to remove the dependency on PsiCommentImpl, register the default ASTFactory implementation as a service

platform/lang-impl/src/com/intellij/lang/ASTFactory.java

@@ -15,6 +15,7 @@
  */
 package com.intellij.lang;
 
+import com.intellij.openapi.components.ServiceManager;
 import com.intellij.psi.TokenType;
 import com.intellij.psi.impl.source.CharTableImpl;
 import com.intellij.psi.impl.source.CodeFragmentElement;
@@ -30,7 +31,7 @@ import org.jetbrains.annotations.Nullable;
  * @author max
  */
 public abstract class ASTFactory {
-  public static final DefaultFactory DEFAULT = new DefaultFactory();
+  public static final ASTFactory DEFAULT = (ASTFactory) ServiceManager.getService(DefaultASTFactory.class);
 
   private static final CharTable WHITESPACES = new CharTableImpl();
 
@@ -103,42 +104,4 @@ public abstract class ASTFactory {
     CodeEditUtil.setNodeGenerated(w, true);
     return w;
   }
-
-  // default implementation
-
-  private static class DefaultFactory extends ASTFactory {
-    @Override
-    @NotNull
-    public LazyParseableElement createLazy(final ILazyParseableElementType type, final CharSequence text) {
-      if (type instanceof IFileElementType) {
-        return new FileElement(type, text);
-      }
-
-      return new LazyParseableElement(type, text);
-    }
-
-    @Override
-    @NotNull
-    public CompositeElement createComposite(final IElementType type) {
-      if (type instanceof IFileElementType) {
-        return new FileElement(type, null);
-      }
-
-      return new CompositeElement(type);
-    }
-
-    @Override
-    @NotNull
-    public LeafElement createLeaf(final IElementType type, final CharSequence text) {
-      final Language lang = type.getLanguage();
-      final ParserDefinition parserDefinition = LanguageParserDefinitions.INSTANCE.forLanguage(lang);
-      if (parserDefinition != null) {
-        if (parserDefinition.getCommentTokens().contains(type)) {
-          return new PsiCommentImpl(type, text);
-        }
-      }
-
-      return new LeafPsiElement(type, text);
-    }
-  }
 }

platform/lang-impl/src/com/intellij/lang/DefaultASTFactory.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2000-2011 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.lang;
+
+/**
+ * Marker interface for retrieving the service which provides a default implementation of ASTFactory.
+ *
+ * @author yole
+ */
+public interface DefaultASTFactory {
+}

platform/lang-impl/src/com/intellij/lang/DefaultASTFactoryImpl.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2000-2011 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.lang;
+
+import com.intellij.psi.impl.source.tree.*;
+import com.intellij.psi.tree.IElementType;
+import com.intellij.psi.tree.IFileElementType;
+import com.intellij.psi.tree.ILazyParseableElementType;
+import org.jetbrains.annotations.NotNull;
+
+public class DefaultASTFactoryImpl extends ASTFactory implements DefaultASTFactory {
+  @Override
+  @NotNull
+  public LazyParseableElement createLazy(final ILazyParseableElementType type, final CharSequence text) {
+    if (type instanceof IFileElementType) {
+      return new FileElement(type, text);
+    }
+
+    return new LazyParseableElement(type, text);
+  }
+
+  @Override
+  @NotNull
+  public CompositeElement createComposite(final IElementType type) {
+    if (type instanceof IFileElementType) {
+      return new FileElement(type, null);
+    }
+
+    return new CompositeElement(type);
+  }
+
+  @Override
+  @NotNull
+  public LeafElement createLeaf(final IElementType type, final CharSequence text) {
+    final Language lang = type.getLanguage();
+    final ParserDefinition parserDefinition = LanguageParserDefinitions.INSTANCE.forLanguage(lang);
+    if (parserDefinition != null) {
+      if (parserDefinition.getCommentTokens().contains(type)) {
+        return new PsiCommentImpl(type, text);
+      }
+    }
+
+    return new LeafPsiElement(type, text);
+  }
+}

platform/platform-resources/src/META-INF/LangExtensions.xml

@@ -156,6 +156,9 @@
   <applicationService serviceInterface="com.intellij.psi.impl.source.codeStyle.IndentHelper"
                       serviceImplementation="com.intellij.psi.impl.source.codeStyle.IndentHelperImpl"/>
 
+  <applicationService serviceInterface="com.intellij.lang.DefaultASTFactory"
+                      serviceImplementation="com.intellij.lang.DefaultASTFactoryImpl"/>
+
   <applicationService serviceInterface="com.intellij.conversion.ConversionService"
                       serviceImplementation="com.intellij.conversion.impl.ConversionServiceImpl"/>