Registry.h should not depend on CommandLine.h.

Split Support/Registry.h into two files so that we have less to
recompile every time CommandLine.h is changed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62312 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/RegistryParser.h

@@ -0,0 +1,55 @@
+//=== RegistryParser.h - Linker-supported plugin registries -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Defines a command-line parser for a registry.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_REGISTRY_PARSER_H
+#define LLVM_SUPPORT_REGISTRY_PARSER_H
+
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Registry.h"
+
+namespace llvm {
+
+  /// A command-line parser for a registry. Use like such:
+  ///
+  ///   static cl::opt<Registry<Collector>::entry, false,
+  ///                  RegistryParser<Collector> >
+  ///   GCOpt("gc", cl::desc("Garbage collector to use."),
+  ///               cl::value_desc());
+  ///
+  /// To make use of the value:
+  ///
+  ///   Collector *TheCollector = GCOpt->instantiate();
+  ///
+  template <typename T, typename U = RegistryTraits<T> >
+  class RegistryParser :
+  public cl::parser<const typename U::entry*>,
+    public Registry<T, U>::listener {
+    typedef U traits;
+    typedef typename U::entry entry;
+    typedef typename Registry<T, U>::listener listener;
+
+  protected:
+    void registered(const entry &E) {
+      addLiteralOption(traits::nameof(E), &E, traits::descof(E));
+    }
+
+  public:
+    void initialize(cl::Option &O) {
+      listener::init();
+      cl::parser<const typename U::entry*>::initialize(O);
+    }
+  };
+
+}
+
+#endif // LLVM_SUPPORT_REGISTRY_PARSER_H