Add initial prototype for the GN meta-buildsystem.

tools/gn/token.h

+// 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_TOKEN_H_
+#define TOOLS_GN_TOKEN_H_
+
+#include "base/strings/string_piece.h"
+#include "tools/gn/location.h"
+
+class Token {
+ public:
+  enum Type {
+    INVALID,
+    INTEGER,    // 123
+    STRING,     // "blah"
+    OPERATOR,   // =, +=, -=, +, -, ==, !=, <=, >=, <, >
+    IDENTIFIER, // foo
+    SCOPER,     // (, ), [, ], {, }
+    SEPARATOR,  // ,
+    COMMENT     // #...\n
+  };
+
+  Token();
+  Token(const Location& location, Type t, const base::StringPiece& v);
+
+  Type type() const { return type_; }
+  const base::StringPiece& value() const { return value_; }
+  const Location& location() const { return location_; }
+  LocationRange range() const {
+    return LocationRange(location_,
+                         Location(location_.file(), location_.line_number(),
+                                  location_.char_offset() + value_.size()));
+  }
+
+  // Helper functions for comparing this token to something.
+  bool IsIdentifierEqualTo(const char* v) const;
+  bool IsOperatorEqualTo(const char* v) const;
+  bool IsScoperEqualTo(const char* v) const;
+  bool IsStringEqualTo(const char* v) const;
+
+  // For STRING tokens, returns the string value (no quotes at end, does
+  // unescaping).
+  std::string StringValue() const;
+
+ private:
+  Type type_;
+  base::StringPiece value_;
+  Location location_;
+};
+
+#endif  // TOOLS_GN_TOKEN_H_