Add initial prototype for the GN meta-buildsystem.

tools/gn/path_output.h

Index: tools/gn/path_output.h
diff --git a/tools/gn/path_output.h b/tools/gn/path_output.h
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+++ b/tools/gn/path_output.h
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+// 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_PATH_OUTPUT_H_
+#define TOOLS_GN_PATH_OUTPUT_H_
+
+#include <iosfwd>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/strings/string_piece.h"
+#include "tools/gn/escape.h"
+#include "tools/gn/source_dir.h"
+
+class OutputFile;
+class SourceFile;
+
+// Writes file names to streams assuming a certain input directory and
+// escaping rules. This gives us a central place for managing this state.
+class PathOutput {
+ public:
+  // Controls whether writing directory names include the trailing slash.
+  // Often we don't want the trailing slash when writing out to a command line,
+  // especially on Windows where it's a backslash and might be interpreted as
+  // escaping the thing following it.
+  enum DirSlashEnding {
+    DIR_INCLUDE_LAST_SLASH,
+    DIR_NO_LAST_SLASH,
+  };
+
+  PathOutput(const SourceDir& current_dir,
+             EscapingMode escaping,
+             bool convert_slashes);
+  ~PathOutput();
+
+  // Read-only since inverse_current_dir_ is computed depending on this.
+  EscapingMode escaping_mode() const { return options_.mode; }
+
+  // When true, converts slashes to the system-type path separators (on
+  // Windows, this is a backslash, this is a NOP otherwise).
+  //
+  // Read-only since inverse_current_dir_ is computed depending on this.
+  bool convert_slashes_to_system() const { return options_.convert_slashes; }
+
+  // When the output escaping is ESCAPE_SHELL, the escaper will normally put
+  // quotes around suspect things. If this value is set to true, we'll disable
+  // the quoting feature. This means that in ESCAPE_SHELL mode, strings with
+  // spaces in them qon't be quoted. This mode is for when quoting is done at
+  // some higher-level. Defaults to false.
+  bool inhibit_quoting() const { return options_.inhibit_quoting; }
+  void set_inhibit_quoting(bool iq) { options_.inhibit_quoting = iq; }
+
+  void WriteFile(std::ostream& out, const SourceFile& file) const;
+  void WriteFile(std::ostream& out, const OutputFile& file) const;
+  void WriteDir(std::ostream& out,
+                const SourceDir& dir,
+                DirSlashEnding slash_ending) const;
+
+  // Backend for WriteFile and WriteDir. This appends the given file or
+  // directory string to the file.
+  void WritePathStr(std::ostream& out, const base::StringPiece& str) const;
+
+ private:
+  // Takes the given string and writes it out, appending to the inverse
+  // current dir. This assumes leading slashes have been trimmed.
+  void WriteSourceRelativeString(std::ostream& out,
+                                 const base::StringPiece& str) const;
+
+  SourceDir current_dir_;
+
+  // Uses system slashes if convert_slashes_to_system_.
+  std::string inverse_current_dir_;
+
+  // Since the inverse_current_dir_ depends on some of these, we don't expose
+  // this directly to modification.
+  EscapeOptions options_;
+};
+
+#endif  // TOOLS_GN_PATH_OUTPUT_H_