stl（GCC4.9.3 in MinGW）中rbtree lower_bound/upper_bound 的实现

 1 template<typename _Key, typename _Val, typename _KeyOfValue,
 2        typename _Compare, typename _Alloc>
 3 typename _Rb_tree<_Key, _Val, _KeyOfValue,
 4           _Compare, _Alloc>::const_iterator
 5 _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
 6 _M_lower_bound(_Const_Link_type __x, _Const_Link_type __y,
 7        const _Key& __k) const
 8 {
 9   while (__x != 0)
10 if (!_M_impl._M_key_compare(_S_key(__x), __k))
11   __y = __x, __x = _S_left(__x);
12 else
13   __x = _S_right(__x);
14   return const_iterator(__y);
15 }
16 
17 template<typename _Key, typename _Val, typename _KeyOfValue,
18        typename _Compare, typename _Alloc>
19 typename _Rb_tree<_Key, _Val, _KeyOfValue,
20           _Compare, _Alloc>::iterator
21 _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
22 _M_upper_bound(_Link_type __x, _Link_type __y,
23        const _Key& __k)
24 {
25   while (__x != 0)
26 if (_M_impl._M_key_compare(__k, _S_key(__x)))
27   __y = __x, __x = _S_left(__x);
28 else
29   __x = _S_right(__x);
30   return iterator(__y);
31 }