Initial Jack import.

Change-Id: I953cf0a520195a7187d791b2885848ad0d5a9b43

1 files changed, 77 insertions, 0 deletions

diff --git a/guava/src/com/google/common/base/FunctionalEquivalence.java b/guava/src/com/google/common/base/FunctionalEquivalence.java
new file mode 100644
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+++ b/guava/src/com/google/common/base/FunctionalEquivalence.java
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+/*
+ * Copyright (C) 2011 The Guava Authors
+ *
+ * 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.common.base;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import com.google.common.annotations.Beta;
+import com.google.common.annotations.GwtCompatible;
+
+import java.io.Serializable;
+
+import javax.annotation.Nullable;
+
+/**
+ * Equivalence applied on functional result.
+ *
+ * @author Bob Lee
+ * @since 10.0
+ */
+@Beta
+@GwtCompatible
+final class FunctionalEquivalence<F, T> extends Equivalence<F>
+    implements Serializable {
+
+  private static final long serialVersionUID = 0;
+
+  private final Function<F, ? extends T> function;
+  private final Equivalence<T> resultEquivalence;
+
+  FunctionalEquivalence(
+      Function<F, ? extends T> function, Equivalence<T> resultEquivalence) {
+    this.function = checkNotNull(function);
+    this.resultEquivalence = checkNotNull(resultEquivalence);
+  }
+
+  @Override protected boolean doEquivalent(F a, F b) {
+    return resultEquivalence.equivalent(function.apply(a), function.apply(b));
+  }
+
+  @Override protected int doHash(F a) {
+    return resultEquivalence.hash(function.apply(a));
+  }
+
+  @Override public boolean equals(@Nullable Object obj) {
+    if (obj == this) {
+      return true;
+    }
+    if (obj instanceof FunctionalEquivalence) {
+      FunctionalEquivalence<?, ?> that = (FunctionalEquivalence<?, ?>) obj;
+      return function.equals(that.function)
+          && resultEquivalence.equals(that.resultEquivalence);
+    }
+    return false;
+  }
+
+  @Override public int hashCode() {
+    return Objects.hashCode(function, resultEquivalence);
+  }
+
+  @Override public String toString() {
+    return resultEquivalence + ".onResultOf(" + function + ")";
+  }
+}