1 files changed, 77 insertions, 0 deletions
diff --git a/java/com/google/gerrit/server/patch/ComparisonType.java b/java/com/google/gerrit/server/patch/ComparisonType.java
new file mode 100644
index 0000000000..260c507144
--- /dev/null
+++ b/java/com/google/gerrit/server/patch/ComparisonType.java
@@ -0,0 +1,77 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.patch;
+
+import static com.google.gerrit.server.ioutil.BasicSerialization.readVarInt32;
+import static com.google.gerrit.server.ioutil.BasicSerialization.writeVarInt32;
+import static java.util.Objects.requireNonNull;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+public class ComparisonType {
+
+  /** 1-based parent */
+  private final Integer parentNum;
+
+  private final boolean autoMerge;
+
+  public static ComparisonType againstOtherPatchSet() {
+    return new ComparisonType(null, false);
+  }
+
+  public static ComparisonType againstParent(int parentNum) {
+    return new ComparisonType(parentNum, false);
+  }
+
+  public static ComparisonType againstAutoMerge() {
+    return new ComparisonType(null, true);
+  }
+
+  private ComparisonType(Integer parentNum, boolean autoMerge) {
+    this.parentNum = parentNum;
+    this.autoMerge = autoMerge;
+  }
+
+  public boolean isAgainstParentOrAutoMerge() {
+    return isAgainstParent() || isAgainstAutoMerge();
+  }
+
+  public boolean isAgainstParent() {
+    return parentNum != null;
+  }
+
+  public boolean isAgainstAutoMerge() {
+    return autoMerge;
+  }
+
+  public int getParentNum() {
+    requireNonNull(parentNum);
+    return parentNum;
+  }
+
+  void writeTo(OutputStream out) throws IOException {
+    writeVarInt32(out, parentNum != null ? parentNum : 0);
+    writeVarInt32(out, autoMerge ? 1 : 0);
+  }
+
+  static ComparisonType readFrom(InputStream in) throws IOException {
+    int p = readVarInt32(in);
+    Integer parentNum = p > 0 ? p : null;
+    boolean autoMerge = readVarInt32(in) != 0;
+    return new ComparisonType(parentNum, autoMerge);
+  }
+}