ConditionalExpressionWithIdenticalBranchesInspection.java

/*
 * Copyright 2003-2017 Dave Griffith, Bas Leijdekkers
 *
 * 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.CleanupLocalInspectionTool;
import com.intellij.codeInspection.ProblemDescriptor;
import com.intellij.openapi.project.Project;
import com.intellij.psi.*;
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.EquivalenceChecker;
import org.jetbrains.annotations.NotNull;

public class ConditionalExpressionWithIdenticalBranchesInspection extends BaseInspection implements CleanupLocalInspectionTool {

  @Override
  @NotNull
  public String getDisplayName() {
    return InspectionGadgetsBundle.message("conditional.expression.with.identical.branches.display.name");
  }

  @Override
  @NotNull
  protected String buildErrorString(Object... infos) {
    return InspectionGadgetsBundle.message("conditional.expression.with.identical.branches.problem.descriptor");
  }

  @Override
  public InspectionGadgetsFix buildFix(Object... infos) {
    return new CollapseConditionalFix();
  }

  private static class CollapseConditionalFix extends InspectionGadgetsFix {

    @Override
    @NotNull
    public String getFamilyName() {
      return InspectionGadgetsBundle.message("conditional.expression.with.identical.branches.collapse.quickfix");
    }

    @Override
    public void doFix(Project project, ProblemDescriptor descriptor) {
      final PsiConditionalExpression conditionalExpression = (PsiConditionalExpression)descriptor.getPsiElement();
      final PsiExpression thenExpression = conditionalExpression.getThenExpression();
      if (thenExpression == null) {
        return;
      }
      final PsiExpression elseExpression = conditionalExpression.getElseExpression();
      if (EquivalenceChecker.getCanonicalPsiEquivalence().expressionsAreEquivalent(thenExpression, elseExpression)) {
        PsiReplacementUtil.replaceExpression(conditionalExpression, thenExpression.getText());
      }
    }
  }

  @Override
  public BaseInspectionVisitor buildVisitor() {
    return new ConditionalExpressionWithIdenticalBranchesVisitor();
  }

  private static class ConditionalExpressionWithIdenticalBranchesVisitor extends BaseInspectionVisitor {

    @Override
    public void visitConditionalExpression(PsiConditionalExpression expression) {
      super.visitConditionalExpression(expression);
      final PsiExpression thenExpression = expression.getThenExpression();
      if (thenExpression == null) {
        return;
      }
      final PsiExpression elseExpression = expression.getElseExpression();
      if (EquivalenceChecker.getCanonicalPsiEquivalence().expressionsAreEquivalent(thenExpression, elseExpression)) {
        registerError(expression);
      }
    }
  }
}