Add initial prototype for the GN meta-buildsystem.

tools/gn/value.cc

Index: tools/gn/value.cc
diff --git a/tools/gn/value.cc b/tools/gn/value.cc
new file mode 100644
index 0000000000000000000000000000000000000000..cb78faadcfda8bea054f7497d877bdfbf4451b1d
--- /dev/null
+++ b/tools/gn/value.cc
@@ -0,0 +1,126 @@
+// 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/value.h"
+
+#include "base/strings/string_number_conversions.h"
+
+Value::Value()
+    : type_(NONE),
+      int_value_(0),
+      origin_(NULL) {
+}
+
+Value::Value(const ParseNode* origin, Type t)
+    : type_(t),
+      int_value_(0),
+      origin_(origin) {
+}
+
+Value::Value(const ParseNode* origin, int64 int_val)
+    : type_(INTEGER),
+      int_value_(int_val),
+      origin_(origin) {
+}
+
+Value::Value(const ParseNode* origin, const base::StringPiece& str_val)
+    : type_(STRING),
+      string_value_(str_val.as_string()),
+      int_value_(0),
+      origin_(origin) {
+}
+
+Value::~Value() {
+}
+
+// static
+const char* Value::DescribeType(Type t) {
+  switch (t) {
+    case NONE:
+      return "none";
+    case INTEGER:
+      return "integer";
+    case STRING:
+      return "string";
+    case LIST:
+      return "list";
+    default:
+      NOTREACHED();
+      return "UNKNOWN";
+  }
+}
+
+int64 Value::InterpretAsInt() const {
+  switch (type_) {
+    case NONE:
+      return 0;
+    case INTEGER:
+      return int_value_;
+    case STRING:
+      return string_value_.empty() ? 0 : 1;
+    case LIST:
+      return list_value_.empty() ? 0 : 1;
+  }
+  return 0;
+}
+
+std::string Value::ToString() const {
+  switch (type_) {
+    case NONE:
+      return "<void>";
+    case INTEGER:
+      return base::Int64ToString(int_value_);
+    case STRING:
+      return string_value_;
+    case LIST: {
+      std::string result = "[";
+      for (size_t i = 0; i < list_value_.size(); i++) {
+        if (i > 0)
+          result += ", ";
+        // TODO(brettw) maybe also want to escape quotes in the string.
+        if (list_value_[i].type() == STRING)
+          result += std::string("\"") + list_value_[i].ToString() + "\"";
+        else
+          result += list_value_[i].ToString();
+      }
+      result.push_back(']');
+      return result;
+    }
+  }
+  return std::string();
+}
+
+bool Value::VerifyTypeIs(Type t, Err* err) const {
+  if (type_ == t)
+    return true;
+
+  *err = Err(origin(), std::string("This is not a ") + DescribeType(t) + ".");
+  return false;
+}
+
+bool Value::operator==(const Value& other) const {
+  if (type_ != other.type_)
+    return false;
+
+  switch (type_) {
+    case Value::INTEGER:
+      return int_value() == other.int_value();
+    case Value::STRING:
+      return string_value() == other.string_value();
+    case Value::LIST:
+      if (list_value().size() != other.list_value().size())
+        return false;
+      for (size_t i = 0; i < list_value().size(); i++) {
+        if (list_value()[i] != other.list_value()[i])
+          return false;
+      }
+      return true;
+    default:
+      return false;
+  }
+}
+
+bool Value::operator!=(const Value& other) const {
+  return !operator==(other);
+}