cleanup

platform/lang-api/src/com/intellij/lang/LanguageDocumentation.java

@@ -21,7 +21,7 @@ package com.intellij.lang;
 
 import com.intellij.lang.documentation.CompositeDocumentationProvider;
 import com.intellij.lang.documentation.DocumentationProvider;
-import org.jetbrains.annotations.NonNls;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.List;
 
@@ -32,11 +32,11 @@ public class LanguageDocumentation extends LanguageExtension<DocumentationProvid
     super("com.intellij.lang.documentationProvider");
   }
 
-  public DocumentationProvider forLanguage(final Language l) {
+  public DocumentationProvider forLanguage(@NotNull final Language l) {
     final List<DocumentationProvider> providers = allForLanguage(l);
     if (providers.size() < 2) {
       return super.forLanguage(l);
     }
     return CompositeDocumentationProvider.wrapProviders(providers);
   }
-}
+}

platform/lang-api/src/com/intellij/lang/folding/LanguageFolding.java

@@ -21,8 +21,8 @@ import com.intellij.lang.Language;
 import com.intellij.lang.LanguageExtension;
 import com.intellij.openapi.editor.Document;
 import com.intellij.openapi.project.DumbService;
-import com.intellij.openapi.project.DumbAware;
 import com.intellij.psi.PsiElement;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.List;
 
@@ -38,7 +38,7 @@ public class LanguageFolding extends LanguageExtension<FoldingBuilder> {
   }
 
   @Override
-  public FoldingBuilder forLanguage(Language l) {
+  public FoldingBuilder forLanguage(@NotNull Language l) {
     FoldingBuilder cached = l.getUserData(getLanguageCache());
     if (cached != null) return cached;
 
@@ -77,4 +77,4 @@ public class LanguageFolding extends LanguageExtension<FoldingBuilder> {
 
     return builder.buildFoldRegions(astNode, document);
   }
-}
+}

platform/lang-impl/src/com/intellij/psi/impl/source/codeStyle/CodeEditUtil.java

@@ -406,8 +406,7 @@ public class CodeEditUtil {
 
   public static void setOldIndentation(final TreeElement treeElement, final int oldIndentation) {
     if(treeElement == null) return;
-    if(oldIndentation >= 0) treeElement.putCopyableUserData(INDENT_INFO, oldIndentation);
-    else treeElement.putCopyableUserData(INDENT_INFO, null);
+    treeElement.putCopyableUserData(INDENT_INFO, oldIndentation >= 0 ? oldIndentation : null);
   }
 
   public static boolean isMarkedToReformatBefore(final TreeElement element) {

platform/lang-impl/src/com/intellij/psi/impl/source/tree/LeafElement.java

@@ -83,7 +83,7 @@ public abstract class LeafElement extends TreeElement {
     return leafTextMatches(text, buffer, start);
   }
 
-  public static int leafTextMatches(CharSequence text, CharSequence buffer, int start) {
+  public static int leafTextMatches(@NotNull CharSequence text, @NotNull CharSequence buffer, int start) {
     final int length = text.length();
     if(buffer.length() - start < length) return -1;
     for(int i = 0; i < length; i++){

platform/platform-api/src/com/intellij/lang/LanguageExtension.java

@@ -43,27 +43,21 @@ public class LanguageExtension<T> extends KeyedExtensionCollector<T, Language> {
     return key.getID();
   }
 
-  public T forLanguage(Language l) {
+  public T forLanguage(@NotNull Language l) {
     T cached = l.getUserData(IN_LANGUAGE_CACHE);
     if (cached != null) return cached;
 
     List<T> extensions = forKey(l);
     T result;
     if (extensions.isEmpty()) {
-
       Language base = l.getBaseLanguage();
-      if (base != null) {
-        result = forLanguage(base);
-      }
-      else {
-        result = myDefaultImplementation;
-      }
+      result = base == null ? myDefaultImplementation : forLanguage(base);
     }
     else {
       result = extensions.get(0);
     }
-
-    l.putUserData(IN_LANGUAGE_CACHE, result);
+    if (result == null) return result;
+    l.putUserDataIfAbsent(IN_LANGUAGE_CACHE, result);
     return result;
   }
 

platform/platform-impl/src/com/intellij/openapi/diff/impl/incrementalMerge/ui/ApplyNonConflicts.java

@@ -28,6 +28,7 @@ import com.intellij.util.containers.FilteringIterator;
 
 import java.util.ArrayList;
 import java.util.Iterator;
+import java.util.List;
 
 public class ApplyNonConflicts extends AnAction implements DumbAware {
   public ApplyNonConflicts() {
@@ -36,7 +37,7 @@ public class ApplyNonConflicts extends AnAction implements DumbAware {
 
   public void actionPerformed(AnActionEvent e) {
     DataContext dataContext = e.getDataContext();
-    ArrayList<Change> notConflicts = ContainerUtil.collect(getNotConflicts(dataContext));
+    List<Change> notConflicts = ContainerUtil.collect(getNotConflicts(dataContext));
     for (Change change : notConflicts) {
       Change.apply(change, MergeList.BRANCH_SIDE);
     }

platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorImpl.java

@@ -228,7 +228,7 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
   private boolean myGutterNeedsUpdate = false;
   private Alarm myAppleRepaintAlarm;
 
-  private Alarm myMouseSelectionStateAlarm = new Alarm(Alarm.ThreadToUse.SWING_THREAD);
+  private final Alarm myMouseSelectionStateAlarm = new Alarm(Alarm.ThreadToUse.SWING_THREAD);
   private Runnable myMouseSelectionStateResetRunnable;
 
   private boolean myEmbeddedIntoDialogWrapper;
@@ -4695,8 +4695,6 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
     }
 
     private boolean processMousePressed(MouseEvent e) {
-      boolean isNavigation = false;
-
       myInitialMouseEvent = e;
 
       if (myMouseSelectionState != MOUSE_SELECTION_STATE_NONE && System.currentTimeMillis() - myMouseSelectionChangeTimestamp > Registry.intValue(
@@ -4711,6 +4709,7 @@ public final class EditorImpl extends UserDataHolderBase implements EditorEx, Hi
       if (y < 0) y = 0;
 
       final EditorMouseEventArea eventArea = getMouseEventArea(e);
+      boolean isNavigation = false;
       if (eventArea == EditorMouseEventArea.FOLDING_OUTLINE_AREA) {
         final FoldRegion range = myGutterComponent.findFoldingAnchorAt(x, y);
         if (range != null) {

platform/platform-impl/testSrc/com/intellij/util/IJSwingUtilitiesTest.java

@@ -20,7 +20,7 @@ import junit.framework.TestCase;
 
 import javax.swing.*;
 import java.awt.*;
-import java.util.ArrayList;
+import java.util.List;
 
 public class IJSwingUtilitiesTest extends TestCase {
   private final JPanel myPanel = new JPanel();
@@ -52,7 +52,7 @@ public class IJSwingUtilitiesTest extends TestCase {
     CHECK.compareAll(new JComponent[]{label1, subPanel, label2, label3, label4}, getChildren());
   }
 
-  private ArrayList<Component> getChildren() {
+  private List<Component> getChildren() {
     return ContainerUtil.collect(IJSwingUtilities.getChildren(myPanel));
   }
 

platform/util/src/com/intellij/util/containers/CollectUtil.java

@@ -17,22 +17,22 @@ package com.intellij.util.containers;
 
 import com.intellij.openapi.util.Condition;
 
-import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Set;
 
 /**
  * @deprecated use {@link ContainerUtil}
  */
 @Deprecated
 public abstract class CollectUtil<E> {
-  public abstract <T extends E> HashSet<T> toSet(Iterator<T> iterator);
+  public abstract <T extends E> Set<T> toSet(Iterator<T> iterator);
 
-  public <Dom, Rng extends E> HashSet<Rng> toSet(Iterator<Dom> iterator, Convertor<Dom, Rng> convertor) {
+  public <Dom, Rng extends E> Set<Rng> toSet(Iterator<Dom> iterator, Convertor<Dom, Rng> convertor) {
     return toSet(ConvertingIterator.create(iterator, convertor));
   }
 
-  public <Dom, Rng extends E> HashSet<Rng> toSet(Dom[] objects, Convertor<Dom, Rng> convertor) {
+  public <Dom, Rng extends E> Set<Rng> toSet(Dom[] objects, Convertor<Dom, Rng> convertor) {
     return toSet(ContainerUtil.iterate(objects), convertor);
   }
 
@@ -40,14 +40,14 @@ public abstract class CollectUtil<E> {
     return toList(iterator).toArray();
   }
 
-  public abstract <T extends E> ArrayList<T> toList(Iterator<E> iterator);
+  public abstract <T extends E> List<T> toList(Iterator<E> iterator);
 
-  public <Dom, Rng extends E> ArrayList<Rng> toList(Iterator<Dom> iterator, Convertor<Dom, E> convertor) {
+  public <Dom, Rng extends E> List<Rng> toList(Iterator<Dom> iterator, Convertor<Dom, E> convertor) {
     ConvertingIterator<Dom, E> iterator1 = ConvertingIterator.create(iterator, convertor);
     return toList(iterator1);
   }
 
-  public <Dom, Rng extends E> ArrayList<Rng> toList(Dom[] objects, Convertor<Dom, E> convertor) {
+  public <Dom, Rng extends E> List<Rng> toList(Dom[] objects, Convertor<Dom, E> convertor) {
     return toList(ContainerUtil.iterate(objects), convertor);
   }
 
@@ -60,12 +60,12 @@ public abstract class CollectUtil<E> {
   }
 
   public static final CollectUtil<Object> COLLECT = new CollectUtil<Object>() {
-    public <T> HashSet<T> toSet(Iterator<T> iterator) {
+    public <T> Set<T> toSet(Iterator<T> iterator) {
       return ContainerUtil.collectSet(iterator);
     }
 
-    public <T> ArrayList<T> toList(Iterator<Object> iterator) {
-      return (ArrayList<T>)ContainerUtil.collect(iterator);
+    public <T> List<T> toList(Iterator<Object> iterator) {
+      return (List)ContainerUtil.collect(iterator);
     }
   };
 
@@ -78,12 +78,12 @@ public abstract class CollectUtil<E> {
       myCondition = condition;
     }
 
-    public <T extends E> ArrayList<T> toList(Iterator<E> iterator) {
+    public <T extends E> List<T> toList(Iterator<E> iterator) {
       Iterator<T> iterator1 = FilteringIterator.create(iterator, myCondition);
       return COLLECT.toList((Iterator<Object>)(Iterator)iterator1);
     }
 
-    public <T extends E> HashSet<T> toSet(Iterator<T> iterator) {
+    public <T extends E> Set<T> toSet(Iterator<T> iterator) {
       return COLLECT.toSet(FilteringIterator.create(iterator, (Condition<T>)myCondition));
     }
   }

platform/util/src/com/intellij/util/containers/ContainerUtil.java

@@ -25,7 +25,6 @@ import gnu.trove.TObjectHashingStrategy;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.io.Serializable;
 import java.lang.reflect.Array;
 import java.util.*;
 import java.util.concurrent.CopyOnWriteArrayList;
@@ -134,15 +133,18 @@ public class ContainerUtil {
     }
   }
 
-  public static <T> ArrayList<T> collect(@NotNull Iterator<T> iterator) {
-    ArrayList<T> list = new ArrayList<T>();
+  @NotNull
+  public static <T> List<T> collect(@NotNull Iterator<T> iterator) {
+    if (!iterator.hasNext()) return Collections.emptyList();
+    List<T> list = new ArrayList<T>();
     addAll(list, iterator);
     return list;
   }
 
   @NotNull
-  public static <T> HashSet<T> collectSet(@NotNull Iterator<T> iterator) {
-    HashSet<T> hashSet = new HashSet<T>();
+  public static <T> Set<T> collectSet(@NotNull Iterator<T> iterator) {
+    if (!iterator.hasNext()) return Collections.emptySet();
+    Set<T> hashSet = new HashSet<T>();
     addAll(hashSet, iterator);
     return hashSet;
   }
@@ -477,7 +479,7 @@ public class ContainerUtil {
   }
 
   @NotNull
-  public static <T> ArrayList<T> collect(@NotNull Iterator<?> iterator, @NotNull FilteringIterator.InstanceOf<T> instanceOf) {
+  public static <T> List<T> collect(@NotNull Iterator<?> iterator, @NotNull FilteringIterator.InstanceOf<T> instanceOf) {
     return collect(FilteringIterator.create((Iterator<T>)iterator, instanceOf));
   }
 
@@ -1087,7 +1089,10 @@ public class ContainerUtil {
     y1.add(newY.toNativeArray());
   }
 
-  private static class EmptyList extends AbstractList<Object> implements RandomAccess, Serializable {
+  /**
+   * has optimized toArray() as opposed to the {@link java.util.Collections#emptyList()}
+   */
+  private static class EmptyList extends AbstractList<Object> implements RandomAccess {
     private static final EmptyList INSTANCE = new EmptyList();
 
     public int size() {