STL_ search()

damo

hallo zusammen,
in STL gibt es die search() Algorithmen, bei der Version_2 verstehe ich nicht die folgende Codes:

**while (__first1 != __last1) {
if (__predicate(*__first1, *__first2)) break;
++__first1;
}
while (__first1 != __last1 && !__predicate(*__first1, *__first2))
++__first1;
**
ich glaube, die zwei while() Schleife funktionieren genau selbe! einmal überflüssig?

version_1:

template <class _ForwardIter1, class _ForwardIter2>
_ForwardIter1 search(_ForwardIter1 __first1, _ForwardIter1 __last1,_ForwardIter2 __first2, _ForwardIter2 __last2)
{
  // Test for empty ranges
  if (__first1 == __last1 || __first2 == __last2)
    return __first1;

  // Test for a pattern of length 1.
  _ForwardIter2 __tmp(__first2);
  ++__tmp;
  if (__tmp == __last2)
    return find(__first1, __last1, *__first2);

  // General case.
  _ForwardIter2 __p1, __p;
  __p1 = __first2; ++__p1;
  _ForwardIter1 __current = __first1;

  while (__first1 != __last1) {
    __first1 = find(__first1, __last1, *__first2);
    if (__first1 == __last1) return __last1;

    __p = __p1;
    __current = __first1;
    if (++__current == __last1)
      return __last1;
    while (*__current == *__p) {
      if (++__p == __last2)
        return __first1;
      if (++__current == __last1)
        return __last1;
    }
    ++__first1;
  }
  return __first1;
}

version_2:

template <class _ForwardIter1, class _ForwardIter2, class _BinaryPred>
_ForwardIter1 search(_ForwardIter1 __first1, _ForwardIter1 __last1,_ForwardIter2 __first2, _ForwardIter2 __last2,
                     _BinaryPred  __predicate)
{
  // Test for empty ranges
  if (__first1 == __last1 || __first2 == __last2)
    return __first1;

  // Test for a pattern of length 1.
  _ForwardIter2 __tmp(__first2);
  ++__tmp;
  if (__tmp == __last2) {
    while (__first1 != __last1 && !__predicate(*__first1, *__first2))
      ++__first1;
    return __first1;    
  }

  // General case.
  _ForwardIter2 __p1, __p;
  __p1 = __first2; ++__p1;
  _ForwardIter1 __current = __first1;

  while (__first1 != __last1) {

//---------------------------------------------------
    while (__first1 != __last1) {
      if (__predicate(*__first1, *__first2)) break;
      ++__first1;
    }
    while (__first1 != __last1 && !__predicate(*__first1, *__first2))
      ++__first1;
//-------------------------------------------------------------

    if (__first1 == __last1) return __last1;

    __p = __p1;
    __current = __first1;
    if (++__current == __last1) return __last1;

    while (__predicate(*__current, *__p)) {
      if (++__p == __last2)
        return __first1;
      if (++__current == __last1)
        return __last1;
    }
    ++__first1;
  }
  return __first1;
}

Badestrand

Ich kann jedenfalls keinen Unterschied bei den while-Schleifen entdecken!