Refactor Subzero initialization and add a browser callback handler.

src/IceCompileServer.h

+//===- subzero/src/IceCompileServer.h - Compile server ----------*- C++ -*-===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the compile server. Given a compiler implementation,
+// it dispatches compile requests to the implementation.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SUBZERO_SRC_ICECOMPILESERVER_H
+#define SUBZERO_SRC_ICECOMPILESERVER_H
+
+#include "IceCompiler.h"
+#include "IceDefs.h"
+#include "IceGlobalContext.h"
+
+namespace llvm {
+class DataStreamer;
+class raw_fd_ostream;
+};
+
+namespace Ice {
+
+// A CompileServer awaits compile requests, and dispatches the requests
+// to a given Compiler. Each request is paired with an input stream,
+// a context (which has the output stream), and a set of arguments.
+// The CompileServer takes over the current thread to listen to requests,
+// and compile requests are handled on separate threads.
+//
+// Currently, this only handles a single request.
+//
+// When run on the commandline, it receives and therefore dispatches
+// the request immediately.  When run in the browser, it blocks waiting
+// for a request.
+class CompileServer {
+  CompileServer() = delete;
+  CompileServer(const CompileServer &) = delete;
+  CompileServer &operator=(const CompileServer &) = delete;
+
+public:
+  explicit CompileServer(Compiler &Comp) : Comp(Comp) {}
+
+  virtual ~CompileServer() {}
+
+  virtual void run() = 0;
+
+  ErrorCode &getErrorCode() { return LastError; }
+  void transferErrorCode(ErrorCodes Code) { LastError.assign(Code); }
+
+protected:
+  Compiler &getCompiler() const { return Comp; }
+
+  Compiler &Comp;
+  ErrorCode LastError;
+};
+
+// Commandline variant of the compile server.
+class CLCompileServer : public CompileServer {
+  CLCompileServer() = delete;
+  CLCompileServer(const CLCompileServer &) = delete;
+  CLCompileServer &operator=(const CLCompileServer &) = delete;
+
+public:
+  CLCompileServer(Compiler &Comp, int argc, char **argv)
+      : CompileServer(Comp), argc(argc), argv(argv) {}
+
+  ~CLCompileServer() final {}
+
+  void run() final;
+
+private:
+  int argc;
+  char **argv;
+  std::unique_ptr<GlobalContext> Ctx;
+};
+
+} // end of namespace Ice
+
+#endif // SUBZERO_SRC_ICECOMPILESERVER_H