cc: Add DEFINE_ENUM macro.

cc/base/util.h

Index: cc/base/util.h
diff --git a/cc/base/util.h b/cc/base/util.h
index 1d716ae2a42f4b4d25f1bf38e6fb38a4a9c806a3..60c5093f400d16a4e2f5137435f6e63c954bfc3d 100644
--- a/cc/base/util.h
+++ b/cc/base/util.h
@@ -9,6 +9,17 @@
 
 #include "base/basictypes.h"
 
+// Declares an enum for which the values can be used to index an array.
+// In addition to the enum, this also declares 3 constants. enumname_MIN,
+// enumname_MAX and enumname_ARRAYSIZE. The last can be used to declare
+// an array that is large enough to allow indexing using all enum values.
+#define DEFINE_ENUM(name, ...)                                       \
+    enum name { __VA_ARGS__ };                                       \
+    const name name ## _MIN = static_cast<name>(0);                  \
+    const name name ## _MAX = static_cast<name>(                     \
+        sizeof((int[]) { __VA_ARGS__ }) / sizeof(name ## _MIN) - 1); \
+    const int name ## _ARRAYSIZE = name ## _MAX + 1
+
 namespace cc {
 
 template <typename T> T RoundUp(T n, T mul) {