Add initial prototype for the GN meta-buildsystem.

tools/gn/toolchain.h

Index: tools/gn/toolchain.h
diff --git a/tools/gn/toolchain.h b/tools/gn/toolchain.h
new file mode 100644
index 0000000000000000000000000000000000000000..22b8151bb001b33de192da57daa7629a10dcf7b9
--- /dev/null
+++ b/tools/gn/toolchain.h
@@ -0,0 +1,94 @@
+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef TOOLS_GN_TOOLCHAIN_H_
+#define TOOLS_GN_TOOLCHAIN_H_
+
+#include "base/compiler_specific.h"
+#include "base/strings/string_piece.h"
+#include "tools/gn/item.h"
+
+// Holds information on a specific toolchain. This data is filled in when we
+// encounter a toolchain definition.
+//
+// This class is an Item so it can participate in dependency management. In
+// particular, when a target uses a toolchain, it should have a dependency on
+// that toolchain's object so that we can be sure we loaded the toolchain
+// before generating the build for that target.
+//
+// Note on threadsafety: The label of the toolchain never changes so can
+// safetly be accessed from any thread at any time (we do this when asking for
+// the toolchain name). But the values in the toolchain do, so these can't
+// be accessed until this Item is resolved.
+class Toolchain : public Item {
+ public:
+  enum ToolType {
+    TYPE_NONE = 0,
+    TYPE_CC,
+    TYPE_CXX,
+    TYPE_ASM,
+    TYPE_ALINK,
+    TYPE_SOLINK,
+    TYPE_SOLINK_MODULE,
+    TYPE_LINK,
+    TYPE_STAMP,
+    TYPE_COPY,
+
+    TYPE_NUMTYPES  // Must be last.
+  };
+
+  static const char* kToolCc;
+  static const char* kToolCxx;
+  static const char* kToolAsm;
+  static const char* kToolAlink;
+  static const char* kToolSolink;
+  static const char* kToolSolinkModule;
+  static const char* kToolLink;
+  static const char* kToolStamp;
+  static const char* kToolCopy;
+
+  struct Tool {
+    Tool();
+    ~Tool();
+
+    bool empty() const {
+      return command.empty() && depfile.empty() && deps.empty() &&
+             description.empty() && pool.empty() && restat.empty() &&
+             rspfile.empty() && rspfile_content.empty();
+    }
+
+    std::string command;
+    std::string depfile;
+    std::string deps;
+    std::string description;
+    std::string pool;
+    std::string restat;
+    std::string rspfile;
+    std::string rspfile_content;
+  };
+
+  Toolchain(const Label& label);
+  virtual ~Toolchain();
+
+  // Item overrides.
+  virtual Toolchain* AsToolchain() OVERRIDE;
+  virtual const Toolchain* AsToolchain() const OVERRIDE;
+
+  // Returns TYPE_NONE on failure.
+  static ToolType ToolNameToType(const base::StringPiece& str);
+  static std::string ToolTypeToName(ToolType type);
+
+  const Tool& GetTool(ToolType type) const;
+  void SetTool(ToolType type, const Tool& t);
+
+  const std::string& environment() const { return environment_; }
+  void set_environment(const std::string& env) { environment_ = env; }
+
+ private:
+  Tool tools_[TYPE_NUMTYPES];
+
+  std::string environment_;
+};
+
+#endif  // TOOLS_GN_TOOLCHAIN_H_