Rewrite base::JSONReader to be 35-40% faster, depending on the input string.

This change does the following:
* Parses the input string and generates the object representation in O(n) time.
* Optimizes string decoding by using StringPiece where possible, which also
  introduces the JSON_DETACHABLE_CHILDREN parser option.
* Makes JSONReader a simpler interface by hiding the parser details in an
  internal JSONParser class.

BUG=49212,111581,121469
TEST=Hopefully covered by all test suites. New tests added for edge cases.

Review URL: https://chromiumcodereview.appspot.com/10035042

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@137430 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 6 insertions, 9 deletions

diff --git a/base/values.h b/base/values.h
index 4bcdc75..1d35d63 100644
--- a/base/values.h
+++ b/base/values.h
@@ -303,11 +303,12 @@ class BASE_EXPORT DictionaryValue : public Value {
   // passed out via out_value.  If |out_value| is NULL, the removed value will
   // be deleted.  This method returns true if |path| is a valid path; otherwise
   // it will return false and the DictionaryValue object will be unchanged.
-  bool Remove(const std::string& path, Value** out_value);
+  virtual bool Remove(const std::string& path, Value** out_value);
 
   // Like Remove(), but without special treatment of '.'.  This allows e.g. URLs
   // to be used as paths.
-  bool RemoveWithoutPathExpansion(const std::string& key, Value** out_value);
+  virtual bool RemoveWithoutPathExpansion(const std::string& key,
+                                          Value** out_value);
 
   // Makes a copy of |this| but doesn't include empty dictionaries and lists in
   // the copy.  This never returns NULL, even if |this| itself is empty.
@@ -321,9 +322,7 @@ class BASE_EXPORT DictionaryValue : public Value {
   void MergeDictionary(const DictionaryValue* dictionary);
 
   // Swaps contents with the |other| dictionary.
-  void Swap(DictionaryValue* other) {
-    dictionary_.swap(other->dictionary_);
-  }
+  virtual void Swap(DictionaryValue* other);
 
   // This class provides an iterator for the keys in the dictionary.
   // It can't be used to modify the dictionary.
@@ -425,7 +424,7 @@ class BASE_EXPORT ListValue : public Value {
   // passed out via |out_value|.  If |out_value| is NULL, the removed value will
   // be deleted.  This method returns true if |index| is valid; otherwise
   // it will return false and the ListValue object will be unchanged.
-  bool Remove(size_t index, Value** out_value);
+  virtual bool Remove(size_t index, Value** out_value);
 
   // Removes the first instance of |value| found in the list, if any, and
   // deletes it. |index| is the location where |value| was found. Returns false
@@ -450,9 +449,7 @@ class BASE_EXPORT ListValue : public Value {
   const_iterator Find(const Value& value) const;
 
   // Swaps contents with the |other| list.
-  void Swap(ListValue* other) {
-    list_.swap(other->list_);
-  }
+  virtual void Swap(ListValue* other);
 
   // Iteration.
   iterator begin() { return list_.begin(); }