SSR: introduce SingleNodeIterator

platform/structuralsearch/source/com/intellij/structuralsearch/Matcher.java

@@ -38,6 +38,7 @@ import com.intellij.structuralsearch.impl.matcher.*;
 import com.intellij.structuralsearch.impl.matcher.compiler.PatternCompiler;
 import com.intellij.structuralsearch.impl.matcher.handlers.MatchingHandler;
 import com.intellij.structuralsearch.impl.matcher.handlers.TopLevelMatchingHandler;
+import com.intellij.structuralsearch.impl.matcher.iterators.SingleNodeIterator;
 import com.intellij.structuralsearch.impl.matcher.iterators.SsrFilteringNodeIterator;
 import com.intellij.structuralsearch.impl.matcher.strategies.MatchingStrategy;
 import com.intellij.structuralsearch.plugin.ui.Configuration;
@@ -480,7 +481,7 @@ public class Matcher {
 
     final Language elementLanguage = element.getLanguage();
     if (strategy.continueMatching(element) && elementLanguage.isKindOf(language)) {
-      visitor.matchContext(new ArrayBackedNodeIterator(new PsiElement[] {element}));
+      visitor.matchContext(new SingleNodeIterator(element));
       return;
     }
     for(PsiElement el=element.getFirstChild();el!=null;el=el.getNextSibling()) {
@@ -551,8 +552,7 @@ public class Matcher {
 
     assert targetNode != null : "Could not match down up when no target node";
 
-    final LanguageFileType fileType = (LanguageFileType)options.getFileType();
-    match(elementToStartMatching, fileType.getLanguage());
+    visitor.matchContext(new SingleNodeIterator(elementToStartMatching));
     matchContext.getSink().matchingFinished();
     return sink.getMatches();
   }

platform/structuralsearch/source/com/intellij/structuralsearch/impl/matcher/iterators/SingleNodeIterator.java

@@ -0,0 +1,43 @@
+// Copyright 2000-2017 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.intellij.structuralsearch.impl.matcher.iterators;
+
+import com.intellij.dupLocator.iterators.NodeIterator;
+import com.intellij.psi.PsiElement;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class SingleNodeIterator extends NodeIterator {
+
+  private final PsiElement myNode;
+  private boolean myHasNext = true;
+
+  public SingleNodeIterator(PsiElement node) {
+    myNode = node;
+  }
+
+  @Override
+  public boolean hasNext() {
+    return myHasNext;
+  }
+
+  @Override
+  public PsiElement current() {
+    return myHasNext ? myNode : null;
+  }
+
+  @Override
+  public void advance() {
+    myHasNext = false;
+  }
+
+  @Override
+  public void rewind() {
+    myHasNext = true;
+  }
+
+  @Override
+  public void reset() {
+    myHasNext = true;
+  }
+}