Add initial prototype for the GN meta-buildsystem.

tools/gn/token.cc

+// 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.
+
+#include "tools/gn/token.h"
+
+#include "base/logging.h"
+
+namespace {
+
+std::string UnescapeString(const base::StringPiece& input) {
+  std::string result;
+  result.reserve(input.size());
+
+  for (size_t i = 0; i < input.size(); i++) {
+    if (input[i] == '\\') {
+      DCHECK(i < input.size() - 1);  // Last char shouldn't be a backslash or
+                                     // it would have escaped the terminator.
+      i++;  // Skip backslash, next char is a literal.
+    }
+    result.push_back(input[i]);
+  }
+  return result;
+}
+
+}  // namespace
+
+Token::Token() : type_(INVALID), value_() {
+}
+
+Token::Token(const Location& location,
+             Type t,
+             const base::StringPiece& v)
+    : type_(t),
+      value_(v),
+      location_(location) {
+}
+
+bool Token::IsIdentifierEqualTo(const char* v) const {
+  return type_ == IDENTIFIER && value_ == v;
+}
+
+bool Token::IsOperatorEqualTo(const char* v) const {
+  return type_ == OPERATOR && value_ == v;
+}
+
+bool Token::IsScoperEqualTo(const char* v) const {
+  return type_ == SCOPER && value_ == v;
+}
+
+bool Token::IsStringEqualTo(const char* v) const {
+  return type_ == STRING && value_ == v;
+}
+
+std::string Token::StringValue() const {
+  DCHECK(type() == STRING);
+
+  // Trim off the string terminators at the end.
+  return UnescapeString(value_.substr(1, value_.size() - 2));
+}