Split ValueSerializer into separate Serializer and Deserializer classes.

base/json/json_string_value_serializer.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.
 
 #ifndef BASE_JSON_JSON_STRING_VALUE_SERIALIZER_H_
 #define BASE_JSON_JSON_STRING_VALUE_SERIALIZER_H_
 
 #include <string>
 
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
 #include "base/strings/string_piece.h"
 #include "base/values.h"
 
 class BASE_EXPORT JSONStringValueSerializer : public base::ValueSerializer {
  public:
   // |json_string| is the string that will be source of the deserialization
   // or the destination of the serialization.  The caller of the constructor
   // retains ownership of the string. |json_string| must not be null.
   explicit JSONStringValueSerializer(std::string* json_string);
 
-  // This version allows initialization with a StringPiece for deserialization
-  // only. Retains a reference to the contents of |json_string|, so the data
-  // must outlive the JSONStringValueSerializer.
-  explicit JSONStringValueSerializer(const base::StringPiece& json_string);
-
   ~JSONStringValueSerializer() override;
 
   // Attempt to serialize the data structure represented by Value into
   // JSON.  If the return value is true, the result will have been written
   // into the string passed into the constructor.
   bool Serialize(const base::Value& root) override;
 
   // Equivalent to Serialize(root) except binary values are omitted from the
   // output.
   bool SerializeAndOmitBinaryValues(const base::Value& root);
 
+  void set_pretty_print(bool new_value) { pretty_print_ = new_value; }
+  bool pretty_print() { return pretty_print_; }
+
+ private:
+  bool SerializeInternal(const base::Value& root, bool omit_binary_values);
+
+  // String for writing. Owned by the caller of the constructor. Will be null if

[Matt Giuca, 2015/02/16 00:18:27]

Rewrite this comment. "String for writing" no longer necessary because we only
write. It cannot be null, because there is no const string constructor.

+  // the serializer was initialized with a const string.

[Matt Giuca, 2015/02/16 00:18:27]

Delete the last sentence; it is no longer possible to initialize with a const
string.

+  std::string* json_string_;
+  bool pretty_print_;  // If true, serialization will span multiple lines.
+
+  DISALLOW_COPY_AND_ASSIGN(JSONStringValueSerializer);
+};
+
+class BASE_EXPORT JSONStringValueDeserializer : public base::ValueDeserializer {
+ public:
+  // |json_string| is the string that will be source of the deserialization.
+  // The caller of the constructor retains ownership of the string.
+  // |json_string| must not be null.
+  explicit JSONStringValueDeserializer(std::string* json_string);

[Matt Giuca, 2015/02/16 00:18:27]

This constructor should be deleted (the whole point of this CL is to fix the
awkwardness of having a read-write and a read-only constructor).

+
+  // This version allows initialization with a StringPiece for deserialization

[Matt Giuca, 2015/02/16 00:18:27]

You will need to update this comment ("This version ..." no longer makes sense
if you delete the other constructor).

+  // only. Retains a reference to the contents of |json_string|, so the data
+  // must outlive the JSONStringValueSerializer.
+  explicit JSONStringValueDeserializer(const base::StringPiece& json_string);
+
+  ~JSONStringValueDeserializer() override;
+
   // Attempt to deserialize the data structure encoded in the string passed
   // in to the constructor into a structure of Value objects.  If the return
   // value is null, and if |error_code| is non-null, |error_code| will
   // contain an integer error code (a JsonParseError in this case).
   // If |error_message| is non-null, it will be filled in with a formatted
   // error message including the location of the error if appropriate.
   // The caller takes ownership of the returned value.
   base::Value* Deserialize(int* error_code,
                            std::string* error_message) override;
 
-  void set_pretty_print(bool new_value) { pretty_print_ = new_value; }
-  bool pretty_print() { return pretty_print_; }
-
   void set_allow_trailing_comma(bool new_value) {
     allow_trailing_comma_ = new_value;
   }
 
  private:
-  bool SerializeInternal(const base::Value& root, bool omit_binary_values);
-
-  // String for writing. Owned by the caller of the constructor. Will be null if
-  // the serializer was initialized with a const string.
-  std::string* json_string_;
   // String for reading. Data is owned by the caller of the constructor. If

[Matt Giuca, 2015/02/16 00:18:27]

As above, rewrite this comment. "String for reading" is not necessary because we
only do reading in this class. There is no |json_string_| so get rid of the last
sentence.

   // |json_string_| is non-null, this is a view onto |json_string_|.
   base::StringPiece json_string_readonly_;

[Matt Giuca, 2015/02/16 00:18:27]

Rename this to |json_string_|. There is no need for the "readonly" any more.

-  bool pretty_print_;  // If true, serialization will span multiple lines.
   // If true, deserialization will allow trailing commas.
   bool allow_trailing_comma_;
 
-  DISALLOW_COPY_AND_ASSIGN(JSONStringValueSerializer);
+  DISALLOW_COPY_AND_ASSIGN(JSONStringValueDeserializer);
 };
 
 #endif  // BASE_JSON_JSON_STRING_VALUE_SERIALIZER_H_
-