Optimize new Gson()

gson/src/main/java/com/google/gson/GsonBuilder.java

@@ -16,24 +16,20 @@
 
 package com.google.gson;
 
-import static com.google.gson.Gson.DEFAULT_COMPLEX_MAP_KEYS;
-import static com.google.gson.Gson.DEFAULT_DATE_PATTERN;
-import static com.google.gson.Gson.DEFAULT_ESCAPE_HTML;
-import static com.google.gson.Gson.DEFAULT_FORMATTING_STYLE;
-import static com.google.gson.Gson.DEFAULT_JSON_NON_EXECUTABLE;
-import static com.google.gson.Gson.DEFAULT_NUMBER_TO_NUMBER_STRATEGY;
-import static com.google.gson.Gson.DEFAULT_OBJECT_TO_NUMBER_STRATEGY;
-import static com.google.gson.Gson.DEFAULT_SERIALIZE_NULLS;
-import static com.google.gson.Gson.DEFAULT_SPECIALIZE_FLOAT_VALUES;
-import static com.google.gson.Gson.DEFAULT_STRICTNESS;
-import static com.google.gson.Gson.DEFAULT_USE_JDK_UNSAFE;
-
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.InlineMe;
 import com.google.gson.annotations.Since;
 import com.google.gson.annotations.Until;
+import com.google.gson.internal.ConstructorConstructor;
 import com.google.gson.internal.Excluder;
+import com.google.gson.internal.bind.ArrayTypeAdapter;
+import com.google.gson.internal.bind.CollectionTypeAdapterFactory;
 import com.google.gson.internal.bind.DefaultDateTypeAdapter;
+import com.google.gson.internal.bind.JsonAdapterAnnotationTypeAdapterFactory;
+import com.google.gson.internal.bind.MapTypeAdapterFactory;
+import com.google.gson.internal.bind.NumberTypeAdapter;
+import com.google.gson.internal.bind.ObjectTypeAdapter;
+import com.google.gson.internal.bind.ReflectiveTypeAdapterFactory;
 import com.google.gson.internal.bind.TreeTypeAdapter;
 import com.google.gson.internal.bind.TypeAdapters;
 import com.google.gson.internal.sql.SqlTypesSupport;
@@ -45,12 +41,16 @@
 import java.text.SimpleDateFormat;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.atomic.AtomicLongArray;
 
 /**
  * Use this builder to construct a {@link Gson} instance when you need to set configuration options
@@ -90,29 +90,64 @@
  * @author Jesse Wilson
  */
 public final class GsonBuilder {
-  private Excluder excluder = Excluder.DEFAULT;
-  private LongSerializationPolicy longSerializationPolicy = LongSerializationPolicy.DEFAULT;
-  private FieldNamingStrategy fieldNamingPolicy = FieldNamingPolicy.IDENTITY;
-  private final Map<Type, InstanceCreator<?>> instanceCreators = new HashMap<>();
-  private final List<TypeAdapterFactory> factories = new ArrayList<>();
+  private static final boolean DEFAULT_JSON_NON_EXECUTABLE = false;
+  // Strictness of `null` is the legacy mode where some Gson APIs are always lenient
+  private static final Strictness DEFAULT_STRICTNESS = null;
+  private static final FormattingStyle DEFAULT_FORMATTING_STYLE = FormattingStyle.COMPACT;
+  private static final boolean DEFAULT_ESCAPE_HTML = true;
+  private static final boolean DEFAULT_SERIALIZE_NULLS = false;
+  private static final boolean DEFAULT_COMPLEX_MAP_KEYS = false;
+  private static final boolean DEFAULT_SPECIALIZE_FLOAT_VALUES = false;
+  private static final boolean DEFAULT_USE_JDK_UNSAFE = true;
+  private static final String DEFAULT_DATE_PATTERN = null;
+  private static final FieldNamingStrategy DEFAULT_FIELD_NAMING_STRATEGY =
+      FieldNamingPolicy.IDENTITY;
+  private static final ToNumberStrategy DEFAULT_OBJECT_TO_NUMBER_STRATEGY = ToNumberPolicy.DOUBLE;
+  private static final ToNumberStrategy DEFAULT_NUMBER_TO_NUMBER_STRATEGY =
+      ToNumberPolicy.LAZILY_PARSED_NUMBER;
+
+  static final ConstructorConstructor DEFAULT_CONSTRUCTOR_CONSTRUCTOR =
+      new ConstructorConstructor(
+          Collections.emptyMap(), DEFAULT_USE_JDK_UNSAFE, Collections.emptyList());
+
+  static final JsonAdapterAnnotationTypeAdapterFactory
+      DEFAULT_JSON_ADAPTER_ANNOTATION_TYPE_ADAPTER_FACTORY =
+          new JsonAdapterAnnotationTypeAdapterFactory(DEFAULT_CONSTRUCTOR_CONSTRUCTOR);
+
+  /**
+   * Default instance of the builder, to be used only by the default {@link Gson#Gson()}
+   * constructor. Must not be used for anything else and must not be leaked to user code, since that
+   * could lead to accidental modification of this default builder.
+   */
+  static final GsonBuilder DEFAULT = new GsonBuilder();
+
+  static final List<TypeAdapterFactory> DEFAULT_TYPE_ADAPTER_FACTORIES =
+      GsonBuilder.DEFAULT.createFactories(
+          DEFAULT_CONSTRUCTOR_CONSTRUCTOR, DEFAULT_JSON_ADAPTER_ANNOTATION_TYPE_ADAPTER_FACTORY);
+
+  Excluder excluder = Excluder.DEFAULT;
+  LongSerializationPolicy longSerializationPolicy = LongSerializationPolicy.DEFAULT;
+  FieldNamingStrategy fieldNamingPolicy = DEFAULT_FIELD_NAMING_STRATEGY;
+  final Map<Type, InstanceCreator<?>> instanceCreators = new HashMap<>();
+  final List<TypeAdapterFactory> factories = new ArrayList<>();
 
   /** tree-style hierarchy factories. These come after factories for backwards compatibility. */
-  private final List<TypeAdapterFactory> hierarchyFactories = new ArrayList<>();
-
-  private boolean serializeNulls = DEFAULT_SERIALIZE_NULLS;
-  private String datePattern = DEFAULT_DATE_PATTERN;
-  private int dateStyle = DateFormat.DEFAULT;
-  private int timeStyle = DateFormat.DEFAULT;
-  private boolean complexMapKeySerialization = DEFAULT_COMPLEX_MAP_KEYS;
-  private boolean serializeSpecialFloatingPointValues = DEFAULT_SPECIALIZE_FLOAT_VALUES;
-  private boolean escapeHtmlChars = DEFAULT_ESCAPE_HTML;
-  private FormattingStyle formattingStyle = DEFAULT_FORMATTING_STYLE;
-  private boolean generateNonExecutableJson = DEFAULT_JSON_NON_EXECUTABLE;
-  private Strictness strictness = DEFAULT_STRICTNESS;
-  private boolean useJdkUnsafe = DEFAULT_USE_JDK_UNSAFE;
-  private ToNumberStrategy objectToNumberStrategy = DEFAULT_OBJECT_TO_NUMBER_STRATEGY;
-  private ToNumberStrategy numberToNumberStrategy = DEFAULT_NUMBER_TO_NUMBER_STRATEGY;
-  private final ArrayDeque<ReflectionAccessFilter> reflectionFilters = new ArrayDeque<>();
+  final List<TypeAdapterFactory> hierarchyFactories = new ArrayList<>();
+
+  boolean serializeNulls = DEFAULT_SERIALIZE_NULLS;
+  String datePattern = DEFAULT_DATE_PATTERN;
+  int dateStyle = DateFormat.DEFAULT;
+  int timeStyle = DateFormat.DEFAULT;
+  boolean complexMapKeySerialization = DEFAULT_COMPLEX_MAP_KEYS;
+  boolean serializeSpecialFloatingPointValues = DEFAULT_SPECIALIZE_FLOAT_VALUES;
+  boolean escapeHtmlChars = DEFAULT_ESCAPE_HTML;
+  FormattingStyle formattingStyle = DEFAULT_FORMATTING_STYLE;
+  boolean generateNonExecutableJson = DEFAULT_JSON_NON_EXECUTABLE;
+  Strictness strictness = DEFAULT_STRICTNESS;
+  boolean useJdkUnsafe = DEFAULT_USE_JDK_UNSAFE;
+  ToNumberStrategy objectToNumberStrategy = DEFAULT_OBJECT_TO_NUMBER_STRATEGY;
+  ToNumberStrategy numberToNumberStrategy = DEFAULT_NUMBER_TO_NUMBER_STRATEGY;
+  final ArrayDeque<ReflectionAccessFilter> reflectionFilters = new ArrayDeque<>();
 
   /**
    * Creates a GsonBuilder instance that can be used to build Gson with various configuration
@@ -884,43 +919,123 @@ public GsonBuilder addReflectionAccessFilter(ReflectionAccessFilter filter) {
    * @return an instance of Gson configured with the options currently set in this builder
    */
   public Gson create() {
-    List<TypeAdapterFactory> factories =
-        new ArrayList<>(this.factories.size() + this.hierarchyFactories.size() + 3);
-    factories.addAll(this.factories);
-    Collections.reverse(factories);
-
-    List<TypeAdapterFactory> hierarchyFactories = new ArrayList<>(this.hierarchyFactories);
-    Collections.reverse(hierarchyFactories);
-    factories.addAll(hierarchyFactories);
-
-    addTypeAdaptersForDate(datePattern, dateStyle, timeStyle, factories);
-
-    return new Gson(
-        excluder,
-        fieldNamingPolicy,
-        new HashMap<>(instanceCreators),
-        serializeNulls,
-        complexMapKeySerialization,
-        generateNonExecutableJson,
-        escapeHtmlChars,
-        formattingStyle,
-        strictness,
-        serializeSpecialFloatingPointValues,
-        useJdkUnsafe,
-        longSerializationPolicy,
-        datePattern,
-        dateStyle,
-        timeStyle,
-        new ArrayList<>(this.factories),
-        new ArrayList<>(this.hierarchyFactories),
-        factories,
-        objectToNumberStrategy,
-        numberToNumberStrategy,
-        new ArrayList<>(reflectionFilters));
-  }
-
-  private static void addTypeAdaptersForDate(
-      String datePattern, int dateStyle, int timeStyle, List<TypeAdapterFactory> factories) {
+    return new Gson(this);
+  }
+
+  List<TypeAdapterFactory> createFactories(
+      ConstructorConstructor constructorConstructor,
+      JsonAdapterAnnotationTypeAdapterFactory jsonAdapterFactory) {
+    ArrayList<TypeAdapterFactory> factories = new ArrayList<>();
+
+    // built-in type adapters that cannot be overridden
+    factories.add(TypeAdapters.JSON_ELEMENT_FACTORY);
+    factories.add(ObjectTypeAdapter.getFactory(objectToNumberStrategy));
+
+    // the excluder must precede all adapters that handle user-defined types
+    factories.add(excluder);
+
+    // users' type adapters
+    addUserDefinedAdapters(factories);
+
+    // custom Date adapters
+    addDateTypeAdapters(factories);
+
+    // type adapters for basic platform types
+    factories.add(TypeAdapters.STRING_FACTORY);
+    factories.add(TypeAdapters.INTEGER_FACTORY);
+    factories.add(TypeAdapters.BOOLEAN_FACTORY);
+    factories.add(TypeAdapters.BYTE_FACTORY);
+    factories.add(TypeAdapters.SHORT_FACTORY);
+    TypeAdapter<Number> longAdapter = longSerializationPolicy.typeAdapter();
+    factories.add(TypeAdapters.newFactory(long.class, Long.class, longAdapter));
+    factories.add(TypeAdapters.newFactory(double.class, Double.class, doubleAdapter()));
+    factories.add(TypeAdapters.newFactory(float.class, Float.class, floatAdapter()));
+    factories.add(NumberTypeAdapter.getFactory(numberToNumberStrategy));
+    factories.add(TypeAdapters.ATOMIC_INTEGER_FACTORY);
+    factories.add(TypeAdapters.ATOMIC_BOOLEAN_FACTORY);
+    factories.add(
+        TypeAdapters.newFactory(AtomicLong.class, TypeAdapters.atomicLongAdapter(longAdapter)));
+    factories.add(
+        TypeAdapters.newFactory(
+            AtomicLongArray.class, TypeAdapters.atomicLongArrayAdapter(longAdapter)));
+    factories.add(TypeAdapters.ATOMIC_INTEGER_ARRAY_FACTORY);
+    factories.add(TypeAdapters.CHARACTER_FACTORY);
+    factories.add(TypeAdapters.STRING_BUILDER_FACTORY);
+    factories.add(TypeAdapters.STRING_BUFFER_FACTORY);
+    factories.add(TypeAdapters.BIG_DECIMAL_FACTORY);
+    factories.add(TypeAdapters.BIG_INTEGER_FACTORY);
+    // Add adapter for LazilyParsedNumber because user can obtain it from Gson and then try to
+    // serialize it again
+    factories.add(TypeAdapters.LAZILY_PARSED_NUMBER_FACTORY);
+    factories.add(TypeAdapters.URL_FACTORY);
+    factories.add(TypeAdapters.URI_FACTORY);
+    factories.add(TypeAdapters.UUID_FACTORY);
+    factories.add(TypeAdapters.CURRENCY_FACTORY);
+    factories.add(TypeAdapters.LOCALE_FACTORY);
+    factories.add(TypeAdapters.INET_ADDRESS_FACTORY);
+    factories.add(TypeAdapters.BIT_SET_FACTORY);
+    factories.add(DefaultDateTypeAdapter.DEFAULT_STYLE_FACTORY);
+    factories.add(TypeAdapters.CALENDAR_FACTORY);
+    factories.addAll(SqlTypesSupport.SQL_TYPE_FACTORIES);
+    factories.add(ArrayTypeAdapter.FACTORY);
+    factories.add(TypeAdapters.CLASS_FACTORY);
+
+    // type adapters for composite and user-defined types
+    factories.add(new CollectionTypeAdapterFactory(constructorConstructor));
+    factories.add(new MapTypeAdapterFactory(constructorConstructor, complexMapKeySerialization));
+    factories.add(jsonAdapterFactory);
+    factories.add(TypeAdapters.ENUM_FACTORY);
+    factories.add(
+        new ReflectiveTypeAdapterFactory(
+            constructorConstructor,
+            fieldNamingPolicy,
+            excluder,
+            jsonAdapterFactory,
+            newImmutableList(reflectionFilters)));
+
+    factories.trimToSize();
+    return Collections.unmodifiableList(factories);
+  }
+
+  static <E> List<E> newImmutableList(Collection<E> collection) {
+    if (collection.isEmpty()) {
+      return Collections.emptyList();
+    }
+    if (collection.size() == 1) {
+      return Collections.singletonList(
+          collection instanceof List
+              ? ((List<E>) collection).get(0)
+              : collection.iterator().next());
+    }
+    @SuppressWarnings("unchecked")
+    List<E> list = (List<E>) Collections.unmodifiableList(Arrays.asList(collection.toArray()));
+    return list;
+  }
+
+  private TypeAdapter<Number> doubleAdapter() {
+    return serializeSpecialFloatingPointValues ? TypeAdapters.DOUBLE : TypeAdapters.DOUBLE_STRICT;
+  }
+
+  private TypeAdapter<Number> floatAdapter() {
+    return serializeSpecialFloatingPointValues ? TypeAdapters.FLOAT : TypeAdapters.FLOAT_STRICT;
+  }
+
+  private void addUserDefinedAdapters(List<TypeAdapterFactory> all) {
+    if (!this.factories.isEmpty()) {
+      List<TypeAdapterFactory> reversedFactories = new ArrayList<>(this.factories);
+      Collections.reverse(reversedFactories);
+      all.addAll(reversedFactories);
+    }
+
+    if (!this.hierarchyFactories.isEmpty()) {
+      List<TypeAdapterFactory> reversedHierarchyFactories =
+          new ArrayList<>(this.hierarchyFactories);
+      Collections.reverse(reversedHierarchyFactories);
+      all.addAll(reversedHierarchyFactories);
+    }
+  }
+
+  private void addDateTypeAdapters(List<TypeAdapterFactory> factories) {
     TypeAdapterFactory dateAdapterFactory;
     boolean sqlTypesSupported = SqlTypesSupport.SUPPORTS_SQL_TYPES;
     TypeAdapterFactory sqlTimestampAdapterFactory = null;

gson/src/main/java/com/google/gson/LongSerializationPolicy.java

@@ -16,6 +16,8 @@
 
 package com.google.gson;
 
+import com.google.gson.internal.bind.TypeAdapters;
+
 /**
  * Defines the expected format for a {@code long} or {@code Long} type when it is serialized.
  *
@@ -39,6 +41,11 @@ public JsonElement serialize(Long value) {
       }
       return new JsonPrimitive(value);
     }
+
+    @Override
+    TypeAdapter<Number> typeAdapter() {
+      return TypeAdapters.LONG;
+    }
   },
 
   /**
@@ -55,6 +62,11 @@ public JsonElement serialize(Long value) {
       }
       return new JsonPrimitive(value.toString());
     }
+
+    @Override
+    TypeAdapter<Number> typeAdapter() {
+      return TypeAdapters.LONG_AS_STRING;
+    }
   };
 
   /**
@@ -64,4 +76,8 @@ public JsonElement serialize(Long value) {
    * @return the serialized version of {@code value}
    */
   public abstract JsonElement serialize(Long value);
+
+  /** Returns the corresponding {@link TypeAdapter} for this serialization policy. */
+  // Internal method
+  abstract TypeAdapter<Number> typeAdapter();
 }