////////////////////////////////////////////////////////////////////////////////
// flex_string
// Copyright (c) 2001 by Andrei Alexandrescu
// Permission to use, copy, modify, distribute and sell this software 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.
// The author makes no representations about the
//     suitability of this software for any purpose. It is provided "as is"
//     without express or implied warranty.
////////////////////////////////////////////////////////////////////////////////

#ifndef FLEX_STRING_SHELL_INC_
#define FLEX_STRING_SHELL_INC_

///////////////////////////////////////////////////////////////////////////////
// class template flex_string
// This file does not include any storage policy headers
///////////////////////////////////////////////////////////////////////////////

#include <memory>
#include <algorithm>
#include <functional>
#include <cassert>
#include <limits>
#include <stdexcept>
#include "flex_string_details.h"
#include <string>

// Forward declaration for default storage policy
template <typename E, class A> class AllocatorStringStorage;


template <class T> class mallocator
{
public:
    typedef T                 value_type;
    typedef value_type*       pointer;
    typedef const value_type* const_pointer;
    typedef value_type&       reference;
    typedef const value_type& const_reference;
    typedef std::size_t       size_type;
    //typedef unsigned int      size_type;
    //typedef std::ptrdiff_t    difference_type;
    typedef int               difference_type;

    template <class U> 
    struct rebind { typedef mallocator<U> other; };

    mallocator() {}
    mallocator(const mallocator&) {}
    //template <class U> 
    //mallocator(const mallocator<U>&) {}
    ~mallocator() {}

    pointer address(reference x) const { return &x; }
    const_pointer address(const_reference x) const 
    { 
        return x;
    }

    pointer allocate(size_type n, const_pointer = 0) 
    {
        using namespace std;
        void* p = malloc(n * sizeof(T));
        if (!p) throw bad_alloc();
        return static_cast<pointer>(p);
    }

    void deallocate(pointer p, size_type) 
    { 
        using namespace std;
        free(p); 
    }

    size_type max_size() const 
    { 
        return static_cast<size_type>(-1) / sizeof(T);
    }

    void construct(pointer p, const value_type& x) 
    { 
        new(p) value_type(x); 
    }

    void destroy(pointer p) 
    { 
        p->~value_type(); 
    }

private:
    void operator=(const mallocator&);
};

template<> class mallocator<void>
{
  typedef void        value_type;
  typedef void*       pointer;
  typedef const void* const_pointer;

  template <class U> 
  struct rebind { typedef mallocator<U> other; };
};

template <class T>
inline bool operator==(const mallocator<T>&, 
                       const mallocator<T>&) {
  return true;
}

template <class T>
inline bool operator!=(const mallocator<T>&, 
                       const mallocator<T>&) {
  return false;
}

template <class Allocator>
typename Allocator::pointer Reallocate(
    Allocator& alloc,
    typename Allocator::pointer p, 
    typename Allocator::size_type oldObjCount,
    typename Allocator::size_type newObjCount,
    void*)
{
    // @@@ not implemented
}

template <class Allocator>
typename Allocator::pointer Reallocate(
    Allocator& alloc,
    typename Allocator::pointer p, 
    typename Allocator::size_type oldObjCount,
    typename Allocator::size_type newObjCount,
    mallocator<void>*)
{
    // @@@ not implemented
}


////////////////////////////////////////////////////////////////////////////////
// class template flex_string
// a std::basic_string compatible implementation 
// Uses a Storage policy 
////////////////////////////////////////////////////////////////////////////////

template <typename E,
    class T = std::char_traits<E>,
    class A = std::allocator<E>,
    class Storage = AllocatorStringStorage<E, A> >
class flex_string : private Storage
{

    template <typename Exception>
    static void Enforce(bool condition, Exception*, const char* msg)
    { if (!condition) throw Exception(msg); }

    bool Sane() const
    {
        return
            begin() <= end() &&
            empty() == (size() == 0) &&
            empty() == (begin() == end()) &&
            size() <= max_size() &&
            capacity() <= max_size() &&
            size() <= capacity();
    }

    struct Invariant;
    friend struct Invariant;
    struct Invariant
    {
#ifndef NDEBUG
		Invariant(const flex_string& s) : s_(s)
        {
            assert(s_.Sane());
        }
        ~Invariant()
        {
            assert(s_.Sane());
        }
    private:
        const flex_string& s_;
#else
		Invariant(const flex_string&) {} 
#endif
    };
    
public:
    // types
    typedef T traits_type;
    typedef typename traits_type::char_type value_type;
    typedef A allocator_type;
    typedef typename A::size_type size_type;
    typedef typename A::difference_type difference_type;
    
    typedef typename Storage::reference reference;
    typedef typename A::const_reference const_reference;
    typedef typename A::pointer pointer;
    typedef typename A::const_pointer const_pointer;
    
    typedef typename Storage::iterator iterator;
    typedef typename Storage::const_iterator const_iterator;
    typedef std::reverse_iterator<iterator
#ifdef NO_ITERATOR_TRAITS
    , value_type
#endif
    > reverse_iterator;
    typedef std::reverse_iterator<const_iterator
#ifdef NO_ITERATOR_TRAITS
    , const value_type 
#endif
    > const_reverse_iterator;

    static const size_type npos;    // = size_type(-1)

private:
    static size_type Min(size_type lhs, size_type rhs)
    { return lhs < rhs ? lhs : rhs; }
	static void Procust(size_type& n, size_type nmax)
	{ if (n > nmax) n = nmax; }
    
public:    
    // 21.3.1 construct/copy/destroy
    explicit flex_string(const A& a = A())
    : Storage(a) 
    {}
    
    flex_string(const flex_string& str)
    : Storage(str) 
    {}
    
    flex_string(const flex_string& str, size_type pos, 
        size_type n = npos, const A& a = A())
    : Storage(a) 
    {
        assign(str, pos, n);
    }
    
    flex_string(const value_type* s, const A& a = A())
    : Storage(s, traits_type::length(s), a)
    {}
    
    flex_string(const value_type* s, size_type n, const A& a = A())
    : Storage(s, n, a)
    {}
    
    flex_string(size_type n, value_type c, const A& a = A())
    : Storage(n, c, a)
    {}

    template <class InputIterator>
    flex_string(InputIterator begin, InputIterator end, const A& a = A())
    : Storage(a)
    {
        assign(begin, end);
    }

    ~flex_string()
    {}
    
    flex_string& operator=(const flex_string& str)
    {
        Storage& s = *this;
        s = str;
        return *this;
    }   
    
    flex_string& operator=(const value_type* s)
    {
        assign(s);
        return *this;
    }

    flex_string& operator=(value_type c)
    {
        assign(1, c);
        return *this;
    }
    
    // 21.3.2 iterators:
    iterator begin()
    { return Storage::begin(); }
    
    const_iterator begin() const
    { return Storage::begin(); }
    
    iterator end()
    { return Storage::end(); }
    
    const_iterator end() const
    { return Storage::end(); }

    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()); }
    
    // 21.3.3 capacity:
    size_type size() const
    { return Storage::size(); }
    
    size_type length() const
    { return size(); }
    
    size_type max_size() const
    { return Storage::max_size(); }

    void resize(size_type n, value_type c)
    { Storage::resize(n, c); }
    
    void resize(size_type n)
    { resize(n, value_type()); }
    
    size_type capacity() const
    { return Storage::capacity(); }
    
    void reserve(size_type res_arg = 0)
    {
        Enforce(res_arg <= max_size(), (std::length_error*)0, "");
        Storage::reserve(res_arg);
    }
    
    void clear()
    { resize(0); } 
    
    bool empty() const
    { return size() == 0; }
    
    // 21.3.4 element access:
    const_reference operator[](size_type pos) const
    { return *(c_str() + pos); }
    
    reference operator[](size_type pos)
    { return *(begin() + pos); }

    const_reference at(size_type n) const
    {
        Enforce(n <= size(), (std::out_of_range*)0, "");
        return (*this)[n];
    }
    
    reference at(size_type n)
    {
        Enforce(n < size(), (std::out_of_range*)0, "");
        return (*this)[n];
    }
    
    // 21.3.5 modifiers:
    flex_string& operator+=(const flex_string& str)
    { return append(str); }
    
    flex_string& operator+=(const value_type* s)
    { return append(s); }

    flex_string& operator+=(const value_type c)
    { 
		push_back(c);
        return *this;
    }
    
    flex_string& append(const flex_string& str)
    { return append(str.data(), str.length()); }
    
    flex_string& append(const flex_string& str, const size_type pos,
        size_type n)
    { 
        const size_type sz = str.size();
        Enforce(pos <= sz, (std::out_of_range*)0, "");
		Procust(n, sz - pos);
        return append(str.data() + pos, n); 
    }
    
    flex_string& append(const value_type* s, const size_type n)
    { 
		Invariant checker(*this); checker; 
        static std::less_equal<const value_type*> le;
		if (le(&*begin(), s) && le(s, &*end())) // aliasing
		{
			const size_type offset = s - &*begin();
			Storage::reserve(size() + n);
			s = &*begin() + offset;
		}
        Storage::append(s, s + n); 
        return *this;
    }
    
    flex_string& append(const value_type* s)
    { return append(s, traits_type::length(s)); }
    
    flex_string& append(size_type n, value_type c)
    { 
        resize(size() + n, c);
        return *this;
    }
    
    template<class InputIterator>
    flex_string& append(InputIterator first, InputIterator last)
    {
		insert(end(), first, last);
        return *this;
    }
    
    void push_back(const value_type c) // primitive
    { 
        const size_type cap = capacity();
        if (size() == cap)
        {
            reserve(cap << 1u);
        }
		Storage::append(&c, &c + 1);
    }

    flex_string& assign(const flex_string& str)
    { 
        if (&str == this) return *this;
        return assign(str.data(), str.size());
    }
    
    flex_string& assign(const flex_string& str, const size_type pos,
        size_type n)
    { 
		const size_type sz = str.size();
        Enforce(pos <= sz, (std::out_of_range*)0, "");
		Procust(n, sz - pos);
        return assign(str.data() + pos, n);
    }
    
    flex_string& assign(const value_type* s, const size_type n)
    {
		Invariant checker(*this); checker; 
        if (size() >= n)
        {
			std::copy(s, s + n, begin());
            resize(n);
        }
        else
        {
			const value_type *const s2 = s + size();
			std::copy(s, s2, begin());
            append(s2, n - size());
        }
        return *this;
    }
    
    flex_string& assign(const value_type* s)
    { return assign(s, traits_type::length(s)); }
    
    template <class ItOrLength, class ItOrChar>
    flex_string& assign(ItOrLength first_or_n, ItOrChar last_or_c)
    { return replace(begin(), end(), first_or_n, last_or_c); }
    
    flex_string& insert(size_type pos1, const flex_string& str)
    { return insert(pos1, str.data(), str.size()); }
    
    flex_string& insert(size_type pos1, const flex_string& str,
        size_type pos2, size_type n)
    { 
        Enforce(pos2 <= str.length(), (std::out_of_range*)0, "");
		Procust(n, str.length() - pos2);
		return insert(pos1, str.data() + pos2, n); 
	}
    
    flex_string& insert(size_type pos, const value_type* s, size_type n)
    { 
        Enforce(pos <= length(), (std::out_of_range*)0, "");
		insert(begin() + pos, s, s + n); 
		return *this;
	}
    
    flex_string& insert(size_type pos, const value_type* s)
    { return insert(pos, s, traits_type::length(s)); }
    
    flex_string& insert(size_type pos, size_type n, value_type c)
    {
        Enforce(pos <= length(), (std::out_of_range*)0, "");
		insert(begin() + pos, n, c);
		return *this;
	}
    
    iterator insert(const iterator p, const value_type c) 
    {
		const size_type pos = p - begin();
        insert(p, 1, c);
        return begin() + pos;
    }
    
private:
    template <int i> class Selector {};

    flex_string& InsertImplDiscr(iterator p, 
        size_type n, value_type c, Selector<1>)
    { 
		Invariant checker(*this); checker; 
		assert(p >= begin() && p <= end());
		if (capacity() - size() < n)
		{
			const size_type sz = p - begin();
			reserve(size() + n);
			p = begin() + sz;
		}
		const iterator oldEnd = end();
		if (p + n < oldEnd)
		{
			append(oldEnd - n, oldEnd);
			//std::copy(
			//	reverse_iterator(oldEnd - n), 
			//	reverse_iterator(p), 
			//	reverse_iterator(oldEnd));
			flex_string_details::pod_move(&*p, &*oldEnd - n, &*p + n);
			std::fill(p, p + n, c);
		}
		else
		{
			append(n - (end() - p), c);
			append(p, oldEnd);
			std::fill(p, oldEnd, c);
		}
		return *this;
    }    

    template<class InputIterator>
    flex_string& InsertImplDiscr(iterator i,
        InputIterator b, InputIterator e, Selector<0>)
    { 
		InsertImpl(i, b, e, 
			std::iterator_traits<InputIterator>::iterator_category());
        return *this;
    }

	template <class FwdIterator>
    void InsertImpl(iterator i,
		FwdIterator s1, FwdIterator s2, std::forward_iterator_tag)
    { 
		Invariant checker(*this); checker; 
		const size_type pos = i - begin();
		const typename std::iterator_traits<FwdIterator>::difference_type n2 = 
			std::distance(s1, s2);
		assert(n2 >= 0);
        using namespace flex_string_details;
        assert(pos <= size());

		const typename std::iterator_traits<FwdIterator>::difference_type maxn2 = 
			capacity() - size();
        if (maxn2 < n2)
        {
            // realloc the string
	        static const std::less_equal<const value_type*> le = 
				std::less_equal<const value_type*>();
	        assert(!(le(&*begin(), &*s1) && le(&*s1, &*end())));
            reserve(size() + n2);
			i = begin() + pos;
        }
		if (pos + n2 <= size())
		{
			//const iterator oldEnd = end();
			//Storage::append(oldEnd - n2, n2);
			//std::copy(i, oldEnd - n2, i + n2);
			const iterator tailBegin = end() - n2;
			Storage::append(tailBegin, tailBegin + n2);
			//std::copy(i, tailBegin, i + n2);
			std::copy(reverse_iterator(tailBegin), reverse_iterator(i), 
				reverse_iterator(tailBegin + n2));
			std::copy(s1, s2, i);
		}
		else
		{
			FwdIterator t = s1;
			const size_type old_size = size();
			std::advance(t, old_size - pos);
			assert(std::distance(t, s2) >= 0);
			Storage::append(t, s2);
			Storage::append(data() + pos, data() + old_size);
			std::copy(s1, t, i);
		}
    }

	template <class InputIterator>
    void InsertImpl(iterator i1, iterator i2,
		InputIterator b, InputIterator e, std::input_iterator_tag)
    { 
		flex_string temp(begin(), i1);
        for (; b != e; ++b)
		{
			temp.push_back(*b);
		}
		temp.append(i2, end());
		swap(temp);
    }

public:
    template <class ItOrLength, class ItOrChar>
    void insert(iterator p, ItOrLength first_or_n, ItOrChar last_or_c)
    { 
		Selector<std::numeric_limits<ItOrLength>::is_specialized> sel;
		InsertImplDiscr(p, first_or_n, last_or_c, sel);
	}
    
    flex_string& erase(size_type pos = 0, size_type n = npos)
    { 
		Invariant checker(*this); checker;
        Enforce(pos <= length(), (std::out_of_range*)0, "");
		Procust(n, length() - pos);
		std::copy(begin() + pos + n, end(), begin() + pos);
		resize(length() - n);
        return *this;
    }
    
    iterator erase(iterator position)
    {
        const size_type pos(position - begin());
        erase(pos, 1);
        return begin() + pos;
    }
    
    iterator erase(iterator first, iterator last)
    {
        const size_type pos(first - begin());
        erase(pos, last - first);
        return begin() + pos;
    }

	// Replaces at most n1 chars of *this, starting with pos1 with the content of str
    flex_string& replace(size_type pos1, size_type n1, const flex_string& str)
    { return replace(pos1, n1, str.data(), str.size()); }
    
	// Replaces at most n1 chars of *this, starting with pos1,
	// with at most n2 chars of str starting with pos2
    flex_string& replace(size_type pos1, size_type n1, const flex_string& str,
        size_type pos2, size_type n2)
    {
        Enforce(pos2 <= str.length(), (std::out_of_range*)0, "");
        return replace(pos1, n1, str.data() + pos2, 
            Min(n2, str.size() - pos2));
    }
    
/*
	// Replaces at most n1 chars of *this, starting with pos,
	// with at most n2 chars of str.
	// str must have at least n2 chars.
	flex_string& replace(const size_type pos, size_type n1, 
		const value_type* s1, const size_type n2)
    {
		Invariant checker(*this); checker;
        Enforce(pos <= size(), (std::out_of_range*)0, "");
        Procust(n1, size() - pos);
		const iterator b = begin() + pos;
		return replace(b, b + n1, s1, s1 + n2);
        using namespace flex_string_details;
        const int delta = int(n2 - n1);
        static const std::less_equal<const value_type*> le;
        const bool aliased = le(&*begin(), s1) && le(s1, &*end());

		// From here on we're dealing with an aliased replace
		if (delta <= 0)
		{
			// simple case, we're shrinking
            pod_move(s1, s1 + n2, &*begin() + pos);
            pod_move(&*begin() + pos + n1, &*end(), &*begin() + pos + n1 + delta);
            resize(size() + delta);
			return *this;
		}

		// From here on we deal with aliased growth
        if (capacity() < size() + delta)
        {
            // realloc the string
            const size_type offset = s1 - data();
            reserve(size() + delta);
            s1 = data() + offset;
        }

        const value_type* s2 = s1 + n2;
        value_type* d1 = &*begin() + pos;
        value_type* d2 = d1 + n1;

        const int tailLen = int(&*end() - d2);

        if (delta <= tailLen)
        {
            value_type* oldEnd = &*end();
            // simple case
            Storage::append(oldEnd - delta, delta);

            pod_move(d2, d2 + (tailLen - delta), d2 + delta);
            if (le(d2, s1))
            {
                pod_copy(s1 + delta, s2 + delta, d1);
            }
            else
            {
                // d2 > s1
                if (le(d2, s2))
                {
                    pod_move(s1, d2, d1);
                    pod_move(d2 + delta, s2 + delta, d1 + (d2 - s1));
                }
                else
                {
                    pod_move(s1, s2, d1);
                }
            }
        }
        else
        {
            const size_type sz = delta - tailLen;
            Storage::append(s2 - sz, sz);
            Storage::append(d2, tailLen);
            pod_move(s1, s2 - (delta - tailLen), d1);
        }
        return *this;
    }
*/

	// Replaces at most n1 chars of *this, starting with pos, with chars from s
    flex_string& replace(size_type pos, size_type n1, const value_type* s)
    { return replace(pos, n1, s, traits_type::length(s)); }
    
	// Replaces at most n1 chars of *this, starting with pos, with n2 occurences of c
	// consolidated with
	// Replaces at most n1 chars of *this, starting with pos,
	// with at most n2 chars of str.
	// str must have at least n2 chars.
    template <class StrOrLength, class NumOrChar>
    flex_string& replace(size_type pos, size_type n1, 
		StrOrLength s_or_n2, NumOrChar n_or_c)
    {
		Invariant checker(*this); checker;
		Enforce(pos <= size(), (std::out_of_range*)0, "");
		Procust(n1, length() - pos);
		const iterator b = begin() + pos;
		return replace(b, b + n1, s_or_n2, n_or_c);
    }
        
    flex_string& replace(iterator i1, iterator i2, const flex_string& str)
    { return replace(i1, i2, str.data(), str.length()); }
    
    flex_string& replace(iterator i1, iterator i2, const value_type* s)
    { return replace(i1, i2, s, traits_type::length(s)); }
    
private:
    flex_string& ReplaceImplDiscr(iterator i1, iterator i2, 
        const value_type* s, size_type n, Selector<2>)
    { 
		assert(i1 <= i2);
		assert(begin() <= i1 && i1 <= end());
		assert(begin() <= i2 && i2 <= end());
		return replace(i1, i2, s, s + n); 
	}
    
    flex_string& ReplaceImplDiscr(iterator i1, iterator i2,
        size_type n2, value_type c, Selector<1>)
    { 
		const size_type n1 = i2 - i1;
		if (n1 > n2)
		{
			std::fill(i1, i1 + n2, c);
			erase(i1 + n2, i2);
		}
		else
		{
			std::fill(i1, i2, c);
			insert(i2, n2 - n1, c);
		}
        return *this;
    }    

	template <class InputIterator>
	flex_string& ReplaceImplDiscr(iterator i1, iterator i2,
        InputIterator b, InputIterator e, Selector<0>)
    { 
		ReplaceImpl(i1, i2, b, e, 
			std::iterator_traits<InputIterator>::iterator_category());
        return *this;
    }

	template <class FwdIterator>
    void ReplaceImpl(iterator i1, iterator i2,
		FwdIterator s1, FwdIterator s2, std::forward_iterator_tag)
    { 
		Invariant checker(*this); checker;
		const typename std::iterator_traits<iterator>::difference_type n1 = 
			i2 - i1;
		assert(n1 >= 0);
		const typename std::iterator_traits<FwdIterator>::difference_type n2 = 
			std::distance(s1, s2);
		assert(n2 >= 0);

		// Handle aliased replace
        static const std::less_equal<const value_type*> le = 
			std::less_equal<const value_type*>();
        const bool aliased = le(&*begin(), &*s1) && le(&*s1, &*end());
		if (aliased /* && capacity() < size() - n1 + n2 */)
		{
			// Aliased replace, copy to new string
			flex_string temp;
			temp.reserve(size() - n1 + n2);
			temp.append(begin(), i1).append(s1, s2).append(i2, end());
			swap(temp);
			return;
		}

		if (n1 > n2)
		{
			// shrinks
			std::copy(s1, s2, i1);
			erase(i1 + n2, i2);
		}
		else
		{
			// grows
			flex_string_details::copy_n(s1, n1, i1);
			advance(s1, n1);
			insert(i2, s1, s2);
		}
    }

	template <class InputIterator>
    void ReplaceImpl(iterator i1, iterator i2,
		InputIterator b, InputIterator e, std::input_iterator_tag)
    {
		flex_string temp(begin(), i1);
		temp.append(b, e).append(i2, end());
		swap(temp);
    }

public:
    template <class T1, class T2>
    flex_string& replace(iterator i1, iterator i2,
        T1 first_or_n_or_s, T2 last_or_c_or_n)
    { 
		const bool 
			num1 = std::numeric_limits<T1>::is_specialized,
			num2 = std::numeric_limits<T2>::is_specialized;
        return ReplaceImplDiscr(i1, i2, first_or_n_or_s, last_or_c_or_n, 
			Selector<num1 ? (num2 ? 1 : -1) : (num2 ? 2 : 0)>()); 
    }
       
    size_type copy(value_type* s, size_type n, size_type pos = 0) const
    {
        Enforce(pos <= size(), (std::out_of_range*)0, "");
        Procust(n, size() - pos);
        
        flex_string_details::pod_copy(
            data() + pos,
            data() + pos + n,
            s);
        return n;
    }
    
    void swap(flex_string& rhs)
    {
        Storage& srhs = rhs;
        this->Storage::swap(srhs);
    }
    
    // 21.3.6 string operations:
    const value_type* c_str() const
    { return Storage::c_str(); }
    
    const value_type* data() const
    { return Storage::data(); }
    
    allocator_type get_allocator() const
    { return Storage::get_allocator(); }
    
    size_type find(const flex_string& str, size_type pos = 0) const
    { return find(str.data(), pos, str.length()); }
    
    size_type find (const value_type* s, size_type pos, size_type n) const
    {
        for (; pos <= size(); ++pos)
        {
            if (traits_type::compare(data() + pos, s, n) == 0)
            {
                return pos;
            }
        }
        return npos;
    }
    
    size_type find (const value_type* s, size_type pos = 0) const
    { return find(s, pos, traits_type::length(s)); }

    size_type find (value_type c, size_type pos = 0) const
    { return find(&c, pos, 1); }
    
    size_type rfind(const flex_string& str, size_type pos = npos) const
    { return rfind(str.data(), pos, str.length()); }
    
    size_type rfind(const value_type* s, size_type pos, size_type n) const
    {
        if (n > length()) return npos;
        pos = Min(pos, length() - n);
        if (n == 0) return pos;

        const_iterator i(begin() + pos);
        for (; ; --i)
        {
            if (traits_type::eq(*i, *s) 
                && traits_type::compare(&*i, s, n) == 0)
            {
                return i - begin();
            }
            if (i == begin()) break;
        }
        return npos;
    }

    size_type rfind(const value_type* s, size_type pos = npos) const
    { return rfind(s, pos, traits_type::length(s)); }

    size_type rfind(value_type c, size_type pos = npos) const
    { return rfind(&c, pos, 1); }
    
    size_type find_first_of(const flex_string& str, size_type pos = 0) const
    { return find_first_of(str.data(), pos, str.length()); }
    
    size_type find_first_of(const value_type* s, 
        size_type pos, size_type n) const
    {
        if (pos > length() || n == 0) return npos;
        const_iterator i(begin() + pos),
            finish(end());
        for (; i != finish; ++i)
        {
            if (traits_type::find(s, n, *i) != 0)
            {
                return i - begin();
            }
        }
        return npos;
    }
        
    size_type find_first_of(const value_type* s, size_type pos = 0) const
    { return find_first_of(s, pos, traits_type::length(s)); }
    
    size_type find_first_of(value_type c, size_type pos = 0) const
    { return find_first_of(&c, pos, 1); }
    
    size_type find_last_of (const flex_string& str,
        size_type pos = npos) const
    { return find_last_of(str.data(), pos, str.length()); }
    
    size_type find_last_of (const value_type* s, size_type pos, 
        size_type n) const
    {
        if (!empty() && n > 0)
        {
            pos = Min(pos, length() - 1);
            const_iterator i(begin() + pos);
            for (;; --i)
            {
                if (traits_type::find(s, n, *i) != 0)
                {
                    return i - begin();
                }
                if (i == begin()) break;
            }
        }
        return npos;
    }

    size_type find_last_of (const value_type* s, 
        size_type pos = npos) const
    { return find_last_of(s, pos, traits_type::length(s)); }

    size_type find_last_of (value_type c, size_type pos = npos) const
    { return find_last_of(&c, pos, 1); }
    
    size_type find_first_not_of(const flex_string& str,
        size_type pos = 0) const
    { return find_first_not_of(str.data(), pos, str.size()); }
    
    size_type find_first_not_of(const value_type* s, size_type pos,
        size_type n) const
    {
        if (pos < length())
        {
            const_iterator 
                i(begin() + pos),
                finish(end());
            for (; i != finish; ++i)
            {
                if (traits_type::find(s, n, *i) == 0)
                {
                    return i - begin();
                }
            }
        }
        return npos;
    }
    
    size_type find_first_not_of(const value_type* s, 
        size_type pos = 0) const
    { return find_first_not_of(s, pos, traits_type::length(s)); }
        
    size_type find_first_not_of(value_type c, size_type pos = 0) const
    { return find_first_not_of(&c, pos, 1); }
    
    size_type find_last_not_of(const flex_string& str,
        size_type pos = npos) const
    { return find_last_not_of(str.data(), pos, str.length()); }
    
    size_type find_last_not_of(const value_type* s, size_type pos,
        size_type n) const
    {
        if (!this->empty())
        {
            pos = Min(pos, size() - 1);
            const_iterator i(begin() + pos);
            for (;; --i)
            {
                if (traits_type::find(s, n, *i) == 0)
                {
                    return i - begin();
                }
                if (i == begin()) break;
            }
        }
        return npos;
    }

    size_type find_last_not_of(const value_type* s, 
        size_type pos = npos) const
    { return find_last_not_of(s, pos, traits_type::length(s)); }
    
    size_type find_last_not_of (value_type c, size_type pos = npos) const
    { return find_last_not_of(&c, pos, 1); }
    
    flex_string substr(size_type pos = 0, size_type n = npos) const
    {
        Enforce(pos <= size(), (std::out_of_range*)0, "");
        return flex_string(data() + pos, Min(n, size() - pos));
    }

    int compare(const flex_string& str) const
	{ return traits_type::compare(data(), str.data(), Min(size(), str.size())); }
    
    int compare(size_type pos1, size_type n1,
        const flex_string& str) const
    { return compare(pos1, n1, str.data(), str.size()); }
    
	// FIX to compare: added the TC 
	// (http://www.comeaucomputing.com/iso/lwg-defects.html number 5)
	// Thanks to Caleb Epstein for the fix

    int compare(size_type pos1, size_type n1,
        const value_type* s) const
    {
		return compare(pos1, n1, s, traits_type::length(s));
    }
    
    int compare(size_type pos1, size_type n1,
        const value_type* s, size_type n2) const
    {
        Enforce(pos1 <= size(), (std::out_of_range*)0, "");
		Procust(n1, size() - pos1);
		return traits_type::compare(data(), s, Min(n1, n2));
    }
    
    int compare(size_type pos1, size_type n1,
        const flex_string& str,
        size_type pos2, size_type n2) const
    {
        Enforce(pos2 <= str.size(), (std::out_of_range*)0, "");
        return compare(pos1, n1, str.data() + pos2, Min(n2, str.size() - pos2));
    }

    int compare(const value_type* s) const
	{ 
		return traits_type::compare(data(), s, 
			Min(size(), traits_type::length(s))); 
	}
};

// non-member functions
template <typename E, class T, class A, class S>
flex_string<E, T, A, S> operator+(const flex_string<E, T, A, S>& lhs, 
    const flex_string<E, T, A, S>& rhs)
{
    flex_string<E, T, A, S> result;
    result.reserve(lhs.size() + rhs.size());
    result.append(lhs).append(rhs);
    return result;
}

template <typename E, class T, class A, class S>
flex_string<E, T, A, S> operator+(const typename flex_string<E, T, A, S>::value_type* lhs, 
    const flex_string<E, T, A, S>& rhs)
{
    flex_string<E, T, A, S> result;
    const typename flex_string<E, T, A, S>::size_type len = 
        flex_string<E, T, A, S>::traits_type::length(lhs);
    result.reserve(len + rhs.size());
    result.append(lhs, len).append(rhs);
    return result;
}

template <typename E, class T, class A, class S>
flex_string<E, T, A, S> operator+(
    typename flex_string<E, T, A, S>::value_type lhs, 
    const flex_string<E, T, A, S>& rhs)
{
    flex_string<E, T, A, S> result;
    result.reserve(1 + rhs.size());
    result.push_back(lhs);
    result.append(rhs);
    return result;
}

template <typename E, class T, class A, class S>
flex_string<E, T, A, S> operator+(const flex_string<E, T, A, S>& lhs, 
    const typename flex_string<E, T, A, S>::value_type* rhs)
{
    typedef typename flex_string<E, T, A, S>::size_type size_type;
    typedef typename flex_string<E, T, A, S>::traits_type traits_type;

    flex_string<E, T, A, S> result;
    const size_type len = traits_type::length(rhs);
    result.reserve(lhs.size() + len);
    result.append(lhs).append(rhs, len);
    return result;
}

template <typename E, class T, class A, class S>
flex_string<E, T, A, S> operator+(const flex_string<E, T, A, S>& lhs, 
    typename flex_string<E, T, A, S>::value_type rhs)
{
    flex_string<E, T, A, S> result;
    result.reserve(lhs.size() + 1);
    result.append(lhs);
    result.push_back(rhs);
    return result;
}

template <typename E, class T, class A, class S>
bool operator==(const flex_string<E, T, A, S>& lhs, 
    const flex_string<E, T, A, S>& rhs)
{ return lhs.compare(rhs) == 0; }

template <typename E, class T, class A, class S>
bool operator==(const typename flex_string<E, T, A, S>::value_type* lhs, 
    const flex_string<E, T, A, S>& rhs)
{ return rhs == lhs; }

template <typename E, class T, class A, class S>
bool operator==(const flex_string<E, T, A, S>& lhs, 
    const typename flex_string<E, T, A, S>::value_type* rhs)
{ return lhs.compare(rhs) == 0; }

template <typename E, class T, class A, class S>
bool operator!=(const flex_string<E, T, A, S>& lhs, 
    const flex_string<E, T, A, S>& rhs)
{ return !(lhs == rhs); }

template <typename E, class T, class A, class S>
bool operator!=(const typename flex_string<E, T, A, S>::value_type* lhs, 
    const flex_string<E, T, A, S>& rhs)
{ return !(lhs == rhs); }

template <typename E, class T, class A, class S>
bool operator!=(const flex_string<E, T, A, S>& lhs, 
    const typename flex_string<E, T, A, S>::value_type* rhs)
{ return !(lhs == rhs); }

template <typename E, class T, class A, class S>
bool operator<(const flex_string<E, T, A, S>& lhs, 
    const flex_string<E, T, A, S>& rhs)
{ return lhs.compare(rhs) < 0; }

template <typename E, class T, class A, class S>
bool operator<(const flex_string<E, T, A, S>& lhs, 
    const typename flex_string<E, T, A, S>::value_type* rhs)
{ return lhs.compare(rhs) < 0; }

template <typename E, class T, class A, class S>
bool operator<(const typename flex_string<E, T, A, S>::value_type* lhs, 
    const flex_string<E, T, A, S>& rhs)
{ return rhs.compare(lhs) > 0; }

template <typename E, class T, class A, class S>
bool operator>(const flex_string<E, T, A, S>& lhs, 
    const flex_string<E, T, A, S>& rhs)
{ return rhs < lhs; }

template <typename E, class T, class A, class S>
bool operator>(const flex_string<E, T, A, S>& lhs, 
    const typename flex_string<E, T, A, S>::value_type* rhs)
{ return rhs < lhs; }

template <typename E, class T, class A, class S>
bool operator>(const typename flex_string<E, T, A, S>::value_type* lhs, 
    const flex_string<E, T, A, S>& rhs)
{ return rhs < lhs; }

template <typename E, class T, class A, class S>
bool operator<=(const flex_string<E, T, A, S>& lhs, 
    const flex_string<E, T, A, S>& rhs)
{ return !(rhs < lhs); }

template <typename E, class T, class A, class S>
bool operator<=(const flex_string<E, T, A, S>& lhs, 
    const typename flex_string<E, T, A, S>::value_type* rhs)
{ return !(rhs < lhs); }

template <typename E, class T, class A, class S>
bool operator<=(const typename flex_string<E, T, A, S>::value_type* lhs, 
    const flex_string<E, T, A, S>& rhs)
{ return !(rhs < lhs); }

template <typename E, class T, class A, class S>
bool operator>=(const flex_string<E, T, A, S>& lhs, 
    const flex_string<E, T, A, S>& rhs)
{ return !(lhs < rhs); }

template <typename E, class T, class A, class S>
bool operator>=(const flex_string<E, T, A, S>& lhs, 
    const typename flex_string<E, T, A, S>::value_type* rhs)
{ return !(lhs < rhs); }

template <typename E, class T, class A, class S>
bool operator>=(const typename flex_string<E, T, A, S>::value_type* lhs, 
    const flex_string<E, T, A, S>& rhs)
{ return !(lhs < rhs); }

// subclause 21.3.7.8:
//void swap(flex_string<E, T, A, S>& lhs, flex_string<E, T, A, S>& rhs);    // to do

template <typename E, class T, class A, class S>
std::basic_istream<typename flex_string<E, T, A, S>::value_type, 
    typename flex_string<E, T, A, S>::traits_type>&
operator>>(
    std::basic_istream<typename flex_string<E, T, A, S>::value_type, 
		typename flex_string<E, T, A, S>::traits_type>& is,
    flex_string<E, T, A, S>& str);

template <typename E, class T, class A, class S>
std::basic_ostream<typename flex_string<E, T, A, S>::value_type,
    typename flex_string<E, T, A, S>::traits_type>&
operator<<(
    std::basic_ostream<typename flex_string<E, T, A, S>::value_type, 
		typename flex_string<E, T, A, S>::traits_type>& os,
    const flex_string<E, T, A, S>& str)
{ return os << str.c_str(); }

template <typename E, class T, class A, class S>
std::basic_istream<typename flex_string<E, T, A, S>::value_type,
    typename flex_string<E, T, A, S>::traits_type>&
getline(
    std::basic_istream<typename flex_string<E, T, A, S>::value_type, 
        typename flex_string<E, T, A, S>::traits_type>& is,
    flex_string<E, T, A, S>& str,
    typename flex_string<E, T, A, S>::value_type delim);

template <typename E, class T, class A, class S>
std::basic_istream<typename flex_string<E, T, A, S>::value_type, 
    typename flex_string<E, T, A, S>::traits_type>&
getline(
    std::basic_istream<typename flex_string<E, T, A, S>::value_type, 
        typename flex_string<E, T, A, S>::traits_type>& is,
    flex_string<E, T, A, S>& str);

template <typename E1, class T, class A, class S>
const typename flex_string<E1, T, A, S>::size_type
flex_string<E1, T, A, S>::npos = (flex_string<E1, T, A, S>::size_type)(-1);

#endif // FLEX_STRING_SHELL_INC_