MakeVoidQuickFix.java

/*
 * Copyright 2000-2017 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.intellij.codeInspection;

import com.intellij.codeInspection.reference.RefElement;
import com.intellij.codeInspection.reference.RefMethod;
import com.intellij.openapi.application.WriteAction;
import com.intellij.openapi.diagnostic.Logger;
import com.intellij.openapi.project.Project;
import com.intellij.psi.*;
import com.intellij.psi.search.searches.OverridingMethodsSearch;
import com.intellij.psi.util.PsiTreeUtil;
import com.intellij.psi.util.PsiUtil;
import com.intellij.refactoring.changeSignature.ChangeSignatureProcessor;
import com.intellij.refactoring.changeSignature.ParameterInfoImpl;
import com.intellij.util.IncorrectOperationException;
import com.siyeh.ig.controlflow.UnnecessaryReturnInspection;
import com.siyeh.ig.psiutils.SideEffectChecker;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

public class MakeVoidQuickFix implements LocalQuickFix {
  private final ProblemDescriptionsProcessor myProcessor;
  private static final Logger LOG = Logger.getInstance(MakeVoidQuickFix.class);

  public MakeVoidQuickFix(@Nullable final ProblemDescriptionsProcessor processor) {
    myProcessor = processor;
  }

  @Override
  @NotNull
  public String getFamilyName() {
    return InspectionsBundle.message("inspection.unused.return.value.make.void.quickfix");
  }

  @Override
  public void applyFix(@NotNull Project project, @NotNull ProblemDescriptor descriptor) {
    PsiMethod psiMethod = null;
    if (myProcessor != null) {
      RefElement refElement = (RefElement)myProcessor.getElement(descriptor);
      if (refElement instanceof RefMethod && refElement.isValid()) {
        RefMethod refMethod = (RefMethod)refElement;
        psiMethod = (PsiMethod)refMethod.getElement();
      }
    }
    else {
      psiMethod = PsiTreeUtil.getParentOfType(descriptor.getPsiElement(), PsiMethod.class);
    }
    if (psiMethod == null) return;
    makeMethodHierarchyVoid(project, psiMethod);
  }

  @Override
  public boolean startInWriteAction() {
    return false;
  }

  @Nullable
  @Override
  public PsiElement getElementToMakeWritable(@NotNull PsiFile currentFile) {
    return currentFile;
  }

  private static void makeMethodHierarchyVoid(Project project, @NotNull PsiMethod psiMethod) {
    replaceReturnStatements(psiMethod);
    for (final PsiMethod oMethod : OverridingMethodsSearch.search(psiMethod)) {
      replaceReturnStatements(oMethod);
    }
    final PsiParameter[] params = psiMethod.getParameterList().getParameters();
    final ParameterInfoImpl[] infos = new ParameterInfoImpl[params.length];
    for (int i = 0; i < params.length; i++) {
      PsiParameter param = params[i];
      infos[i] = new ParameterInfoImpl(i, param.getName(), param.getType());
    }

    final ChangeSignatureProcessor csp = new ChangeSignatureProcessor(project,
                                                                      psiMethod,
                                                                      false, null, psiMethod.getName(),
                                                                      PsiType.VOID,
                                                                      infos);

    csp.run();
  }

  private static void replaceReturnStatements(@NotNull final PsiMethod method) {
    final PsiReturnStatement[] statements = PsiUtil.findReturnStatements(method);
    for (int i = statements.length - 1; i >= 0; i--) {
      final PsiReturnStatement returnStatement = statements[i];
      try {
        final PsiExpression expression = returnStatement.getReturnValue();
        if (expression != null) {
          WriteAction.run(() -> {
            final boolean mayHaveSideEffects = SideEffectChecker.mayHaveSideEffects(expression);
            final PsiElementFactory factory = JavaPsiFacade.getElementFactory(method.getProject());
            final PsiReturnStatement ret =
              (PsiReturnStatement)returnStatement.replace(factory.createStatementFromText("return;", returnStatement));
            if (mayHaveSideEffects) {
              final PsiStatement statement = factory.createStatementFromText(expression.getText() + ";", method);
              ret.getParent().addBefore(statement, ret);
            }
            if (UnnecessaryReturnInspection.isReturnRedundant(ret, false, null)) {
              ret.delete();
            }
          });
        }
      }
      catch (IncorrectOperationException e) {
        LOG.error(e);
      }
    }
  }
}