/*******************************************************************************
 * Copyright (c) 2000, 2017 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Konstantin Scheglov (scheglov_ke@nlmk.ru) - initial API and implementation
 *          (reports 71244 & 74746: New Quick Assist's [quick assist])
 *   IBM Corporation - implementation
 *   Billy Huang <billyhuang31@gmail.com> - [quick assist] concatenate/merge string literals - https://bugs.eclipse.org/77632
 *******************************************************************************/
package org.eclipse.jdt.internal.ui.text.correction;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.eclipse.swt.graphics.Image;

import org.eclipse.core.runtime.CoreException;

import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.NamingConventions;
import org.eclipse.jdt.core.dom.AST;
import org.eclipse.jdt.core.dom.ASTMatcher;
import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.ASTVisitor;
import org.eclipse.jdt.core.dom.AssertStatement;
import org.eclipse.jdt.core.dom.Assignment;
import org.eclipse.jdt.core.dom.Block;
import org.eclipse.jdt.core.dom.BooleanLiteral;
import org.eclipse.jdt.core.dom.BreakStatement;
import org.eclipse.jdt.core.dom.CastExpression;
import org.eclipse.jdt.core.dom.ChildListPropertyDescriptor;
import org.eclipse.jdt.core.dom.ClassInstanceCreation;
import org.eclipse.jdt.core.dom.CompilationUnit;
import org.eclipse.jdt.core.dom.ConditionalExpression;
import org.eclipse.jdt.core.dom.ConstructorInvocation;
import org.eclipse.jdt.core.dom.ContinueStatement;
import org.eclipse.jdt.core.dom.DoStatement;
import org.eclipse.jdt.core.dom.EnhancedForStatement;
import org.eclipse.jdt.core.dom.EnumConstantDeclaration;
import org.eclipse.jdt.core.dom.Expression;
import org.eclipse.jdt.core.dom.ExpressionStatement;
import org.eclipse.jdt.core.dom.ForStatement;
import org.eclipse.jdt.core.dom.IBinding;
import org.eclipse.jdt.core.dom.IMethodBinding;
import org.eclipse.jdt.core.dom.ITypeBinding;
import org.eclipse.jdt.core.dom.IVariableBinding;
import org.eclipse.jdt.core.dom.IfStatement;
import org.eclipse.jdt.core.dom.InfixExpression;
import org.eclipse.jdt.core.dom.InfixExpression.Operator;
import org.eclipse.jdt.core.dom.InstanceofExpression;
import org.eclipse.jdt.core.dom.LambdaExpression;
import org.eclipse.jdt.core.dom.MethodDeclaration;
import org.eclipse.jdt.core.dom.MethodInvocation;
import org.eclipse.jdt.core.dom.Modifier;
import org.eclipse.jdt.core.dom.Name;
import org.eclipse.jdt.core.dom.ParenthesizedExpression;
import org.eclipse.jdt.core.dom.PrefixExpression;
import org.eclipse.jdt.core.dom.PrimitiveType;
import org.eclipse.jdt.core.dom.QualifiedName;
import org.eclipse.jdt.core.dom.ReturnStatement;
import org.eclipse.jdt.core.dom.SimpleName;
import org.eclipse.jdt.core.dom.SingleVariableDeclaration;
import org.eclipse.jdt.core.dom.Statement;
import org.eclipse.jdt.core.dom.StringLiteral;
import org.eclipse.jdt.core.dom.StructuralPropertyDescriptor;
import org.eclipse.jdt.core.dom.SuperConstructorInvocation;
import org.eclipse.jdt.core.dom.SuperMethodInvocation;
import org.eclipse.jdt.core.dom.SwitchCase;
import org.eclipse.jdt.core.dom.SwitchStatement;
import org.eclipse.jdt.core.dom.ThrowStatement;
import org.eclipse.jdt.core.dom.Type;
import org.eclipse.jdt.core.dom.VariableDeclarationFragment;
import org.eclipse.jdt.core.dom.VariableDeclarationStatement;
import org.eclipse.jdt.core.dom.WhileStatement;
import org.eclipse.jdt.core.dom.rewrite.ASTRewrite;
import org.eclipse.jdt.core.dom.rewrite.ImportRewrite;
import org.eclipse.jdt.core.dom.rewrite.ImportRewrite.ImportRewriteContext;
import org.eclipse.jdt.core.dom.rewrite.ImportRewrite.TypeLocation;
import org.eclipse.jdt.core.dom.rewrite.ListRewrite;

import org.eclipse.jdt.internal.core.manipulation.dom.ASTResolving;
import org.eclipse.jdt.internal.corext.codemanipulation.ContextSensitiveImportRewriteContext;
import org.eclipse.jdt.internal.corext.codemanipulation.StubUtility;
import org.eclipse.jdt.internal.corext.dom.ASTNodes;
import org.eclipse.jdt.internal.corext.dom.GenericVisitor;
import org.eclipse.jdt.internal.corext.dom.LinkedNodeFinder;
import org.eclipse.jdt.internal.corext.dom.NecessaryParenthesesChecker;
import org.eclipse.jdt.internal.corext.dom.StatementRewrite;
import org.eclipse.jdt.internal.corext.fix.CleanUpConstants;
import org.eclipse.jdt.internal.corext.fix.ExpressionsFix;
import org.eclipse.jdt.internal.corext.fix.IProposableFix;
import org.eclipse.jdt.internal.corext.refactoring.code.Invocations;
import org.eclipse.jdt.internal.corext.refactoring.code.OperatorPrecedence;
import org.eclipse.jdt.internal.corext.refactoring.util.NoCommentSourceRangeComputer;
import org.eclipse.jdt.internal.corext.refactoring.util.TightSourceRangeComputer;
import org.eclipse.jdt.internal.corext.util.JavaModelUtil;
import org.eclipse.jdt.internal.corext.util.Messages;

import org.eclipse.jdt.ui.cleanup.CleanUpOptions;
import org.eclipse.jdt.ui.text.java.IInvocationContext;
import org.eclipse.jdt.ui.text.java.IJavaCompletionProposal;
import org.eclipse.jdt.ui.text.java.IProblemLocation;
import org.eclipse.jdt.ui.text.java.IQuickAssistProcessor;
import org.eclipse.jdt.ui.text.java.correction.ASTRewriteCorrectionProposal;
import org.eclipse.jdt.ui.text.java.correction.ICommandAccess;

import org.eclipse.jdt.internal.ui.JavaPluginImages;
import org.eclipse.jdt.internal.ui.fix.ExpressionsCleanUp;
import org.eclipse.jdt.internal.ui.text.correction.proposals.FixCorrectionProposal;
import org.eclipse.jdt.internal.ui.text.correction.proposals.LinkedCorrectionProposal;

/**
 */
public class AdvancedQuickAssistProcessor implements IQuickAssistProcessor {
	public AdvancedQuickAssistProcessor() {
		super();
	}

	@Override
	public boolean hasAssists(IInvocationContext context) throws CoreException {
		ASTNode coveringNode= context.getCoveringNode();
		if (coveringNode != null) {
			ArrayList<ASTNode> coveredNodes= getFullyCoveredNodes(context, coveringNode);
			return getConvertToIfReturnProposals(context, coveringNode, null)
					|| getInverseIfProposals(context, coveringNode, null)
					|| getIfReturnIntoIfElseAtEndOfVoidMethodProposals(context, coveringNode, null)
					|| getInverseIfContinueIntoIfThenInLoopsProposals(context, coveringNode, null)
					|| getInverseIfIntoContinueInLoopsProposals(context, coveringNode, null)
					|| getInverseConditionProposals(context, coveringNode, coveredNodes, null)
					|| getRemoveExtraParenthesesProposals(context, coveringNode, coveredNodes, null)
					|| getAddParanoidalParenthesesProposals(context, coveredNodes, null)
					|| getAddParenthesesForExpressionProposals(context, coveringNode, null)
					|| getJoinAndIfStatementsProposals(context, coveringNode, null)
					|| getSplitAndConditionProposals(context, coveringNode, null)
					|| getJoinOrIfStatementsProposals(context, coveringNode, coveredNodes, null)
					|| getSplitOrConditionProposals(context, coveringNode, null)
					|| getInverseConditionalExpressionProposals(context, coveringNode, null)
					|| getExchangeInnerAndOuterIfConditionsProposals(context, coveringNode, null)
					|| getExchangeOperandsProposals(context, coveringNode, null)
					|| getCastAndAssignIfStatementProposals(context, coveringNode, null)
					|| getCombineStringProposals(context, coveringNode, null)
					|| getPickOutStringProposals(context, coveringNode, null)
					|| getReplaceIfElseWithConditionalProposals(context, coveringNode, null)
					|| getReplaceConditionalWithIfElseProposals(context, coveringNode, null)
					|| getInverseLocalVariableProposals(context, coveringNode, null)
					|| getPushNegationDownProposals(context, coveringNode, null)
					|| getPullNegationUpProposals(context, coveredNodes, null)
					|| getJoinIfListInIfElseIfProposals(context, coveringNode, coveredNodes, null)
					|| getConvertSwitchToIfProposals(context, coveringNode, null)
					|| getConvertIfElseToSwitchProposals(context, coveringNode, null)
					|| GetterSetterCorrectionSubProcessor.addGetterSetterProposal(context, coveringNode, null, null);
		}
		return false;
	}

	@Override
	public IJavaCompletionProposal[] getAssists(IInvocationContext context, IProblemLocation[] locations) throws CoreException {
		ASTNode coveringNode= context.getCoveringNode();
		if (coveringNode != null) {
			ArrayList<ASTNode> coveredNodes= getFullyCoveredNodes(context, coveringNode);
			ArrayList<ICommandAccess> resultingCollections= new ArrayList<>();

			//quick assists that show up also if there is an error/warning
			getReplaceConditionalWithIfElseProposals(context, coveringNode, resultingCollections);

			if (QuickAssistProcessor.noErrorsAtLocation(locations)) {
				getConvertToIfReturnProposals(context, coveringNode, resultingCollections);
				getInverseIfProposals(context, coveringNode, resultingCollections);
				getIfReturnIntoIfElseAtEndOfVoidMethodProposals(context, coveringNode, resultingCollections);
				getInverseIfContinueIntoIfThenInLoopsProposals(context, coveringNode, resultingCollections);
				getInverseIfIntoContinueInLoopsProposals(context, coveringNode, resultingCollections);
				getInverseConditionProposals(context, coveringNode, coveredNodes, resultingCollections);
				getRemoveExtraParenthesesProposals(context, coveringNode, coveredNodes, resultingCollections);
				getAddParanoidalParenthesesProposals(context, coveredNodes, resultingCollections);
				getAddParenthesesForExpressionProposals(context, coveringNode, resultingCollections);
				getJoinAndIfStatementsProposals(context, coveringNode, resultingCollections);
				getSplitAndConditionProposals(context, coveringNode, resultingCollections);
				getJoinOrIfStatementsProposals(context, coveringNode, coveredNodes, resultingCollections);
				getSplitOrConditionProposals(context, coveringNode, resultingCollections);
				getInverseConditionalExpressionProposals(context, coveringNode, resultingCollections);
				getExchangeInnerAndOuterIfConditionsProposals(context, coveringNode, resultingCollections);
				getExchangeOperandsProposals(context, coveringNode, resultingCollections);
				getCastAndAssignIfStatementProposals(context, coveringNode, resultingCollections);
				getCombineStringProposals(context, coveringNode, resultingCollections);
				getPickOutStringProposals(context, coveringNode, resultingCollections);
				getReplaceIfElseWithConditionalProposals(context, coveringNode, resultingCollections);
				getInverseLocalVariableProposals(context, coveringNode, resultingCollections);
				getPushNegationDownProposals(context, coveringNode, resultingCollections);
				getPullNegationUpProposals(context, coveredNodes, resultingCollections);
				getJoinIfListInIfElseIfProposals(context, coveringNode, coveredNodes, resultingCollections);
				getConvertSwitchToIfProposals(context, coveringNode, resultingCollections);
				getConvertIfElseToSwitchProposals(context, coveringNode, resultingCollections);
				GetterSetterCorrectionSubProcessor.addGetterSetterProposal(context, coveringNode, locations, resultingCollections);
			}

			return resultingCollections.toArray(new IJavaCompletionProposal[resultingCollections.size()]);
		}
		return null;
	}

	private static boolean getConvertToIfReturnProposals(IInvocationContext context, ASTNode coveringNode, ArrayList<ICommandAccess> resultingCollections) {
		if (!(coveringNode instanceof IfStatement)) {
			return false;
		}
		IfStatement ifStatement= (IfStatement) coveringNode;
		if (ifStatement.getElseStatement() != null) {
			return false;
		}

		// enclosing lambda or method should return 'void'
		LambdaExpression enclosingLambda= ASTResolving.findEnclosingLambdaExpression(ifStatement);
		if (enclosingLambda != null) {
			IMethodBinding lambdaMethodBinding= enclosingLambda.resolveMethodBinding();
			if (lambdaMethodBinding == null) {
				return false;
			}
			if (!(ifStatement.getAST().resolveWellKnownType("void").equals(lambdaMethodBinding.getReturnType()))) { //$NON-NLS-1$
				return false;
			}
		} else {
			MethodDeclaration coveringMethod= ASTResolving.findParentMethodDeclaration(ifStatement);
			if (coveringMethod == null) {
				return false;
			}
			Type returnType= coveringMethod.getReturnType2();
			if (!isVoid(returnType)) {
				return false;
			}
		}

		// should be present in a block
		if (!(ifStatement.getParent() instanceof Block)) {
			return false;
		}
		// should have at least one statement in 'then' part other than 'return'
		Statement thenStatement= ifStatement.getThenStatement();
		if (thenStatement instanceof ReturnStatement) {
			return false;
		}
		if (thenStatement instanceof Block) {
			List<Statement> thenStatements= ((Block) thenStatement).statements();
			if (thenStatements.isEmpty() || (thenStatements.size() == 1 && (thenStatements.get(0) instanceof ReturnStatement))) {
				return false;
			}
		}
		// should have no further executable statement
		if (!isLastStatementInEnclosingMethodOrLambda(ifStatement)) {
			return false;
		}
		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}

		AST ast= coveringNode.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);

		// create inverted 'if' statement
		Expression inversedExpression= getInversedExpression(rewrite, ifStatement.getExpression());
		IfStatement newIf= ast.newIfStatement();
		newIf.setExpression(inversedExpression);
		newIf.setThenStatement(ast.newReturnStatement());
		ListRewrite listRewriter= rewrite.getListRewrite(ifStatement.getParent(), (ChildListPropertyDescriptor) ifStatement.getLocationInParent());
		listRewriter.replace(ifStatement, newIf, null);
		// remove last 'return' in 'then' block
		ArrayList<Statement> statements= getUnwrappedStatements(ifStatement.getThenStatement());
		Statement lastStatement= statements.get(statements.size() - 1);
		if (lastStatement instanceof ReturnStatement) {
			statements.remove(lastStatement);
		}
		// add statements from 'then' to the end of block
		for (Statement statement : statements) {
			listRewriter.insertLast(rewrite.createMoveTarget(statement), null);
		}

		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_convertToIfReturn;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.CONVERT_TO_IF_RETURN, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean isVoid(Type type) {
		return type instanceof PrimitiveType && ((PrimitiveType) type).getPrimitiveTypeCode() == PrimitiveType.VOID;
	}

	private static boolean isLastStatementInEnclosingMethodOrLambda(Statement statement) {
		ASTNode currentStructure= statement;
		ASTNode currentParent= statement.getParent();
		while (!(currentParent instanceof MethodDeclaration || currentParent instanceof LambdaExpression)) {
			// should not be in a loop
			if (currentParent instanceof ForStatement || currentParent instanceof EnhancedForStatement
					|| currentParent instanceof WhileStatement || currentParent instanceof DoStatement) {
				return false;
			}
			if (currentParent instanceof Block) {
				Block parentBlock= (Block) currentParent;
				if (parentBlock.statements().indexOf(currentStructure) != parentBlock.statements().size() - 1) { // not last statement in the block
					return false;
				}
			}
			currentStructure= currentParent;
			currentParent= currentParent.getParent();
		}
		return true;
	}

	private static boolean getIfReturnIntoIfElseAtEndOfVoidMethodProposals(IInvocationContext context, ASTNode covering, Collection<ICommandAccess> resultingCollections) {
		if (!(covering instanceof IfStatement)) {
			return false;
		}
		IfStatement ifStatement= (IfStatement) covering;
		if (ifStatement.getElseStatement() != null) {
			return false;
		}
		// 'then' block should have 'return' as last statement
		Statement thenStatement= ifStatement.getThenStatement();
		if (!(thenStatement instanceof Block)) {
			return false;
		}
		Block thenBlock= (Block) thenStatement;
		List<Statement> thenStatements= thenBlock.statements();
		if (thenStatements.isEmpty() || !(thenStatements.get(thenStatements.size() - 1) instanceof ReturnStatement)) {
			return false;
		}
		// method should return 'void'
		MethodDeclaration coveringMetod= ASTResolving.findParentMethodDeclaration(covering);
		if (coveringMetod == null) {
			return false;
		}
		Type returnType= coveringMetod.getReturnType2();
		if (!isVoid(returnType)) {
			return false;
		}
		//
		List<Statement> statements= coveringMetod.getBody().statements();
		int ifIndex= statements.indexOf(ifStatement);
		if (ifIndex == -1) {
			return false;
		}
		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}
		//
		AST ast= covering.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);
		// remove last 'return' in 'then' block
		ListRewrite listRewriter= rewrite.getListRewrite(thenBlock, (ChildListPropertyDescriptor) ifStatement.getLocationInParent());
		listRewriter.remove(thenStatements.get(thenStatements.size() - 1), null);
		// prepare original nodes
		Expression conditionPlaceholder= (Expression) rewrite.createMoveTarget(ifStatement.getExpression());
		Statement thenPlaceholder= (Statement) rewrite.createMoveTarget(ifStatement.getThenStatement());
		// prepare 'else' block
		Block elseBlock= ast.newBlock();
		for (int i= ifIndex + 1; i < statements.size(); i++) {
			Statement statement= statements.get(i);
			elseBlock.statements().add(rewrite.createMoveTarget(statement));
		}
		// prepare new 'if' statement
		IfStatement newIf= ast.newIfStatement();
		newIf.setExpression(conditionPlaceholder);
		newIf.setThenStatement(thenPlaceholder);
		newIf.setElseStatement(elseBlock);
		rewrite.replace(ifStatement, newIf, null);
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_convertToIfElse_description;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.CONVERT_TO_IF_ELSE, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean getInverseIfProposals(IInvocationContext context, ASTNode covering, Collection<ICommandAccess> resultingCollections) {
		if (!(covering instanceof IfStatement)) {
			return false;
		}
		IfStatement ifStatement= (IfStatement) covering;
		if (ifStatement.getElseStatement() == null) {
			return false;
		}
		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}
		//
		AST ast= covering.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);
		Statement thenStatement= ifStatement.getThenStatement();
		Statement elseStatement= ifStatement.getElseStatement();

		// prepare original nodes
		Expression inversedExpression= getInversedExpression(rewrite, ifStatement.getExpression());

		Statement newElseStatement= (Statement) rewrite.createMoveTarget(thenStatement);
		Statement newThenStatement= (Statement) rewrite.createMoveTarget(elseStatement);
		// set new nodes
		rewrite.set(ifStatement, IfStatement.EXPRESSION_PROPERTY, inversedExpression, null);

		if (elseStatement instanceof IfStatement) {// bug 79507 && bug 74580
			Block elseBlock= ast.newBlock();
			elseBlock.statements().add(newThenStatement);
			newThenStatement= elseBlock;
		}
		rewrite.set(ifStatement, IfStatement.THEN_STATEMENT_PROPERTY, newThenStatement, null);
		rewrite.set(ifStatement, IfStatement.ELSE_STATEMENT_PROPERTY, newElseStatement, null);
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_inverseIf_description;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.INVERSE_IF_STATEMENT, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean getInverseIfContinueIntoIfThenInLoopsProposals(IInvocationContext context, ASTNode covering, Collection<ICommandAccess> resultingCollections) {
		if (!(covering instanceof IfStatement)) {
			return false;
		}
		IfStatement ifStatement= (IfStatement) covering;
		if (ifStatement.getElseStatement() != null) {
			return false;
		}
		// check that 'then' is 'continue'
		if (!(ifStatement.getThenStatement() instanceof ContinueStatement)) {
			return false;
		}
		// check that 'if' statement is statement in block that is body of loop
		Block loopBlock= null;
		if (ifStatement.getParent() instanceof Block && ifStatement.getParent().getParent() instanceof ForStatement) {
			loopBlock= (Block) ifStatement.getParent();
		} else if (ifStatement.getParent() instanceof Block && ifStatement.getParent().getParent() instanceof WhileStatement) {
			loopBlock= (Block) ifStatement.getParent();
		} else {
			return false;
		}
		if (resultingCollections == null) {
			return true;
		}
		//
		AST ast= covering.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);
		// create inverted 'if' statement
		Expression inversedExpression= getInversedExpression(rewrite, ifStatement.getExpression());
		IfStatement newIf= ast.newIfStatement();
		newIf.setExpression(inversedExpression);
		// prepare 'then' for new 'if'
		Block thenBlock= ast.newBlock();
		int ifIndex= loopBlock.statements().indexOf(ifStatement);
		for (int i= ifIndex + 1; i < loopBlock.statements().size(); i++) {
			Statement statement= (Statement) loopBlock.statements().get(i);
			thenBlock.statements().add(rewrite.createMoveTarget(statement));
		}
		newIf.setThenStatement(thenBlock);
		// replace 'if' statement in loop
		rewrite.replace(ifStatement, newIf, null);
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_inverseIfContinue_description;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.INVERSE_IF_CONTINUE, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean getInverseIfIntoContinueInLoopsProposals(IInvocationContext context, ASTNode covering, Collection<ICommandAccess> resultingCollections) {
		if (!(covering instanceof IfStatement)) {
			return false;
		}
		IfStatement ifStatement= (IfStatement) covering;
		if (ifStatement.getElseStatement() != null) {
			return false;
		}
		// prepare outer control structure and block that contains 'if' statement
		ASTNode ifParent= ifStatement.getParent();
		Block ifParentBlock= null;
		ASTNode ifParentStructure= ifParent;
		if (ifParentStructure instanceof Block) {
			ifParentBlock= (Block) ifParent;
			ifParentStructure= ifParentStructure.getParent();
		}
		// check that control structure is loop and 'if' statement if last statement
		if (!(ifParentStructure instanceof ForStatement) && !(ifParentStructure instanceof WhileStatement)) {
			return false;
		}
		if (ifParentBlock != null && ifParentBlock.statements().indexOf(ifStatement) != ifParentBlock.statements().size() - 1) {
			return false;
		}
		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}
		//
		AST ast= covering.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);
		// create inverted 'if' statement
		Expression inversedExpression= getInversedExpression(rewrite, ifStatement.getExpression());
		IfStatement newIf= ast.newIfStatement();
		newIf.setExpression(inversedExpression);
		newIf.setThenStatement(ast.newContinueStatement());
		//
		if (ifParentBlock == null) {
			// if there is no block, create it
			ifParentBlock= ast.newBlock();
			ifParentBlock.statements().add(newIf);
			for (Iterator<Statement> iter= getUnwrappedStatements(ifStatement.getThenStatement()).iterator(); iter.hasNext();) {
				Statement statement= iter.next();
				ifParentBlock.statements().add(rewrite.createMoveTarget(statement));
			}
			// replace 'if' statement as body with new block
			if (ifParentStructure instanceof ForStatement) {
				rewrite.set(ifParentStructure, ForStatement.BODY_PROPERTY, ifParentBlock, null);
			} else if (ifParentStructure instanceof WhileStatement) {
				rewrite.set(ifParentStructure, WhileStatement.BODY_PROPERTY, ifParentBlock, null);
			}
		} else {
			// if there was block, replace
			ListRewrite listRewriter= rewrite.getListRewrite(ifParentBlock, (ChildListPropertyDescriptor) ifStatement.getLocationInParent());
			listRewriter.replace(ifStatement, newIf, null);
			// add statements from 'then' to the end of block
			for (Iterator<Statement> iter= getUnwrappedStatements(ifStatement.getThenStatement()).iterator(); iter.hasNext();) {
				Statement statement= iter.next();
				listRewriter.insertLast(rewrite.createMoveTarget(statement), null);
			}
		}
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_inverseIfToContinue_description;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.INVERT_IF_TO_CONTINUE, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static ArrayList<Statement> getUnwrappedStatements(Statement body) {
		ArrayList<Statement> statements= new ArrayList<>();
		if (body instanceof Block) {
			for (Iterator<Statement> iter= ((Block) body).statements().iterator(); iter.hasNext();) {
				Statement statement= iter.next();
				statements.add(statement);
			}
		} else {
			statements.add(body);
		}
		return statements;
	}

	private static boolean getInverseConditionProposals(IInvocationContext context, ASTNode covering, ArrayList<ASTNode> coveredNodes, Collection<ICommandAccess> resultingCollections) {
		if (coveredNodes.isEmpty()) {
			return false;
		}
		//
		final AST ast= covering.getAST();
		final ASTRewrite rewrite= ASTRewrite.create(ast);
		// check sub-expressions in fully covered nodes
		boolean hasChanges= false;
		for (Iterator<ASTNode> iter= coveredNodes.iterator(); iter.hasNext();) {
			ASTNode covered= iter.next();
			Expression coveredExpression= getBooleanExpression(covered);
			if (coveredExpression != null) {
				Expression inversedExpression= getInversedExpression(rewrite, coveredExpression);
				rewrite.replace(coveredExpression, inversedExpression, null);
				hasChanges= true;
			}
		}
		//
		if (!hasChanges) {
			return false;
		}
		if (resultingCollections == null) {
			return true;
		}
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_inverseConditions_description;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.INVERSE_CONDITIONS, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static Expression getInversedExpression(ASTRewrite rewrite, Expression expression) {
		return getInversedExpression(rewrite, expression, null);
	}
	private interface SimpleNameRenameProvider {
		SimpleName getRenamed(SimpleName name);
	}

	private static Expression getRenamedNameCopy(SimpleNameRenameProvider provider, ASTRewrite rewrite, Expression expression) {
		if (provider != null) {
			if (expression instanceof SimpleName) {
				SimpleName name= (SimpleName) expression;
				SimpleName newName= provider.getRenamed(name);
				if (newName != null) {
					return newName;
				}
			}
		}
		return (Expression) rewrite.createCopyTarget(expression);
	}

	private static Expression getInversedExpression(ASTRewrite rewrite, Expression expression, SimpleNameRenameProvider provider) {
		AST ast= rewrite.getAST();
		//
		if (expression instanceof BooleanLiteral) {
			return ast.newBooleanLiteral(!((BooleanLiteral) expression).booleanValue());
		}
		if (expression instanceof InfixExpression) {
			InfixExpression infixExpression= (InfixExpression) expression;
			InfixExpression.Operator operator= infixExpression.getOperator();
			if (operator == InfixExpression.Operator.LESS) {
				return getInversedInfixExpression(rewrite, infixExpression, InfixExpression.Operator.GREATER_EQUALS, provider);
			}
			if (operator == InfixExpression.Operator.GREATER) {
				return getInversedInfixExpression(rewrite, infixExpression, InfixExpression.Operator.LESS_EQUALS, provider);
			}
			if (operator == InfixExpression.Operator.LESS_EQUALS) {
				return getInversedInfixExpression(rewrite, infixExpression, InfixExpression.Operator.GREATER, provider);
			}
			if (operator == InfixExpression.Operator.GREATER_EQUALS) {
				return getInversedInfixExpression(rewrite, infixExpression, InfixExpression.Operator.LESS, provider);
			}
			if (operator == InfixExpression.Operator.EQUALS) {
				return getInversedInfixExpression(rewrite, infixExpression, InfixExpression.Operator.NOT_EQUALS, provider);
			}
			if (operator == InfixExpression.Operator.NOT_EQUALS) {
				return getInversedInfixExpression(rewrite, infixExpression, InfixExpression.Operator.EQUALS, provider);
			}
			if (operator == InfixExpression.Operator.CONDITIONAL_AND) {
				return getInversedAndOrExpression(rewrite, infixExpression, InfixExpression.Operator.CONDITIONAL_OR, provider);
			}
			if (operator == InfixExpression.Operator.CONDITIONAL_OR) {
				return getInversedAndOrExpression(rewrite, infixExpression, InfixExpression.Operator.CONDITIONAL_AND, provider);
			}
			if (operator == InfixExpression.Operator.AND) {
				return getInversedAndOrExpression(rewrite, infixExpression, InfixExpression.Operator.OR, provider);
			}
			if (operator == InfixExpression.Operator.OR) {
				return getInversedAndOrExpression(rewrite, infixExpression, InfixExpression.Operator.AND, provider);
			}
			if (operator == InfixExpression.Operator.XOR) {
				return getInversedNotExpression(rewrite, expression, ast);
			}
		}
		if (expression instanceof PrefixExpression) {
			PrefixExpression prefixExpression= (PrefixExpression) expression;
			if (prefixExpression.getOperator() == PrefixExpression.Operator.NOT) {
				Expression operand= prefixExpression.getOperand();
				if ((operand instanceof ParenthesizedExpression)
						&& NecessaryParenthesesChecker.canRemoveParentheses(operand, expression.getParent(), expression.getLocationInParent())) {
					operand= ((ParenthesizedExpression)operand).getExpression();
				}
				Expression renamedNameCopy= getRenamedNameCopy(provider, rewrite, operand);
				if (renamedNameCopy instanceof InfixExpression) {
					InfixExpression infixExpression= (InfixExpression) renamedNameCopy;
					infixExpression.setOperator(((InfixExpression) operand).getOperator());
				}
				return renamedNameCopy;
			}
		}
		if (expression instanceof InstanceofExpression) {
			return getInversedNotExpression(rewrite, expression, ast);
		}
		if (expression instanceof ParenthesizedExpression) {
			ParenthesizedExpression parenthesizedExpression= (ParenthesizedExpression) expression;
			Expression innerExpression= parenthesizedExpression.getExpression();
			while (innerExpression instanceof ParenthesizedExpression) {
				innerExpression= ((ParenthesizedExpression) innerExpression).getExpression();
			}
			if (innerExpression instanceof InstanceofExpression) {
				return getInversedExpression(rewrite, innerExpression, provider);
			}
			parenthesizedExpression= getParenthesizedExpression(ast, getInversedExpression(rewrite, innerExpression, provider));
			return parenthesizedExpression;
		}
		if (expression instanceof ConditionalExpression) {
			ConditionalExpression conditionalExpression= (ConditionalExpression)expression;
			ConditionalExpression newExpression= ast.newConditionalExpression();
			newExpression.setExpression((Expression)rewrite.createCopyTarget(conditionalExpression.getExpression()));
			newExpression.setThenExpression(getInversedExpression(rewrite, conditionalExpression.getThenExpression()));
			newExpression.setElseExpression(getInversedExpression(rewrite, conditionalExpression.getElseExpression()));
			return newExpression;
		}

		PrefixExpression prefixExpression= ast.newPrefixExpression();
		prefixExpression.setOperator(PrefixExpression.Operator.NOT);
		Expression renamedNameCopy= getRenamedNameCopy(provider, rewrite, expression);
		if (NecessaryParenthesesChecker.needsParentheses(renamedNameCopy, prefixExpression, PrefixExpression.OPERAND_PROPERTY)) {
			renamedNameCopy= getParenthesizedExpression(ast, renamedNameCopy);
		}
		prefixExpression.setOperand(renamedNameCopy);
		return prefixExpression;
	}

	private static Expression getInversedNotExpression(ASTRewrite rewrite, Expression expression, AST ast) {
		PrefixExpression prefixExpression= ast.newPrefixExpression();
		prefixExpression.setOperator(PrefixExpression.Operator.NOT);
		ParenthesizedExpression parenthesizedExpression= getParenthesizedExpression(ast, (Expression)rewrite.createCopyTarget(expression));
		prefixExpression.setOperand(parenthesizedExpression);
		return prefixExpression;
	}

	private static boolean isBoolean(Expression expression) {
		ITypeBinding typeBinding= expression.resolveTypeBinding();
		AST ast= expression.getAST();
		return typeBinding == ast.resolveWellKnownType("boolean") //$NON-NLS-1$
				|| typeBinding == ast.resolveWellKnownType("java.lang.Boolean"); //$NON-NLS-1$
	}

	private static Expression getInversedInfixExpression(ASTRewrite rewrite, InfixExpression expression, InfixExpression.Operator newOperator, SimpleNameRenameProvider provider) {
		InfixExpression newExpression= rewrite.getAST().newInfixExpression();
		newExpression.setOperator(newOperator);
		newExpression.setLeftOperand(getRenamedNameCopy(provider, rewrite, expression.getLeftOperand()));
		newExpression.setRightOperand(getRenamedNameCopy(provider, rewrite, expression.getRightOperand()));
		return newExpression;
	}

	private static Expression parenthesizeIfRequired(Expression operand, int newOperatorPrecedence) {
		if (newOperatorPrecedence > OperatorPrecedence.getExpressionPrecedence(operand)) {
			return getParenthesizedExpression(operand.getAST(), operand);
		}
		return operand;
	}

	private static Expression getInversedAndOrExpression(ASTRewrite rewrite, InfixExpression infixExpression, Operator newOperator, SimpleNameRenameProvider provider) {
		InfixExpression newExpression= rewrite.getAST().newInfixExpression();
		newExpression.setOperator(newOperator);

		int newOperatorPrecedence= OperatorPrecedence.getOperatorPrecedence(newOperator);
		//
		Expression leftOperand= getInversedExpression(rewrite, infixExpression.getLeftOperand(), provider);
		newExpression.setLeftOperand(parenthesizeIfRequired(leftOperand, newOperatorPrecedence));

		Expression rightOperand= getInversedExpression(rewrite, infixExpression.getRightOperand(), provider);
		newExpression.setRightOperand(parenthesizeIfRequired(rightOperand, newOperatorPrecedence));

		List<Expression> extraOperands= infixExpression.extendedOperands();
		List<Expression> newExtraOperands= newExpression.extendedOperands();
		for (int i= 0; i < extraOperands.size(); i++) {
			Expression extraOperand= getInversedExpression(rewrite, extraOperands.get(i), provider);
			newExtraOperands.add(parenthesizeIfRequired(extraOperand, newOperatorPrecedence));
		}
		return newExpression;
	}

	private static boolean getRemoveExtraParenthesesProposals(IInvocationContext context, ASTNode covering, ArrayList<ASTNode> coveredNodes, Collection<ICommandAccess> resultingCollections) {
		ArrayList<ASTNode> nodes;
		if (context.getSelectionLength() == 0 && covering instanceof ParenthesizedExpression) {
			nodes= new ArrayList<>();
			nodes.add(covering);
		} else {
			nodes= coveredNodes;
		}
		if (nodes.isEmpty())
			return false;

		IProposableFix fix= ExpressionsFix.createRemoveUnnecessaryParenthesisFix(context.getASTRoot(), nodes.toArray(new ASTNode[nodes.size()]));
		if (fix == null)
			return false;

		if (resultingCollections == null)
			return true;

		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_REMOVE);
		Map<String, String> options= new Hashtable<>();
		options.put(CleanUpConstants.EXPRESSIONS_USE_PARENTHESES, CleanUpOptions.TRUE);
		options.put(CleanUpConstants.EXPRESSIONS_USE_PARENTHESES_NEVER, CleanUpOptions.TRUE);
		FixCorrectionProposal proposal= new FixCorrectionProposal(fix, new ExpressionsCleanUp(options), IProposalRelevance.REMOVE_EXTRA_PARENTHESES, image, context);
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean getAddParanoidalParenthesesProposals(IInvocationContext context, ArrayList<ASTNode> coveredNodes, Collection<ICommandAccess> resultingCollections) {

		IProposableFix fix= ExpressionsFix.createAddParanoidalParenthesisFix(context.getASTRoot(), coveredNodes.toArray(new ASTNode[coveredNodes.size()]));
		if (fix == null)
			return false;

		if (resultingCollections == null)
			return true;

		// add correction proposal
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CAST);
		Map<String, String> options= new Hashtable<>();
		options.put(CleanUpConstants.EXPRESSIONS_USE_PARENTHESES, CleanUpOptions.TRUE);
		options.put(CleanUpConstants.EXPRESSIONS_USE_PARENTHESES_ALWAYS, CleanUpOptions.TRUE);
		FixCorrectionProposal proposal= new FixCorrectionProposal(fix, new ExpressionsCleanUp(options), IProposalRelevance.ADD_PARANOIDAL_PARENTHESES, image, context);
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean getAddParenthesesForExpressionProposals(IInvocationContext context, ASTNode coveringNode, Collection<ICommandAccess> resultingCollections) {
		ASTNode node;

		if (context.getSelectionLength() == 0) {
			node= coveringNode;
			while (node != null && !(node instanceof CastExpression) && !(node instanceof InfixExpression) && !(node instanceof InstanceofExpression) && !(node instanceof ConditionalExpression)) {
				node= node.getParent();
			}
		} else {
			node= context.getCoveredNode();
		}

		String label= null;
		if (node instanceof CastExpression) {
			label= CorrectionMessages.UnresolvedElementsSubProcessor_missingcastbrackets_description;
		} else if (node instanceof InstanceofExpression) {
			label= CorrectionMessages.LocalCorrectionsSubProcessor_setparenteses_instanceof_description;
		} else if (node instanceof InfixExpression) {
			InfixExpression infixExpression= (InfixExpression)node;
			label= Messages.format(CorrectionMessages.LocalCorrectionsSubProcessor_setparenteses_description, infixExpression.getOperator().toString());
		} else if (node instanceof ConditionalExpression) {
			label= CorrectionMessages.AdvancedQuickAssistProcessor_putConditionalExpressionInParentheses;
		} else {
			return false;
		}

		if (node.getParent() instanceof ParenthesizedExpression)
			return false;

		if (resultingCollections == null)
			return true;

		AST ast= node.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);

		ParenthesizedExpression parenthesizedExpression= ast.newParenthesizedExpression();
		parenthesizedExpression.setExpression((Expression)rewrite.createCopyTarget(node));
		rewrite.replace(node, parenthesizedExpression, null);

		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CAST);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.ADD_PARENTHESES_FOR_EXPRESSION, image);
		resultingCollections.add(proposal);
		return true;
	}

	static ArrayList<ASTNode> getFullyCoveredNodes(IInvocationContext context, ASTNode coveringNode) {
		final ArrayList<ASTNode> coveredNodes= new ArrayList<>();
		final int selectionBegin= context.getSelectionOffset();
		final int selectionEnd= selectionBegin + context.getSelectionLength();
		coveringNode.accept(new GenericVisitor() {
			@Override
			protected boolean visitNode(ASTNode node) {
				int nodeStart= node.getStartPosition();
				int nodeEnd= nodeStart + node.getLength();
				// if node does not intersects with selection, don't visit children
				if (nodeEnd < selectionBegin || selectionEnd < nodeStart) {
					return false;
				}
				// if node is fully covered, we don't need to visit children
				if (isCovered(node)) {
					ASTNode parent= node.getParent();
					if (parent == null || !isCovered(parent)) {
						coveredNodes.add(node);
						return false;
					}
				}
				// if node only partly intersects with selection, we try to find fully covered children
				return true;
			}

			private boolean isCovered(ASTNode node) {
				int begin= node.getStartPosition();
				int end= begin + node.getLength();
				return begin >= selectionBegin && end <= selectionEnd;
			}
		});
		return coveredNodes;
	}

	private static boolean getJoinAndIfStatementsProposals(IInvocationContext context, ASTNode node, Collection<ICommandAccess> resultingCollections) {

		//
		if (!(node instanceof IfStatement)) {
			return false;
		}
		IfStatement ifStatement= (IfStatement) node;
		if (ifStatement.getElseStatement() != null) {
			return false;
		}
		// case when current IfStatement is sole child of another IfStatement
		{
			IfStatement outerIf= null;
			if (ifStatement.getParent() instanceof IfStatement) {
				outerIf= (IfStatement) ifStatement.getParent();
			} else if (ifStatement.getParent() instanceof Block) {
				Block block= (Block) ifStatement.getParent();
				if (block.getParent() instanceof IfStatement && block.statements().size() == 1) {
					outerIf= (IfStatement) block.getParent();
				}
			}
			if (outerIf != null && outerIf.getElseStatement() == null) {
				if (resultingCollections == null) {
					return true;
				}
				//
				AST ast= node.getAST();
				ASTRewrite rewrite= ASTRewrite.create(ast);
				// create compound condition
				InfixExpression condition= ast.newInfixExpression();
				condition.setOperator(InfixExpression.Operator.CONDITIONAL_AND);
				// prepare condition parts, add parentheses if needed
				Expression outerCondition= getParenthesizedExpressionIfNeeded(ast, rewrite, outerIf.getExpression(), condition, InfixExpression.LEFT_OPERAND_PROPERTY);
				Expression innerCondition= getParenthesizedExpressionIfNeeded(ast, rewrite, ifStatement.getExpression(), condition, InfixExpression.RIGHT_OPERAND_PROPERTY);
				condition.setLeftOperand(outerCondition);
				condition.setRightOperand(innerCondition);
				// create new IfStatement
				IfStatement newIf= ast.newIfStatement();
				newIf.setExpression(condition);
				Statement bodyPlaceholder= (Statement) rewrite.createCopyTarget(ifStatement.getThenStatement());
				newIf.setThenStatement(bodyPlaceholder);
				rewrite.setTargetSourceRangeComputer(new NoCommentSourceRangeComputer());
				rewrite.replace(outerIf, newIf, null);
				// add correction proposal
				String label= CorrectionMessages.AdvancedQuickAssistProcessor_joinWithOuter_description;
				Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
				ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.JOIN_IF_WITH_OUTER_IF, image);
				resultingCollections.add(proposal);
			}
		}
		// case when current IfStatement has another IfStatement as sole child
		{
			IfStatement innerIf= null;
			if (ifStatement.getThenStatement() instanceof IfStatement) {
				innerIf= (IfStatement) ifStatement.getThenStatement();
			} else if (ifStatement.getThenStatement() instanceof Block) {
				Block block= (Block) ifStatement.getThenStatement();
				if (block.statements().size() == 1 && block.statements().get(0) instanceof IfStatement) {
					innerIf= (IfStatement) block.statements().get(0);
				}
			}
			if (innerIf != null && innerIf.getElseStatement() == null) {
				if (resultingCollections == null) {
					return true;
				}
				//
				AST ast= node.getAST();
				ASTRewrite rewrite= ASTRewrite.create(ast);
				// create compound condition
				InfixExpression condition= ast.newInfixExpression();
				condition.setOperator(InfixExpression.Operator.CONDITIONAL_AND);
				// prepare condition parts, add parentheses if needed
				Expression outerCondition= getParenthesizedExpressionIfNeeded(ast, rewrite, ifStatement.getExpression(), condition, InfixExpression.LEFT_OPERAND_PROPERTY);
				Expression innerCondition= getParenthesizedExpressionIfNeeded(ast, rewrite, innerIf.getExpression(), condition, InfixExpression.RIGHT_OPERAND_PROPERTY);
				condition.setLeftOperand(outerCondition);
				condition.setRightOperand(innerCondition);
				// create new IfStatement
				IfStatement newIf= ast.newIfStatement();
				newIf.setExpression(condition);
				Statement bodyPlaceholder= (Statement) rewrite.createCopyTarget(innerIf.getThenStatement());
				newIf.setThenStatement(bodyPlaceholder);
				rewrite.setTargetSourceRangeComputer(new NoCommentSourceRangeComputer());
				rewrite.replace(ifStatement, newIf, null);
				// add correction proposal
				String label= CorrectionMessages.AdvancedQuickAssistProcessor_joinWithInner_description;
				Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
				ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.JOIN_IF_WITH_INNER_IF, image);
				resultingCollections.add(proposal);
			}
		}
		return true;
	}

	private static Expression getParenthesizedExpressionIfNeeded(AST ast, ASTRewrite rewrite, Expression expression, ASTNode parent, StructuralPropertyDescriptor locationInParent) {
		boolean addParentheses= NecessaryParenthesesChecker.needsParentheses(expression, parent, locationInParent);
		expression= (Expression)rewrite.createCopyTarget(expression);
		if (addParentheses) {
			return getParenthesizedExpression(ast, expression);
		}
		return expression;
	}

	private static ParenthesizedExpression getParenthesizedExpression(AST ast, Expression expression) {
		ParenthesizedExpression parenthesizedExpression= ast.newParenthesizedExpression();
		parenthesizedExpression.setExpression(expression);
		return parenthesizedExpression;
	}

	public static boolean getSplitAndConditionProposals(IInvocationContext context, ASTNode node, Collection<ICommandAccess> resultingCollections) {
		Operator andOperator= InfixExpression.Operator.CONDITIONAL_AND;
		// check that user invokes quick assist on infix expression
		if (!(node instanceof InfixExpression)) {
			return false;
		}
		InfixExpression infixExpression= (InfixExpression) node;
		if (infixExpression.getOperator() != andOperator) {
			return false;
		}
		int offset= isOperatorSelected(infixExpression, context.getSelectionOffset(), context.getSelectionLength());
		if (offset == -1) {
			return false;
		}

		// check that infix expression belongs to IfStatement
		Statement statement= ASTResolving.findParentStatement(node);
		if (!(statement instanceof IfStatement)) {
			return false;
		}
		IfStatement ifStatement= (IfStatement) statement;

		// check that infix expression is part of first level && condition of IfStatement
		InfixExpression topInfixExpression= infixExpression;
		while (topInfixExpression.getParent() instanceof InfixExpression && ((InfixExpression) topInfixExpression.getParent()).getOperator() == andOperator) {
			topInfixExpression= (InfixExpression) topInfixExpression.getParent();
		}
		if (ifStatement.getExpression() != topInfixExpression) {
			return false;
		}
		//
		if (resultingCollections == null) {
			return true;
		}
		AST ast= ifStatement.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);

		// prepare left and right conditions
		Expression[] newOperands= { null, null };
		breakInfixOperationAtOperation(rewrite, topInfixExpression, andOperator, offset, true, newOperands);

		Expression leftCondition= newOperands[0];
		Expression rightCondition= newOperands[1];

		// replace conditions in outer IfStatement
		rewrite.set(ifStatement, IfStatement.EXPRESSION_PROPERTY, leftCondition, null);
		
		// prepare inner IfStatement
		IfStatement innerIf= ast.newIfStatement();
		
		innerIf.setExpression(rightCondition);
		innerIf.setThenStatement((Statement) rewrite.createMoveTarget(ifStatement.getThenStatement()));
		Block innerBlock= ast.newBlock();
		innerBlock.statements().add(innerIf);
		
		Statement elseStatement= ifStatement.getElseStatement();
		if (elseStatement != null) {
			innerIf.setElseStatement((Statement) rewrite.createCopyTarget(elseStatement));
		}
		
		// replace outer thenStatement
		rewrite.replace(ifStatement.getThenStatement(), innerBlock, null);
		
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_splitAndCondition_description;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.SPLIT_AND_CONDITION, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean isSelectingOperator(ASTNode n1, ASTNode n2, int offset, int length) {
		// between the nodes
		if (offset + length <= n2.getStartPosition() && offset >= ASTNodes.getExclusiveEnd(n1)) {
			return true;
		}
		// or exactly select the node (but not with infix expressions)
		if (n1.getStartPosition() == offset && ASTNodes.getExclusiveEnd(n2) == offset + length) {
			if (n1 instanceof InfixExpression || n2 instanceof InfixExpression) {
				return false;
			}
			return true;
		}
		return false;
	}

	private static int isOperatorSelected(InfixExpression infixExpression, int offset, int length) {
		ASTNode left= infixExpression.getLeftOperand();
		ASTNode right= infixExpression.getRightOperand();

		if (isSelectingOperator(left, right, offset, length)) {
			return ASTNodes.getExclusiveEnd(left);
		}
		List<Expression> extended= infixExpression.extendedOperands();
		for (int i= 0; i < extended.size(); i++) {
			left= right;
			right= extended.get(i);
			if (isSelectingOperator(left, right, offset, length)) {
				return ASTNodes.getExclusiveEnd(left);
			}
		}
		return -1;
	}

	private static boolean getJoinOrIfStatementsProposals(IInvocationContext context, ASTNode covering, ArrayList<ASTNode> coveredNodes, Collection<ICommandAccess> resultingCollections) {
		Operator orOperator= InfixExpression.Operator.CONDITIONAL_OR;
		if (coveredNodes.size() < 2)
			return false;
		// check that all covered nodes are IfStatement's with same 'then' statement and without 'else'
		String commonThenSource= null;
		for (Iterator<ASTNode> iter= coveredNodes.iterator(); iter.hasNext();) {
			ASTNode node= iter.next();
			if (!(node instanceof IfStatement))
				return false;
			//
			IfStatement ifStatement= (IfStatement) node;
			if (ifStatement.getElseStatement() != null)
				return false;
			//
			Statement thenStatement= ifStatement.getThenStatement();
			try {
				String thenSource= context.getCompilationUnit().getBuffer().getText(thenStatement.getStartPosition(), thenStatement.getLength());
				if (commonThenSource == null) {
					commonThenSource= thenSource;
				} else {
					if (!commonThenSource.equals(thenSource))
						return false;
				}
			} catch (Throwable e) {
				return false;
			}
		}
		if (resultingCollections == null) {
			return true;
		}
		//
		final AST ast= covering.getAST();
		final ASTRewrite rewrite= ASTRewrite.create(ast);
		// prepare OR'ed condition
		InfixExpression condition= null;
		boolean hasRightOperand= false;
		Statement thenStatement= null;
		for (Iterator<ASTNode> iter= coveredNodes.iterator(); iter.hasNext();) {
			IfStatement ifStatement= (IfStatement) iter.next();
			if (thenStatement == null)
				thenStatement= (Statement) rewrite.createCopyTarget(ifStatement.getThenStatement());
			if (condition == null) {
				condition= ast.newInfixExpression();
				condition.setOperator(orOperator);
				condition.setLeftOperand(getParenthesizedExpressionIfNeeded(ast, rewrite, ifStatement.getExpression(), condition, InfixExpression.LEFT_OPERAND_PROPERTY));
			} else if (!hasRightOperand) {
				condition.setRightOperand(getParenthesizedExpressionIfNeeded(ast, rewrite, ifStatement.getExpression(), condition, InfixExpression.RIGHT_OPERAND_PROPERTY));
				hasRightOperand= true;
			} else {
				InfixExpression newCondition= ast.newInfixExpression();
				newCondition.setOperator(orOperator);
				newCondition.setLeftOperand(condition);
				newCondition.setRightOperand(getParenthesizedExpressionIfNeeded(ast, rewrite, ifStatement.getExpression(), condition, InfixExpression.RIGHT_OPERAND_PROPERTY));
				condition= newCondition;
			}
		}
		// prepare new IfStatement with OR'ed condition
		IfStatement newIf= ast.newIfStatement();
		newIf.setExpression(condition);
		newIf.setThenStatement(thenStatement);
		//
		ListRewrite listRewriter= null;
		for (Iterator<ASTNode> iter= coveredNodes.iterator(); iter.hasNext();) {
			IfStatement ifStatement= (IfStatement) iter.next();
			if (listRewriter == null) {
				Block sourceBlock= (Block) ifStatement.getParent();
				//int insertIndex = sourceBlock.statements().indexOf(ifStatement);
				listRewriter= rewrite.getListRewrite(sourceBlock, (ChildListPropertyDescriptor) ifStatement.getLocationInParent());
			}
			if (newIf != null) {
				listRewriter.replace(ifStatement, newIf, null);
				newIf= null;
			} else {
				listRewriter.remove(ifStatement, null);
			}
		}
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_joinWithOr_description;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.JOIN_IF_STATEMENTS_WITH_OR, image);
		resultingCollections.add(proposal);
		return true;
	}

	public static boolean getSplitOrConditionProposals(IInvocationContext context, ASTNode node, Collection<ICommandAccess> resultingCollections) {
		Operator orOperator= InfixExpression.Operator.CONDITIONAL_OR;
		// check that user invokes quick assist on infix expression
		if (!(node instanceof InfixExpression)) {
			return false;
		}
		InfixExpression infixExpression= (InfixExpression) node;
		if (infixExpression.getOperator() != orOperator) {
			return false;
		}
		int offset= isOperatorSelected(infixExpression, context.getSelectionOffset(), context.getSelectionLength());
		if (offset == -1) {
			return false;
		}
		// check that infix expression belongs to IfStatement
		Statement statement= ASTResolving.findParentStatement(node);
		if (!(statement instanceof IfStatement)) {
			return false;
		}
		IfStatement ifStatement= (IfStatement) statement;

		// check that infix expression is part of first level || condition of IfStatement
		InfixExpression topInfixExpression= infixExpression;
		while (topInfixExpression.getParent() instanceof InfixExpression && ((InfixExpression) topInfixExpression.getParent()).getOperator() == orOperator) {
			topInfixExpression= (InfixExpression) topInfixExpression.getParent();
		}
		if (ifStatement.getExpression() != topInfixExpression) {
			return false;
		}
		//
		if (resultingCollections == null) {
			return true;
		}
		AST ast= ifStatement.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);

		// prepare left and right conditions
		Expression[] newOperands= { null, null };
		breakInfixOperationAtOperation(rewrite, topInfixExpression, orOperator, offset, true, newOperands);

		Expression leftCondition= newOperands[0];
		Expression rightCondition= newOperands[1];

		// prepare first statement
		rewrite.replace(ifStatement.getExpression(), leftCondition, null);

		IfStatement secondIf= ast.newIfStatement();
		secondIf.setExpression(rightCondition);
		secondIf.setThenStatement((Statement) rewrite.createCopyTarget(ifStatement.getThenStatement()));

		Statement elseStatement= ifStatement.getElseStatement();
		if (elseStatement == null) {
			rewrite.set(ifStatement, IfStatement.ELSE_STATEMENT_PROPERTY, secondIf, null);
		} else {
			rewrite.replace(elseStatement, secondIf, null);
			secondIf.setElseStatement((Statement) rewrite.createMoveTarget(elseStatement));
		}

		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_splitOrCondition_description;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.SPLIT_OR_CONDITION, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean getInverseConditionalExpressionProposals(IInvocationContext context, ASTNode covering, Collection<ICommandAccess> resultingCollections) {
		// try to find conditional expression as parent
		while (covering instanceof Expression) {
			if (covering instanceof ConditionalExpression)
				break;
			covering= covering.getParent();
		}
		if (!(covering instanceof ConditionalExpression)) {
			return false;
		}
		ConditionalExpression expression= (ConditionalExpression) covering;
		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}
		//
		AST ast= covering.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);
		// prepare new conditional expression
		ConditionalExpression newExpression= ast.newConditionalExpression();
		newExpression.setExpression(getInversedExpression(rewrite, expression.getExpression()));
		newExpression.setThenExpression((Expression) rewrite.createCopyTarget(expression.getElseExpression()));
		newExpression.setElseExpression((Expression) rewrite.createCopyTarget(expression.getThenExpression()));
		// replace old expression with new
		rewrite.replace(expression, newExpression, null);
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_inverseConditionalExpression_description;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.INVERSE_CONDITIONAL_EXPRESSION, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean getExchangeInnerAndOuterIfConditionsProposals(IInvocationContext context, ASTNode node, Collection<ICommandAccess> resultingCollections) {
		boolean result= false;
		//
		if (!(node instanceof IfStatement)) {
			return false;
		}
		IfStatement ifStatement= (IfStatement) node;
		if (ifStatement.getElseStatement() != null) {
			return false;
		}
		// case when current IfStatement is sole child of another IfStatement
		{
			IfStatement outerIf= null;
			if (ifStatement.getParent() instanceof IfStatement) {
				outerIf= (IfStatement) ifStatement.getParent();
			} else if (ifStatement.getParent() instanceof Block) {
				Block block= (Block) ifStatement.getParent();
				if (block.getParent() instanceof IfStatement && block.statements().size() == 1) {
					outerIf= (IfStatement) block.getParent();
				}
			}
			if (outerIf != null && outerIf.getElseStatement() == null) {
				if (resultingCollections == null) {
					return true;
				}
				//
				AST ast= node.getAST();
				ASTRewrite rewrite= ASTRewrite.create(ast);
				// prepare conditions
				Expression outerCondition= (Expression) rewrite.createCopyTarget(outerIf.getExpression());
				Expression innerCondition= (Expression) rewrite.createCopyTarget(ifStatement.getExpression());
				// exchange conditions
				rewrite.replace(outerIf.getExpression(), innerCondition, null);
				rewrite.replace(ifStatement.getExpression(), outerCondition, null);
				// add correction proposal
				String label= CorrectionMessages.AdvancedQuickAssistProcessor_exchangeInnerAndOuterIfConditions_description;
				Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
				ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.EXCHANGE_INNER_AND_OUTER_IF_CONDITIONS, image);
				resultingCollections.add(proposal);
				result= true;
			}
		}
		// case when current IfStatement has another IfStatement as sole child
		{
			IfStatement innerIf= null;
			if (ifStatement.getThenStatement() instanceof IfStatement) {
				innerIf= (IfStatement) ifStatement.getThenStatement();
			} else if (ifStatement.getThenStatement() instanceof Block) {
				Block block= (Block) ifStatement.getThenStatement();
				if (block.statements().size() == 1 && block.statements().get(0) instanceof IfStatement) {
					innerIf= (IfStatement) block.statements().get(0);
				}
			}
			if (innerIf != null && innerIf.getElseStatement() == null) {
				if (resultingCollections == null) {
					return true;
				}
				//
				AST ast= node.getAST();
				ASTRewrite rewrite= ASTRewrite.create(ast);
				// prepare conditions
				Expression innerCondition= (Expression) rewrite.createCopyTarget(innerIf.getExpression());
				Expression outerCondition= (Expression) rewrite.createCopyTarget(ifStatement.getExpression());
				// exchange conditions
				rewrite.replace(innerIf.getExpression(), outerCondition, null);
				rewrite.replace(ifStatement.getExpression(), innerCondition, null);
				// add correction proposal
				String label= CorrectionMessages.AdvancedQuickAssistProcessor_exchangeInnerAndOuterIfConditions_description;
				Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
				ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.EXCHANGE_INNER_AND_OUTER_IF_CONDITIONS, image);
				resultingCollections.add(proposal);
				result= true;
			}
		}
		return result;
	}

	private static boolean getExchangeOperandsProposals(IInvocationContext context, ASTNode node, Collection<ICommandAccess> resultingCollections) {
		// check that user invokes quick assist on infix expression
		if (!(node instanceof InfixExpression)) {
			return false;
		}
		InfixExpression infixExpression= (InfixExpression)node;
		Operator operator= infixExpression.getOperator();
		if (operator != InfixExpression.Operator.CONDITIONAL_AND && operator != InfixExpression.Operator.AND
				&& operator != InfixExpression.Operator.CONDITIONAL_OR && operator != InfixExpression.Operator.OR
				&& operator != InfixExpression.Operator.EQUALS && operator != InfixExpression.Operator.NOT_EQUALS
				&& operator != InfixExpression.Operator.LESS && operator != InfixExpression.Operator.LESS_EQUALS
				&& operator != InfixExpression.Operator.GREATER && operator != InfixExpression.Operator.GREATER_EQUALS
				&& operator != InfixExpression.Operator.PLUS && operator != InfixExpression.Operator.TIMES
				&& operator != InfixExpression.Operator.XOR) {
			return false;
		}

		int offset= isOperatorSelected(infixExpression, context.getSelectionOffset(), context.getSelectionLength());
		if (offset == -1) {
			return false;
		}

		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}
		AST ast= infixExpression.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);
		// prepare left and right expressions
		Expression leftExpression= null;
		Expression rightExpression= null;
		InfixExpression currentExpression= infixExpression;
		leftExpression= combineOperands(rewrite, leftExpression, infixExpression.getLeftOperand(), false, operator);
		if (infixExpression.getRightOperand().getStartPosition() <= context.getSelectionOffset()) {
			leftExpression= combineOperands(rewrite, leftExpression, infixExpression.getRightOperand(), false, operator);
		} else {
			rightExpression= combineOperands(rewrite, rightExpression, infixExpression.getRightOperand(), false, operator);
		}
		for (Iterator<Expression> iter= currentExpression.extendedOperands().iterator(); iter.hasNext();) {
			Expression extendedOperand= iter.next();
			if (extendedOperand.getStartPosition() <= context.getSelectionOffset()) {
				leftExpression= combineOperands(rewrite, leftExpression, extendedOperand, false, operator);
			} else {
				rightExpression= combineOperands(rewrite, rightExpression, extendedOperand, false, operator);
			}
		}

		if (NecessaryParenthesesChecker.needsParentheses(leftExpression, infixExpression, InfixExpression.RIGHT_OPERAND_PROPERTY)) {
			leftExpression= getParenthesizedExpression(ast, leftExpression);
		}
		if (NecessaryParenthesesChecker.needsParentheses(rightExpression, infixExpression, InfixExpression.LEFT_OPERAND_PROPERTY)) {
			rightExpression= getParenthesizedExpression(ast, rightExpression);
		}

		if (operator == InfixExpression.Operator.LESS) {
			operator= InfixExpression.Operator.GREATER;
		} else if (operator == InfixExpression.Operator.LESS_EQUALS) {
			operator= InfixExpression.Operator.GREATER_EQUALS;
		} else if (operator == InfixExpression.Operator.GREATER) {
			operator= InfixExpression.Operator.LESS;
		} else if (operator == InfixExpression.Operator.GREATER_EQUALS) {
			operator= InfixExpression.Operator.LESS_EQUALS;
		}

		// create new infix expression
		InfixExpression newInfix= ast.newInfixExpression();
		newInfix.setOperator(operator);
		newInfix.setLeftOperand(rightExpression);
		newInfix.setRightOperand(leftExpression);
		rewrite.replace(infixExpression, newInfix, null);
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_exchangeOperands_description;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.EXCHANGE_OPERANDS, image);
		resultingCollections.add(proposal);
		return true;
	}

	/*
	 * Breaks an infix operation with possible extended operators at the given operator and returns the new left and right operands.
	 * a & b & c   ->  [[a' & b' ] & c' ]   (c' == copy of c)
	 */
	private static void breakInfixOperationAtOperation(ASTRewrite rewrite, Expression expression, Operator operator, int operatorOffset, boolean removeParentheses, Expression[] res) {
		if (expression.getStartPosition() + expression.getLength() <= operatorOffset) {
			// add to the left
			res[0]= combineOperands(rewrite, res[0], expression, removeParentheses, operator);
			return;
		}
		if (operatorOffset <= expression.getStartPosition()) {
			// add to the right
			res[1]= combineOperands(rewrite, res[1], expression, removeParentheses, operator);
			return;
		}
		if (!(expression instanceof InfixExpression)) {
			throw new IllegalArgumentException("Cannot break up non-infix expression"); //$NON-NLS-1$
		}
		InfixExpression infixExpression= (InfixExpression) expression;
		if (infixExpression.getOperator() != operator) {
			throw new IllegalArgumentException("Incompatible operator"); //$NON-NLS-1$
		}
		breakInfixOperationAtOperation(rewrite, infixExpression.getLeftOperand(), operator, operatorOffset, removeParentheses, res);
		breakInfixOperationAtOperation(rewrite, infixExpression.getRightOperand(), operator, operatorOffset, removeParentheses, res);

		List<Expression> extended= infixExpression.extendedOperands();
		for (int i= 0; i < extended.size(); i++) {
			breakInfixOperationAtOperation(rewrite, extended.get(i), operator, operatorOffset, removeParentheses, res);
		}
	}

	private static Expression combineOperands(ASTRewrite rewrite, Expression existing, Expression originalNode, boolean removeParentheses, Operator operator) {
		if (existing == null && removeParentheses) {
			while (originalNode instanceof ParenthesizedExpression) {
				originalNode= ((ParenthesizedExpression)originalNode).getExpression();
			}
		}
		Expression newRight= (Expression)rewrite.createMoveTarget(originalNode);
		if (originalNode instanceof InfixExpression) {
			((InfixExpression)newRight).setOperator(((InfixExpression)originalNode).getOperator());
		}

		if (existing == null) {
			return newRight;
		}
		AST ast= rewrite.getAST();
		InfixExpression infix= ast.newInfixExpression();
		infix.setOperator(operator);
		infix.setLeftOperand(existing);
		infix.setRightOperand(newRight);
		return infix;
	}

	private static boolean getCastAndAssignIfStatementProposals(IInvocationContext context, ASTNode node, Collection<ICommandAccess> resultingCollections) {
		if (node instanceof IfStatement) {
			node= ((IfStatement)node).getExpression();
		} else if (node instanceof WhileStatement) {
			node= ((WhileStatement)node).getExpression();
		} else if (node instanceof Block) {
			List<Statement> statements= ((Block)node).statements();
			if (statements.size() > 0) {
				if (context.getSelectionOffset() > statements.get(0).getStartPosition()) {
					return false;
				}
			}
			ASTNode parent= node.getParent();
			Expression expression= null;
			if (parent instanceof IfStatement) {
				expression= ((IfStatement)parent).getExpression();
			} else if (parent instanceof WhileStatement) {
				expression= ((WhileStatement)parent).getExpression();
			} else {
				return false;
			}

			if (expression instanceof InstanceofExpression) {
				node= expression;
			} else {
				final ArrayList<InstanceofExpression> nodes= new ArrayList<>();
				expression.accept(new ASTVisitor() {
					@Override
					public boolean visit(InstanceofExpression instanceofExpression) {
						nodes.add(instanceofExpression);
						return false;
					}
				});

				if (nodes.size() != 1) {
					return false;
				}
				node= nodes.get(0);
			}
		} else {
			while (node != null && !(node instanceof InstanceofExpression) && !(node instanceof Statement)) {
				node= node.getParent();
			}
		}

		if (!(node instanceof InstanceofExpression)) {
			return false;
		}
		InstanceofExpression expression= (InstanceofExpression)node;
		// test that we are the expression of a 'while' or 'if'
		while (node.getParent() instanceof Expression) {
			node= node.getParent();
		}
		StructuralPropertyDescriptor locationInParent= node.getLocationInParent();

		boolean negated= isNegated(expression);

		Statement body= null;
		ASTNode insertionPosition= null;
		if (negated) {
			insertionPosition= node.getParent();
			if (locationInParent == IfStatement.EXPRESSION_PROPERTY) {
				body= ((IfStatement)node.getParent()).getElseStatement();
				if (body != null) {
					negated= false;
				}
			}
			if (body == null && insertionPosition.getParent() instanceof Block) {
				body= (Statement)insertionPosition.getParent();
			}
		} else {
			if (locationInParent == IfStatement.EXPRESSION_PROPERTY) {
				body= ((IfStatement)node.getParent()).getThenStatement();
			} else if (locationInParent == WhileStatement.EXPRESSION_PROPERTY) {
				body= ((WhileStatement)node.getParent()).getBody();
			}
		}
		if (body == null) {
			return false;
		}

		Type originalType= expression.getRightOperand();
		if (originalType.resolveBinding() == null) {
			return false;
		}

		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}

		final String KEY_NAME= "name"; //$NON-NLS-1$
		final String KEY_TYPE= "type"; //$NON-NLS-1$
		//
		AST ast= expression.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);
		ICompilationUnit cu= context.getCompilationUnit();
		// prepare correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_castAndAssign;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_LOCAL);
		LinkedCorrectionProposal proposal= new LinkedCorrectionProposal(label, cu, rewrite, IProposalRelevance.CAST_AND_ASSIGN, image);
		// prepare possible variable names
		List<String> excludedNames= Arrays.asList(ASTResolving.getUsedVariableNames(body));
		String[] varNames= suggestLocalVariableNames(cu, originalType.resolveBinding(), excludedNames);
		for (int i= 0; i < varNames.length; i++) {
			proposal.addLinkedPositionProposal(KEY_NAME, varNames[i], null);
		}
		CastExpression castExpression= ast.newCastExpression();
		castExpression.setExpression((Expression)rewrite.createCopyTarget(expression.getLeftOperand()));
		castExpression.setType((Type)ASTNode.copySubtree(ast, originalType));
		// prepare new variable declaration
		VariableDeclarationFragment vdf= ast.newVariableDeclarationFragment();
		vdf.setName(ast.newSimpleName(varNames[0]));
		vdf.setInitializer(castExpression);
		// prepare new variable declaration statement
		VariableDeclarationStatement vds= ast.newVariableDeclarationStatement(vdf);
		vds.setType((Type)ASTNode.copySubtree(ast, originalType));

		// add new variable declaration statement
		if (negated) {
			ListRewrite listRewriter= rewrite.getListRewrite(body, Block.STATEMENTS_PROPERTY);
			listRewriter.insertAfter(vds, insertionPosition, null);
		} else {
			if (body instanceof Block) {
				ListRewrite listRewriter= rewrite.getListRewrite(body, Block.STATEMENTS_PROPERTY);
				listRewriter.insertAt(vds, 0, null);
			} else {
				Block newBlock= ast.newBlock();
				List<Statement> statements= newBlock.statements();
				statements.add(vds);
				statements.add((Statement) rewrite.createMoveTarget(body));
				rewrite.replace(body, newBlock, null);
			}
		}

		// setup linked positions
		proposal.addLinkedPosition(rewrite.track(vdf.getName()), true, KEY_NAME);
		proposal.addLinkedPosition(rewrite.track(vds.getType()), false, KEY_TYPE);
		proposal.addLinkedPosition(rewrite.track(castExpression.getType()), false, KEY_TYPE);
		proposal.setEndPosition(rewrite.track(vds)); // set cursor after expression statement
		// add correction proposal
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean isNegated(Expression expression) {
		if (!(expression.getParent() instanceof ParenthesizedExpression))
			return false;

		ParenthesizedExpression parenthesis= (ParenthesizedExpression) expression.getParent();
		if (!(parenthesis.getParent() instanceof PrefixExpression))
			return false;

		PrefixExpression prefix= (PrefixExpression) parenthesis.getParent();
		if (!(prefix.getOperator() == PrefixExpression.Operator.NOT))
			return false;

		return true;
	}

	private static String[] suggestLocalVariableNames(ICompilationUnit cu, ITypeBinding binding, List<String> excluded) {
		return StubUtility.getVariableNameSuggestions(NamingConventions.VK_LOCAL, cu.getJavaProject(), binding, null, excluded);
	}

	private static boolean getCombineStringProposals(IInvocationContext context, ASTNode node, Collection<ICommandAccess> resultingCollections) {
		// we work with InfixExpressions
		InfixExpression infixExpression;
		if (node instanceof InfixExpression) {
			infixExpression= (InfixExpression) node;
		} else if (node.getParent() instanceof InfixExpression) {
			infixExpression= (InfixExpression) node.getParent();
		} else {
			return false;
		}
		
		
		// only + is valid for combining strings
		if (!(infixExpression.getOperator().equals(InfixExpression.Operator.PLUS))) {
			return false;
		}
		
		// all expressions must be strings
		Expression leftOperand= infixExpression.getLeftOperand();
		Expression rightOperand= infixExpression.getRightOperand();
		if (!(leftOperand instanceof StringLiteral && rightOperand instanceof StringLiteral)) {
			return false;
		}
		
		StringLiteral leftString= (StringLiteral) leftOperand;
		StringLiteral rightString= (StringLiteral) rightOperand;
		
		if (resultingCollections == null) {
			return true;
		}
		
		// begin building combined string
		StringBuilder stringBuilder= new StringBuilder(leftString.getLiteralValue());
		stringBuilder.append(rightString.getLiteralValue());
		
		// append extended string literals
		for (Object operand : infixExpression.extendedOperands()) {
			if (!(operand instanceof StringLiteral))
				return false;
			StringLiteral stringLiteral= (StringLiteral) operand;
			stringBuilder.append(stringLiteral.getLiteralValue());
		}
		
		// prepare new string literal
		AST ast= node.getAST();
		StringLiteral combinedStringLiteral= ast.newStringLiteral();
		combinedStringLiteral.setLiteralValue(stringBuilder.toString());
		
		ASTRewrite rewrite= ASTRewrite.create(ast);
		rewrite.replace(infixExpression, combinedStringLiteral, null);
		
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_combineSelectedStrings;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		LinkedCorrectionProposal proposal= new LinkedCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.COMBINE_STRINGS, image);
		resultingCollections.add(proposal);
		return true;
	}
	
	private static boolean getPickOutStringProposals(IInvocationContext context, ASTNode node, Collection<ICommandAccess> resultingCollections) {
		// we work with String's
		if (!(node instanceof StringLiteral)) {
			return false;
		}
		// user should select part of String
		int selectionPos= context.getSelectionOffset();
		int selectionLen= context.getSelectionLength();
		if (selectionLen == 0) {
			return false;
		}
		int valueStart= node.getStartPosition() + 1;
		int valueEnd= node.getStartPosition() + node.getLength() - 1;

		// selection must be inside node and the quotes and not contain the full value
		if (selectionPos < valueStart || selectionPos + selectionLen > valueEnd || valueEnd - valueStart == selectionLen) {
			return false;
		}

		// prepare string parts positions
		StringLiteral stringLiteral= (StringLiteral) node;
		String stringValue= stringLiteral.getEscapedValue();

		int firstPos= selectionPos - node.getStartPosition();
		int secondPos= firstPos + selectionLen;


		// prepare new string literals

		AST ast= node.getAST();
		StringLiteral leftLiteral= ast.newStringLiteral();
		StringLiteral centerLiteral= ast.newStringLiteral();
		StringLiteral rightLiteral= ast.newStringLiteral();
		try {
			leftLiteral.setEscapedValue('"' + stringValue.substring(1, firstPos) + '"');
			centerLiteral.setEscapedValue('"' + stringValue.substring(firstPos, secondPos) + '"');
			rightLiteral.setEscapedValue('"' + stringValue.substring(secondPos, stringValue.length() - 1) + '"');
		} catch (IllegalArgumentException e) {
			return false;
		}
		if (resultingCollections == null) {
			return true;
		}

		ASTRewrite rewrite= ASTRewrite.create(ast);

		// prepare new expression instead of StringLiteral
		InfixExpression expression= ast.newInfixExpression();
		expression.setOperator(InfixExpression.Operator.PLUS);
		if (firstPos != 1) {
			expression.setLeftOperand(leftLiteral);
		}


		if (firstPos == 1) {
			expression.setLeftOperand(centerLiteral);
		} else {
			expression.setRightOperand(centerLiteral);
		}

		if (secondPos < stringValue.length() - 1) {
			if (firstPos == 1) {
				expression.setRightOperand(rightLiteral);
			} else {
				expression.extendedOperands().add(rightLiteral);
			}
		}
		// use new expression instead of old StirngLiteral
		rewrite.replace(stringLiteral, expression, null);
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_pickSelectedString;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		LinkedCorrectionProposal proposal= new LinkedCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.PICK_SELECTED_STRING, image);
		proposal.addLinkedPosition(rewrite.track(centerLiteral), true, "CENTER_STRING"); //$NON-NLS-1$
		resultingCollections.add(proposal);
		return true;
	}

	private static Statement getSingleStatement(Statement statement) {
		if (statement instanceof Block) {
			List<Statement> blockStatements= ((Block) statement).statements();
			if (blockStatements.size() != 1) {
				return null;
			}
			return blockStatements.get(0);
		}
		return statement;
	}

	private static boolean getReplaceIfElseWithConditionalProposals(IInvocationContext context, ASTNode node, Collection<ICommandAccess> resultingCollections) {
		if (!(node instanceof IfStatement)) {
			return false;
		}
		IfStatement ifStatement= (IfStatement) node;
		Statement thenStatement= getSingleStatement(ifStatement.getThenStatement());
		Statement elseStatement= getSingleStatement(ifStatement.getElseStatement());
		if (thenStatement == null || elseStatement == null) {
			return false;
		}
		Expression assigned= null;
		Expression thenExpression= null;
		Expression elseExpression= null;

		ITypeBinding exprBinding= null;
		if (thenStatement instanceof ReturnStatement && elseStatement instanceof ReturnStatement) {
			thenExpression= ((ReturnStatement) thenStatement).getExpression();
			elseExpression= ((ReturnStatement) elseStatement).getExpression();
			MethodDeclaration declaration= ASTResolving.findParentMethodDeclaration(node);
			if (declaration == null || declaration.isConstructor()) {
				return false;
			}
			exprBinding= declaration.getReturnType2().resolveBinding();
		} else if (thenStatement instanceof ExpressionStatement && elseStatement instanceof ExpressionStatement) {
			Expression inner1= ((ExpressionStatement) thenStatement).getExpression();
			Expression inner2= ((ExpressionStatement) elseStatement).getExpression();
			if (inner1 instanceof Assignment && inner2 instanceof Assignment) {
				Assignment assign1= (Assignment) inner1;
				Assignment assign2= (Assignment) inner2;
				Expression left1= assign1.getLeftHandSide();
				Expression left2= assign2.getLeftHandSide();
				if (left1 instanceof Name && left2 instanceof Name && assign1.getOperator() == assign2.getOperator()) {
					IBinding bind1= ((Name) left1).resolveBinding();
					IBinding bind2= ((Name) left2).resolveBinding();
					if (bind1 == bind2 && bind1 instanceof IVariableBinding) {
						assigned= left1;
						exprBinding= ((IVariableBinding) bind1).getType();
						thenExpression= assign1.getRightHandSide();
						elseExpression= assign2.getRightHandSide();
					}
				}
			}
		}
		if (thenExpression == null || elseExpression == null) {
			return false;
		}

		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}
		//
		AST ast= node.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);
		TightSourceRangeComputer sourceRangeComputer= new TightSourceRangeComputer();
		sourceRangeComputer.addTightSourceNode(ifStatement);
		rewrite.setTargetSourceRangeComputer(sourceRangeComputer);

		String label= CorrectionMessages.AdvancedQuickAssistProcessor_replaceIfWithConditional;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.REPLACE_IF_ELSE_WITH_CONDITIONAL, image);


		// prepare conditional expression
		ConditionalExpression conditionalExpression= ast.newConditionalExpression();
		Expression conditionCopy= (Expression) rewrite.createCopyTarget(ifStatement.getExpression());
		conditionalExpression.setExpression(conditionCopy);
		Expression thenCopy= (Expression) rewrite.createCopyTarget(thenExpression);
		Expression elseCopy= (Expression) rewrite.createCopyTarget(elseExpression);


		IJavaProject project= context.getCompilationUnit().getJavaProject();
		if (!JavaModelUtil.is50OrHigher(project)) {
			ITypeBinding thenBinding= thenExpression.resolveTypeBinding();
			ITypeBinding elseBinding= elseExpression.resolveTypeBinding();
			if (thenBinding != null && elseBinding != null && exprBinding != null && !elseBinding.isAssignmentCompatible(thenBinding)) {
				CastExpression castException= ast.newCastExpression();
				ImportRewrite importRewrite= proposal.createImportRewrite(context.getASTRoot());
				ImportRewriteContext importRewriteContext= new ContextSensitiveImportRewriteContext(node, importRewrite);
				castException.setType(importRewrite.addImport(exprBinding, ast, importRewriteContext, TypeLocation.CAST));
				castException.setExpression(elseCopy);
				elseCopy= castException;
			}
		} else if (JavaModelUtil.is17OrHigher(project)) {
			addExplicitTypeArgumentsIfNecessary(rewrite, proposal, thenExpression);
			addExplicitTypeArgumentsIfNecessary(rewrite, proposal, elseExpression);
		}
		conditionalExpression.setThenExpression(thenCopy);
		conditionalExpression.setElseExpression(elseCopy);

		// replace 'if' statement with conditional expression
		if (assigned == null) {
			ReturnStatement returnStatement= ast.newReturnStatement();
			returnStatement.setExpression(conditionalExpression);
			rewrite.replace(ifStatement, returnStatement, null);
		} else {
			Assignment assignment= ast.newAssignment();
			assignment.setLeftHandSide((Expression) rewrite.createCopyTarget(assigned));
			assignment.setRightHandSide(conditionalExpression);
			assignment.setOperator(((Assignment) assigned.getParent()).getOperator());

			ExpressionStatement expressionStatement= ast.newExpressionStatement(assignment);
			rewrite.replace(ifStatement, expressionStatement, null);
		}

		// add correction proposal
		resultingCollections.add(proposal);
		return true;
	}

	private static void addExplicitTypeArgumentsIfNecessary(ASTRewrite rewrite, ASTRewriteCorrectionProposal proposal, Expression invocation) {
		if (Invocations.isResolvedTypeInferredFromExpectedType(invocation)) {
			ITypeBinding[] typeArguments= Invocations.getInferredTypeArguments(invocation);
			if (typeArguments == null)
				return;
			
			ImportRewrite importRewrite= proposal.getImportRewrite();
			if (importRewrite == null) {
				importRewrite= proposal.createImportRewrite((CompilationUnit) invocation.getRoot());
			}
			ImportRewriteContext importRewriteContext= new ContextSensitiveImportRewriteContext(invocation, importRewrite);
			
			AST ast= invocation.getAST();
			ListRewrite typeArgsRewrite= Invocations.getInferredTypeArgumentsRewrite(rewrite, invocation);
			
			for (int i= 0; i < typeArguments.length; i++) {
				Type typeArgumentNode= importRewrite.addImport(typeArguments[i], ast, importRewriteContext, TypeLocation.TYPE_ARGUMENT);
				typeArgsRewrite.insertLast(typeArgumentNode, null);
			}
			
			if (invocation instanceof MethodInvocation) {
				MethodInvocation methodInvocation= (MethodInvocation) invocation;
				Expression expression= methodInvocation.getExpression();
				if (expression == null) {
					IMethodBinding methodBinding= methodInvocation.resolveMethodBinding();
					if (methodBinding != null && Modifier.isStatic(methodBinding.getModifiers())) {
						expression= ast.newName(importRewrite.addImport(methodBinding.getDeclaringClass().getTypeDeclaration(), importRewriteContext));
					} else {
						expression= ast.newThisExpression();
					}
					rewrite.set(invocation, MethodInvocation.EXPRESSION_PROPERTY, expression, null);
				}
			}
		}
	}
	
	private static ReturnStatement createReturnExpression(ASTRewrite rewrite, Expression expression) {
		AST ast= rewrite.getAST();
		ReturnStatement thenReturn= ast.newReturnStatement();
		thenReturn.setExpression((Expression) rewrite.createCopyTarget(expression));
		return thenReturn;
	}

	private static Statement createAssignmentStatement(ASTRewrite rewrite, Assignment.Operator assignmentOperator, Expression origAssignee, Expression origAssigned) {
		AST ast= rewrite.getAST();
		Assignment elseAssignment= ast.newAssignment();
		elseAssignment.setOperator(assignmentOperator);
		elseAssignment.setLeftHandSide((Expression) rewrite.createCopyTarget(origAssignee));
		elseAssignment.setRightHandSide((Expression) rewrite.createCopyTarget(origAssigned));
		ExpressionStatement statement= ast.newExpressionStatement(elseAssignment);
		return statement;
	}

	private static boolean getReplaceConditionalWithIfElseProposals(IInvocationContext context, ASTNode covering, Collection<ICommandAccess> resultingCollections) {
		ASTNode node= covering;
		while (!(node instanceof ConditionalExpression) && node instanceof Expression) {
			node= node.getParent();
		}
		if (!(node instanceof ConditionalExpression)) {
			node= covering;
			while (node != null && !(node instanceof Statement)) {
				node= node.getParent();
			}
			if (node instanceof VariableDeclarationStatement) {
				node= (ASTNode)(((VariableDeclarationStatement)node).fragments().get(0));
				node= ((VariableDeclarationFragment)node).getInitializer();
			}
			if (node instanceof ExpressionStatement) {
				node= ((ExpressionStatement)node).getExpression();
				if (node instanceof Assignment) {
					node= ((Assignment)node).getRightHandSide();
				}
			}
			if (node instanceof ReturnStatement) {
				node= ((ReturnStatement)node).getExpression();
			}
		}

		if (!(node instanceof ConditionalExpression)) {
			return false;
		}
		covering= node;

		StructuralPropertyDescriptor locationInParent= covering.getLocationInParent();
		if (locationInParent == Assignment.RIGHT_HAND_SIDE_PROPERTY) {
			if (covering.getParent().getLocationInParent() != ExpressionStatement.EXPRESSION_PROPERTY) {
				return false;
			}
		} else if (locationInParent == VariableDeclarationFragment.INITIALIZER_PROPERTY) {
			ASTNode statement= covering.getParent().getParent();
			if (!(statement instanceof VariableDeclarationStatement) || statement.getLocationInParent() != Block.STATEMENTS_PROPERTY) {
				return false;
			}
		} else if (locationInParent != ReturnStatement.EXPRESSION_PROPERTY) {
			return false;
		}

		ConditionalExpression conditional= (ConditionalExpression) covering;
		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}
		//
		AST ast= covering.getAST();
		ASTRewrite rewrite= ASTRewrite.create(ast);
		// prepare new 'if' statement
		Expression expression= conditional.getExpression();
		while (expression instanceof ParenthesizedExpression) {
			expression= ((ParenthesizedExpression) expression).getExpression();
		}
		IfStatement ifStatement= ast.newIfStatement();
		ifStatement.setExpression((Expression) rewrite.createCopyTarget(expression));
		if (locationInParent == Assignment.RIGHT_HAND_SIDE_PROPERTY) {
			Assignment assignment= (Assignment) covering.getParent();
			Expression assignee= assignment.getLeftHandSide();
			Assignment.Operator op= assignment.getOperator();

			ifStatement.setThenStatement(createAssignmentStatement(rewrite, op, assignee, conditional.getThenExpression()));
			ifStatement.setElseStatement(createAssignmentStatement(rewrite, op, assignee, conditional.getElseExpression()));

			// replace return conditional expression with if/then/else/return
			rewrite.replace(covering.getParent().getParent(), ifStatement, null);

		} else if (locationInParent == ReturnStatement.EXPRESSION_PROPERTY) {
			ifStatement.setThenStatement(createReturnExpression(rewrite, conditional.getThenExpression()));
			ifStatement.setElseStatement(createReturnExpression(rewrite, conditional.getElseExpression()));
			//
			// replace return conditional expression with if/then/else/return
			rewrite.replace(conditional.getParent(), ifStatement, null);
		} else if (locationInParent == VariableDeclarationFragment.INITIALIZER_PROPERTY) {
			VariableDeclarationFragment frag= (VariableDeclarationFragment) covering.getParent();
			Assignment.Operator op= Assignment.Operator.ASSIGN;

			Expression assignee= frag.getName();
			ifStatement.setThenStatement(createAssignmentStatement(rewrite, op, assignee, conditional.getThenExpression()));
			ifStatement.setElseStatement(createAssignmentStatement(rewrite, op, assignee, conditional.getElseExpression()));

			rewrite.set(frag, VariableDeclarationFragment.INITIALIZER_PROPERTY, null, null); // clear initializer

			ASTNode statement= frag.getParent();
			rewrite.getListRewrite(statement.getParent(), Block.STATEMENTS_PROPERTY).insertAfter(ifStatement, statement, null);
		}

		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_replaceConditionalWithIf;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.REPLACE_CONDITIONAL_WITH_IF_ELSE, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean getInverseLocalVariableProposals(IInvocationContext context, ASTNode covering, Collection<ICommandAccess> resultingCollections) {
		final AST ast= covering.getAST();
		// cursor should be placed on variable name
		if (!(covering instanceof SimpleName)) {
			return false;
		}
		SimpleName coveringName= (SimpleName) covering;
		if (!coveringName.isDeclaration()) {
			return false;
		}
		// prepare bindings
		final IBinding variableBinding= coveringName.resolveBinding();
		if (!(variableBinding instanceof IVariableBinding)) {
			return false;
		}
		IVariableBinding binding= (IVariableBinding) variableBinding;
		if (binding.isField()) {
			return false;
		}
		// we operate only on boolean variable
		if (!isBoolean(coveringName)) {
			return false;
		}
		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}
		// find linked nodes
		final MethodDeclaration method= ASTResolving.findParentMethodDeclaration(covering);
		SimpleName[] linkedNodes= LinkedNodeFinder.findByBinding(method, variableBinding);
		//
		final ASTRewrite rewrite= ASTRewrite.create(ast);
		// create proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_inverseBooleanVariable;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		final String KEY_NAME= "name"; //$NON-NLS-1$
		final LinkedCorrectionProposal proposal= new LinkedCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.INVERSE_BOOLEAN_VARIABLE, image);
		// prepare new variable identifier
		final String oldIdentifier= coveringName.getIdentifier();
		final String notString= Messages.format(CorrectionMessages.AdvancedQuickAssistProcessor_negatedVariableName, ""); //$NON-NLS-1$
		final String newIdentifier;
		if (oldIdentifier.startsWith(notString)) {
			int notLength= notString.length();
			if (oldIdentifier.length() > notLength) {
				newIdentifier= Character.toLowerCase(oldIdentifier.charAt(notLength)) + oldIdentifier.substring(notLength + 1);
			} else {
				newIdentifier= oldIdentifier;
			}
		} else {
			newIdentifier= Messages.format(CorrectionMessages.AdvancedQuickAssistProcessor_negatedVariableName, Character.toUpperCase(oldIdentifier.charAt(0)) + oldIdentifier.substring(1));
		}
		//
		proposal.addLinkedPositionProposal(KEY_NAME, newIdentifier, null);
		proposal.addLinkedPositionProposal(KEY_NAME, oldIdentifier, null);
		// iterate over linked nodes and replace variable references with negated reference
		final HashSet<SimpleName> renamedNames= new HashSet<>();
		for (int i= 0; i < linkedNodes.length; i++) {
			SimpleName name= linkedNodes[i];
			if (renamedNames.contains(name)) {
				continue;
			}
			// prepare new name with new identifier
			SimpleName newName= ast.newSimpleName(newIdentifier);
			proposal.addLinkedPosition(rewrite.track(newName), name == coveringName, KEY_NAME);
			//
			StructuralPropertyDescriptor location= name.getLocationInParent();
			if (location == SingleVariableDeclaration.NAME_PROPERTY) {
				// set new name
				rewrite.replace(name, newName, null);
			} else if (location == Assignment.LEFT_HAND_SIDE_PROPERTY) {
				Assignment assignment= (Assignment) name.getParent();
				Expression expression= assignment.getRightHandSide();
				int exStart= expression.getStartPosition();
				int exEnd= exStart + expression.getLength();
				// collect all names that are used in assignments
				HashSet<SimpleName> overlapNames= new HashSet<>();
				for (int j= 0; j < linkedNodes.length; j++) {
					SimpleName name2= linkedNodes[j];
					if (name2 == null) {
						continue;
					}
					int name2Start= name2.getStartPosition();
					if (exStart <= name2Start && name2Start < exEnd) {
						overlapNames.add(name2);
					}
				}
				// prepare inverted expression
				SimpleNameRenameProvider provider= new SimpleNameRenameProvider() {
					@Override
					public SimpleName getRenamed(SimpleName simpleName) {
						if (simpleName.resolveBinding() == variableBinding) {
							renamedNames.add(simpleName);
							return ast.newSimpleName(newIdentifier);
						}
						return null;
					}
				};
				Expression inversedExpression= getInversedExpression(rewrite, expression, provider);
				// if any name was not renamed during expression inverting, we can not already rename it, so fail to create assist
				for (Iterator<SimpleName> iter= overlapNames.iterator(); iter.hasNext();) {
					Object o= iter.next();
					if (!renamedNames.contains(o)) {
						return false;
					}
				}
				// check operator and replace if needed
				Assignment.Operator operator= assignment.getOperator();
				if (operator == Assignment.Operator.BIT_AND_ASSIGN) {
					Assignment newAssignment= ast.newAssignment();
					newAssignment.setLeftHandSide(newName);
					newAssignment.setRightHandSide(inversedExpression);
					newAssignment.setOperator(Assignment.Operator.BIT_OR_ASSIGN);
					rewrite.replace(assignment, newAssignment, null);
				} else if (operator == Assignment.Operator.BIT_OR_ASSIGN) {
					Assignment newAssignment= ast.newAssignment();
					newAssignment.setLeftHandSide(newName);
					newAssignment.setRightHandSide(inversedExpression);
					newAssignment.setOperator(Assignment.Operator.BIT_AND_ASSIGN);
					rewrite.replace(assignment, newAssignment, null);
				} else {
					rewrite.replace(expression, inversedExpression, null);
					// set new name
					rewrite.replace(name, newName, null);
				}
			} else if (location == VariableDeclarationFragment.NAME_PROPERTY) {
				// replace initializer for variable
				VariableDeclarationFragment vdf= (VariableDeclarationFragment) name.getParent();
				Expression expression= vdf.getInitializer();
				if (expression != null) {
					rewrite.replace(expression, getInversedExpression(rewrite, expression), null);
				}
				// set new name
				rewrite.replace(name, newName, null);
			} else if (name.getParent() instanceof PrefixExpression && ((PrefixExpression) name.getParent()).getOperator() == PrefixExpression.Operator.NOT) {
				rewrite.replace(name.getParent(), newName, null);
			} else {
				PrefixExpression expression= ast.newPrefixExpression();
				expression.setOperator(PrefixExpression.Operator.NOT);
				expression.setOperand(newName);
				rewrite.replace(name, expression, null);
			}
		}
		// add correction proposal
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean getPushNegationDownProposals(IInvocationContext context, ASTNode covering, Collection<ICommandAccess> resultingCollections) {
		PrefixExpression negationExpression= null;
		ParenthesizedExpression parenthesizedExpression= null;
		// check for case when cursor is on '!' before parentheses
		if (covering instanceof PrefixExpression) {
			PrefixExpression prefixExpression= (PrefixExpression) covering;
			if (prefixExpression.getOperator() == PrefixExpression.Operator.NOT && prefixExpression.getOperand() instanceof ParenthesizedExpression) {
				negationExpression= prefixExpression;
				parenthesizedExpression= (ParenthesizedExpression) prefixExpression.getOperand();
			}
		}
		// check for case when cursor is on parenthesized expression that is negated
		if (covering instanceof ParenthesizedExpression && covering.getParent() instanceof PrefixExpression && ((PrefixExpression) covering.getParent()).getOperator() == PrefixExpression.Operator.NOT) {
			negationExpression= (PrefixExpression) covering.getParent();
			parenthesizedExpression= (ParenthesizedExpression) covering;
		}
		if (negationExpression == null || (!(parenthesizedExpression.getExpression() instanceof InfixExpression) && !(parenthesizedExpression.getExpression() instanceof ConditionalExpression))) {
			return false;
		}
		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}
		//
		final AST ast= covering.getAST();
		final ASTRewrite rewrite= ASTRewrite.create(ast);
		// prepared inverted expression
		Expression inversedExpression= getInversedExpression(rewrite, parenthesizedExpression.getExpression());
		// check, may be we should keep parentheses
		boolean keepParentheses= false;
		if (negationExpression.getParent() instanceof Expression) {
			int parentPrecedence= OperatorPrecedence.getExpressionPrecedence(((Expression) negationExpression.getParent()));
			int inversedExpressionPrecedence= OperatorPrecedence.getExpressionPrecedence(inversedExpression);
			keepParentheses= parentPrecedence > inversedExpressionPrecedence;
		}
		// replace negated expression with inverted one
		if (keepParentheses) {
			ParenthesizedExpression pe= ast.newParenthesizedExpression();
			pe.setExpression(inversedExpression);
			rewrite.replace(negationExpression, pe, null);
		} else {
			rewrite.replace(negationExpression, inversedExpression, null);
		}
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_pushNegationDown;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.PULL_NEGATION_DOWN, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static Expression getBooleanExpression(ASTNode node) {
		if (!(node instanceof Expression)) {
			return null;
		}

		// check if the node is a location where it can be negated
		StructuralPropertyDescriptor locationInParent= node.getLocationInParent();
		if (locationInParent == QualifiedName.NAME_PROPERTY) {
			node= node.getParent();
			locationInParent= node.getLocationInParent();
		}
		while (locationInParent == ParenthesizedExpression.EXPRESSION_PROPERTY) {
			node= node.getParent();
			locationInParent= node.getLocationInParent();
		}
		Expression expression= (Expression) node;
		if (!isBoolean(expression)) {
			return null;
		}
		if (expression.getParent() instanceof InfixExpression) {
			return expression;
		}
		if (locationInParent == Assignment.RIGHT_HAND_SIDE_PROPERTY || locationInParent == IfStatement.EXPRESSION_PROPERTY
				|| locationInParent == WhileStatement.EXPRESSION_PROPERTY || locationInParent == DoStatement.EXPRESSION_PROPERTY
				|| locationInParent == ReturnStatement.EXPRESSION_PROPERTY || locationInParent == ForStatement.EXPRESSION_PROPERTY
				|| locationInParent == AssertStatement.EXPRESSION_PROPERTY || locationInParent == MethodInvocation.ARGUMENTS_PROPERTY
				|| locationInParent == ConstructorInvocation.ARGUMENTS_PROPERTY || locationInParent == SuperMethodInvocation.ARGUMENTS_PROPERTY
				|| locationInParent == EnumConstantDeclaration.ARGUMENTS_PROPERTY || locationInParent == SuperConstructorInvocation.ARGUMENTS_PROPERTY
				|| locationInParent == ClassInstanceCreation.ARGUMENTS_PROPERTY || locationInParent == ConditionalExpression.EXPRESSION_PROPERTY
				|| locationInParent == PrefixExpression.OPERAND_PROPERTY) {
			return expression;
		}
		return null;
	}

	private static boolean getPullNegationUpProposals(IInvocationContext context, ArrayList<ASTNode> coveredNodes, Collection<ICommandAccess> resultingCollections) {
		if (coveredNodes.size() != 1) {
			return false;
		}
		//
		ASTNode fullyCoveredNode= coveredNodes.get(0);

		Expression expression= getBooleanExpression(fullyCoveredNode);
		if (expression == null || (!(expression instanceof InfixExpression) && !(expression instanceof ConditionalExpression))) {
			return false;
		}
		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}
		//
		AST ast= expression.getAST();
		final ASTRewrite rewrite= ASTRewrite.create(ast);
		// prepared inverted expression
		Expression inversedExpression= getInversedExpression(rewrite, expression);
		// prepare ParenthesizedExpression
		ParenthesizedExpression parenthesizedExpression= ast.newParenthesizedExpression();
		parenthesizedExpression.setExpression(inversedExpression);
		// prepare NOT prefix expression
		PrefixExpression prefixExpression= ast.newPrefixExpression();
		prefixExpression.setOperator(PrefixExpression.Operator.NOT);
		prefixExpression.setOperand(parenthesizedExpression);
		// replace old expression
		rewrite.replace(expression, prefixExpression, null);
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_pullNegationUp;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.PULL_NEGATION_UP, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean getJoinIfListInIfElseIfProposals(IInvocationContext context, ASTNode covering, ArrayList<ASTNode> coveredNodes, Collection<ICommandAccess> resultingCollections) {
		if (coveredNodes.isEmpty()) {
			return false;
		}
		// check that we have more than one covered statement
		if (coveredNodes.size() < 2) {
			return false;
		}
		// check that all selected nodes are 'if' statements with only 'then' statement
		for (Iterator<ASTNode> iter= coveredNodes.iterator(); iter.hasNext();) {
			ASTNode node= iter.next();
			if (!(node instanceof IfStatement)) {
				return false;
			}
			IfStatement ifStatement= (IfStatement) node;
			if (ifStatement.getElseStatement() != null) {
				return false;
			}
		}
		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}
		//
		final AST ast= covering.getAST();
		final ASTRewrite rewrite= ASTRewrite.create(ast);
		//
		IfStatement firstIfStatement= (IfStatement) coveredNodes.get(0);
		IfStatement firstNewIfStatement= null;
		//
		IfStatement prevIfStatement= null;
		for (Iterator<ASTNode> iter= coveredNodes.iterator(); iter.hasNext();) {
			IfStatement ifStatement= (IfStatement) iter.next();
			// prepare new 'if' statement
			IfStatement newIfStatement= ast.newIfStatement();
			newIfStatement.setExpression((Expression) rewrite.createMoveTarget(ifStatement.getExpression()));
			// prepare 'then' statement and convert into block if needed
			Statement thenStatement= (Statement) rewrite.createMoveTarget(ifStatement.getThenStatement());
			if (ifStatement.getThenStatement() instanceof IfStatement) {
				IfStatement ifBodyStatement= (IfStatement) ifStatement.getThenStatement();
				if (ifBodyStatement.getElseStatement() == null) {
					Block thenBlock= ast.newBlock();
					thenBlock.statements().add(thenStatement);
					thenStatement= thenBlock;
				}
			}
			newIfStatement.setThenStatement(thenStatement);
			//
			if (prevIfStatement != null) {
				prevIfStatement.setElseStatement(newIfStatement);
				rewrite.remove(ifStatement, null);
			} else {
				firstNewIfStatement= newIfStatement;
			}
			prevIfStatement= newIfStatement;
		}
		rewrite.replace(firstIfStatement, firstNewIfStatement, null);
		// add correction proposal
		String label= CorrectionMessages.AdvancedQuickAssistProcessor_joinIfSequence;
		Image image= JavaPluginImages.get(JavaPluginImages.IMG_CORRECTION_CHANGE);
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.JOIN_IF_SEQUENCE, image);
		resultingCollections.add(proposal);
		return true;
	}

	private static boolean getConvertSwitchToIfProposals(IInvocationContext context, ASTNode covering, Collection<ICommandAccess> resultingCollections) {
		if (!(covering instanceof SwitchStatement)) {
			return false;
		}
		//  we could produce quick assist (if all 'case' statements end with 'break')
		if (resultingCollections == null) {
			return true;
		}
		if (!getConvertSwitchToIfProposals(context, covering, resultingCollections, false))
			return false;
		return getConvertSwitchToIfProposals(context, covering, resultingCollections, true);
	}

	private static boolean getConvertSwitchToIfProposals(IInvocationContext context, ASTNode covering, Collection<ICommandAccess> resultingCollections, boolean preserveNPE) {
		final AST ast= covering.getAST();
		final ASTRewrite rewrite= ASTRewrite.create(ast);
		final ImportRewrite importRewrite= StubUtility.createImportRewrite(context.getASTRoot(), true);
		//
		SwitchStatement switchStatement= (SwitchStatement) covering;
		ITypeBinding expressionType= switchStatement.getExpression().resolveTypeBinding();
		boolean isStringsInSwitch= expressionType != null && "java.lang.String".equals(expressionType.getQualifiedName()); //$NON-NLS-1$

		if (!isStringsInSwitch && preserveNPE)
			return false;

		IfStatement firstIfStatement= null;
		IfStatement currentIfStatement= null;
		Block currentBlock= null;
		boolean hasStopAsLastExecutableStatement= false;
		Block defaultBlock= null;
		Expression currentCondition= null;
		boolean defaultFound= false;

		ArrayList<Block> allBlocks= new ArrayList<>();
		ImportRewriteContext importRewriteContext= new ContextSensitiveImportRewriteContext(ASTResolving.findParentBodyDeclaration(covering), importRewrite);

		Expression switchExpression= switchStatement.getExpression();
		Name varName;
		VariableDeclarationStatement variableDeclarationStatement= null;
		if (switchExpression instanceof Name) {
			varName= (Name) switchExpression;
		} else {
			// Switch expression could have side effects, see bug 252040
			VariableDeclarationFragment variableDeclarationFragment= ast.newVariableDeclarationFragment();
			String[] varNames= StubUtility.getVariableNameSuggestions(NamingConventions.VK_LOCAL, context.getCompilationUnit().getJavaProject(), expressionType, switchExpression, null);
			varName= ast.newSimpleName(varNames[0]);
			variableDeclarationFragment.setName((SimpleName) varName);
			variableDeclarationFragment.setStructuralProperty(VariableDeclarationFragment.INITIALIZER_PROPERTY, rewrite.createCopyTarget(switchExpression));

			variableDeclarationStatement= ast.newVariableDeclarationStatement(variableDeclarationFragment);
			Type type= importRewrite.addImport(expressionType, ast, importRewriteContext, TypeLocation.LOCAL_VARIABLE);
			variableDeclarationStatement.setType(type);
		}

		for (Iterator<Statement> iter= switchStatement.statements().iterator(); iter.hasNext();) {
			Statement statement= iter.next();
			if (statement instanceof SwitchCase) {
				SwitchCase switchCase= (SwitchCase) statement;
				// special case: pass through
				if (currentBlock != null) {
					if (!hasStopAsLastExecutableStatement) {
						return false;
					}
					currentBlock= null;
				}
				
				if (defaultFound) {
					// This gets too complicated. We only support 'default' as last SwitchCase.
					return false;
				}
				if (switchCase.isDefault()) {
					defaultFound= true;
				}
				// prepare condition (is null for 'default')
				Expression switchCaseCondition= createSwitchCaseCondition(ast, rewrite, importRewrite, importRewriteContext, varName, switchCase, isStringsInSwitch, preserveNPE);
				if (currentCondition == null) {
					currentCondition= switchCaseCondition;
				} else {
					InfixExpression condition= ast.newInfixExpression();
					condition.setOperator(InfixExpression.Operator.CONDITIONAL_OR);
					condition.setLeftOperand(currentCondition);
					if (switchCaseCondition == null)
						switchCaseCondition= ast.newBooleanLiteral(true);
					condition.setRightOperand(switchCaseCondition);
					currentCondition= condition;
				}
			} else {
				// ensure that current block exists as 'then' statement of 'if'
				if (currentBlock == null) {
					if (currentCondition != null) {
						IfStatement ifStatement;
						if (firstIfStatement == null) {
							firstIfStatement= ast.newIfStatement();
							ifStatement= firstIfStatement;
						} else {
							ifStatement= ast.newIfStatement();
							currentIfStatement.setElseStatement(ifStatement);
						}
						currentIfStatement= ifStatement;
						ifStatement.setExpression(currentCondition);
						currentCondition= null;
						currentBlock= ast.newBlock();
						ifStatement.setThenStatement(currentBlock);
						allBlocks.add(currentBlock);
					} else {
						// case for default:
						defaultBlock= ast.newBlock();
						currentBlock= defaultBlock;
						allBlocks.add(currentBlock);
						// delay adding of default block
					}
				}
				if (statement instanceof BreakStatement) {
					currentBlock= null;
				} else {
					// add current statement in current block

					hasStopAsLastExecutableStatement= hasStopAsLastExecutableStatement(statement);
					Statement copyStatement= copyStatementExceptBreak(ast, rewrite, statement);

					currentBlock.statements().add(copyStatement);
				}
			}
		}
		// check, may be we have delayed default block
		if (defaultBlock != null) {
			currentIfStatement.setElseStatement(defaultBlock);
		}
		// remove unnecessary blocks in blocks
		for (int i= 0; i < allBlocks.size(); i++) {
			Block block= allBlocks.get(i);
			List<Statement> statements= block.statements();
			if (statements.size() == 1 && statements.get(0) instanceof Block) {
				Block innerBlock= (Block) statements.remove(0);
				block.getParent().setStructuralProperty(block.getLocationInParent(), innerBlock);
			}
		}

		if (variableDeclarationStatement == null) {
			// replace 'switch' with single if-else-if statement
			rewrite.replace(switchStatement, firstIfStatement, null);
		} else {
			new StatementRewrite(rewrite, new ASTNode[] { switchStatement }).replace(new ASTNode[] { variableDeclarationStatement, firstIfStatement }, null);
		}

		// add correction proposal
		String source= ASTNodes.asString(switchExpression).replaceAll("\r\n?|\n", " "); //$NON-NLS-1$ //$NON-NLS-2$
		String label= preserveNPE ? Messages.format(CorrectionMessages.AdvancedQuickAssistProcessor_convertSwitchToIf_preserveNPE, source) : CorrectionMessages.AdvancedQuickAssistProcessor_convertSwitchToIf;
		ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.CONVERT_SWITCH_TO_IF_ELSE);
		proposal.setImportRewrite(importRewrite);
		resultingCollections.add(proposal);
		return true;
	}

	private static Expression createSwitchCaseCondition(AST ast, ASTRewrite rewrite, ImportRewrite importRewrite, ImportRewriteContext importRewriteContext, Name switchExpression,
			SwitchCase switchCase, boolean isStringsInSwitch, boolean preserveNPE) {
		Expression expression= switchCase.getExpression();
		if (expression == null)
			return null;
		
		if (isStringsInSwitch) {
			MethodInvocation methodInvocation= ast.newMethodInvocation();
			methodInvocation.setName(ast.newSimpleName("equals")); //$NON-NLS-1$
			if (preserveNPE) {
				methodInvocation.setExpression((Expression) rewrite.createStringPlaceholder(switchExpression.getFullyQualifiedName(), ASTNode.QUALIFIED_NAME));
				methodInvocation.arguments().add(rewrite.createCopyTarget(expression));
			} else {
				methodInvocation.setExpression((Expression) rewrite.createCopyTarget(expression));
				methodInvocation.arguments().add(rewrite.createStringPlaceholder(switchExpression.getFullyQualifiedName(), ASTNode.QUALIFIED_NAME));
			}
			return methodInvocation;
		} else {
			InfixExpression condition= ast.newInfixExpression();
			condition.setOperator(InfixExpression.Operator.EQUALS);
			condition.setLeftOperand((Expression) rewrite.createStringPlaceholder(switchExpression.getFullyQualifiedName(), ASTNode.QUALIFIED_NAME));

			Expression rightExpression= null;
			if (expression instanceof SimpleName && ((SimpleName) expression).resolveBinding() instanceof IVariableBinding) {
				IVariableBinding binding= (IVariableBinding) ((SimpleName) expression).resolveBinding();
				if (binding.isEnumConstant()) {
					String qualifiedName= importRewrite.addImport(binding.getDeclaringClass(), importRewriteContext) + '.' + binding.getName();
					rightExpression= ast.newName(qualifiedName);
				}
			}
			if (rightExpression == null) {
				rightExpression= (Expression) rewrite.createCopyTarget(expression);
			}
			condition.setRightOperand(rightExpression);
			return condition;
		}
	}


	private static boolean hasStopAsLastExecutableStatement(Statement lastStatement) {
		if (lastStatement instanceof ReturnStatement || lastStatement instanceof BreakStatement) {
			return true;
		}
		if (lastStatement instanceof Block) {
			Block block= (Block) lastStatement;
			lastStatement= (Statement) block.statements().get(block.statements().size() - 1);
			return hasStopAsLastExecutableStatement(lastStatement);
		}
		return false;
	}

	private static Statement copyStatementExceptBreak(AST ast, ASTRewrite rewrite, Statement source) {
		if (source instanceof Block) {
			Block block= (Block) source;
			Block newBlock= ast.newBlock();
			for (Iterator<Statement> iter= block.statements().iterator(); iter.hasNext();) {
				Statement statement= iter.next();
				if (statement instanceof BreakStatement) {
					continue;
				}
				newBlock.statements().add(copyStatementExceptBreak(ast, rewrite, statement));
			}
			return newBlock;
		}
		return (Statement) rewrite.createMoveTarget(source);
	}

	private static boolean getConvertIfElseToSwitchProposals(IInvocationContext context, ASTNode coveringNode, ArrayList<ICommandAccess> resultingCollections) {
		if (!(coveringNode instanceof IfStatement)) {
			return false;
		}
		//  we could produce quick assist
		if (resultingCollections == null) {
			return true;
		}

		if(!getConvertIfElseToSwitchProposals(context, coveringNode, resultingCollections, true))
			return false;
		return getConvertIfElseToSwitchProposals(context, coveringNode, resultingCollections, false);
	}

	private static boolean getConvertIfElseToSwitchProposals(IInvocationContext context, ASTNode coveringNode, ArrayList<ICommandAccess> resultingCollections, boolean handleNullArg) {
		final AST ast= coveringNode.getAST();
		final ASTRewrite rewrite= ASTRewrite.create(ast);
		final ImportRewrite importRewrite= StubUtility.createImportRewrite(context.getASTRoot(), true);
		ImportRewriteContext importRewriteContext= new ContextSensitiveImportRewriteContext(ASTResolving.findParentBodyDeclaration(coveringNode), importRewrite);
		IfStatement ifStatement= (IfStatement) coveringNode;
		IfStatement currentIf= ifStatement;
		Statement currentStatement= ifStatement;
		Expression currentExpression= currentIf.getExpression();
		SwitchStatement switchStatement= ast.newSwitchStatement();
		Expression switchExpression= null;
		boolean executeDefaultOnNullExpression= false;
		Statement defaultStatement=null;

		while (currentStatement != null) {
			Expression expression= null;
			List<Expression> caseExpressions= new ArrayList<>();
			if (currentIf != null) {
				while (currentExpression != null) { // loop for fall through cases - multiple expressions with || operator
					Expression leftOperand;
					Expression rightOperand;
					boolean isMethodInvocationCase= false;
					if (currentExpression instanceof MethodInvocation) {
						isMethodInvocationCase= true;
						if (!(((MethodInvocation) currentExpression).getName().getIdentifier()).equals("equals")) //$NON-NLS-1$
							return false;
	
						MethodInvocation invocation= (MethodInvocation) currentExpression;
						leftOperand= invocation.getExpression();
						if (leftOperand == null)
							return false;
						ITypeBinding leftBinding= leftOperand.resolveTypeBinding();
						if (leftBinding != null) {
							if (leftBinding.getQualifiedName().equals("java.lang.String")) { //$NON-NLS-1$
								if (!JavaModelUtil.is17OrHigher(context.getCompilationUnit().getJavaProject()))
									return false;
							} else if (!leftBinding.isEnum()) {
								return false;
							}
						}
						
						List<Expression> arguments= invocation.arguments();
						if (arguments.size() != 1)
							return false;
						rightOperand= arguments.get(0);
						ITypeBinding rightBinding= leftOperand.resolveTypeBinding();
						if (rightBinding != null) {
							if (rightBinding.getQualifiedName().equals("java.lang.String")) { //$NON-NLS-1$
								if (!JavaModelUtil.is17OrHigher(context.getCompilationUnit().getJavaProject()))
									return false;
							} else if (!rightBinding.isEnum()) {
								return false;
							}
						}
	
	
					} else if (currentExpression instanceof InfixExpression) {
						InfixExpression infixExpression= (InfixExpression) currentExpression;
						Operator operator= infixExpression.getOperator();
						if (!(operator.equals(InfixExpression.Operator.CONDITIONAL_OR) || operator.equals(InfixExpression.Operator.EQUALS)))
							return false;
	
						leftOperand= infixExpression.getLeftOperand();
						rightOperand= infixExpression.getRightOperand();
	
						if (operator.equals(InfixExpression.Operator.EQUALS)) {
							ITypeBinding typeBinding= leftOperand.resolveTypeBinding();
							if (typeBinding != null && typeBinding.getQualifiedName().equals("java.lang.String")) { //$NON-NLS-1$
								return false; // don't propose quick assist when == is used to compare strings, since switch will use equals()
							}
						} else if (operator.equals(InfixExpression.Operator.CONDITIONAL_OR)) {
							currentExpression= leftOperand;
							continue;
						}
					} else {
						return false;
					}
	
					if (leftOperand.resolveConstantExpressionValue() != null) {
						caseExpressions.add(leftOperand);
						expression= rightOperand;
						executeDefaultOnNullExpression|= isMethodInvocationCase;
					} else if (rightOperand.resolveConstantExpressionValue() != null) {
						caseExpressions.add(rightOperand);
						expression= leftOperand;
					} else if (leftOperand instanceof QualifiedName) {
						QualifiedName qualifiedName= (QualifiedName) leftOperand;
						IVariableBinding binding= (IVariableBinding) qualifiedName.resolveBinding();
						if (binding == null || !binding.isEnumConstant())
							return false;
						importRewrite.addImport(binding.getDeclaringClass(), importRewriteContext);
						caseExpressions.add(qualifiedName.getName());
						expression= rightOperand;
						executeDefaultOnNullExpression|= isMethodInvocationCase;
					} else if (rightOperand instanceof QualifiedName) {
						QualifiedName qualifiedName= (QualifiedName) rightOperand;
						IVariableBinding binding= (IVariableBinding) qualifiedName.resolveBinding();
						if (binding == null || !binding.isEnumConstant())
							return false;
						importRewrite.addImport(binding.getDeclaringClass(), importRewriteContext);
						caseExpressions.add(qualifiedName.getName());
						expression= leftOperand;
					} else {
						return false;
					}
					if (expression == null) { // paranoidal check: this condition should never be true
						return false;
					}
					
					if (currentExpression.getParent() instanceof InfixExpression) {
						currentExpression= getNextSiblingExpression(currentExpression);
					} else {
						currentExpression= null;
					}
	
					if (switchExpression == null) {
						switchExpression= expression;
					}
	
					if (!switchExpression.subtreeMatch(new ASTMatcher(), expression)) {
						return false;
					}
				}
			}

			Statement thenStatement;
			if (currentIf == null) {
				thenStatement= currentStatement; //currentStatement has the default else block
				defaultStatement= currentStatement;
			} else {
				thenStatement= currentIf.getThenStatement();
			}
			
			SwitchCase[] switchCaseStatements= createSwitchCaseStatements(ast, rewrite, caseExpressions);
			for (int i= 0; i < switchCaseStatements.length; i++) {
				switchStatement.statements().add(switchCaseStatements[i]);
			}
			boolean isBreakRequired= true;
			if (thenStatement instanceof Block) {
				Statement statement= null;
				for (Iterator<Statement> iter= ((Block) thenStatement).statements().iterator(); iter.hasNext();) {
					statement= iter.next();
					switchStatement.statements().add(rewrite.createCopyTarget(statement));
				}
				if (statement instanceof ReturnStatement || statement instanceof ThrowStatement)
					isBreakRequired= false;
			} else {
				if (thenStatement instanceof ReturnStatement || thenStatement instanceof ThrowStatement)
					isBreakRequired= false;
				switchStatement.statements().add(rewrite.createCopyTarget(thenStatement));
			}
			if (isBreakRequired)
				switchStatement.statements().add(ast.newBreakStatement());

			// advance currentStatement to the next "else if" or "else":
			if (currentIf != null && currentIf.getElseStatement() != null) {
				Statement elseStatement= currentIf.getElseStatement();
				if (elseStatement instanceof IfStatement) {
					currentIf= (IfStatement) elseStatement;
					currentStatement= currentIf;
					currentExpression= currentIf.getExpression();
				} else {
					currentIf= null;
					currentStatement= elseStatement;
					currentExpression= null;
				}
			} else {
				currentStatement= null;
			}
		}

		if (switchExpression == null)
			return false;
		switchStatement.setExpression((Expression) rewrite.createCopyTarget(switchExpression));
		
		if (handleNullArg) {
			if (executeDefaultOnNullExpression) {
				IfStatement newIfStatement= ast.newIfStatement();

				InfixExpression infixExpression= ast.newInfixExpression();
				infixExpression.setLeftOperand((Expression) rewrite.createCopyTarget(switchExpression));
				infixExpression.setRightOperand(ast.newNullLiteral());
				infixExpression.setOperator(InfixExpression.Operator.EQUALS);
				newIfStatement.setExpression(infixExpression);

				if (defaultStatement == null) {
					Block block= ast.newBlock();
					newIfStatement.setThenStatement(block);
				} else if (defaultStatement instanceof Block) {
					Block block= ast.newBlock();
					for (Iterator<Statement> iter= ((Block) defaultStatement).statements().iterator(); iter.hasNext();) {
						block.statements().add(rewrite.createCopyTarget(iter.next()));
					}
					newIfStatement.setThenStatement(block);
				} else {
					newIfStatement.setThenStatement((Statement) rewrite.createCopyTarget(defaultStatement));
				}
				Block block= ast.newBlock();
				block.statements().add(switchStatement);
				newIfStatement.setElseStatement(block);

				rewrite.replace(ifStatement, newIfStatement, null);

				String source= ASTNodes.asString(switchExpression).replaceAll("\r\n?|\n", " "); //$NON-NLS-1$ //$NON-NLS-2$
				String label= Messages.format(CorrectionMessages.AdvancedQuickAssistProcessor_convertIfElseToSwitch_handleNullArg, source);
				ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.CONVERT_IF_ELSE_TO_SWITCH);
				proposal.setImportRewrite(importRewrite);
				resultingCollections.add(proposal);
			}
		} else {
			rewrite.replace(ifStatement, switchStatement, null);

			String label= CorrectionMessages.AdvancedQuickAssistProcessor_convertIfElseToSwitch;
			ASTRewriteCorrectionProposal proposal= new ASTRewriteCorrectionProposal(label, context.getCompilationUnit(), rewrite, IProposalRelevance.CONVERT_IF_ELSE_TO_SWITCH);
			proposal.setImportRewrite(importRewrite);
			resultingCollections.add(proposal);
		}
		return true;
	}

	private static Expression getNextSiblingExpression(Expression expression) {
		InfixExpression parentInfixExpression= (InfixExpression) expression.getParent();
		Expression sibiling;
		if (expression.equals(parentInfixExpression.getLeftOperand())) {
			sibiling= parentInfixExpression.getRightOperand();
		} else if (expression.equals(parentInfixExpression.getRightOperand())) {
			if (parentInfixExpression.getParent() instanceof InfixExpression)
				sibiling= getNextSiblingExpression(parentInfixExpression);
			else
				sibiling= null;
		} else {
			sibiling= null;
		}
		return sibiling;
	}

	private static SwitchCase[] createSwitchCaseStatements(AST ast, ASTRewrite rewrite, List<Expression> caseExpressions) {
		int len= (caseExpressions.size() == 0) ? 1 : caseExpressions.size();
		SwitchCase[] switchCaseStatements= new SwitchCase[len];
		if (caseExpressions.size() == 0) {
			switchCaseStatements[0]= ast.newSwitchCase();
			switchCaseStatements[0].setExpression(null);
		} else {
			for (int i= 0; i < caseExpressions.size(); i++) {
				ASTNode astNode= caseExpressions.get(i);
				switchCaseStatements[i]= ast.newSwitchCase();
				switchCaseStatements[i].setExpression((Expression) rewrite.createCopyTarget(astNode));
			}
		}
		return switchCaseStatements;
	}

}