| /* |
| * Copyright 2011-2013 Jetbrains s.r.o. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package com.siyeh.ig.controlflow; |
| |
| import com.intellij.codeInspection.ProblemDescriptor; |
| import com.intellij.openapi.project.Project; |
| import com.intellij.psi.*; |
| import com.intellij.psi.tree.IElementType; |
| import com.intellij.psi.util.PsiTreeUtil; |
| import com.siyeh.InspectionGadgetsBundle; |
| import com.siyeh.ig.BaseInspection; |
| import com.siyeh.ig.BaseInspectionVisitor; |
| import com.siyeh.ig.InspectionGadgetsFix; |
| import com.siyeh.ig.PsiReplacementUtil; |
| import com.siyeh.ig.psiutils.ParenthesesUtils; |
| import org.jetbrains.annotations.Nls; |
| import org.jetbrains.annotations.NotNull; |
| import org.jetbrains.annotations.Nullable; |
| |
| /** |
| * This inspection finds instances of null checks followed by an instanceof check |
| * on the same variable. For instance: |
| * <code> |
| * if (x != null && x instanceof String) { ... } |
| * </code> |
| * The instanceof operator returns false when passed a null, so the null check is pointless. |
| * |
| * @author Lars Fischer |
| * @author Etienne Studer |
| * @author Hamlet D'Arcy |
| */ |
| public class PointlessNullCheckInspection extends BaseInspection { |
| @Nls |
| @NotNull |
| @Override |
| public String getDisplayName() { |
| return InspectionGadgetsBundle.message("pointless.nullcheck.display.name"); |
| } |
| |
| @NotNull |
| @Override |
| protected String buildErrorString(Object... infos) { |
| return InspectionGadgetsBundle.message("pointless.nullcheck.problem.descriptor"); |
| } |
| |
| @Override |
| public BaseInspectionVisitor buildVisitor() { |
| return new PointlessNullCheckVisitor(); |
| } |
| |
| @Override |
| public InspectionGadgetsFix buildFix(Object... infos) { |
| final PsiExpression expression = (PsiExpression)infos[0]; |
| return new PointlessNullCheckFix(expression.getText()); |
| } |
| |
| private static class PointlessNullCheckFix extends InspectionGadgetsFix { |
| |
| private final String myExpressionText; |
| |
| public PointlessNullCheckFix(String expressionText) { |
| myExpressionText = expressionText; |
| } |
| |
| @Override |
| @NotNull |
| public String getName() { |
| return InspectionGadgetsBundle.message("pointless.nullcheck.simplify.quickfix", myExpressionText); |
| } |
| |
| @NotNull |
| @Override |
| public String getFamilyName() { |
| return "Simplify"; |
| } |
| |
| @Override |
| public void doFix(Project project, ProblemDescriptor descriptor) { |
| final PsiElement element = descriptor.getPsiElement(); |
| final PsiBinaryExpression binaryExpression = PsiTreeUtil.getParentOfType(element, PsiBinaryExpression.class); |
| if (binaryExpression == null) { |
| return; |
| } |
| final PsiExpression lhs = binaryExpression.getLOperand(); |
| final PsiExpression rhs = binaryExpression.getROperand(); |
| if (rhs == null) { |
| return; |
| } |
| if (PsiTreeUtil.isAncestor(rhs, element, false)) { |
| PsiReplacementUtil.replaceExpression(binaryExpression, lhs.getText()); |
| } |
| else if (PsiTreeUtil.isAncestor(lhs, element, false)) { |
| PsiReplacementUtil.replaceExpression(binaryExpression, rhs.getText()); |
| } |
| } |
| } |
| |
| private static class PointlessNullCheckVisitor extends BaseInspectionVisitor { |
| |
| @Override |
| public void visitBinaryExpression(PsiBinaryExpression expression) { |
| super.visitBinaryExpression(expression); |
| final IElementType operationTokenType = expression.getOperationTokenType(); |
| final PsiExpression lhs = ParenthesesUtils.stripParentheses(expression.getLOperand()); |
| final PsiExpression rhs = ParenthesesUtils.stripParentheses(expression.getROperand()); |
| final PsiBinaryExpression binaryExpression; |
| final PsiExpression possibleInstanceofExpression; |
| if (operationTokenType.equals(JavaTokenType.ANDAND)) { |
| if (lhs instanceof PsiBinaryExpression) { |
| binaryExpression = (PsiBinaryExpression)lhs; |
| possibleInstanceofExpression = rhs; |
| } |
| else if (rhs instanceof PsiBinaryExpression) { |
| binaryExpression = (PsiBinaryExpression)rhs; |
| possibleInstanceofExpression = lhs; |
| } |
| else { |
| return; |
| } |
| final IElementType tokenType = binaryExpression.getOperationTokenType(); |
| if (!tokenType.equals(JavaTokenType.NE)) { |
| return; |
| } |
| } |
| else if (operationTokenType.equals(JavaTokenType.OROR)) { |
| if (lhs instanceof PsiBinaryExpression && rhs instanceof PsiPrefixExpression) { |
| final PsiPrefixExpression prefixExpression = (PsiPrefixExpression)rhs; |
| final IElementType prefixTokenType = prefixExpression.getOperationTokenType(); |
| if (!JavaTokenType.EXCL.equals(prefixTokenType)) { |
| return; |
| } |
| binaryExpression = (PsiBinaryExpression)lhs; |
| possibleInstanceofExpression = ParenthesesUtils.stripParentheses(prefixExpression.getOperand()); |
| } |
| else if (rhs instanceof PsiBinaryExpression && lhs instanceof PsiPrefixExpression) { |
| final PsiPrefixExpression prefixExpression = (PsiPrefixExpression)lhs; |
| final IElementType prefixTokenType = prefixExpression.getOperationTokenType(); |
| if (!JavaTokenType.EXCL.equals(prefixTokenType)) { |
| return; |
| } |
| binaryExpression = (PsiBinaryExpression)rhs; |
| possibleInstanceofExpression = ParenthesesUtils.stripParentheses(prefixExpression.getOperand()); |
| } |
| else { |
| return; |
| } |
| final IElementType tokenType = binaryExpression.getOperationTokenType(); |
| if (!tokenType.equals(JavaTokenType.EQEQ)) { |
| return; |
| } |
| } |
| else { |
| return; |
| } |
| final PsiReferenceExpression referenceExpression1 = getReferenceFromNullCheck(binaryExpression); |
| if (referenceExpression1 == null) { |
| return; |
| } |
| final PsiReferenceExpression referenceExpression2 = getReferenceFromInstanceofExpression(possibleInstanceofExpression); |
| if (!referencesEqual(referenceExpression1, referenceExpression2)) { |
| return; |
| } |
| registerError(binaryExpression, binaryExpression); |
| } |
| |
| @Nullable |
| private static PsiReferenceExpression getReferenceFromNullCheck(PsiBinaryExpression expression) { |
| final PsiExpression lhs = ParenthesesUtils.stripParentheses(expression.getLOperand()); |
| final PsiExpression rhs = ParenthesesUtils.stripParentheses(expression.getROperand()); |
| if (lhs instanceof PsiReferenceExpression) { |
| if (!(rhs instanceof PsiLiteralExpression && PsiType.NULL.equals(rhs.getType()))) { |
| return null; |
| } |
| return (PsiReferenceExpression)lhs; |
| } |
| else if (rhs instanceof PsiReferenceExpression) { |
| if (!(lhs instanceof PsiLiteralExpression && PsiType.NULL.equals(lhs.getType()))) { |
| return null; |
| } |
| return (PsiReferenceExpression)rhs; |
| } |
| else { |
| return null; |
| } |
| } |
| |
| @Nullable |
| private static PsiReferenceExpression getReferenceFromInstanceofExpression(PsiExpression expression) { |
| if (expression instanceof PsiParenthesizedExpression) { |
| final PsiParenthesizedExpression parenthesizedExpression = (PsiParenthesizedExpression)expression; |
| return getReferenceFromInstanceofExpression(parenthesizedExpression.getExpression()); |
| } |
| else if (expression instanceof PsiInstanceOfExpression) { |
| final PsiInstanceOfExpression instanceOfExpression = (PsiInstanceOfExpression)expression; |
| final PsiExpression operand = ParenthesesUtils.stripParentheses(instanceOfExpression.getOperand()); |
| if (!(operand instanceof PsiReferenceExpression)) { |
| return null; |
| } |
| return (PsiReferenceExpression)operand; |
| } |
| else if (expression instanceof PsiPolyadicExpression) { |
| final PsiPolyadicExpression polyadicExpression = (PsiPolyadicExpression)expression; |
| final IElementType tokenType = polyadicExpression.getOperationTokenType(); |
| if (JavaTokenType.OROR != tokenType) { |
| return null; |
| } |
| final PsiExpression[] operands = polyadicExpression.getOperands(); |
| final PsiReferenceExpression referenceExpression = getReferenceFromInstanceofExpression(operands[0]); |
| if (referenceExpression == null) { |
| return null; |
| } |
| for (int i = 1, operandsLength = operands.length; i < operandsLength; i++) { |
| if (!referencesEqual(referenceExpression, getReferenceFromInstanceofExpression(operands[i]))) { |
| return null; |
| } |
| } |
| return referenceExpression; |
| } else { |
| return null; |
| } |
| } |
| } |
| |
| private static boolean referencesEqual(PsiReferenceExpression reference1, PsiReferenceExpression reference2) { |
| if (reference1 == null || reference2 == null) { |
| return false; |
| } |
| final PsiElement target1 = reference1.resolve(); |
| if (target1 == null) { |
| return false; |
| } |
| final PsiElement target2 = reference2.resolve(); |
| return target1.equals(target2); |
| } |
| } |