#include"string.h"
size_t bit::string::npos = -1;

bit::string::iterator bit::string::begin()
{
    return _str;
}
bit::string::iterator bit::string::end()
{
    return _str + _size;
}

bit::string::const_iterator bit::string::begin() const
{
    return _str;
}

bit::string::const_iterator bit::string::end() const
{
    return _str + _size;
}

/*bit::string& bit::string::operator=(const string &s)
{
  if(this != &s)
  {
    char* tmp=new char[s._capacity+1];
    strcpy(tmp, s._str);

    delete[] _str;
    _str=tmp;
    _size=s._size;
    _capacity=s._capacity;
  }

  return *this;
}*/

bit::string& bit::string::operator=(string s)
{
    swap(s);
    return *this;
}

bit::string& bit::string::operator=(char c)
{ 
    *this += c;

    return *this;
}
//modify

void bit::string::reserve(size_t n)
{
    if (n > _capacity)
    {
        char* tmp = new char[n + 1];
        strcpy(tmp, _str);
        delete[] _str;

        _str = tmp;
        _capacity = n;

    }
}

void bit::string::push_back(char c)
{
    /*if(_size==_capacity)
    {
      size_t capacity= _capacity==0? 4 : 2*_capacity;

      reserve(capacity);
    }
    _str[_size]=c;
    ++_size;
    _str[_size]='\0';
  */

    insert(_size, c);
}


bit::string& bit::string::operator+=(char c)
{
    push_back(c);
    return *this;
}

void bit::string::append(const char* str)
{
    /* size_t len = strlen(str);

     if(_size + len > _capacity)
     {
       reserve(_size + len);
     }

     strcpy(_str+_size, str);
     _size = _size + len;
     _str[_size] = '\0';
   */

    insert(_size, str);
}

bit::string& bit::string::operator+=(const string& str)
{
    append(str._str);
    return *this;
}
bit::string& bit::string::operator+=(const char* str)
{
    append(str);
    return *this;
}

void bit::string::clear()
{
    _str[0] = '\0';
    _size = 0;
}

const char* bit::string::c_str() const
{
    return _str;
}


size_t bit::string::size() const
{
    return _size;
}

size_t bit::string::capacity() const
{
    return _capacity;
}

bool bit::string::empty() const
{
    return _capacity == 0;
}

char& bit::string::operator[](size_t pos)
{
    assert(pos < _size);

    return _str[pos];
}

const char& bit::string::operator[](size_t pos) const
{
    assert(pos < _size);

    return _str[pos];
}

void bit::string::resize(size_t n, char c)
{
    reserve(n);

    if (n > _size)
    {
        //插入
        for (size_t i = _size; i < n; i++)
        {
            _str[i] = c;
        }
        _str[n] = '\0';
        _size = n;
    }
    else
    {
        _str[n] = '\0';
        _size = n;
    }

}
bit::string& bit::string::insert(size_t pos, char c)
{
    assert(pos <= _size);
    //扩容 
    if (_size == _capacity)
    {
        size_t capacity = _capacity == 0 ? 4 : 2 * _capacity;

        reserve(capacity);
    }

    size_t end = _size + 1;
    while (end > pos)
    {
        _str[end] = _str[end - 1];
        --end;
    }

    _str[pos] = c;
    ++_size;

    return *this;
}
bit::string& bit::string::insert(size_t pos, const char* str)
{
    assert(pos <= _size);
    size_t len = strlen(str);
    //扩容
    if (_size + len > _capacity)
    {
        reserve(_size + len);
    }

    size_t end = _size + len;
    while (end > pos)
    {
        _str[end] = _str[end - 1];
        --end;
    }
    strcpy(_str + pos, str);
    _size += len;

    return *this;
}

bit::string& bit::string::erase(size_t pos, size_t len)
{
    assert(pos < _size);

    if (len == npos || len + pos >= _size)
    {
        _str[pos] = '\0';
        _size = pos;
    }
    else
    {
        strcpy(_str + pos, _str + pos + len);
        _size -= len;
    }

    return *this;
}

//
bool bit::string::operator<(const string& s)
{
    return !(*this >= s);
}

bool bit::string::operator<=(const string& s)
{
    return strcmp(_str, s._str) <= 0;
}

bool bit::string::operator>(const string& s)
{
    return !(*this <= s);
}

bool bit::string::operator>=(const string& s)
{
    return strcmp(_str, s._str) >= 0;
}

bool bit::string::operator==(const string& s)
{
    return strcmp(_str, s._str) == 0;
}

bool bit::string::operator!=(const string& s)
{
    return !(*this == s);
}


// 返回c在string中第一次出现的位置     
size_t bit::string::find(char c, size_t pos) const
{
    assert(pos < _size);

    for (size_t i = pos; i < pos; ++i)
    {
        if (_str[i] == c)
        {
            return i;
        }

    }

    return npos;
}

// 返回子串s在string中第一次出现的位置     

size_t bit::string::find(const char* s, size_t pos) const
{
    assert(pos < _size);
    assert(s);

    const char* str = strstr(_str + pos, s);
    if (str == nullptr)
    {
        return npos;
    }
    else
    {
        return str - _str;
    }

}

// 返回字字符串
bit::string bit::string::substr(size_t pos, size_t len) const
{
    assert(pos < _size);

    size_t reallen = len;
    if (len == npos || pos + len > _size)
    {
        reallen = _size - pos;
    }
    else
    {
        reallen -= pos;
    }

    string sub;
    for (size_t i = pos; i < reallen; ++i)
    {
        sub += _str + i;
    }

    return sub;
}

ostream& bit::operator<<(ostream& out, const string& s)
{
    for (size_t i = 0; i < s.size(); ++i)
    {
        out << s[i];
    }

    return out;
}

istream& bit::operator>>(istream& in, string& s)
{
    //当字符串很长的时候，会不断扩容，效率底。
    char ch;
    ch = in.get();

    while ((ch != ' ') || (ch != '\n'))
    {
        s += ch;
        ch = in.get();
    }

    return in;
}