optimize JsonWriter::validate #1171

Author: BillyDonahue

src/lib_json/json_writer.cpp

@@ -1198,34 +1198,30 @@ StreamWriter* StreamWriterBuilder::newStreamWriter() const {
                                      endingLineFeedSymbol, usf, emitUTF8, pre,
                                      precisionType);
 }
-static void getValidWriterKeys(std::set<String>* valid_keys) {
-  valid_keys->clear();
-  valid_keys->insert("indentation");
-  valid_keys->insert("commentStyle");
-  valid_keys->insert("enableYAMLCompatibility");
-  valid_keys->insert("dropNullPlaceholders");
-  valid_keys->insert("useSpecialFloats");
-  valid_keys->insert("emitUTF8");
-  valid_keys->insert("precision");
-  valid_keys->insert("precisionType");
-}
+
 bool StreamWriterBuilder::validate(Json::Value* invalid) const {
-  Json::Value my_invalid;
-  if (!invalid)
-    invalid = &my_invalid; // so we do not need to test for NULL
-  Json::Value& inv = *invalid;
-  std::set<String> valid_keys;
-  getValidWriterKeys(&valid_keys);
-  Value::Members keys = settings_.getMemberNames();
-  size_t n = keys.size();
-  for (size_t i = 0; i < n; ++i) {
-    String const& key = keys[i];
-    if (valid_keys.find(key) == valid_keys.end()) {
-      inv[key] = settings_[key];
-    }
+  static const auto& valid_keys = *new std::set<String>{
+      "indentation",
+      "commentStyle",
+      "enableYAMLCompatibility",
+      "dropNullPlaceholders",
+      "useSpecialFloats",
+      "emitUTF8",
+      "precision",
+      "precisionType",
+  };
+  for (auto si = settings_.begin(); si != settings_.end(); ++si) {
+    auto key = si.name();
+    if (valid_keys.count(key))
+      continue;
+    if (invalid)
+      (*invalid)[std::move(key)] = *si;
+    else
+      return false;
   }
-  return inv.empty();
+  return invalid ? invalid->empty() : true;
 }
+
 Value& StreamWriterBuilder::operator[](const String& key) {
   return settings_[key];
 }