static void SplitStringT(const STR& str,
     const typename STR::value_type s,
     bool trim_whitespace,
     std::vector<STR>* r)
 {
     size_t last = 0;
     size_t i;
     size_t c = str.size();
     for(i=0; i<=c; ++i)
     {
         if(i==c || str[i]==s)
         {
             size_t len = i - last;
             STR tmp = str.substr(last, len);
             if(trim_whitespace)
             {
                 STR t_tmp;
                 TrimWhitespace(tmp, TRIM_ALL, &t_tmp);
                 r->push_back(t_tmp);
             }
             else
             {
                 r->push_back(tmp);
             }
             last = i + 1;
         }
     }
 }

int CSV_Parser::parse_quoted_fields(const STR& input_line, STR& field, int& i)
{
    /*
        Quoted fields are the ones which are enclosed within quotes
        For instance - Consider that input_line is - 1997,Ford,E350,"Super, luxurious truck"
        An example for a quoted field would be - Super luxurious truck
        Another instance being - 1997,Ford,E350,"Super, ""luxurious"" truck"
    */
    int j;
    field = "";

    for(j=i; j<input_line.length(); j++)
    {
        if(input_line[j] == '"' && input_line[++j] != '"')
        {
            int k = input_line.find_first_of(CSV_DELIMITER, j);
            if(k > input_line.length())
            {
                k = input_line.length();
            }
            for(k -= j; k-- > 0; )
            {
                field += input_line[j++];
            }
            break;
        }
        else
        {
            field += input_line[j];
        }
    }
    return j;
}

bool CSV_Parser::parse(const STR& input_line, CSV_FIELDS& output_fields)
{
    /*
        A private method which handles the parsing logic used by both the overloaded public methods
    */
    STR field;
    int i, j;

    if(input_line.length() == 0)
    {
        return false;
    }

    i = 0;
    do
    {
        if(i < input_line.length() && input_line[i] == CSV_QUOTE)
        {
            j = parse_quoted_fields(input_line, field, ++i);
        }
        else
        {
            j = parse_normal_fields(input_line, field, i);
        }
        output_fields.push_back(field);
        i = j + 1;
    }while(j < input_line.length());

    return true;
}

	/*
	 * Returns true if the specified string is a Palindrome.
	 */
	bool isPalindrome( STR str ) {
		str.erase( std::remove_if( str.begin(), str.end(), ::isspace ), str.end() );
		STR copy = str;
		std::reverse( copy.begin(), copy.end() );
		
		return ( strcmp( str.c_str(), copy.c_str() ) == 0 );
	} 

	/*
	 * Returns a vector of strings from the specified string, which has
	 * been sliced at each position where the delimiter appears.
	 */
	std::vector<STR> distribute( STR str, CSTR_R delimiter ) {
		std::vector<STR> slices;
		std::size_t pos = 0;

		while ( ( pos = str.find( delimiter ) ) != STR::npos ) {
			slices.push_back( str.substr( 0, pos ) );
			str.erase( 0, ( pos + delimiter.length() ) );
		}

		return slices;
	}

	/*
	 * Returns a scrambled string.
	 */
	STR scramble( STR str ) {
		std::seed_seq sd( str.begin(), str.end() );
		std::default_random_engine gen;

		for ( int i = str.size() - 1; i > 0; --i ) {
			gen.seed( sd );
			std::uniform_int_distribution<int> dist( 0, i );
			std::swap( str[i], str[dist( gen )] );
		}

		return str;
	}

static bool ContainsOnlyCharsT(const STR& input, const STR& characters)
{
    for(typename STR::const_iterator iter=input.begin();
        iter!=input.end(); ++iter)
    {
        if(characters.find(*iter) == STR::npos)
        {
            return false;
        }
    }
    return true;
}

STR CCrypt::md5(STR value){
    MD5_CTX ctx;
    unsigned char buff[MD5_DIGEST_LENGTH];
    MD5_Init(&ctx);
    MD5_Update(&ctx, value.c_str(), value.length());
    MD5_Final(buff, &ctx);
    char res[33];
    for(int i = 0; i < 16; i++){
        sprintf(res+i*2, "%02x", buff[i]);
    }
    return STR(res);
}

	/*
	 * Returns the longest word found in the specified string.
	 */
	STR longest_word( CSTR_R str ) {
		STR builder = "", longest = "";
		
		for ( unsigned i = 0; i < str.size(); ++i ) {
			if ( ( str[i] >= 'A' && str[i] <= 'Z' ) ||
				 ( str[i] >= 'a' && str[i] <= 'z' ) )
				builder += str[i];
			else
				builder.clear();
				
			if ( builder.size() > longest.size() )
				longest = builder;
		}
		
		return longest;
	}

int CSV_Parser::parse_normal_fields(const STR& input_line, STR& field, int& i)
{
    /*
        Normal fields are the ones which contain no escaped or quoted characters
        For instance - Consider that input_line is - 1997,Ford,E350,"Super, luxurious truck"
        An example for a normal field would be - Ford
    */
    int j;
    j = input_line.find_first_of(CSV_DELIMITER, i);
    if(j > input_line.length())
    {
        j = input_line.length();
    }
    field = std :: string(input_line, i, j-i);
    return j;
}

void SplitStringAlongWhitespaceT(const STR& str, std::vector<STR>* result)
{
    const size_t length = str.length();
    if(!length)
    {
        return;
    }

    bool last_was_ws = false;
    size_t last_non_ws_start = 0;
    for(size_t i=0; i<length; ++i)
    {
        switch(str[i])
        {
            // HTML 5定义的空白: space, tab, LF, line tab, FF, or CR.
        case L' ':
        case L'\t':
        case L'\xA':
        case L'\xB':
        case L'\xC':
        case L'\xD':
            if(!last_was_ws)
            {
                if(i > 0)
                {
                    result->push_back(str.substr(last_non_ws_start,
                        i-last_non_ws_start));
                }
                last_was_ws = true;
            }
            break;

        default: // 不是空白字符.
            if(last_was_ws)
            {
                last_was_ws = false;
                last_non_ws_start = i;
            }
            break;
        }
    }
    if(!last_was_ws)
    {
        result->push_back(str.substr(last_non_ws_start,
            length-last_non_ws_start));
    }
}

	static bool DoIsStringASCII(const STR& str) {
		for (size_t i = 0; i < str.length(); i++) {
			typename ToUnsigned<typename STR::value_type>::Unsigned c = str[i];
			if (c > 0x7F)
				return false;
		}
		return true;
	}

bool FileExists(STR fn){
    FILE *F = fopen(fn.c_str(), "r");
    if(F){
        fclose(F);
        return true;
    }
    return false;
}

static size_t TokenizeT(const STR& str,
	const STR& delimiters,
	std::vector<STR>* tokens) {
	tokens->clear();

	size_t start = str.find_first_not_of(delimiters);
	while (start != STR::npos) {
		size_t end = str.find_first_of(delimiters, start + 1);
		if (end == STR::npos) {
			tokens->push_back(str.substr(start));
			break;
		}
		else {
			tokens->push_back(str.substr(start, end - start));
			start = str.find_first_not_of(delimiters, end + 1);
		}
	}

	return tokens->size();
}

	TrimPositions TrimStringT(const STR& input,
		const STR& trim_chars,
		TrimPositions positions,
		STR* output) {
		// Find the edges of leading/trailing whitespace as desired.
		const size_t last_char = input.length() - 1;
		const size_t first_good_char = (positions & TRIM_LEADING) ?
			input.find_first_not_of(trim_chars) : 0;
		const size_t last_good_char = (positions & TRIM_TRAILING) ?
			input.find_last_not_of(trim_chars) : last_char;

		// When the string was all whitespace, report that we stripped off whitespace
		// from whichever position the caller was interested in.  For empty input, we
		// stripped no whitespace, but we still need to clear |output|.
		if (input.empty() ||
			(first_good_char == STR::npos) || (last_good_char == STR::npos)) {
			bool input_was_empty = input.empty();  // in case output == &input
			output->clear();
			return input_was_empty ? TRIM_NONE : positions;
		}

		// Trim the whitespace.
		*output =
			input.substr(first_good_char, last_good_char - first_good_char + 1);

		// Return where we trimmed from.
		return static_cast<TrimPositions>(
			((first_good_char == 0) ? TRIM_NONE : TRIM_LEADING) |
			((last_good_char == last_char) ? TRIM_NONE : TRIM_TRAILING));
	}

TrimPositions TrimStringT(const STR& input,
                          const typename STR::value_type trim_chars[],
                          TrimPositions positions,
                          STR* output)
{
    // 根据移除选项positions查找两端边界.
    const typename STR::size_type last_char = input.length() - 1;
    const typename STR::size_type first_good_char = (positions&TRIM_LEADING) ?
        input.find_first_not_of(trim_chars) : 0;
    const typename STR::size_type last_good_char = (positions&TRIM_TRAILING) ?
        input.find_last_not_of(trim_chars) : last_char;

    // 当字符串所有字符都是空白, 根据调用传入的positions返回TrimPositions.
    // 对于空输入没有去除任何空白, 但仍需要对output串调用clear.
    if(input.empty() || (first_good_char==STR::npos) || (last_good_char==STR::npos))
    {
        bool input_was_empty = input.empty();
        output->clear();
        return input_was_empty ? TRIM_NONE : positions;
    }

    // 移除空白.
    *output = input.substr(first_good_char, last_good_char-first_good_char+1);

    // 返回两端哪边移除过.
    return static_cast<TrimPositions>(
        ((first_good_char==0)?TRIM_NONE:TRIM_LEADING) |
        ((last_good_char==last_char)?TRIM_NONE:TRIM_TRAILING));
}

bool StartsWithT(const STR& str, const STR& search, bool case_sensitive) {
	if (case_sensitive) {
		return str.compare(0, search.length(), search) == 0;
	}
	else {
		if (search.size() > str.size())
			return false;
		return std::equal(search.begin(), search.end(), str.begin(),
			base::CaseInsensitiveCompare<typename STR::value_type>());
	}
}

 static void SplitStringUsingSubstrT(const STR& str,
     const STR& s, std::vector<STR>* r)
 {
     typename STR::size_type begin_index = 0;
     while(true)
     {
         const typename STR::size_type end_index = str.find(s, begin_index);
         if(end_index == STR::npos)
         {
             const STR term = str.substr(begin_index);
             STR tmp;
             TrimWhitespace(term, TRIM_ALL, &tmp);
             r->push_back(tmp);
             return;
         }
         const STR term = str.substr(begin_index, end_index-begin_index);
         STR tmp;
         TrimWhitespace(term, TRIM_ALL, &tmp);
         r->push_back(tmp);
         begin_index = end_index + s.size();
     }
 }

	int code_conv(const STR& src, const STR& tbl, STR& dst) {
		int n = 0;
		uint32_t tsz = tbl.size();
		if(tsz & 1) --tsz;
		for(auto ch : src) {
			for(uint32_t i = 0; i < tsz; i += 2) {
				if(ch == tbl[i]) {
					ch = tbl[i + 1];
					++n;
				}
			}
			if(ch) dst += ch;
		}
		return n;
	}

bool EndsWithT(const STR& str, const STR& search, bool case_sensitive) {
	size_t str_length = str.length();
	size_t search_length = search.length();
	if (search_length > str_length)
		return false;
	if (case_sensitive)
		return str.compare(str_length - search_length, search_length, search) == 0;
	return std::equal(search.begin(), search.end(),
		str.begin() + (str_length - search_length),
		base::CaseInsensitiveCompare<typename STR::value_type>());
}