Imported gcc-4.4.3

[msp430-gcc.git] / libstdc++-v3 / testsuite / ext / pb_ds / example / hash_initial_size.cc

diff --git a/libstdc++-v3/testsuite/ext/pb_ds/example/hash_initial_size.cc b/libstdc++-v3/testsuite/ext/pb_ds/example/hash_initial_size.cc
new file mode 100644 (file)
index 0000000..4efe8aa
--- /dev/null
+++ b/libstdc++-v3/testsuite/ext/pb_ds/example/hash_initial_size.cc
@@ -0,0 +1,110 @@
+// -*- C++ -*-
+
+// Copyright (C) 2005, 2006, 2009 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the terms
+// of the GNU General Public License as published by the Free Software
+// Foundation; either version 3, or (at your option) any later
+// version.
+
+// This library is distributed in the hope that it will be useful, but
+// WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+
+// Copyright (C) 2004 Ami Tavory and Vladimir Dreizin, IBM-HRL.
+
+// Permission to use, copy, modify, sell, and distribute this software
+// is hereby granted without fee, provided that the above copyright
+// notice appears in all copies, and that both that copyright notice
+// and this permission notice appear in supporting documentation. None
+// of the above authors, nor IBM Haifa Research Laboratories, make any
+// representation about the suitability of this software for any
+// purpose. It is provided "as is" without express or implied
+// warranty.
+
+/**
+ * @file hash_initial_size_example.cpp
+ * An example of setting an initial size for a container object.
+ */
+
+/**
+ * This example shows how to set the initial size of a hash-based
+ * container object through its resize-policy object.
+ */
+
+#include <cassert>
+#include <ext/pb_ds/assoc_container.hpp>
+#include <ext/pb_ds/hash_policy.hpp>
+
+using namespace std;
+using namespace __gnu_pbds;
+
+// A simple hash functor.
+// hash could serve instead of this functor, but it is not yet
+// standard everywhere.
+struct int_hash : public unary_function<int, size_t>
+{
+  inline size_t
+  operator()(const int& r_i) const
+  { return r_i; }
+};
+
+int main()
+{
+  // Resize policy type.
+  typedef
+    hash_standard_resize_policy<
+    // Size-policy type.
+    hash_exponential_size_policy<>,
+    // Trigger-policy type.
+    hash_load_check_resize_trigger<>,
+    /* Allow external access to size.
+     *     This is just used in this example for using the
+     *     get_actual_size method (which won't be accessible without
+     *     this flag.
+     */
+    true>
+    resize_policy_t;
+
+  // A collision-probing hash table mapping ints to chars.
+  typedef
+    gp_hash_table<
+    int,
+    char,
+    int_hash,
+    equal_to<
+    int>,
+    // Combining function.
+    direct_mask_range_hashing<>,
+    // Probe function.
+    linear_probe_fn<>,
+    // Resize policy.
+    resize_policy_t>
+    map_t;
+
+  // A resize-policy object with suggested initial size 256.
+  resize_policy_t res(hash_exponential_size_policy<>(256));
+
+  map_t g(int_hash(),
+         equal_to<int>(),
+         direct_mask_range_hashing<>(),
+         linear_probe_fn<>(),
+         res);
+
+  // Check the actual size of the container object. In this case, this
+  // should be the initial size given by the size policy object.
+  assert(g.get_actual_size() == 256);
+
+  // The logical size of g, though is 0 (it does not contain any elements).
+  assert(g.size() == 0);
+
+  return 0;
+}
+