#pragma once
#include <algorithm>
#include <string>
#include <vector>
#include <stdarg.h>
#include <functional>

#ifndef _WIN32
#include <cstring>
#endif
namespace std
{

/**
         * An extension of STL's string providing additional functionality that is often availiable in
         * higher-level languages such as Python.
         */
class string_ref : public string
{
public:
    //static unsigned GetAutoSenseRadix(string_ref& Str) {
    //      if (Str.empty())
    //              return 10;

    //      if (Str.start_with("0x") || Str.start_with("0X")) {
    //              Str = Str.substr(2);
    //              return 16;
    //      }

    //      if (Str.start_with("0b") || Str.start_with("0B")) {
    //              Str = Str.substr(2);
    //              return 2;
    //      }

    //      if (Str.start_with("0o")) {
    //              Str = Str.substr(2);
    //              return 8;
    //      }

    //      if (Str[0] == '0' && Str.size() > 1 && std::isdigit(Str[1])) {
    //              Str = Str.substr(1);
    //              return 8;
    //      }

    //      return 10;
    //}

    //static bool consumeUnsignedInteger(string_ref& Str, unsigned Radix,
    //      unsigned long long& Result) {
    //      // Autosense radix if not specified.
    //      if (Radix == 0)
    //              Radix = GetAutoSenseRadix(Str);

    //      // Empty strings (after the radix autosense) are invalid.
    //      if (Str.empty()) return true;

    //      // Parse all the bytes of the string given this radix.  Watch for overflow.
    //      string_ref Str2 = Str;
    //      Result = 0;
    //      while (!Str2.empty()) {
    //              unsigned CharVal;
    //              if (Str2[0] >= '0' && Str2[0] <= '9')
    //                      CharVal = Str2[0] - '0';
    //              else if (Str2[0] >= 'a' && Str2[0] <= 'z')
    //                      CharVal = Str2[0] - 'a' + 10;
    //              else if (Str2[0] >= 'A' && Str2[0] <= 'Z')
    //                      CharVal = Str2[0] - 'A' + 10;
    //              else
    //                      break;

    //              // If the parsed value is larger than the integer radix, we cannot
    //              // consume any more characters.
    //              if (CharVal >= Radix)
    //                      break;

    //              // Add in this character.
    //              unsigned long long PrevResult = Result;
    //              Result = Result * Radix + CharVal;

    //              // Check for overflow by shifting back and seeing if bits were lost.
    //              if (Result / Radix < PrevResult)
    //                      return true;

    //              Str2 = Str2.substr(1);
    //      }

    //      // We consider the operation a failure if no characters were consumed
    //      // successfully.
    //      if (Str.size() == Str2.size())
    //              return true;

    //      Str = Str2;
    //      return false;
    //}

    //static bool consumeSignedInteger(string_ref& Str, unsigned Radix,
    //      long long& Result) {
    //      unsigned long long ULLVal;

    //      // Handle positive strings first.
    //      if (Str.empty() || Str.front() != '-') {
    //              if (consumeUnsignedInteger(Str, Radix, ULLVal) ||
    //                      // Check for value so large it overflows a signed value.
    //                      (long long)ULLVal < 0)
    //                      return true;
    //              Result = ULLVal;
    //              return false;
    //      }

    //      // Get the positive part of the value.
    //      string_ref Str2 = Str.drop_front(1);
    //      if (consumeUnsignedInteger(Str2, Radix, ULLVal) ||
    //              // Reject values so large they'd overflow as negative signed, but allow
    //              // "-0".  This negates the unsigned so that the negative isn't undefined
    //              // on signed overflow.
    //              (long long)-ULLVal > 0)
    //              return true;

    //      Str = Str2;
    //      Result = -ULLVal;
    //      return false;
    //}

    ///// GetAsUnsignedInteger - Workhorse method that converts a integer character
    ///// sequence of radix up to 36 to an unsigned long long value.
    //static        bool getAsUnsignedInteger(string_ref Str, unsigned Radix,
    //      unsigned long long& Result) {
    //      if (consumeUnsignedInteger(Str, Radix, Result))
    //              return true;

    //      // For getAsUnsignedInteger, we require the whole string to be consumed or
    //      // else we consider it a failure.
    //      return !Str.empty();
    //}

    //static  bool getAsSignedInteger(string_ref Str, unsigned Radix,
    //      long long& Result) {
    //      if (consumeSignedInteger(Str, Radix, Result))
    //              return true;

    //      // For getAsSignedInteger, we require the whole string to be consumed or else
    //      // we consider it a failure.
    //      return !Str.empty();
    //}

    ///// Parse the current string as an integer of the specified radix.  If
    ///// \p Radix is specified as zero, this does radix autosensing using
    ///// extended C rules: 0 is octal, 0x is hex, 0b is binary.
    /////
    ///// If the string is invalid or if only a subset of the string is valid,
    ///// this returns true to signify the error.  The string is considered
    ///// erroneous if empty or if it overflows T.
    //template <typename T>
    //std::enable_if_t<std::numeric_limits<T>::is_signed, bool>
    //      getAsInteger(unsigned Radix, T& Result) const {
    //      long long LLVal;
    //      if (getAsSignedInteger(*this, Radix, LLVal) ||
    //              static_cast<T>(LLVal) != LLVal)
    //              return true;
    //      Result = LLVal;
    //      return false;
    //}

    //template <typename T>
    //std::enable_if_t<!std::numeric_limits<T>::is_signed, bool>
    //      getAsInteger(unsigned Radix, T& Result) const {
    //      unsigned long long ULLVal;
    //      // The additional cast to unsigned long long is required to avoid the
    //      // Visual C++ warning C4805: '!=' : unsafe mix of type 'bool' and type
    //      // 'unsigned __int64' when instantiating getAsInteger with T = bool.
    //      if (getAsUnsignedInteger(*this, Radix, ULLVal) ||
    //              static_cast<unsigned long long>(static_cast<T>(ULLVal)) != ULLVal)
    //              return true;
    //      Result = ULLVal;
    //      return false;
    //}

    /**`
                 * Default constructor
                 *
                 * Constructs an empty string_ref ("")
                 */
    string_ref() : string()
    {
    }

    /**
                 * Duplicate the STL string copy constructor
                 *
                 * @param[in] s   The string to copy
                 * @param[in] pos The starting position in the string to copy from
                 * @param[in] n   The number of characters to copy
                 */
    string_ref(string const& s, size_type pos = 0, size_type n = npos) : string(s, pos, n)
    {
    }

    /**
                 * Construct an string_ref from a null-terminated character array
                 *
                 * @param[in] s The character array to copy into the new string
                 */
    string_ref(value_type const* s) : string(s)
    {
    }

    /**
                 * Construct an string_ref from a character array and a length
                 *
                 * @param[in] s The character array to copy into the new string
                 * @param[in] n The number of characters to copy
                 */
    string_ref(value_type const* s, size_type n) : string(s, n)
    {
    }

    /**
                 * Create an string_ref with @p n copies of @p c
                 *
                 * @param[in] n The number of copies
                 * @param[in] c The character to copy @p n times
                 */
    string_ref(size_type n, value_type c) : string(n, c)
    {
    }

    /**
                 * Create a string from a range
                 *
                 * @param[in] first The first element to copy in
                 * @param[in] last  The last element to copy in
                 */
    template<class InputIterator>
    string_ref(InputIterator first, InputIterator last) : string(first, last)
    {
    }

    /**
                 * The destructor
                 */
    ~string_ref()
    {
    }

    /**
                 * Split a string by whitespace
                 *
                 * @return A vector of strings, each of which is a substring of the string
                 */
    vector<string_ref> split(size_type limit = npos) const
    {
        vector<string_ref> v;

        const_iterator i = begin(), last = i;
        for (; i != end(); i++)
        {
            if (*i == ' ' || *i == '\n' || *i == '\t' || *i == '\r')
            {
                if (i + 1 != end() && (i[1] == ' ' || i[1] == '\n' || i[1] == '\t' || i[1] == '\r'))
                {
                    continue;
                }
                v.push_back(string_ref(last, i));
                last = i + 1;
                if (v.size() >= limit - 1)
                {
                    v.push_back(string_ref(last, end()));
                    return v;
                }
            }
        }

        if (last != i)
        {
            v.push_back(string_ref(last, i));
        }

        return v;
    }

    /**
                 * Split a string by a character
                 *
                 * Returns a vector of ext_strings, each of which is a substring of the string formed by splitting
                 * it on boundaries formed by the character @p separator.  If @p limit is set, the returned vector
                 * will contain a maximum of @p limit elements with the last element containing the rest of
                 * the string.
                 *
                 * If @p separator is not found in the string, a single element will be returned in the vector
                 * containing the entire string.
                 *
                 * The separators are removed from the output
                 *
                 * @param[in] separator The character separator to split the string on
                 * @param[in] limit     The maximum number of output elements
                 * @return A vector of strings, each of which is a substring of the string
                 *
                 * @section split_ex Example
                 * @code
                 * std::string_ref s("This|is|a|test.");
                 * std::vector<std::string_ref> v = s.split('|');
                 * std::copy(v.begin(), v.end(), std::ostream_iterator<std::string_ref>(std::cout, "\n"));
                 *
                 * This
                 * is
                 * a
                 * test.
                 * @endcode
                 */
    vector<string_ref> split(value_type separator, size_type limit = npos) const
    {
        vector<string_ref> v;

        const_iterator i = begin(), last = i;
        for (; i != end(); i++)
        {
            if (*i == separator)
            {
                v.push_back(string_ref(last, i));
                last = i + 1;
                if (v.size() >= limit - 1)
                {
                    v.push_back(string_ref(last, end()));
                    return v;
                }
            }
        }

        if (last != i)
        {
            v.push_back(string_ref(last, i));
        }

        return v;
    }

    /**
                 * Split a string by another string
                 *
                 * Returns a vector of ext_strings, each of which is a substring of the string formed by
                 * splitting it on boundaries formed by the string @p separator.  If @p limit is set, the
                 * returned vector will contain a maximum of @p limit elements with the last element
                 * containing the rest of the string.
                 *
                 * If @p separator is not found in the string, a single element will be returned in the
                 * vector containing the entire string.
                 *
                 * The separators are removed from the output
                 *
                 * @param[in] separator The string separator to split the string on
                 * @param[in] limit     The maximum number of output elements
                 * @return A vector of strings, each of which is a substring of the string
                 *
                 * @ref split_ex
                 */
    vector<string_ref> split(string const& separator, size_type limit = npos) const
    {
        vector<string_ref> v;

        const_iterator i = begin(), last = i;
        for (; i != end(); i++)
        {
            if (string(i, i + separator.length()) == separator)
            {
                v.push_back(string_ref(last, i));
                last = i + separator.length();

                if (v.size() >= limit - 1)
                {
                    v.push_back(string_ref(last, end()));
                    return v;
                }
            }
        }

        if (last != i)
        {
            v.push_back(string_ref(last, i));
        }

        return v;
    }

    /**
                 * Convert a string into an integer
                 *
                 * Convert the initial portion of a string into a signed integer.  Once a non-numeric
                 * character is reached, the remainder of @p string is ignored and the integer that was
                 * read returned.
                 *
                 * @param s The string to convert
                 * @return The integer converted from @p string
                 */
    static long int integer(string const& s)
    {
        long int retval = 0;
        bool neg = false;

        for (const_iterator i = s.begin(); i != s.end(); i++)
        {
            if (i == s.begin())
            {
                if (*i == '-')
                {
                    neg = true;
                    continue;
                }
                else if (*i == '+')
                {
                    continue;
                }
            }
            if (*i >= '0' && *i <= '9')
            {
                retval *= 10;
                retval += *i - '0';
            }
            else
            {
                break;
            }
        }

        if (neg)
        {
            retval *= -1;
        }

        return retval;
    }

    /**
                 * Convert the string to an integer
                 *
                 * Convert the initial portion of the string into a signed integer.  Once a non-numeric
                 * character is reached, the remainder of the string is ignored and the integer that had
                 * been read thus far is returned.
                 *
                 * @return The integer converted from the string
                 */
    long int integer() const
    {
        return integer(*this);
    }

    /**
                 * Split a string into chunks of size @p chunklen.  Returns a vector of strings.
                 *
                 * Splits a string into chunks of the given size.  The final chunk may not fill its
                 * entire allocated number of characters.
                 *
                 * @param[in] chunklen The number of characters per chunk
                 * @return A vector of strings, each of length <= chunklen
                 *
                 * @section chunk_split-ex Example
                 * @code
                 * std::string_ref s("abcdefghijk");
                 * std::vector<std::string_ref> v = s.chunk_split(3);
                 * std::copy(v.begin(), v.end(), ostream_iterator<std::string_ref>(cout, " "));
                 *
                 * abc def ghi jk
                 * @endcode
                 */
    vector<string_ref> chunk_split(size_type chunklen) const
    {
        vector<string_ref> retval;
        retval.reserve(size() / chunklen + 1);

        size_type count = 0;
        const_iterator i = begin(), last = i;
        for (; i != end(); i++, count++)
        {
            if (count == chunklen)
            {
                count = 0;
                retval.push_back(string_ref(last, i));
                last = i;
            }
        }

        if (last != i)
        {
            retval.push_back(string_ref(last, i));
        }

        return retval;
    }

    /**
                 * Join a sequence of strings by some glue to create a new string
                 *
                 * Glue is not added to the end of the string.
                 *
                 * @pre [first, last) is a valid range
                 * @pre InputIterator is a model of STL's Input Iterator
                 * @pre InputIterator must point to a string type (std::string, std::string_ref, char *)
                 *
                 * @param[in] glue  The glue to join strings with
                 * @param[in] first The beginning of the range to join
                 * @param[in] last  The end of the range to join
                 * @return A string constructed of each element of the range connected together with @p glue
                 *
                 * @section join_ex Example
                 * @code
                 * std::vector<std::string_ref> v;
                 * v.push_back("This");
                 * v.push_back("is");
                 * v.push_back("a");
                 * v.push_back("test.");
                 * std::cout << std::string_ref::join("|", v.begin(), v.end()) << std::endl;
                 *
                 * This|is|a|test.
                 * @endcode
                 */
    template<class InputIterator>
    static string_ref join(string const& glue, InputIterator first, InputIterator last)
    {
        string_ref retval;

        for (; first != last; ++first)
        {
            retval.append(*first);
            retval.append(glue);
        }
        retval.erase(retval.length() - glue.length());

        return retval;
    }

    /**
                 * Join a sequence of strings by some glue to create a new string
                 *
                 * @copydoc join
                 * @ref join_ex
                 */
    template<class InputIterator>
    static string_ref join(value_type glue, InputIterator first, InputIterator last)
    {
        string_ref retval;

        for (; first != last; ++first)
        {
            retval.append(*first);
            retval.append(1, glue);
        }
        retval.erase(retval.length() - 1);

        return retval;
    }

    /**
                 * Search for any instances of @p needle and replace them with @p s
                 *
                 * @param[in] needle The string to replace
                 * @param[in] s      The replacement string
                 * @return                              *this
                 * @post                                        All instances of @p needle in the string are replaced with @p s
                 *
                 * @section replace-ex Example
                 * @code
                 * std::string_ref s("This is a test.");
                 * s.replace("is", "ere");
                 * std::cout << s << std::endl;
                 *
                 * There ere a test.
                 * @endcode
                 */
    string_ref& replace(string const& needle, string const& s)
    {
        size_type lastpos = 0, thispos;

        while ((thispos = find(needle, lastpos)) != npos)
        {
            string::replace(thispos, needle.length(), s);
            lastpos = thispos + 1;
        }
        return *this;
    }
    string_ref& replace_first(string const& needle, string const& s)
    {
        size_type lastpos = 0, thispos;

        if ((thispos = find(needle, lastpos)) != npos)
        {
            string::replace(thispos, needle.length(), s);
            lastpos = thispos + 1;
        }
        return *this;
    }
    /**
                 * Search of any instances of @p needle and replace them with @p c
                 *
                 * @param[in] needle The character to replace
                 * @param[in] c      The replacement character
                 * @return           *this
                 * @post             All instances of @p needle in the string are replaced with @p c
                 *
                 * @ref replace-ex
                 */
    string_ref& replace(value_type needle, value_type c)
    {
        for (iterator i = begin(); i != end(); i++)
        {
            if (*i == needle)
            {
                *i = c;
            }
        }

        return *this;
    }

    /**
                 * Repeat a string @p n times
                 *
                 * @param[in] n The number of times to repeat the string
                 * @return string_ref containing @p n copies of the string
                 *
                 * @section repeat-ex Example
                 * @code
                 * std::string_ref s("123");
                 * s = s * 3;
                 * std::cout << s << std::endl;
                 *
                 * 123123123
                 * @endcode
                 */
    string_ref operator*(size_type n)
    {
        string_ref retval;
        for (size_type i = 0; i < n; i++)
        {
            retval.append(*this);
        }

        return retval;
    }

    /**
                 * Convert the string to lowercase
                 *
                 * @return *this
                 * @post The string is converted to lowercase
                 */
    string_ref& tolower()
    {
        for (iterator i = begin(); i != end(); i++)
        {
            if (*i >= 'A' && *i <= 'Z')
            {
                *i = (*i) + ('a' - 'A');
            }
        }
        return *this;
    }

    /**
                 * Convert the string to uppercase
                 *
                 * @return *this
                 * @post The string is converted to uppercase
                 */
    string_ref& toupper()
    {
        for (iterator i = begin(); i != end(); i++)
        {
            if (*i >= 'a' && *i <= 'z')
            {
                *i = (*i) - ('a' - 'A');
            }
        }
        return *this;
    }

    /**
                 * Count the occurances of @p str in the string.
                 *
                 * @return The count of substrings @p str in the string
                 */
    size_type count(string const& str) const
    {
        size_type count = 0, last = 0, cur = 0;

        while ((cur = find(str, last + 1)) != npos)
        {
            count++;
            last = cur;
        }

        return count;
    }

    /**
                 * Determine if the string is alphanumeric
                 *
                 * @return true if the string contains only characters between a-z, A-Z and 0-9 and
                 * contains at least one character, else false
                 */
    bool is_alnum() const
    {
        if (length() == 0)
        {
            return false;
        }

        for (const_iterator i = begin(); i != end(); i++)
        {
            if (*i < 'A' || *i > 'Z')
            {
                if (*i < '0' || *i > '9')
                {
                    if (*i < 'a' || *i > 'z')
                    {
                        return false;
                    }
                }
            }
        }

        return true;
    }

    /**
                 * Determine if the string is alphabetic only
                 *
                 * @return true of the string contains only characters between a-z and A-Z and contains at
                 * least one character, else false
                 */
    bool is_alpha() const
    {
        if (length() == 0)
        {
            return false;
        }

        for (const_iterator i = begin(); i != end(); i++)
        {
            if (*i < 'A' || (*i > 'Z' && (*i < 'a' || *i > 'z')))
            {
                return false;
            }
        }

        return true;
    }

    /**
                 * Determine if the string is numeric only
                 *
                 * @return true if the string contains only characters between 0-9 and contains at least
                 * one character, else false
                 */
    bool is_numeric() const
    {
        if (length() == 0)
        {
            return false;
        }

        for (const_iterator i = begin(); i != end(); i++)
        {
            if (*i < '0' || *i > '9')
            {
                return false;
            }
        }

        return true;
    }

    /**
                 * Determine if a string is all lower case
                 *
                 * @return true if there is at least one character, and all characters are lowercase
                 * letters, else false
                 */
    bool is_lower() const
    {
        if (length() == 0)
        {
            return false;
        }

        for (const_iterator i = begin(); i != end(); i++)
        {
            if (*i < 'a' || *i < 'z')
            {
                return false;
            }
        }

        return true;
    }

    /**
                 * Determine if a string is all upper case
                 *
                 * @return true if there is at least one character, and all characters are uppercase
                 * letters, else false
                 */
    bool is_upper() const
    {
        if (length() == 0)
        {
            return false;
        }

        for (const_iterator i = begin(); i != end(); i++)
        {
            if (*i < 'A' || *i > 'Z')
            {
                return false;
            }
        }

        return true;
    }

    /**
                 * Swap the case of a string
                 *
                 * @post Converts all uppercase to lowercase, and all lowercase to uppercase in the string
                 * @return *this
                 */
    string_ref& swapcase()
    {
        for (iterator i = begin(); i != end(); i++)
        {
            if (*i >= 'A' && *i <= 'Z')
            {
                *i += ('a' - 'A');
            }
            else if (*i >= 'a' && *i <= 'z')
            {
                *i -= ('a' - 'A');
            }
        }

        return *this;
    }

    /*******************************************************************************
                        Function:       std::string_ref::start_with
                        Access:         public
                        Qualifier:      const
                        Parameter:      const string & str
                        Returns:        bool

                        Purpose:        is the string start with str
                *******************************************************************************/
    bool start_with(string const& str) const
    {
        return (this->find(str) == 0);
    }

    /// Return a string_ref equal to 'this' but with only the last \p N
    /// elements remaining.  If \p N is greater than the length of the
    /// string, the entire string is returned.

    string_ref take_back(size_t N = 1) const
    {
        if (N >= size())
        {
            return *this;
        }
        return drop_front(size() - N);
    }
    /// Return a string_ref equal to 'this' but with the first \p N elements
    /// dropped.

    string_ref drop_front(size_t N = 1) const
    {
        //assert(size() >= N && "Dropping more elements than exist");
        return substr(N);
    }

    /// Return a string_ref equal to 'this' but with the last \p N elements
    /// dropped.

    string_ref drop_back(size_t N = 1) const
    {

        return substr(0, size() - N);
    }

    /// Return a string_ref equal to 'this', but with all characters satisfying
    /// the given predicate dropped from the beginning of the string.

    string_ref drop_while(std::function<bool(char)> F) const
    {
        return substr(std::find_if_not(begin(), end(), F) - begin());
    }

    /// Return a string_ref equal to 'this', but with all characters not
    /// satisfying the given predicate dropped from the beginning of the string.

    string_ref drop_until(std::function<bool(char)> F) const
    {
        return substr(std::find_if(begin(), end(), F) - begin());
    }

    /// Returns true if this string_ref has the given prefix and removes that
    /// prefix.
    bool consume_front(string_ref Prefix)
    {
        if (!start_with(Prefix))
        {
            return false;
        }

        *this = drop_front(Prefix.size());
        return true;
    }

    /// Returns true if this string_ref has the given suffix and removes that
    /// suffix.
    bool consume_back(string_ref Suffix)
    {
        if (!end_with(Suffix))
        {
            return false;
        }

        *this = drop_back(Suffix.size());
        return true;
    }

    /*******************************************************************************
                        Function:       std::string_ref::end_with
                        Access:         public
                        Qualifier:      const
                        Parameter:      const string & str
                        Returns:        bool

                        Purpose:        is the string end with str
                *******************************************************************************/
    bool end_with(string const& str) const
    {
        if (str.length() > this->length())
        {
            return false;
        }
        size_type off = this->length() - str.length();
        return (find(str, off) == off);
    }

    /*******************************************************************************
                        Function:       hl_lib::string_ref::format
                        Access:         public
                        Qualifier:
                        Parameter:      const char * format_string
                        Parameter:      ...
                        Returns:        string_ref&

                        Purpose:        format the string
                *******************************************************************************/
    string_ref& format(char const* format_string, ...)
    {
        if (format_string == 0)
        {
            return *this;
        }

        va_list argList;
        va_start(argList, format_string);

#ifdef _WIN32
        int len = _vscprintf(format_string, argList);
        char* pbuf = new char[len + 1];
        if (pbuf != 0)
        {
            vsprintf_s(pbuf, len + 1, format_string, argList);
            *this = pbuf;
            delete[] pbuf;
        }
#else
        int const INLINE_FORMAT_BUFFER_LEN = 2048;
        char* buf = new char[INLINE_FORMAT_BUFFER_LEN + 1];
        if (buf != 0)
        {
            int len = vsnprintf(buf, INLINE_FORMAT_BUFFER_LEN, format_string, argList);
            assign(buf, buf + len);
            delete[] buf;
        }
#endif
        va_end(argList);
        return *this;
    }

    /*******************************************************************************
                        Function:       hl_lib::string_ref::trim_left
                        Access:         public
                        Qualifier:
                        Parameter:      value_type ch
                        Returns:        string_ref&

                        Purpose:        delete all char which is ch at the left of the string
                *******************************************************************************/
    string_ref& trim_left(value_type ch = ' ')
    {
        size_type off = this->find_first_not_of(ch);
        if (off != string::npos)
        {
            this->erase(0, off);
        }
        return *this;
    }

    /*******************************************************************************
                        Function:       hl_lib::string_ref::trim_right
                        Access:         public
                        Qualifier:
                        Parameter:      value_type ch
                        Returns:        string_ref&

                        Purpose:        delete all char which is ch at the right of the string
                *******************************************************************************/
    string_ref& trim_right(value_type ch = ' ')
    {
        size_type off = this->find_last_not_of(ch);
        if (off == string::npos)
        {
            off = 0;
        }
        else
        {
            off++;
        }
        this->erase(off, length() - off);
        return *this;
    }

    /*******************************************************************************
                        Function:       hl_lib::string_ref::trim
                        Access:         public
                        Qualifier:
                        Parameter:      value_type ch
                        Returns:        string_ref&

                        Purpose:        delete all char which is ch at the left and right of the string
                *******************************************************************************/
    string_ref& trim(value_type ch = ' ')
    {
        trim_left(ch);
        trim_right(ch);
        return *this;
    }

    /*******************************************************************************
                        Function:       hl_lib::string_ref::float_num
                        Access:         public static
                        Qualifier:
                        Parameter:      const string & str
                        Returns:        double

                        Purpose:        parse str to a float number
                *******************************************************************************/
    static double float_num(string const& str)
    {
        return atof(str.c_str());
    }

    /*******************************************************************************
                        Function:       hl_lib::string_ref::float_num
                        Access:         public static
                        Qualifier:
                        Returns:        double

                        Purpose:        parse this to a float number
                *******************************************************************************/
    double float_num() const
    {
        return float_num(*this);
    }

    /*******************************************************************************
                        Function:       hl_lib::string_ref::compare_nocase
                        Access:         public
                        Qualifier:      const
                        Parameter:      const string & str
                        Returns:        int

                        Purpose:        compare string no case
                *******************************************************************************/
    int compare_nocase(string const& str) const
    {
#ifdef _WIN32
        return _stricmp(this->c_str(), str.c_str());
#else
        return strcasecmp(this->c_str(), str.c_str());
#endif
    }

    /*******************************************************************************
                        Function:       hl_lib::string_ref::compare_nocase
                        Access:         public
                        Qualifier:      const
                        Parameter:      size_type index
                        Parameter:      size_type length
                        Parameter:      const string & str
                        Returns:        int

                        Purpose:        compare substring no case
                *******************************************************************************/
    int compare_nocase(size_type index, size_type length, string const& str) const
    {
        string_ref temp = this->substr(index, length);
        return temp.compare_nocase(str);
    }

    /*******************************************************************************
                        Function:       hl_lib::string_ref::compare_nocase
                        Access:         public
                        Qualifier:      const
                        Parameter:      size_type index
                        Parameter:      size_type length
                        Parameter:      const string & str
                        Parameter:      size_type index2
                        Parameter:      size_type length2
                        Returns:        int

                        Purpose:        compare two substring no case
                *******************************************************************************/
    int compare_nocase(size_type index, size_type length, string const& str, size_type index2, size_type length2) const
    {
        string_ref temp1 = this->substr(index, length);
        string_ref temp2 = str.substr(index2, length2);
        return temp1.compare_nocase(temp2);
    }
};

} // namespace std