tempstr.hpp

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#ifndef CORELIB___TEMPSTR__HPP
#define CORELIB___TEMPSTR__HPP
 
/*  $Id: tempstr.hpp 99233 2023-03-01 16:19:54Z ucko $
 * ===========================================================================
 *
 *                            PUBLIC DOMAIN NOTICE
 *               National Center for Biotechnology Information
 *
 *  This software/database is a "United States Government Work" under the
 *  terms of the United States Copyright Act.  It was written as part of
 *  the author's official duties as a United States Government employee and
 *  thus cannot be copyrighted.  This software/database is freely available
 *  to the public for use. The National Library of Medicine and the U.S.
 *  Government have not placed any restriction on its use or reproduction.
 *
 *  Although all reasonable efforts have been taken to ensure the accuracy
 *  and reliability of the software and data, the NLM and the U.S.
 *  Government do not and cannot warrant the performance or results that
 *  may be obtained by using this software or data. The NLM and the U.S.
 *  Government disclaim all warranties, express or implied, including
 *  warranties of performance, merchantability or fitness for any particular
 *  purpose.
 *
 *  Please cite the author in any work or product based on this material.
 *
 * ===========================================================================
 *
 * Authors:  Mike DiCuccio, Eugene Vasilchenko, Aaron Ucko, Vladimir Ivanov
 *
 * File Description:
 *
 *  CTempString -- Light-weight const string class that can wrap an std::string
 *                 or C-style char array.
 *
 */
 
#include <corelib/ncbiexpt.hpp>
#include <algorithm>
 
#ifdef NCBI_HAVE_CXX17
    #include <string_view>
#endif
 
 
BEGIN_NCBI_SCOPE
 
 
/** @addtogroup String
 *
 * @{
 */
 
/////////////////////////////////////////////////////////////////////////////
///
/// CTempString implements a light-weight string on top of a storage buffer
/// whose lifetime management is known and controlled.  CTempString is designed
/// to perform no memory allocation but provide a string interaction interface
/// congruent with std::basic_string<char>.  As such, CTempString provides a
/// const-only access interface to its underlying storage.  Care has been taken
/// to avoid allocations and other expensive operations wherever possible.
///
 
class CTempString
{
public:
    /// @name std::basic_string<> compatibility typedefs and enums
    /// @{
    typedef char            value_type;
    typedef size_t          size_type;
    typedef const char*     const_iterator;
    static const size_type  npos = static_cast<size_type>(-1);
    /// @}
 
    CTempString(void);
    CTempString(const char* str);
    CTempString(const char* str, size_type len);
    /// Use CTempString(const char* str + pos, size_type len - pos) instead
    NCBI_DEPRECATED_CTOR(CTempString(const char* str, size_type pos, size_type len));
 
    CTempString(const string& str);
    /// Use CTempString(const string& str, 0, size_type len) instead
    NCBI_DEPRECATED_CTOR(CTempString(const string& str, size_type len));
    CTempString(const string& str, size_type pos, size_type len);
 
    CTempString(const CTempString& str);
    CTempString(const CTempString& str, size_type pos);
    CTempString(const CTempString& str, size_type pos, size_type len);
 
    #ifdef NCBI_HAVE_CXX17
        CTempString(const string_view&  str_view);
    #endif
 
    /// Copy a substring into a string
    /// Somewhat similar to basic_string::assign()
    void Copy(string& dst, size_type pos, size_type len) const;
 
    /// @name std::basic_string<> compatibility interface
    /// @{
    
    /// Assign new values to the content of the a string
    CTempString& assign(const char* src_str, size_type len);
    CTempString& assign(const CTempString src_str);
    CTempString& assign(const CTempString src_str, size_type pos, size_type len);
    CTempString& operator=(const CTempString str);
    
 
    /// Return an iterator to the string's starting position
    const_iterator begin() const;
 
    /// Return an iterator to the string's ending position (one past the end of
    /// the represented sequence)
    const_iterator end() const;
 
    /// Return a pointer to the array represented.  As with
    /// std::basic_string<>, this is not guaranteed to be NULL terminated.
    const char* data(void) const;
 
    /// Return the length of the represented array.
    size_type length(void) const;
 
    /// Return the length of the represented array.
    size_type size(void) const;
 
    /// Return true if the represented string is empty (i.e., the length is
    /// zero)
    bool empty(void)  const;
 
    /// Clears the string
    void clear(void);
 
    /// Truncate the string at some specified position
    /// Note: basic_string<> supports additional erase() options that we
    /// do not provide here
    void erase(size_type pos = 0);
 
    /// Find the first instance of the entire matching string within the
    /// current string, beginning at an optional offset.
    size_type find(const CTempString match,
                   size_type pos = 0) const;
 
    /// Find the first instance of a given character string within the
    /// current string in a forward direction, beginning at an optional offset.
    size_type find(char match, size_type pos = 0) const;
 
    /// Find the first instance of the entire matching string within the
    /// current string in a backward direction, beginning at an optional offset.
    size_type rfind(const CTempString match,
                    size_type pos = npos) const;
 
    /// Find the last instance of a given character string within the
    /// current string, beginning at an optional offset.
    size_type rfind(char match, size_type pos = npos) const;
 
    /// Find the first occurrence of any character in the matching string
    /// within the current string, beginning at an optional offset.
    size_type find_first_of(const CTempString match,
                            size_type pos = 0) const;
 
    /// Find the first occurrence of any character not in the matching string
    /// within the current string, beginning at an optional offset.
    size_type find_first_not_of(const CTempString match,
                                size_type pos = 0) const;
 
    /// Find the last occurrence of any character in the matching string
    /// within the current string, beginning at an optional offset.
    size_type find_last_of(const CTempString match,
                           size_type pos = npos) const;
 
    /// Find the last occurrence of any character not in the matching string
    /// within the current string, beginning at an optional offset.
    size_type find_last_not_of(const CTempString match,
                               size_type pos = npos) const;
 
    /// Obtain a substring from this string, beginning at a given offset
    CTempString substr(size_type pos) const;
    /// Obtain a substring from this string, beginning at a given offset
    /// and extending a specified length
    CTempString substr(size_type pos, size_type len) const;
 
    /// Index into the current string and provide its character in a read-
    /// only fashion.  If the index is beyond the length of the string,
    /// a NULL character is returned.
    char operator[](size_type pos) const;
 
    /// Compare the current string with a given string.
    int compare(const CTempString str) const;
 
    // Comparison operators, see compare().
    bool operator==(const CTempString str) const;
    bool operator!=(const CTempString str) const;
    bool operator< (const CTempString str) const;
    bool operator> (const CTempString str) const;
 
    /// @}
 
    operator string(void) const;
 
    #ifdef NCBI_HAVE_CXX17
        operator string_view(void) const;
    #endif
 
private:
    const char* m_String;  ///< Stored pointer to string
    size_type   m_Length;  ///< Length of string
 
private:
    // Initialize CTempString with bounds checks
    void x_Init(const char* str, size_type str_len, size_type pos, size_type len);
    void x_Init(const char* str, size_type str_len, size_type pos);
 
#if defined(NCBI_TEMPSTR_USE_A_COPY)
    /// @attention This (making copy of the string) is turned off by default!
    void x_MakeCopy(void);
    /// @attention This (making copy of the string) is turned off by default!
    void x_DestroyCopy(void);
#endif
};
 
 
/////////////////////////////////////////////////////////////////////////////
 
 
// Operator +
 
/// @internal
inline
string g_CTempString_plus(const char* str1, size_t len1,
                          const char* str2, size_t len2)
{
    string tmp;
    tmp.reserve(len1 + len2);
    tmp.assign(str1, len1);
    tmp.append(str2, len2);
    return tmp;
}
 
inline
string operator+(const char* str1, const CTempString str2)
{
    return g_CTempString_plus(str1, strlen(str1),
                              str2.data(), str2.length());
}
 
inline
string operator+(const CTempString str1, const char* str2)
{
    return g_CTempString_plus(str1.data(), str1.length(),
                              str2, strlen(str2));
}
 
inline
string operator+(const string& str1, const CTempString str2)
{
    return g_CTempString_plus(str1.data(), str1.length(),
                              str2.data(), str2.length());
}
 
inline
string operator+(const CTempString str1, const string& str2)
{
    return g_CTempString_plus(str1.data(), str1.length(),
                              str2.data(), str2.length());
}
 
inline
string operator+(const CTempString str1, const CTempString str2)
{
    return g_CTempString_plus(str1.data(), str1.length(),
                              str2.data(), str2.length());
}
 
 
// Put CTempString to stream
inline
CNcbiOstream& operator<<(CNcbiOstream& out, const CTempString str)
{
    return out.write(str.data(), str.length());
}
 
 
 
/////////////////////////////////////////////////////////////////////////////
 
#if defined(NCBI_TEMPSTR_USE_A_COPY)
// This is NOT a default behavior.
// The NCBI_TEMPSTR_USE_A_COPY define has been introduced specifically for
// SWIG. Making copies in the CTempString allows using this class naturally in
// the generated Python wrappers.
#  define NCBI_TEMPSTR_MAKE_COPY()     x_MakeCopy()
#  define NCBI_TEMPSTR_DESTROY_COPY()  x_DestroyCopy()
#else
#  define NCBI_TEMPSTR_MAKE_COPY()
#  define NCBI_TEMPSTR_DESTROY_COPY()
#endif
 
 
inline
CTempString::const_iterator CTempString::begin() const
{
    return m_String;
}
 
 
inline
CTempString::const_iterator CTempString::end() const
{
    return m_String + m_Length;
}
 
 
inline
const char* CTempString::data(void) const
{
    return m_String;
}
 
 
inline
CTempString::size_type CTempString::length(void) const
{
    return m_Length;
}
 
 
inline
CTempString::size_type CTempString::size(void) const
{
    return m_Length;
}
 
 
inline
bool CTempString::empty(void) const
{
    return m_Length == 0;
}
 
 
inline
char CTempString::operator[](size_type pos) const
{
    if ( pos < m_Length ) {
        return m_String[pos];
    }
    return '\0';
}
 
 
inline
void CTempString::clear(void)
{
    NCBI_TEMPSTR_DESTROY_COPY();
    // clear() assures that m_String points to a NULL-terminated c-style
    // string as a fall-back.
    m_String = "";
    m_Length = 0;
    NCBI_TEMPSTR_MAKE_COPY();
}
 
 
inline
void CTempString::x_Init(const char* str, size_type str_len,
                         size_type pos)
{
    if ( pos >= str_len ) {
        clear();
    }
    else {
        m_String = str + pos;
        m_Length = str_len - pos;
    }
}
 
 
inline
void CTempString::x_Init(const char* str, size_type str_len,
                         size_type pos, size_type len)
{
    if ( pos >= str_len ) {
        clear();
    }
    else {
        m_String = str + pos;
        m_Length = min(len, str_len - pos);
    }
}
 
 
#if defined(NCBI_TEMPSTR_USE_A_COPY)
inline
void CTempString::x_MakeCopy()
{
    // 1 extra byte is for last 0 unconditionally
    char* copy = new char[m_Length+1];
    memcpy(copy, m_String, m_Length);
    copy[m_Length] = 0;
    m_String = copy;
}
 
inline
void CTempString::x_DestroyCopy(void)
{
    delete [] m_String;
    m_String = NULL;
    m_Length = 0;
}
#endif
 
 
inline
CTempString::CTempString(void)
#if defined(NCBI_TEMPSTR_USE_A_COPY)
    : m_String(NULL)
#endif
{
    clear();
}
 
 
inline
CTempString::CTempString(const char* str)
#if defined(NCBI_TEMPSTR_USE_A_COPY)
    : m_String(NULL)
#endif
{
    if ( !str ) {
        clear();
        return;
    }
    m_String = str;
    m_Length = strlen(str);
    NCBI_TEMPSTR_MAKE_COPY();
}
 
 
/// Templatized initialization from a string literal.  This version is
/// optimized to deal specifically with constant-sized built-in arrays.
template<size_t Size>
inline
CTempString literal(const char (&str)[Size])
{
    return CTempString(str, Size-1);
}
 
 
inline
CTempString::CTempString(const char* str, size_type len)
    : m_String(str), m_Length(len)
{
    NCBI_TEMPSTR_MAKE_COPY();
}
 
 
inline
CTempString::CTempString(const string& str)
    : m_String(str.data()), m_Length(str.size())
{
    NCBI_TEMPSTR_MAKE_COPY();
}
 
 
inline
CTempString::CTempString(const string& str, size_type pos, size_type len)
#if defined(NCBI_TEMPSTR_USE_A_COPY)
    : m_String(NULL)
#endif
{
    x_Init(str.data(), str.size(), pos, len);
    NCBI_TEMPSTR_MAKE_COPY();
}
 
 
inline
CTempString::CTempString(const CTempString& str)
    : m_String(str.data()), m_Length(str.size())
{
    NCBI_TEMPSTR_MAKE_COPY();
}
 
 
inline
CTempString::CTempString(const CTempString& str, size_type pos)
#if defined(NCBI_TEMPSTR_USE_A_COPY)
    : m_String(NULL)
#endif
{
    x_Init(str.data(), str.size(), pos);
    NCBI_TEMPSTR_MAKE_COPY();
}
 
 
inline
CTempString::CTempString(const CTempString& str, size_type pos, size_type len)
#if defined(NCBI_TEMPSTR_USE_A_COPY)
    : m_String(NULL)
#endif
{
    x_Init(str.data(), str.size(), pos, len);
    NCBI_TEMPSTR_MAKE_COPY();
}
 
#ifdef NCBI_HAVE_CXX17
inline
CTempString::CTempString(const string_view&  str_view)
    : m_String(str_view.data()), m_Length(str_view.size())
{
    NCBI_TEMPSTR_MAKE_COPY();
}
#endif
 
 
inline
void CTempString::erase(size_type pos)
{
    if (pos < m_Length) {
        m_Length = pos;
    }
}
 
 
/// Copy a substring into a string.
/// These are analogs of basic_string::assign().
inline
void CTempString::Copy(string& dst, size_type pos, size_type len) const
{
    if (pos < length()) {
        len = min(len, length()-pos);
        dst.assign(begin() + pos, begin() + pos + len);
    }
    else {
        dst.erase();
    }
}
 
 
inline
CTempString::size_type CTempString::find_first_of(const CTempString match,
                                                  size_type pos) const
{
    if (match.length()  &&  pos < length()) {
        const_iterator it = std::find_first_of(begin() + pos, end(),
                                               match.begin(), match.end());
        if (it != end()) {
            return it - begin();
        }
    }
    return npos;
}
 
 
inline
CTempString::size_type CTempString::find_first_not_of(const CTempString match,
                                                      size_type pos) const
{
    if (match.length()  &&  pos < length()) {
        const_iterator it = begin() + pos;
        const_iterator end_it = end();
        const_iterator match_begin = match.begin();
        const_iterator match_end   = match.end();
        for ( ;  it != end_it;  ++it) {
            bool found = false;
            for (const_iterator match_it = match_begin;
                 match_it != match_end;  ++match_it) {
                if (*it == *match_it) {
                    found = true;
                    break;
                }
            }
            if ( !found ) {
                return it - begin();
            }
        }
    }
    return npos;
}
 
 
inline
CTempString::size_type CTempString::find_last_of(const CTempString match,
                                                 size_type pos) const
{
    if (match.length()) {
        if (pos >= length()) {
            pos = length() - 1;
        }
        const_iterator it = begin() + pos;
        const_iterator end_it = begin();
        const_iterator match_begin = match.begin();
        const_iterator match_end   = match.end();
        for ( ;  it >= end_it;  --it) {
            bool found = false;
            for (const_iterator match_it = match_begin;
                 match_it != match_end;  ++match_it) {
                if (*it == *match_it) {
                    found = true;
                    break;
                }
            }
            if ( found ) {
                return it - begin();
            }
        }
    }
    return npos;
}
 
 
inline
CTempString::size_type CTempString::find_last_not_of(const CTempString match,
                                                     size_type pos) const
{
    if (match.length()) {
        if (pos >= length()) {
            pos = length() - 1;
        }
        const_iterator it = begin() + pos;
        const_iterator end_it = begin();
        const_iterator match_begin = match.begin();
        const_iterator match_end   = match.end();
        for ( ;  it >= end_it;  --it) {
            bool found = false;
            for (const_iterator match_it = match_begin;
                 match_it != match_end;  ++match_it) {
                if (*it == *match_it) {
                    found = true;
                    break;
                }
            }
            if ( !found ) {
                return it - begin();
            }
        }
    }
    return npos;
}
 
 
inline
CTempString::size_type CTempString::find(char match, size_type pos) const
{
    if (pos + 1 > length()) {
        return npos;
    }
    for (size_type i = pos;  i < length();  ++i) {
        if (m_String[i] == match) {
            return i;
        }
    }
    return npos;
}
 
 
inline
CTempString::size_type CTempString::find(const CTempString match,
                                         size_type pos) const
{
    if (pos + match.length() > length()) {
        return npos;
    }
    if (match.length() == 0) {
        return pos;
    }
    size_type length_limit = length() - match.length();
    while ( (pos = find_first_of(CTempString(match, 0, 1), pos)) !=
            string::npos) {
        if (pos > length_limit) {
            return npos;
        }
        int res = memcmp(begin() + pos + 1,
                         match.begin() + 1,
                         match.length() - 1);
        if (res == 0) {
            return pos;
        }
        ++pos;
    }
    return npos;
}
 
 
inline
CTempString::size_type CTempString::rfind(char match, size_type pos) const
{
    if (length() == 0) {
        return npos;
    }
    if (pos >= length()) {
        pos = length() - 1;
    }
    for (size_type i = pos;;) {
        if (m_String[i] == match) {
            return i;
        }
        if (!i) {
            break;
        }
        --i;
    }
    return npos;
}
 
 
inline
CTempString::size_type CTempString::rfind(const CTempString match,
                                          size_type pos) const
{
    if (match.length() > length()) {
        return npos;
    }
    if (match.length() == 0) {
        return length();
    }
    pos = min(pos, length() - match.length());
    while ( (pos = find_last_of(CTempString(match, 0, 1), pos)) !=
            string::npos) {
        int res = memcmp(begin() + pos + 1,
                         match.begin() + 1,
                         match.length() - 1);
        if (res == 0) {
            return pos;
        }
        if (!pos) {
            break;
        }
        --pos;
    }
    return npos;
}
 
 
inline
CTempString& CTempString::assign(const char* src, size_type len)
{
    NCBI_TEMPSTR_DESTROY_COPY();
    m_String = src;
    m_Length = len;
    NCBI_TEMPSTR_MAKE_COPY();
    return *this;
}
 
 
inline
CTempString& CTempString::assign(const CTempString src_str)
{
    if (this != &src_str) {
        NCBI_TEMPSTR_DESTROY_COPY();
        m_String = src_str.m_String;
        m_Length = src_str.m_Length;
        NCBI_TEMPSTR_MAKE_COPY();
    }
    return *this;
}
 
 
inline
CTempString& CTempString::assign(const CTempString src_str,
                                 size_type          pos, 
                                 size_type          len)
{
    NCBI_TEMPSTR_DESTROY_COPY();
    x_Init(src_str.data(), src_str.size(), pos, len);
    NCBI_TEMPSTR_MAKE_COPY();
    return *this;
}
 
 
inline
CTempString& CTempString::operator=(const CTempString src_str)
{
    return assign(src_str);
}
 
 
inline
CTempString CTempString::substr(size_type pos) const
{
    return CTempString(*this, pos);
}
 
 
inline
CTempString CTempString::substr(size_type pos, size_type len) const
{
    return CTempString(*this, pos, len);
}
 
 
inline
CTempString::operator string(void) const
{
    return string(data(), length());
}
 
 
#ifdef NCBI_HAVE_CXX17
inline
CTempString::operator string_view(void) const
{
    return string_view(data(), length());
}
#endif
 
 
inline
int CTempString::compare(const CTempString str) const
{
    const int kLess    = -1;
    const int kEqual   =  0;
    const int kGreater =  1;
 
    size_type n1 = length();
    size_type n2 = str.length();
 
    if ( !n1 ) {
        return n2 ? kLess : kEqual;
    }
    if ( !n2 ) {
        return kGreater;
    }
    int res = memcmp(data(), str.data(), min(n1, n2));
    if ( res ) {
        return res;
    }
    if (n1 < n2) {
        return kLess;
    }
    if (n1 > n2) {
        return kGreater;
    }
    return kEqual;
}
 
 
inline
bool CTempString::operator==(const CTempString str) const
{
    return length() == str.length() && memcmp(data(), str.data(), length()) == 0;
}
 
inline
bool CTempString::operator!=(const CTempString str) const
{
    return !(*this == str);
}
 
inline
bool CTempString::operator<(const CTempString str) const
{
    return compare(str) < 0;
}
 
inline
bool CTempString::operator>(const CTempString str) const
{
    return compare(str) > 0;
}
 
// Global comparison operators (counterparts for CTempString::operator's).
 
inline
bool operator==(const char* str1, const CTempString str2)
{
    return str2 == CTempString(str1);
}
 
inline
bool operator==(const string& str1, const CTempString str2)
{
    return str2 == CTempString(str1);
}
 
inline
bool operator!=(const char* str1, const CTempString str2)
{
    return str2 != str1;
}
 
inline
bool operator!=(const string& str1, const CTempString str2)
{
    return str2 != str1;
}
 
inline
bool operator<(const char* str1, const CTempString str2)
{
    return str2 > str1;
}
 
inline
bool operator<(const string& str1, const CTempString str2)
{
    return str2 > str1;
}
 
inline
bool operator>(const char* str1, const CTempString str2)
{
    return str2 < str1;
}
 
inline
bool operator>(const string& str1, const CTempString str2)
{
    return str2 < str1;
}
 
 
class CTempStringEx : public CTempString
{
public:
    enum EZeroAtEnd { ///< For compatibility with older code
        eNoZeroAtEnd,
        eHasZeroAtEnd
    };
    CTempStringEx(void)
        : m_ZeroAtEnd(eNoZeroAtEnd)
        {
        }
    CTempStringEx(const char* str)
        : CTempString(str),
          m_ZeroAtEnd(eHasZeroAtEnd)
        {
        }
    CTempStringEx(const char* str, size_type len)
        : CTempString(str, len),
          m_ZeroAtEnd(eNoZeroAtEnd)
        {
        }
    CTempStringEx(const char* str, size_type len, EZeroAtEnd zero_at_end)
        : CTempString(str, len),
          m_ZeroAtEnd(zero_at_end)
        {
        }
    CTempStringEx(const string& str)
        : CTempString(str.c_str(), str.size()),
          m_ZeroAtEnd(eHasZeroAtEnd)
        {
        }
    CTempStringEx(const string& str, size_type pos, size_type len)
        : CTempString(str, pos, len),
          m_ZeroAtEnd(eNoZeroAtEnd)
        {
        }
    CTempStringEx(const CTempString& str)
        : CTempString(str),
          m_ZeroAtEnd(eNoZeroAtEnd)
        {
        }
    #ifdef NCBI_HAVE_CXX17
    CTempStringEx(const string_view&  str_view)
        : CTempString(str_view),
          m_ZeroAtEnd(eNoZeroAtEnd)
        {
        }
    #endif
    CTempStringEx(const CTempString& str, size_type pos)
        : CTempString(str, pos),
          m_ZeroAtEnd(eNoZeroAtEnd)
        {
        }
    CTempStringEx(const CTempString& str, size_type pos, size_type len)
        : CTempString(str, pos, len),
          m_ZeroAtEnd(eNoZeroAtEnd)
        {
        }
 
    /// Assign new values to the content of the a string
    CTempStringEx& assign(const char* str, size_type len)
        {
            m_ZeroAtEnd = eNoZeroAtEnd;
            CTempString::assign(str, len);
            return *this;
        }
    CTempStringEx& assign(const char* str, size_type len,
                          EZeroAtEnd zero_at_end)
        {
            m_ZeroAtEnd = zero_at_end;
            CTempString::assign(str, len);
            return *this;
        }
    CTempStringEx& assign(const CTempString& str)
        {
            m_ZeroAtEnd = eNoZeroAtEnd;
            CTempString::assign(str);
            return *this;
        }
    CTempStringEx& assign(const CTempStringEx& str)
        {
            return *this = str;
        }
    CTempStringEx& assign(const CTempString str,
                          size_type         pos, 
                          size_type         count)
        {
            m_ZeroAtEnd = eNoZeroAtEnd;
            CTempString::assign(str, pos, count);
            return *this;
        }
 
    /// Clear value to an empty string
    void clear(void)
        {
            CTempString::clear();
            m_ZeroAtEnd = eHasZeroAtEnd;
        }
 
    /// Obtain a substring from this string, beginning at a given offset
    CTempStringEx substr(size_type pos) const
        {
            size_type max = size();
            if ( pos > max ) {
                pos = max;
            }
            size_type rem = max - pos;
            return CTempStringEx(data()+pos, rem, m_ZeroAtEnd);
        }
    /// Obtain a substring from this string, beginning at a given offset
    /// and extending a specified length
    CTempStringEx substr(size_type pos, size_type len) const
        {
            size_type max = size();
            if ( pos > max ) {
                pos = max;
            }
            size_type rem = max - pos;
            EZeroAtEnd zero_at_end = eNoZeroAtEnd;
            if ( len >= rem ) {
                len = rem;
                zero_at_end = m_ZeroAtEnd;
            }
            return CTempStringEx(data()+pos, len, zero_at_end);
        }
 
    bool HasZeroAtEnd(void) const
        {
            return m_ZeroAtEnd != eNoZeroAtEnd;
        }
 
private:
    EZeroAtEnd m_ZeroAtEnd;
};
 
 
/// Helper class to allocate memory for CTempString[Ex] on demand
/// in the functions which need to modify the strings (e.g. NStr::Split).
 
 
class NCBI_XNCBI_EXPORT CTempString_Storage
{
public:
    typedef CTempString::size_type size_type;
 
    CTempString_Storage(void);
    ~CTempString_Storage(void);
 
    char* Allocate(CTempString::size_type len);
 
private:
    typedef char* TBuffer;
    typedef list<TBuffer> TData;
 
    TData m_Data;
};
 
 
END_NCBI_SCOPE
 
 
/* @} */
 
#endif  // CORELIB___TEMPSTR__HPP