safe_cast: add a new cast function for casts that should always succeed.

In DEBUG mode, this does a dynamic_cast and asserts that the result is
non null.  Otherwise, it just does a static_cast.  Again, this is only
intended for cases where the cast should always succeed and what's
desired is a debugging check to make sure.

diff --git a/src/base/cast.hh b/src/base/cast.hh
new file mode 100644 (file)
index 0000000..30a065c
--- /dev/null
+++ b/src/base/cast.hh
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2008 The Hewlett-Packard Development Company
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Nathan Binkert
+ */
+
+#ifndef __BASE_CAST_HH__
+#define __BASE_CAST_HH__
+
+#include <cassert>
+
+// This is designed for situations where we have a pointer to a base
+// type, but in all cases when we cast it to a derived type, we know
+// by construction that it should work correctly.
+
+#if defined(DEBUG)
+
+// In debug builds, do the dynamic cast and assert the result is good
+
+template <class T, class U>
+inline T
+safe_cast(U ptr)
+{
+    T ret = dynamic_cast<T>(ptr);
+    assert(ret);
+    return ret;
+}
+
+#else
+
+// In non debug builds statically cast the result to the pointer we
+// want to use.  This is technically unsafe, but this is only for
+// cases where we know that this should work by construction.
+
+template <class T, class U>
+inline T
+safe_cast(U ptr)
+{
+    return static_cast<T>(ptr);
+}
+
+#endif
+
+#endif // __BASE_CAST_HH__