C++ basic_string::begin方法代码示例

std::vector<std::basic_string<T_Char>> split(
                                        const std::basic_string<T_Char>& src,
const std::basic_string<T_Char>& delimit) {
    std::vector<std::basic_string<T_Char>> array;
    typedef typename std::basic_string<T_Char>::size_type size_type;
    typedef typename std::basic_string<T_Char>::const_iterator const_iterator;
    std::basic_string<T_Char> tmp;

    if (src.empty())
        return array;

    if (delimit.empty()) {
        array.reserve(array.size() + src.size());
        for (const_iterator it = src.begin(); it != src.end(); ++it)
            array.push_back(std::basic_string<T_Char>(1, *it));
        return array;
    }

    size_type src_pos = 0;
    while (src.begin() + src_pos != src.end()) {
        size_type fnd_pos = src.find(delimit, src_pos);
        if (fnd_pos == std::basic_string<T_Char>::npos) {
            array.push_back(std::basic_string<T_Char>(src, src_pos));
            break;
        }
        array.push_back(
            std::basic_string<T_Char>(src, src_pos, fnd_pos - src_pos));
        src_pos = fnd_pos + delimit.length();
    }
    return array;
}

std::size_t regex_split(OutputIterator out,
                   std::basic_string<charT, Traits1, Alloc1>& s, 
                   const basic_regex<charT, Traits2>& e,
                   match_flag_type flags,
                   std::size_t max_split)
{
   typedef typename std::basic_string<charT, Traits1, Alloc1>::const_iterator  ci_t;
   //typedef typename match_results<ci_t>::allocator_type                        match_allocator;
   ci_t last = s.begin();
   std::size_t init_size = max_split;
   re_detail::split_pred<OutputIterator, charT, Traits1, Alloc1> pred(&last, &out, &max_split);
   ci_t i, j;
   i = s.begin();
   j = s.end();
   regex_grep(pred, i, j, e, flags);
   //
   // if there is still input left, do a final push as long as max_split
   // is not exhausted, and we're not splitting sub-expressions rather 
   // than whitespace:
   if(max_split && (last != s.end()) && (e.mark_count() == 0))
   {
      *out = std::basic_string<charT, Traits1, Alloc1>((ci_t)last, (ci_t)s.end());
      ++out;
      last = s.end();
      --max_split;
   }
   //
   // delete from the string everything that has been processed so far:
   s.erase(0, last - s.begin());
   //
   // return the number of new records pushed:
   return init_size - max_split;
}

bool compare(const std::basic_string<CharT> &lhs, const std::basic_string<CharT> &rhs)
{
	return std::equal(lhs.begin(), lhs.end(), rhs.begin(), [](const CharT l, const CharT r)->bool
	{
		return ::toupper(l) == ::toupper(r);
	});
}

bool is_palindrome(std::basic_string<Char, Traits, Allocater> str) {
    typedef typename std::basic_string<Char, Traits, Allocater> string;
    typename string::iterator end {std::remove_if(str.begin(), str.end(), non_letter<Char>)};
    string reversed{str.begin(), end};
    std::reverse(reversed.begin(), reversed.end());
    return not reversed.empty() and std::equal(str.begin(), end, reversed.begin(), is_same_character<Char>);
}

void
test(const std::basic_string<CharT>& x, const std::basic_string<CharT>& y, bool doCStrTests = true)
{
    typedef std::basic_string<CharT> string;
    typedef std::sub_match<typename string::const_iterator> sub_match;
    sub_match sm1;
    sm1.first = x.begin();
    sm1.second = x.end();
    sm1.matched = true;
    sub_match sm2;
    sm2.first = y.begin();
    sm2.second = y.end();
    sm2.matched = true;
    assert((sm1 == sm2) == (x == y));
    assert((sm1 != sm2) == (x != y));
    assert((sm1 < sm2) == (x < y));
    assert((sm1 > sm2) == (x > y));
    assert((sm1 <= sm2) == (x <= y));
    assert((sm1 >= sm2) == (x >= y));
    assert((x == sm2) == (x == y));
    assert((x != sm2) == (x != y));
    assert((x < sm2) == (x < y));
    assert((x > sm2) == (x > y));
    assert((x <= sm2) == (x <= y));
    assert((x >= sm2) == (x >= y));
    assert((sm1 == y) == (x == y));
    assert((sm1 != y) == (x != y));
    assert((sm1 < y) == (x < y));
    assert((sm1 > y) == (x > y));
    assert((sm1 <= y) == (x <= y));
    assert((sm1 >= y) == (x >= y));
    if (doCStrTests) {
        assert((x.c_str() == sm2) == (x == y));
        assert((x.c_str() != sm2) == (x != y));
        assert((x.c_str() < sm2) == (x < y));
        assert((x.c_str() > sm2) == (x > y));
        assert((x.c_str() <= sm2) == (x <= y));
        assert((x.c_str() >= sm2) == (x >= y));
        assert((sm1 == y.c_str()) == (x == y));
        assert((sm1 != y.c_str()) == (x != y));
        assert((sm1 < y.c_str()) == (x < y));
        assert((sm1 > y.c_str()) == (x > y));
        assert((sm1 <= y.c_str()) == (x <= y));
        assert((sm1 >= y.c_str()) == (x >= y));
        }
    assert((x[0] == sm2) == (string(1, x[0]) == y));
    assert((x[0] != sm2) == (string(1, x[0]) != y));
    assert((x[0] < sm2) == (string(1, x[0]) < y));
    assert((x[0] > sm2) == (string(1, x[0]) > y));
    assert((x[0] <= sm2) == (string(1, x[0]) <= y));
    assert((x[0] >= sm2) == (string(1, x[0]) >= y));
    assert((sm1 == y[0]) == (x == string(1, y[0])));
    assert((sm1 != y[0]) == (x != string(1, y[0])));
    assert((sm1 < y[0]) == (x < string(1, y[0])));
    assert((sm1 > y[0]) == (x > string(1, y[0])));
    assert((sm1 <= y[0]) == (x <= string(1, y[0])));
    assert((sm1 >= y[0]) == (x >= string(1, y[0])));
}

		std::basic_string < Elem, Traits > cell_encode(std::basic_string < Elem, Traits > Str, Elem Sep_, Elem Esc){
			if(Str.find(Sep_) < Str.size() || Str.find(Esc) < Str.size()){
				for(auto itr = Str.begin(); itr != Str.end(); ++itr){
					if(*itr == Esc){
						itr = Str.insert(++itr, Esc);
					}
				}

				Str.insert(Str.begin(), Esc);
				Str.push_back(Esc);
			}

			return std::move(Str);
		}

		std::basic_string<CharType> escape_argument(const std::basic_string<CharType>& arg)
		{
			std::basic_string<CharType> result(1, argument_helper<CharType>::QUOTE_CHARACTER);

			for (auto it = arg.begin();; ++it)
			{
				unsigned int escapes_count = 0;

				while ((it != arg.end()) && (*it == argument_helper<CharType>::ESCAPE_CHARACTER))
				{
					++it;
					++escapes_count;
				}

				if (it == arg.end())
				{
					result.append(escapes_count * 2, argument_helper<CharType>::ESCAPE_CHARACTER);
					break;
				}
				else if (*it == argument_helper<CharType>::QUOTE_CHARACTER)
				{
					result.append(escapes_count * 2 + 1, argument_helper<CharType>::ESCAPE_CHARACTER);
					result.push_back(*it);
				}
				else
				{
					result.append(escapes_count, argument_helper<CharType>::ESCAPE_CHARACTER);
					result.push_back(*it);
				}
			}

			result.push_back(argument_helper<CharType>::QUOTE_CHARACTER);

			return result;
		}

inline unsigned int regex_grep(bool (*foo)(const match_results<std::basic_string<wchar_t>::const_iterator>&), 
                     const std::basic_string<wchar_t>& s, 
                        const wregex& e, 
                        match_flag_type flags = match_default)
{
   return regex_grep(foo, s.begin(), s.end(), e, flags);
}

 std::basic_string<Ch> decode_char_entities(const std::basic_string<Ch> &s)
 {
     typedef typename std::basic_string<Ch> Str;
     Str r;
     typename Str::const_iterator end = s.end();
     for (typename Str::const_iterator it = s.begin(); it != end; ++it)
     {
         if (*it == Ch('&'))
         {
             typename Str::const_iterator semicolon = std::find(it + 1, end, Ch(';'));
             if (semicolon == end)
                 throw xml_parser_error("invalid character entity", "", 0);
             Str ent(it + 1, semicolon);
             if (ent == detail::widen<Ch>("lt")) r += Ch('<');
             else if (ent == detail::widen<Ch>("gt")) r += Ch('>');
             else if (ent == detail::widen<Ch>("amp")) r += Ch('&');
             else
                 throw xml_parser_error("invalid character entity", "", 0);
             it = semicolon;
         }
         else
             r += *it;
     }
     return r;
 }

inline bool regex_match(const std::basic_string<wchar_t>& s, 
                        match_results<std::basic_string<wchar_t>::const_iterator>& m,
                        const basic_regex<wchar_t, c_regex_traits<wchar_t> >& e, 
                        match_flag_type flags = match_default)
{
   return regex_match(s.begin(), s.end(), m, e, flags);
}

inline bool regex_search(const std::basic_string<wchar_t>& s, 
                        wsmatch& m,
                        const wregex& e, 
                        match_flag_type flags = match_default)
{
   return regex_search(s.begin(), s.end(), m, e, flags);
}

void IO::TrimRight(std::basic_string<charType> & str, const char* chars2remove)
{
	if (!str.empty()) {  	//trim the characters in chars2remove from the right
		std::string::size_type pos = 0;
		if (chars2remove != NULL) {
			pos = str.find_last_not_of(chars2remove);

			if (pos != std::string::npos)
				str.erase(pos+1);
			else
				str.erase( str.begin() , str.end() ); // make empty
		}
		else {       		//trim space
			pos = std::string::npos;
			for (int i = str.size()-1; i >= 0; --i) {
				if (!isspace(str[i])) {
					pos = i;
					break;
				}
			}
			if (pos != std::string::npos) {
				if (pos+1 != str.size())
					str.resize(pos+1);
			}
			else {
				str.clear();
			}
		}
	}
}

    std::basic_string<Ch> encode_char_entities(const std::basic_string<Ch> &s)
    {
        // Don't do anything for empty strings.
        if(s.empty()) return s;

        typedef typename std::basic_string<Ch> Str;
        Str r;
        // To properly round-trip spaces and not uglify the XML beyond
        // recognition, we have to encode them IF the text contains only spaces.
        Str sp(1, Ch(' '));
        if(s.find_first_not_of(sp) == Str::npos) {
            // The first will suffice.
            r = detail::widen<Ch>("&#32;");
            r += Str(s.size() - 1, Ch(' '));
        } else {
            typename Str::const_iterator end = s.end();
            for (typename Str::const_iterator it = s.begin(); it != end; ++it)
            {
                switch (*it)
                {
                    case Ch('<'): r += detail::widen<Ch>("&lt;"); break;
                    case Ch('>'): r += detail::widen<Ch>("&gt;"); break;
                    case Ch('&'): r += detail::widen<Ch>("&amp;"); break;
                    case Ch('"'): r += detail::widen<Ch>("&quot;"); break;
                    case Ch('\''): r += detail::widen<Ch>("&apos;"); break;
                    default: r += *it; break;
                }
            }
        }
        return r;
    }

 std::basic_string<Ch> trim(const std::basic_string<Ch> &s,
                            const std::locale &loc = std::locale())
 {
     typename std::basic_string<Ch>::const_iterator first = s.begin();
     typename std::basic_string<Ch>::const_iterator end = s.end();
     while (first != end && std::isspace(*first, loc))
         ++first;
     if (first == end)
         return std::basic_string<Ch>();
     typename std::basic_string<Ch>::const_iterator last = end;
     do --last; while (std::isspace(*last, loc));
     if (first != s.begin() || last + 1 != end)
         return std::basic_string<Ch>(first, last + 1);
     else
         return s;
 }

//! Converts escape sequences to the corresponding characters
void char_constants< char >::translate_escape_sequences(std::basic_string< char_type >& str)
{
    using namespace std; // to make sure we can use C functions unqualified

    std::basic_string< char_type >::iterator it = str.begin();
    while (it != str.end())
    {
        it = std::find(it, str.end(), '\\');
        if (std::distance(it, str.end()) >= 2)
        {
            it = str.erase(it);
            switch (*it)
            {
            case 'n':
                *it = '\n'; break;
            case 'r':
                *it = '\r'; break;
            case 'a':
                *it = '\a'; break;
            case '\\':
                ++it; break;
            case 't':
                *it = '\t'; break;
            case 'b':
                *it = '\b'; break;
            case 'x':
                {
                    std::basic_string< char_type >::iterator b = it;
                    if (std::distance(++b, str.end()) >= 2)
                    {
                        char_type c1 = *b++, c2 = *b++;
                        if (isxdigit(c1) && isxdigit(c2))
                        {
                            *it++ = char_type((to_number(c1) << 4) | to_number(c2));
                            it = str.erase(it, b);
                        }
                    }
                    break;
                }
            default:
                {
                    if (*it >= '0' && *it <= '7')
                    {
                        std::basic_string< char_type >::iterator b = it;
                        int c = (*b++) - '0';
                        if (*b >= '0' && *b <= '7')
                            c = c * 8 + (*b++) - '0';
                        if (*b >= '0' && *b <= '7')
                            c = c * 8 + (*b++) - '0';

                        *it++ = char_type(c);
                        it = str.erase(it, b);
                    }
                    break;
                }
            }
        }
    }
}