diff: move trivial implementation inside interface

platform/diff-impl/src/com/intellij/diff/comparison/iterables/ChangeDiffIterableBase.java

@@ -20,7 +20,7 @@ import org.jetbrains.annotations.NotNull;
 
 import java.util.Iterator;
 
-abstract class ChangeDiffIterableBase extends DiffIterableBase {
+abstract class ChangeDiffIterableBase implements DiffIterable {
   private final int myLength1;
   private final int myLength2;
 
@@ -42,7 +42,7 @@ abstract class ChangeDiffIterableBase extends DiffIterableBase {
   @NotNull
   @Override
   public Iterator<Range> changes() {
-    return new MyIterator<Range>() {
+    return new Iterator<Range>() {
       @NotNull private final ChangeIterable myIterable = createChangeIterable();
 
       @Override
@@ -62,7 +62,7 @@ abstract class ChangeDiffIterableBase extends DiffIterableBase {
   @NotNull
   @Override
   public Iterator<Range> unchanged() {
-    return new MyIterator<Range>() {
+    return new Iterator<Range>() {
       @NotNull private final ChangeIterable myIterable = createChangeIterable();
 
       int lastIndex1 = 0;

platform/diff-impl/src/com/intellij/diff/comparison/iterables/DiffIterable.java

@@ -36,8 +36,12 @@ public interface DiffIterable {
   Iterator<Range> unchanged();
 
   @NotNull
-  Iterable<Range> iterateChanges();
+  default Iterable<Range> iterateChanges() {
+    return this::changes;
+  }
 
   @NotNull
-  Iterable<Range> iterateUnchanged();
+  default Iterable<Range> iterateUnchanged() {
+    return this::unchanged;
+  }
 }

platform/diff-impl/src/com/intellij/diff/comparison/iterables/DiffIterableBase.java

@@ -1,42 +0,0 @@
-/*
- * Copyright 2000-2015 JetBrains s.r.o.
- *
- * 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.intellij.diff.comparison.iterables;
-
-import com.intellij.diff.util.Range;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.Iterator;
-
-abstract class DiffIterableBase implements DiffIterable {
-  @NotNull
-  @Override
-  public Iterable<Range> iterateUnchanged() {
-    return this::unchanged;
-  }
-
-  @NotNull
-  @Override
-  public Iterable<Range> iterateChanges() {
-    return this::changes;
-  }
-
-  protected static abstract class MyIterator<T> implements Iterator<T> {
-    @Override
-    public void remove() {
-      throw new UnsupportedOperationException();
-    }
-  }
-}

platform/diff-impl/src/com/intellij/diff/comparison/iterables/FairDiffIterableWrapper.java

@@ -20,7 +20,7 @@ import org.jetbrains.annotations.NotNull;
 
 import java.util.Iterator;
 
-class FairDiffIterableWrapper extends DiffIterableBase implements FairDiffIterable {
+class FairDiffIterableWrapper implements FairDiffIterable {
   @NotNull private final DiffIterable myIterable;
 
   public FairDiffIterableWrapper(@NotNull DiffIterable iterable) {

platform/diff-impl/src/com/intellij/diff/comparison/iterables/InvertedDiffIterableWrapper.java

@@ -20,7 +20,7 @@ import org.jetbrains.annotations.NotNull;
 
 import java.util.Iterator;
 
-class InvertedDiffIterableWrapper extends DiffIterableBase {
+class InvertedDiffIterableWrapper implements DiffIterable {
   @NotNull private final DiffIterable myIterable;
 
   public InvertedDiffIterableWrapper(@NotNull DiffIterable iterable) {