path: root/java/java-psi-impl/src/com/intellij/codeInsight/folding/impl/JavaFoldingBuilderBase.java

/*
 * Copyright 2000-2014 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.codeInsight.folding.impl;

import com.intellij.codeInsight.daemon.impl.CollectHighlightsUtil;
import com.intellij.codeInsight.daemon.impl.analysis.HighlightUtilBase;
import com.intellij.codeInsight.folding.JavaCodeFoldingSettings;
import com.intellij.codeInsight.generation.OverrideImplementExploreUtil;
import com.intellij.lang.ASTNode;
import com.intellij.lang.folding.CustomFoldingBuilder;
import com.intellij.lang.folding.FoldingDescriptor;
import com.intellij.lang.folding.NamedFoldingDescriptor;
import com.intellij.openapi.diagnostic.Logger;
import com.intellij.openapi.editor.Document;
import com.intellij.openapi.editor.FoldingGroup;
import com.intellij.openapi.progress.ProgressIndicatorProvider;
import com.intellij.openapi.project.DumbAware;
import com.intellij.openapi.project.DumbService;
import com.intellij.openapi.project.IndexNotReadyException;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.util.TextRange;
import com.intellij.openapi.util.UnfairTextRange;
import com.intellij.openapi.util.text.StringUtil;
import com.intellij.psi.*;
import com.intellij.psi.impl.source.PsiClassReferenceType;
import com.intellij.psi.impl.source.SourceTreeToPsiMap;
import com.intellij.psi.impl.source.tree.JavaDocElementType;
import com.intellij.psi.impl.source.tree.JavaElementType;
import com.intellij.psi.javadoc.PsiDocComment;
import com.intellij.psi.tree.IElementType;
import com.intellij.psi.util.*;
import com.intellij.util.Function;
import com.intellij.util.ObjectUtils;
import com.intellij.util.text.CharArrayUtil;
import org.jetbrains.annotations.NonNls;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public abstract class JavaFoldingBuilderBase extends CustomFoldingBuilder implements DumbAware {
  private static final Logger LOG = Logger.getInstance("#com.intellij.codeInsight.folding.impl.JavaFoldingBuilder");
  private static final String SMILEY = "<~>";

  private static String getPlaceholderText(PsiElement element) {
    if (element instanceof PsiImportList) {
      return "...";
    }
    else if (element instanceof PsiMethod || element instanceof PsiClassInitializer || element instanceof PsiClass) {
      return "{...}";
    }
    else if (element instanceof PsiDocComment) {
      return "/**...*/";
    }
    else if (element instanceof PsiFile) {
      return "/.../";
    }
    else if (element instanceof PsiAnnotation) {
      return "@{...}";
    }
    else if (element instanceof PsiReferenceParameterList) {
      return SMILEY;
    }
    else if (element instanceof PsiComment) {
      return "//...";
    }
    return "...";
  }

  private static boolean areOnAdjacentLines(PsiElement e1, PsiElement e2, Document document) {
    return document.getLineNumber(e1.getTextRange().getEndOffset()) + 1 == document.getLineNumber(e2.getTextRange().getStartOffset());
  }

  private static boolean isSimplePropertyAccessor(PsiMethod method) {
    PsiCodeBlock body = method.getBody();
    if (body == null || body.getLBrace() == null || body.getRBrace() == null) return false;
    PsiStatement[] statements = body.getStatements();
    if (statements.length == 0) return false;

    PsiStatement statement = statements[0];
    if (PropertyUtil.isSimplePropertyGetter(method)) {
      if (statement instanceof PsiReturnStatement) {
        return ((PsiReturnStatement)statement).getReturnValue() instanceof PsiReferenceExpression;
      }
      return false;
    }

    // builder-style setter?
    if (statements.length > 1 && !(statements[1] instanceof PsiReturnStatement)) return false;
    
    // any setter? 
    if (statement instanceof PsiExpressionStatement) {
      PsiExpression expr = ((PsiExpressionStatement)statement).getExpression();
      if (expr instanceof PsiAssignmentExpression) {
        PsiExpression lhs = ((PsiAssignmentExpression)expr).getLExpression();
        PsiExpression rhs = ((PsiAssignmentExpression)expr).getRExpression();
        return lhs instanceof PsiReferenceExpression && 
               rhs instanceof PsiReferenceExpression && 
               !((PsiReferenceExpression)rhs).isQualified() && 
               PropertyUtil.isSimplePropertySetter(method); // last check because it can perform long return type resolve
      }
    }
    return false;
  }

  @Nullable
  public TextRange getRangeToFold(PsiElement element) {
    if (element instanceof SyntheticElement) {
      return null;
    }
    if (element instanceof PsiMethod) {
      PsiCodeBlock body = ((PsiMethod)element).getBody();
      if (body == null) return null;
      return body.getTextRange();
    }
    if (element instanceof PsiClassInitializer) {
      return ((PsiClassInitializer)element).getBody().getTextRange();
    }
    if (element instanceof PsiClass) {
      PsiClass aClass = (PsiClass)element;
      PsiElement lBrace = aClass.getLBrace();
      if (lBrace == null) return null;
      PsiElement rBrace = aClass.getRBrace();
      if (rBrace == null) return null;
      return new TextRange(lBrace.getTextOffset(), rBrace.getTextOffset() + 1);
    }
    if (element instanceof PsiJavaFile) {
      return getFileHeader((PsiJavaFile)element);
    }
    if (element instanceof PsiImportList) {
      PsiImportList list = (PsiImportList)element;
      PsiImportStatementBase[] statements = list.getAllImportStatements();
      if (statements.length == 0) return null;
      final PsiElement importKeyword = statements[0].getFirstChild();
      if (importKeyword == null) return null;
      int startOffset = importKeyword.getTextRange().getEndOffset() + 1;
      int endOffset = statements[statements.length - 1].getTextRange().getEndOffset();
      if (!hasErrorElementsNearby(element.getContainingFile(), startOffset, endOffset)) {
        return new TextRange(startOffset, endOffset);
      }
    }
    if (element instanceof PsiDocComment) {
      return element.getTextRange();
    }
    if (element instanceof PsiAnnotation) {
      int startOffset = element.getTextRange().getStartOffset();
      PsiElement last = element;
      while (element instanceof PsiAnnotation) {
        last = element;
        element = PsiTreeUtil.skipSiblingsForward(element, PsiWhiteSpace.class, PsiComment.class);
      }

      return new TextRange(startOffset, last.getTextRange().getEndOffset());
    }
    return null;
  }

  public static boolean hasErrorElementsNearby(final PsiFile file, int startOffset, int endOffset) {
    endOffset = CharArrayUtil.shiftForward(file.getViewProvider().getContents(), endOffset, " \t\n");
    for (PsiElement element : CollectHighlightsUtil.getElementsInRange(file, startOffset, endOffset)) {
      if (element instanceof PsiErrorElement) {
        return true;
      }
    }
    return false;
  }

  @Nullable
  private static TextRange getFileHeader(PsiJavaFile file) {
    PsiElement first = file.getFirstChild();
    if (first instanceof PsiWhiteSpace) first = first.getNextSibling();
    PsiElement element = first;
    while (element instanceof PsiComment) {
      element = element.getNextSibling();
      if (element instanceof PsiWhiteSpace) {
        element = element.getNextSibling();
      }
      else {
        break;
      }
    }
    if (element == null) return null;
    if (element.getPrevSibling() instanceof PsiWhiteSpace) element = element.getPrevSibling();
    if (element == null || element.equals(first)) return null;
    return new UnfairTextRange(first.getTextOffset(), element.getTextOffset());
  }

  private void addAnnotationsToFold(PsiModifierList modifierList, List<FoldingDescriptor> foldElements, Document document) {
    if (modifierList == null) return;
    PsiElement[] children = modifierList.getChildren();
    for (int i = 0; i < children.length; i++) {
      PsiElement child = children[i];
      if (child instanceof PsiAnnotation) {
        addToFold(foldElements, child, document, false);
        int j;
        for (j = i + 1; j < children.length; j++) {
          PsiElement nextChild = children[j];
          if (nextChild instanceof PsiModifier) break;
        }

        //noinspection AssignmentToForLoopParameter
        i = j;
      }
    }
  }

  /**
   * We want to allow to fold subsequent single line comments like
   * <pre>
   *     // this is comment line 1
   *     // this is comment line 2
   * </pre>
   *
   * @param comment             comment to check
   * @param processedComments   set that contains already processed elements. It is necessary because we process all elements of
   *                            the PSI tree, hence, this method may be called for both comments from the example above. However,
   *                            we want to create fold region during the first comment processing, put second comment to it and
   *                            skip processing when current method is called for the second element
   * @param foldElements        fold descriptors holder to store newly created descriptor (if any)
   */
  private static void addCommentFolds(@NotNull PsiComment comment, @NotNull Set<PsiElement> processedComments,
                                      @NotNull List<FoldingDescriptor> foldElements)
  {
    if (processedComments.contains(comment) || comment.getTokenType() != JavaTokenType.END_OF_LINE_COMMENT) {
      return;
    }

    PsiElement end = null;
    for (PsiElement current = comment.getNextSibling(); current != null; current = current.getNextSibling()) {
      ASTNode node = current.getNode();
      if (node == null) {
        break;
      }
      IElementType elementType = node.getElementType();
      if (elementType == JavaTokenType.END_OF_LINE_COMMENT) {
        end = current;
        // We don't want to process, say, the second comment in case of three subsequent comments when it's being examined
        // during all elements traversal. I.e. we expect to start from the first comment and grab as many subsequent
        // comments as possible during the single iteration.
        processedComments.add(current);
        continue;
      }
      if (elementType == TokenType.WHITE_SPACE) {
        continue;
      }
      break;
    }

    if (end != null) {
      foldElements.add(
        new FoldingDescriptor(comment, new TextRange(comment.getTextRange().getStartOffset(), end.getTextRange().getEndOffset()))
      );
    }
  }

  private static void addMethodGenericParametersFolding(PsiMethodCallExpression expression, List<FoldingDescriptor> foldElements, Document document, boolean quick) {
    final PsiReferenceExpression methodExpression = expression.getMethodExpression();
    final PsiReferenceParameterList list = methodExpression.getParameterList();
    if (list == null || list.getTextLength() <= 5) {
      return;
    }

    PsiMethodCallExpression element = expression;
    while (true) {
      if (!quick && !resolvesCorrectly(element.getMethodExpression())) return;
      final PsiElement parent = element.getParent();
      if (!(parent instanceof PsiExpressionList) || !(parent.getParent() instanceof PsiMethodCallExpression)) break;
      element = (PsiMethodCallExpression)parent.getParent();
    }

    addTypeParametersFolding(foldElements, document, list, 3, quick);
  }

  private static boolean resolvesCorrectly(PsiReferenceExpression expression) {
    for (final JavaResolveResult result : expression.multiResolve(true)) {
  if (!result.isValidResult()) {
    return false;
  }
}
    return true;
  }

  private static void addGenericParametersFolding(PsiNewExpression expression, List<FoldingDescriptor> foldElements, Document document, boolean quick) {
    final PsiElement parent = expression.getParent();
    if (!(parent instanceof PsiVariable)) {
      return;
    }

    final PsiType declType = ((PsiVariable)parent).getType();
    if (!(declType instanceof PsiClassReferenceType)) {
      return;
    }

    final PsiType[] parameters = ((PsiClassType)declType).getParameters();
    if (parameters.length == 0) {
      return;
    }

   PsiJavaCodeReferenceElement classReference = expression.getClassReference();
    if (classReference == null) {
      final PsiAnonymousClass anonymousClass = expression.getAnonymousClass();
      if (anonymousClass != null) {
        classReference = anonymousClass.getBaseClassReference();

        if (quick || seemsLikeLambda(anonymousClass.getSuperClass())) {
          return;
        }
      }
    }

    if (classReference != null) {
      final PsiReferenceParameterList list = classReference.getParameterList();
      if (list != null) {
        if (quick) {
          final PsiJavaCodeReferenceElement declReference = ((PsiClassReferenceType)declType).getReference();
          final PsiReferenceParameterList declList = declReference.getParameterList();
          if (declList == null || !list.getText().equals(declList.getText())) {
            return;
          }
        } else {
          if (!Arrays.equals(list.getTypeArguments(), parameters)) {
            return;
          }
        }

        addTypeParametersFolding(foldElements, document, list, 5, quick);
      }
    }
  }

  private static void addTypeParametersFolding(List<FoldingDescriptor> foldElements, Document document, PsiReferenceParameterList list,
                                        final int ifLongerThan, boolean quick) {
    if (!quick) {
      for (final PsiType type : list.getTypeArguments()) {
        if (!type.isValid()) {
          return;
        }
        if (type instanceof PsiClassType || type instanceof PsiArrayType) {
          if (PsiUtil.resolveClassInType(type) == null) {
            return;
          }
        }
      }
    }

    final String text = list.getText();
    if (text.startsWith("<") && text.endsWith(">") && text.length() > ifLongerThan) {
      final TextRange range = list.getTextRange();
      addFoldRegion(foldElements, list, document, true, range);
    }
  }

  private static boolean hasOnlyOneLambdaMethod(@NotNull PsiAnonymousClass anonymousClass, boolean checkResolve) {
    PsiField[] fields = anonymousClass.getFields();
    if (fields.length != 0) {
      if (fields.length == 1 && HighlightUtilBase.SERIAL_VERSION_UID_FIELD_NAME.equals(fields[0].getName()) &&
          fields[0].hasModifierProperty(PsiModifier.STATIC)) {
        //ok
      } else {
        return false;
      }
    }
    if (anonymousClass.getInitializers().length != 0) {
      return false;
    }
    if (anonymousClass.getInnerClasses().length != 0) {
      return false;
    }

    if (anonymousClass.getMethods().length != 1) {
      return false;
    }

    PsiMethod method = anonymousClass.getMethods()[0];
    if (method.hasModifierProperty(PsiModifier.SYNCHRONIZED)) {
      return false;
    }

    if (checkResolve) {
      PsiReferenceList throwsList = method.getThrowsList();
      for (PsiClassType type : throwsList.getReferencedTypes()) {
        if (type.resolve() == null) {
          return false;
        }
      }
    }

    return true;
  }

  private String getOptionalLambdaType(PsiAnonymousClass anonymousClass, PsiNewExpression expression) {
    if (shouldShowExplicitLambdaType(anonymousClass, expression)) {
      final String baseClassName = ObjectUtils.assertNotNull(anonymousClass.getBaseClassType().resolve()).getName();
      if (baseClassName != null) {
        return "(" + baseClassName + ") ";
      }
    }
    return "";
  }

  protected abstract boolean shouldShowExplicitLambdaType(PsiAnonymousClass anonymousClass, PsiNewExpression expression);

  private static boolean seemsLikeLambda(@Nullable final PsiClass baseClass) {
    return baseClass != null && PsiUtil.hasDefaultConstructor(baseClass, true);
  }

  private static boolean isImplementingLambdaMethod(PsiClass baseClass) {
    if (!baseClass.hasModifierProperty(PsiModifier.ABSTRACT)) return false;

    for (final PsiMethod method : baseClass.getMethods()) {
      if (method.hasModifierProperty(PsiModifier.ABSTRACT)) {
        return true;
      }
    }

    try {
      return !OverrideImplementExploreUtil.getMethodSignaturesToImplement(baseClass).isEmpty();
    }
    catch (IndexNotReadyException e) {
      return false;
    }
  }

  private boolean addToFold(List<FoldingDescriptor> list, PsiElement elementToFold, Document document, boolean allowOneLiners) {
    PsiUtilCore.ensureValid(elementToFold);
    TextRange range = getRangeToFold(elementToFold);
    if (range == null) return false;
    return addFoldRegion(list, elementToFold, document, allowOneLiners, range);
  }

  private static boolean addFoldRegion(final List<FoldingDescriptor> list, final PsiElement elementToFold, final Document document,
                                final boolean allowOneLiners,
                                final TextRange range) {
    final TextRange fileRange = elementToFold.getContainingFile().getTextRange();
    if (range.equals(fileRange)) return false;

    LOG.assertTrue(range.getStartOffset() >= 0 && range.getEndOffset() <= fileRange.getEndOffset());
    // PSI element text ranges may be invalid because of reparse exception (see, for example, IDEA-10617)
    if (range.getStartOffset() < 0 || range.getEndOffset() > fileRange.getEndOffset()) {
      return false;
    }
    if (!allowOneLiners) {
      int startLine = document.getLineNumber(range.getStartOffset());
      int endLine = document.getLineNumber(range.getEndOffset() - 1);
      if (startLine < endLine && range.getLength() > 1) {
        list.add(new FoldingDescriptor(elementToFold, range));
        return true;
      }
      return false;
    }
    else {
      if (range.getLength() > getPlaceholderText(elementToFold).length()) {
        list.add(new FoldingDescriptor(elementToFold, range));
        return true;
      }
      return false;
    }
  }

  @Override
  protected void buildLanguageFoldRegions(@NotNull List<FoldingDescriptor> descriptors,
                                          @NotNull PsiElement root,
                                          @NotNull Document document,
                                          boolean quick) {
    if (!(root instanceof PsiJavaFile)) {
      return;
    }
    PsiJavaFile file = (PsiJavaFile) root;

    PsiImportList importList = file.getImportList();
    if (importList != null) {
      PsiImportStatementBase[] statements = importList.getAllImportStatements();
      if (statements.length > 1) {
        final TextRange rangeToFold = getRangeToFold(importList);
        if (rangeToFold != null && rangeToFold.getLength() > 1) {
          descriptors.add(new FoldingDescriptor(importList, rangeToFold));
        }
      }
    }

    PsiClass[] classes = file.getClasses();
    for (PsiClass aClass : classes) {
      ProgressIndicatorProvider.checkCanceled();
      addElementsToFold(descriptors, aClass, document, true, quick);
    }

    TextRange range = getFileHeader(file);
    if (range != null && range.getLength() > 1 && document.getLineNumber(range.getEndOffset()) > document.getLineNumber(range.getStartOffset())) {
      PsiElement anchorElementToUse = file;
      PsiElement candidate = file.getFirstChild();

      // We experienced the following problem situation:
      //     1. There is a collapsed class-level javadoc;
      //     2. User starts typing at class definition line (e.g. we had definition like 'public class Test' and user starts
      //        typing 'abstract' between 'public' and 'class');
      //     3. Collapsed class-level javadoc automatically expanded. That happened because PSI structure became invalid (because
      //        class definition line at start looks like 'public class Test');
      // So, our point is to preserve fold descriptor referencing javadoc PSI element.
      if (candidate != null && candidate.getTextRange().equals(range)) {
        ASTNode node = candidate.getNode();
        if (node != null && node.getElementType() == JavaDocElementType.DOC_COMMENT) {
          anchorElementToUse = candidate;
        }
      }
      descriptors.add(new FoldingDescriptor(anchorElementToUse, range));
    }
  }

  private void addElementsToFold(List<FoldingDescriptor> list, PsiClass aClass, Document document, boolean foldJavaDocs, boolean quick) {
    if (!(aClass.getParent() instanceof PsiJavaFile) || ((PsiJavaFile)aClass.getParent()).getClasses().length > 1) {
      addToFold(list, aClass, document, true);
    }

    PsiDocComment docComment;
    if (foldJavaDocs) {
      docComment = aClass.getDocComment();
      if (docComment != null) {
        addToFold(list, docComment, document, true);
      }
    }
    addAnnotationsToFold(aClass.getModifierList(), list, document);

    PsiElement[] children = aClass.getChildren();
    Set<PsiElement> processedComments = new HashSet<PsiElement>();
    for (PsiElement child : children) {
      ProgressIndicatorProvider.checkCanceled();

      if (child instanceof PsiMethod) {
        PsiMethod method = (PsiMethod)child;
        boolean oneLiner = addOneLineMethodFolding(list, method);
        if (!oneLiner) {
          addToFold(list, method, document, true);
        }
        addAnnotationsToFold(method.getModifierList(), list, document);

        if (foldJavaDocs) {
          docComment = method.getDocComment();
          if (docComment != null) {
            addToFold(list, docComment, document, true);
          }
        }

        PsiCodeBlock body = method.getBody();
        if (body != null && !oneLiner) {
          addCodeBlockFolds(body, list, processedComments, document, quick);
        }
      }
      else if (child instanceof PsiField) {
        PsiField field = (PsiField)child;
        if (foldJavaDocs) {
          docComment = field.getDocComment();
          if (docComment != null) {
            addToFold(list, docComment, document, true);
          }
        }
        addAnnotationsToFold(field.getModifierList(), list, document);
        PsiExpression initializer = field.getInitializer();
        if (initializer != null) {
          addCodeBlockFolds(initializer, list, processedComments, document, quick);
        } else if (field instanceof PsiEnumConstant) {
          addCodeBlockFolds(field, list, processedComments, document, quick);
        }
      }
      else if (child instanceof PsiClassInitializer) {
        PsiClassInitializer initializer = (PsiClassInitializer)child;
        addToFold(list, initializer, document, true);
        addCodeBlockFolds(initializer, list, processedComments, document, quick);
      }
      else if (child instanceof PsiClass) {
        addElementsToFold(list, (PsiClass)child, document, true, quick);
      }
      else if (child instanceof PsiComment && !isCustomRegionStart(child.getNode()) && !isCustomRegionEnd(child.getNode())) {
        addCommentFolds((PsiComment)child, processedComments, list);
      }
    }
  }

  private boolean addOneLineMethodFolding(List<FoldingDescriptor> descriptorList, PsiMethod method) {
    if (!JavaCodeFoldingSettings.getInstance().isCollapseOneLineMethods()) {
      return false;
    }

    Document document = method.getContainingFile().getViewProvider().getDocument();
    PsiCodeBlock body = method.getBody();
    PsiIdentifier nameIdentifier = method.getNameIdentifier();
    if (body == null || document == null || nameIdentifier == null) {
      return false;
    }
    if (document.getLineNumber(nameIdentifier.getTextRange().getStartOffset()) !=
        document.getLineNumber(method.getParameterList().getTextRange().getEndOffset())) {
      return false;
    }

    PsiJavaToken lBrace = body.getLBrace();
    PsiJavaToken rBrace = body.getRBrace();
    PsiStatement[] statements = body.getStatements();
    if (lBrace == null || rBrace == null || statements.length != 1) {
      return false;
    }

    PsiStatement statement = statements[0];
    if (statement.textContains('\n')) {
      return false;
    }

    if (!areOnAdjacentLines(lBrace, statement, document) || !areOnAdjacentLines(statement, rBrace, document)) {
      //the user might intend to type at an empty line
      return false;
    }

    int leftStart = method.getParameterList().getTextRange().getEndOffset();
    int leftEnd = statement.getTextRange().getStartOffset();
    int rightStart = statement.getTextRange().getEndOffset();
    int rightEnd = body.getTextRange().getEndOffset();
    if (leftEnd <= leftStart + 1 || rightEnd <= rightStart + 1) {
      return false;
    }

    String leftText = " { ";
    String rightText = " }";
    if (!fitsRightMargin(method, document, leftStart, rightEnd, rightStart - leftEnd + leftText.length() + rightText.length())) {
      return false;
    }

    FoldingGroup group = FoldingGroup.newGroup("one-liner");
    descriptorList.add(new NamedFoldingDescriptor(lBrace, leftStart, leftEnd, group, leftText));
    descriptorList.add(new NamedFoldingDescriptor(rBrace, rightStart, rightEnd, group, rightText));
    return true;
  }
  
  @Override
  protected String getLanguagePlaceholderText(@NotNull ASTNode node, @NotNull TextRange range) {
    return getPlaceholderText(SourceTreeToPsiMap.treeElementToPsi(node));
  }

  @Override
  protected boolean isRegionCollapsedByDefault(@NotNull ASTNode node) {
    final PsiElement element = SourceTreeToPsiMap.treeElementToPsi(node);
    JavaCodeFoldingSettings settings = JavaCodeFoldingSettings.getInstance();
    if (element instanceof PsiNewExpression || element instanceof PsiJavaToken && 
                                               element.getParent() instanceof PsiAnonymousClass) {
      return settings.isCollapseLambdas();
    }
    if (element instanceof PsiJavaToken &&
        element.getParent() instanceof PsiCodeBlock &&
        element.getParent().getParent() instanceof PsiMethod) {
      return settings.isCollapseOneLineMethods();
    }
    if (element instanceof PsiReferenceParameterList) {
      return settings.isCollapseConstructorGenericParameters();
    }

    if (element instanceof PsiImportList) {
      return settings.isCollapseImports();
    }
    else if (element instanceof PsiMethod || element instanceof PsiClassInitializer || element instanceof PsiCodeBlock) {
      if (element instanceof PsiMethod && isSimplePropertyAccessor((PsiMethod)element)) {
        return settings.isCollapseAccessors();
      }
      return settings.isCollapseMethods();
    }
    else if (element instanceof PsiAnonymousClass) {
      return settings.isCollapseAnonymousClasses();
    }
    else if (element instanceof PsiClass) {
      return !(element.getParent() instanceof PsiFile) && settings.isCollapseInnerClasses();
    }
    else if (element instanceof PsiDocComment) {
      PsiElement parent = element.getParent();
      if (parent instanceof PsiJavaFile) {
        if (((PsiJavaFile)parent).getName().equals(PsiPackage.PACKAGE_INFO_FILE)) {
          return false;
        }
        PsiElement firstChild = parent.getFirstChild();
        if (firstChild instanceof PsiWhiteSpace) {
          firstChild = firstChild.getNextSibling();
        }
        if (element.equals(firstChild)) {
          return settings.isCollapseFileHeader();
        }
      }
      return settings.isCollapseJavadocs();
    }
    else if (element instanceof PsiJavaFile) {
      return settings.isCollapseFileHeader();
    }
    else if (element instanceof PsiAnnotation) {
      return settings.isCollapseAnnotations();
    }
    else if (element instanceof PsiComment) {
      return settings.isCollapseEndOfLineComments();
    }
    else if (ParameterNameFoldingManager.isLiteralExpression(element)
             && element.getParent() instanceof PsiExpressionList
             && (element.getParent().getParent() instanceof PsiCallExpression
                 || element.getParent().getParent() instanceof PsiAnonymousClass)) {
      return settings.isInlineParameterNamesForLiteralCallArguments();
    }
    else {
      LOG.error("Unknown element:" + element);
      return false;
    }
  }

  private void addCodeBlockFolds(PsiElement scope, final List<FoldingDescriptor> foldElements,
                                 final @NotNull Set<PsiElement> processedComments, final Document document, final boolean quick) {
    final boolean dumb = DumbService.isDumb(scope.getProject());
    scope.accept(new JavaRecursiveElementWalkingVisitor() {
      @Override
      public void visitClass(PsiClass aClass) {
        if (dumb || !addClosureFolding(aClass, document, foldElements, processedComments, quick)) {
          addToFold(foldElements, aClass, document, true);
          addElementsToFold(foldElements, aClass, document, false, quick);
        }
      }

      @Override
      public void visitMethodCallExpression(PsiMethodCallExpression expression) {
        if (!dumb) {
          addMethodGenericParametersFolding(expression, foldElements, document, quick);
          inlineLiteralArgumentsNames(expression, foldElements, quick);
        }

        super.visitMethodCallExpression(expression);
      }

      @Override
      public void visitNewExpression(PsiNewExpression expression) {
        if (!dumb) {
          addGenericParametersFolding(expression, foldElements, document, quick);
          inlineLiteralArgumentsNames(expression, foldElements, quick);
        }

        super.visitNewExpression(expression);
      }

      @Override
      public void visitComment(PsiComment comment) {
        addCommentFolds(comment, processedComments, foldElements);
        super.visitComment(comment);
      }
    });
  }

  private static void inlineLiteralArgumentsNames(@NotNull PsiCallExpression expression,
                                                  @NotNull List<FoldingDescriptor> foldElements,
                                                  boolean quick)
  {
    if (quick || !JavaCodeFoldingSettings.getInstance().isInlineParameterNamesForLiteralCallArguments()) {
      return;
    }
    ParameterNameFoldingManager manager = new ParameterNameFoldingManager(expression);
    foldElements.addAll(manager.buildDescriptors());
  }

  private boolean addClosureFolding(final PsiClass aClass, final Document document, final List<FoldingDescriptor> foldElements,
                                    @NotNull Set<PsiElement> processedComments, final boolean quick) {
    if (!JavaCodeFoldingSettings.getInstance().isCollapseLambdas()) {
      return false;
    }

    boolean isClosure = false;
    if (aClass instanceof PsiAnonymousClass) {
      final PsiAnonymousClass anonymousClass = (PsiAnonymousClass)aClass;
      final PsiElement element = anonymousClass.getParent();
      if (element instanceof PsiNewExpression) {
        final PsiNewExpression expression = (PsiNewExpression)element;
        final PsiExpressionList argumentList = expression.getArgumentList();
        if (argumentList != null && argumentList.getExpressions().length == 0) {
          final PsiMethod[] methods = anonymousClass.getMethods();
          PsiClass baseClass = anonymousClass.getBaseClassType().resolve();
          if (hasOnlyOneLambdaMethod(anonymousClass, !quick) && seemsLikeLambda(baseClass) && !PsiUtil.isLanguageLevel8OrHigher(anonymousClass)) {
            final PsiMethod method = methods[0];
            final PsiCodeBlock body = method.getBody();
            if (body != null) {
              isClosure = true;
              int rangeStart = body.getTextRange().getStartOffset();
              int rangeEnd = body.getTextRange().getEndOffset();
              final PsiJavaToken lbrace = body.getLBrace();
              if (lbrace != null) rangeStart = lbrace.getTextRange().getEndOffset();
              final PsiJavaToken rbrace = body.getRBrace();
              if (rbrace != null) rangeEnd = rbrace.getTextRange().getStartOffset();

              final CharSequence seq = document.getCharsSequence();
              final PsiElement classRBrace = anonymousClass.getRBrace();
              if (classRBrace != null && rbrace != null) {
                final int methodEndLine = document.getLineNumber(rangeEnd);
                final int methodEndLineStart = document.getLineStartOffset(methodEndLine);
                if ("}".equals(seq.subSequence(methodEndLineStart, document.getLineEndOffset(methodEndLine)).toString().trim())) {
                  int classEndStart = classRBrace.getTextRange().getStartOffset();
                  int classEndCol = classEndStart - document.getLineStartOffset(document.getLineNumber(classEndStart));
                  rangeEnd = classEndCol + methodEndLineStart;
                }
              }

              int firstLineStart = CharArrayUtil.shiftForward(seq, rangeStart, " \t");
              if (firstLineStart < seq.length() - 1 && seq.charAt(firstLineStart) == '\n') firstLineStart++;

              int lastLineEnd = CharArrayUtil.shiftBackward(seq, rangeEnd - 1, " \t");
              if (lastLineEnd > 0 && seq.charAt(lastLineEnd) == '\n') lastLineEnd--;
              if (lastLineEnd < firstLineStart) return false;

              String type = quick ? "" : getOptionalLambdaType(anonymousClass, expression);
              String methodName = quick || !isImplementingLambdaMethod(baseClass) ? method.getName() : "";

              final String params = StringUtil.join(method.getParameterList().getParameters(), new Function<PsiParameter, String>() {
                @Override
                public String fun(final PsiParameter psiParameter) {
                  return psiParameter.getName();
                }
              }, ", ");
              @NonNls final String lambdas = type + methodName + "(" + params + ") -> {";

              final int closureStart = expression.getTextRange().getStartOffset();
              final int closureEnd = expression.getTextRange().getEndOffset();
              boolean oneLine = false;
              String contents = seq.subSequence(firstLineStart, lastLineEnd).toString();
              if (contents.indexOf('\n') < 0 &&
                  fitsRightMargin(aClass, document, closureStart, closureEnd, lambdas.length() + contents.length() + 5)) {
                rangeStart = CharArrayUtil.shiftForward(seq, rangeStart, " \n\t");
                rangeEnd = CharArrayUtil.shiftBackward(seq, rangeEnd - 1, " \n\t") + 1;
                oneLine = true;
              }

              if (rangeStart >= rangeEnd) return false;

              FoldingGroup group = FoldingGroup.newGroup("lambda");
              final String prettySpace = oneLine ? " " : "";
              foldElements.add(new NamedFoldingDescriptor(expression, closureStart, rangeStart, group, lambdas + prettySpace));
              if (rbrace != null && rangeEnd + 1 < closureEnd) {
                foldElements.add(new NamedFoldingDescriptor(rbrace, rangeEnd, closureEnd, group, prettySpace + "}"));
              }

              addCodeBlockFolds(body, foldElements, processedComments, document, quick);
            }
          }
        }
      }
    }
    return isClosure;
  }

  private boolean fitsRightMargin(PsiElement element, Document document, int foldingStart, int foldingEnd, int collapsedLength) {
    final int beforeLength = foldingStart - document.getLineStartOffset(document.getLineNumber(foldingStart));
    final int afterLength = document.getLineEndOffset(document.getLineNumber(foldingEnd)) - foldingEnd;
    return isBelowRightMargin(element.getProject(), beforeLength + collapsedLength + afterLength);
  }

  protected abstract boolean isBelowRightMargin (Project project, final int lineLength);

  @Override
  protected boolean isCustomFoldingCandidate(ASTNode node) {
    return node.getElementType() == JavaTokenType.END_OF_LINE_COMMENT;
  }

  @Override
  protected boolean isCustomFoldingRoot(ASTNode node) {
    IElementType nodeType = node.getElementType();
    if (nodeType == JavaElementType.CLASS) {
      ASTNode parent = node.getTreeParent();
      return parent == null || parent.getElementType() != JavaElementType.CLASS;
    }
    return nodeType == JavaElementType.CODE_BLOCK;
  }
}