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diff --git a/java/core/src/main/java/com/google/protobuf/Proto2SchemaFactory.java b/java/core/src/main/java/com/google/protobuf/Proto2SchemaFactory.java
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+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import static com.google.protobuf.Internal.checkNotNull;
+
+/** Manufactures instances of {@link Proto3TableSchema}. */
+@ExperimentalApi
+public final class Proto2SchemaFactory implements SchemaFactory {
+  /**
+   * The mode with which to generate schemas.
+   *
+   * <p>For testing purposes only.
+   */
+  public enum Mode {
+    /** Always use a table-based indexing of fields. */
+    TABLE,
+
+    /** Always used lookup-based (i.e. binary search) indexing of fields. */
+    LOOKUP,
+
+    /**
+     * Default. Determine the appropriate field indexing mode based on how sparse the field numbers
+     * are for the message.
+     */
+    DYNAMIC
+  }
+
+  private final MessageInfoFactory messageDescriptorFactory;
+  private final Mode mode;
+
+  public Proto2SchemaFactory() {
+    this(DescriptorMessageInfoFactory.getInstance());
+  }
+
+  public Proto2SchemaFactory(MessageInfoFactory messageDescriptorFactory) {
+    this(messageDescriptorFactory, Mode.DYNAMIC);
+  }
+
+  /** For testing purposes only. Allows specification of {@link Mode}. */
+  public Proto2SchemaFactory(MessageInfoFactory messageDescriptorFactory, Mode mode) {
+    if (!isSupported()) {
+      throw new IllegalStateException("Schema factory is unsupported on this platform");
+    }
+    this.messageDescriptorFactory =
+        checkNotNull(messageDescriptorFactory, "messageDescriptorFactory");
+    this.mode = checkNotNull(mode, "mode");
+  }
+
+  public static boolean isSupported() {
+    return UnsafeUtil.hasUnsafeArrayOperations() && UnsafeUtil.hasUnsafeByteBufferOperations();
+  }
+
+  @Override
+  public <T> Schema<T> createSchema(Class<T> messageType) {
+    SchemaUtil.requireGeneratedMessage(messageType);
+
+    MessageInfo descriptor = messageDescriptorFactory.messageInfoFor(messageType);
+    switch (mode) {
+      case TABLE:
+        return newTableSchema(messageType, descriptor);
+      case LOOKUP:
+        return newLookupSchema(messageType, descriptor);
+      default:
+        return SchemaUtil.shouldUseTableSwitch(descriptor.getFields())
+            ? newTableSchema(messageType, descriptor)
+            : newLookupSchema(messageType, descriptor);
+    }
+  }
+
+  private <T> Schema<T> newTableSchema(Class<T> messageType, MessageInfo descriptor) {
+    if (GeneratedMessageLite.class.isAssignableFrom(messageType)) {
+      return new Proto2LiteTableSchema<T>(messageType, descriptor);
+    }
+    return new Proto2TableSchema<T>(messageType, descriptor);
+  }
+
+  private <T> Schema<T> newLookupSchema(Class<T> messageType, MessageInfo descriptor) {
+    if (GeneratedMessageLite.class.isAssignableFrom(messageType)) {
+      return new Proto2LiteLookupSchema<T>(messageType, descriptor);
+    }
+    return new Proto2LookupSchema<T>(messageType, descriptor);
+  }
+}