Seperated out my template algorithms and stuff.

git-svn-id: svn://rakshasa.no/libtorrent/trunk/rtorrent@334 e378c898-3ddf-0310-93e7-cc216c733640

rak/algorithm.h

@@ -0,0 +1,58 @@
+#ifndef RTORRENT_UTILS_ALGORITHM_H
+#define RTORRENT_UTILS_ALGORITHM_H
+
+#include <algorithm>
+
+namespace rak {
+
+template <typename _InputIter, typename _Function>
+_Function
+for_each_pre(_InputIter __first, _InputIter __last, _Function __f) {
+  _InputIter __tmp;
+
+  while (__first != __last) {
+    __tmp = __first++;
+    
+    __f(*__tmp);
+  }
+
+  return __f;
+}
+
+// Return a range with a distance of no more than __distance and
+// between __first and __last, centered on __middle1.
+template <typename _InputIter, typename _Distance>
+std::pair<_InputIter, _InputIter>
+advance_bidirectional(_InputIter __first, _InputIter __middle1, _InputIter __last, _Distance __distance) {
+  _InputIter __middle2 = __middle1;
+
+  do {
+    if (!__distance)
+      break;
+
+    if (__middle1 != __first) {
+      --__middle1;
+      --__distance;
+
+    } else if (__middle2 == __last) {
+      break;
+    }
+
+    if (!__distance)
+      break;
+
+    if (__middle2 != __last) {
+      ++__middle2;
+      --__distance;
+
+    } else if (__middle1 == __first) {
+      break;
+    }
+  } while (true);
+
+  return std::make_pair(__middle1, __middle2);
+}
+
+}
+
+#endif