Implement comparison operators for base::Value

base/values.h

 // Copyright (c) 2012 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.
 
 // This file specifies a recursive data storage class called Value intended for
 // storing settings and other persistable data.
 //
 // A Value represents something that can be stored in JSON or passed to/from
 // JavaScript. As such, it is NOT a generalized variant type, since only the
 // types supported by JavaScript/JSON are supported.
@@ skipping 143 matching lines @@
   // Note: Do not add more types. See the file-level comment above for why.
 
   // This creates a deep copy of the entire Value tree, and returns a pointer
   // to the copy. The caller gets ownership of the copy, of course.
   // Subclasses return their own type directly in their overrides;
   // this works because C++ supports covariant return types.
   Value* DeepCopy() const;
   // Preferred version of DeepCopy. TODO(estade): remove the above.
   std::unique_ptr<Value> CreateDeepCopy() const;
 
+  // Comparison operators so that Values can easily be used with standard
+  // library algorithms and associative containers.
+  BASE_EXPORT friend bool operator==(const Value& lhs, const Value& rhs);
+  BASE_EXPORT friend bool operator!=(const Value& lhs, const Value& rhs);
+  BASE_EXPORT friend bool operator<(const Value& lhs, const Value& rhs);
+  BASE_EXPORT friend bool operator>(const Value& lhs, const Value& rhs);
+  BASE_EXPORT friend bool operator<=(const Value& lhs, const Value& rhs);
+  BASE_EXPORT friend bool operator>=(const Value& lhs, const Value& rhs);
+
   // Compares if two Value objects have equal contents.
+  // DEPRECATED, use operator==(const Value& lhs, const Value& rhs) instead.
+  // TODO(crbug.com/646113): Delete this and migrate callsites.
   bool Equals(const Value* other) const;
 
   // Compares if two Value objects have equal contents. Can handle NULLs.
   // NULLs are considered equal but different from Value::CreateNullValue().
+  // DEPRECATED, use operator==(const Value& lhs, const Value& rhs) instead.
+  // TODO(crbug.com/646113): Delete this and migrate callsites.
   static bool Equals(const Value* a, const Value* b);
 
  protected:
   // TODO(crbug.com/646113): Make these private once DictionaryValue and
   // ListValue are properly inlined.
   Type type_;
 
   union {
     bool bool_value_;
     int int_value_;
@@ skipping 334 matching lines @@
   return out << static_cast<const Value&>(value);
 }
 
 // Stream operator so that enum class Types can be used in log statements.
 BASE_EXPORT std::ostream& operator<<(std::ostream& out,
                                      const Value::Type& type);
 
 }  // namespace base
 
 #endif  // BASE_VALUES_H_