffer_size
                : -((-offset + buffer_size - 1) / buffer_size);
            if (num_node_to_jump == 0)
                current += n;
            else {
                node = node + num_node_to_jump;
                first = *node;
                last = first + buffer_size;
                current = first + (offset - num_node_to_jump * buffer_size);
            }
            return *this;
        }
        const_iterator& operator-=(difference_type n) { return *this += -n; }
        const_iterator operator+(difference_type n) const {
            const_iterator tmp = *this;
            return tmp += n;
        }
        const_iterator operator-(difference_type n) const {
            const_iterator tmp = *this;
            return tmp -= n;
        }
        const_reference operator[](difference_type n) { 
            return *(*this + n); 
        }
        bool operator==(const const_iterator& x) const {      
            return current == x.current || 
                ((current == first || x.current == x.first) && 
                 *this - x == 0);
        }
        bool operator<(const const_iterator& x) const {
            return (node == x.node) ? (current < x.current) : (node < x.node);
        }
    };
    typedef reverse_iterator<const_iterator, value_type, const_reference, 
                             difference_type>  const_reverse_iterator;
    typedef reverse_iterator<iterator, value_type, reference, difference_type>
        reverse_iterator; 
protected:    
    iterator start;
    iterator finish;
    size_type length;
    map_pointer map;
    size_type map_size;

    void allocate_at_begin();
    void allocate_at_end();
    void deallocate_at_begin();
    void deallocate_at_end();

public:
    deque() : start(), finish(), length(0), map(0), map_size(0) {
        buffer_size = data_allocator.init_page_size();
    }
    iterator begin() { return start; }
    const_iterator begin() const { return start; }
    iterator end() { return finish; }
    const_iterator end() const { return finish; }
    reverse_iterator rbegin() { return reverse_iterator(end()); }
    const_reverse_iterator rbegin() const { 
        return const_reverse_iterator(end()); 
    }
    reverse_iterator rend() { return reverse_iterator(begin()); }
    const_reverse_iterator rend() const { 
        return const_reverse_iterator(begin()); 
    } 
    bool empty() const { return length == 0; }
    size_type size() const { return length; }
    size_type max_size() const { return data_allocator.max_size(); }
    reference operator[](size_type n) { return *(begin() + n); }
    const_reference operator[](size_type n) const { return *(begin() + n); }
    reference front() { return *begin(); }
    const_reference front() const { return *begin(); }
    reference back() { return *(end() - 1); }
    const_reference back() const { return *(end() - 1); }
    void push_front(const T& x) {
        if (empty() || begin().current == begin().first)
            allocate_at_begin();
        --start.current;
        construct(start.current, x);
        ++length;
        if (end().current == end().last) allocate_at_end();
    }
    void push_back(const T& x) {
        if (empty()) allocate_at_end();
        construct(finish.current, x);
        ++finish.current;
        ++length;
        if (end().current == end().last) allocate_at_end();
    }
    void pop_front() {
        destroy(start.current);
        ++start.current;
        --length;