[serialization] Push record layout info into a private header.

The reader and writer will need to share this information, but there's no
reason anyone else will need it.

Swift SVN r5133

lib/Serialization/ModuleFormat.h

@@ -0,0 +1,90 @@
+//===--- ModuleFormat.h - The internals of serialized modules ---*- C++ -*-===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See http://swift.org/LICENSE.txt for license information
+// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file Contains various constants and helper types to deal with serialized
+/// modules.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef SWIFT_SERIALIZATION_MODULEFORMAT_H
+#define SWIFT_SERIALIZATION_MODULEFORMAT_H
+
+#include "swift/Serialization/BCRecordLayout.h"
+#include "llvm/Bitcode/BitCodes.h"
+
+namespace swift {
+namespace serialization {
+
+/// Magic number for serialized module files.
+const char Signature[] = "SMod";
+
+/// Serialized module format major version number.
+///
+/// When the format changes in such a way that older compilers will not be
+/// able to read the file at all, this number should be incremented.
+const unsigned VERSION_MAJOR = 1;
+
+/// Serialized module format minor version number.
+///
+/// When the format changes in a backwards-compatible way, this number should
+/// be incremented.
+const unsigned VERSION_MINOR = 0;
+
+/// The various types of blocks that can occur within a serialized Swift
+/// module.
+enum BlockID {
+  /// The control block, which contains all of the information that needs to
+  /// be validated prior to committing to loading the serialized module.
+  ///
+  /// \sa control_block
+  CONTROL_BLOCK_ID = llvm::bitc::FIRST_APPLICATION_BLOCKID,
+
+  /// The input block, which contains all the files this module depends on.
+  ///
+  /// \sa input_block
+  INPUT_BLOCK_ID
+};
+
+/// The record types within the control block.
+///
+/// \sa CONTROL_BLOCK_ID
+namespace control_block {
+  enum {
+    METADATA = 1
+  };
+
+  using MetadataLayout = BCRecordLayout<
+    METADATA, // ID
+    BCFixed<16>, // Module format major version
+    BCFixed<16>, // Module format minor version
+    BCBlob // misc. version information
+  >;
+}
+
+/// The record types within the input block.
+///
+/// \sa INPUT_BLOCK_ID
+namespace input_block {
+  enum {
+    SOURCE_FILE = 1
+  };
+
+  using SourceFileLayout = BCRecordLayout<
+    SOURCE_FILE, // ID
+    BCBlob // path
+  >;
+}
+
+} // end namespace serialization
+} // end namespace swift
+
+#endif