flex_string.hpp

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    // 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 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)
    {
#ifndef NDEBUG
        Invariant checker(*this); 
#endif
        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.c_str(), 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)
    { 
#ifndef NDEBUG
        Invariant checker(*this); 
#endif
        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);
            std::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, "");
        n = Min(n, size() - pos);
        
        flex_string_details::pod_copy(
            &*begin() + pos,
            &*begin() + 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(&*begin() + 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.c_str(), 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.c_str(), 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.c_str(), 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.c_str(), pos, str.length()); }
    
    size_type find_last_not_of(const value_type* s, size_type pos,
        size_type n) const
    {
        if (!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));
    }

    std::ptrdiff_t compare(const flex_string& str) const
    { 
        // FIX due to Goncalo N M de Carvalho July 18, 2005
        return compare(0, size(), str);
    }
    
    std::ptrdiff_t 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
    std::ptrdiff_t compare(size_type pos1, size_type n1,
        const value_type* s) const
    {
        return compare(pos1, n1, s, traits_type::length(s));
    }
    
    std::ptrdiff_t 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);
        const int r = traits_type::compare(data()+pos1, s, Min(n1, n2));
        return 
            r != 0 ? r :
            n1 > n2 ? 1 :
            n1 < n2 ? -1 :
            0;
    }

    std::ptrdiff_t 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));
    }

    std::ptrdiff_t compare(const value_type* s) const
    { 
        return traits_type::compare(data(), s, 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>
inline 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>
inline 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>
inline 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>
inline 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>
inline 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>
inline bool operator!=(const flex_string<E, T, A, S>& lhs, 
    const typename flex_string<E, T, A, S>::value_type* rhs)
{ return !(lhs =