com.siyeh.ig.controlflow.IfStatementWithIdenticalBranchesInspection Maven / Gradle / Ivy

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A packaging of the IntelliJ Community Edition java-analysis-impl library. This is release number 1 of trunk branch 142.
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/*
 * Copyright 2003-2014 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.ProblemDescriptor;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.util.Ref;
import com.intellij.psi.*;
import com.intellij.psi.search.LocalSearchScope;
import com.intellij.psi.util.PsiTreeUtil;
import com.intellij.refactoring.extractMethod.InputVariables;
import com.intellij.refactoring.util.duplicates.ConditionalReturnStatementValue;
import com.intellij.refactoring.util.duplicates.DuplicatesFinder;
import com.intellij.refactoring.util.duplicates.Match;
import com.intellij.refactoring.util.duplicates.ReturnValue;
import com.intellij.util.IncorrectOperationException;
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.ControlFlowUtils;
import com.siyeh.ig.psiutils.EquivalenceChecker;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.Collections;

public class IfStatementWithIdenticalBranchesInspection
  extends BaseInspection {

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

  @Override
  @NotNull
  public String buildErrorString(Object... infos) {
    return InspectionGadgetsBundle.message(
      "if.statement.with.identical.branches.problem.descriptor");
  }

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

  private static class CollapseIfFix extends InspectionGadgetsFix {

    public CollapseIfFix() {
    }

    @Override
    @NotNull
    public String getName() {
      return InspectionGadgetsBundle.message(
        "if.statement.with.identical.branches.collapse.quickfix");
    }

    @NotNull
    @Override
    public String getFamilyName() {
      return getName();
    }

    @Override
    public void doFix(@NotNull Project project,
                      ProblemDescriptor descriptor)
      throws IncorrectOperationException {
      final PsiElement identifier = descriptor.getPsiElement();
      final PsiIfStatement statement =
        (PsiIfStatement)identifier.getParent();
      assert statement != null;
      final PsiStatement thenBranch = statement.getThenBranch();
      if (thenBranch == null) {
        return;
      }
      final PsiStatement elseBranch = statement.getElseBranch();
      if (elseBranch == null) {
        // implicit else branch after the if
        statement.delete();
        return;
      }
      if (elseBranch instanceof PsiIfStatement) {
        final PsiIfStatement elseIfStatement =
          (PsiIfStatement)elseBranch;
        final PsiExpression condition1 = statement.getCondition();
        final PsiExpression condition2 = elseIfStatement.getCondition();
        if (condition1 == null) {
          return;
        }
        PsiReplacementUtil.replaceExpression(condition1, buildOrExpressionText(
          condition1, condition2));
        final PsiStatement elseElseBranch =
          elseIfStatement.getElseBranch();
        if (elseElseBranch == null) {
          elseIfStatement.delete();
        }
        else {
          elseIfStatement.replace(elseElseBranch);
        }
      }
      else {
        final PsiElement parent = statement.getParent();
        if (thenBranch instanceof PsiBlockStatement) {
          final PsiBlockStatement blockStatement =
            (PsiBlockStatement)thenBranch;
          if (parent instanceof PsiCodeBlock) {
            final PsiCodeBlock codeBlock =
              blockStatement.getCodeBlock();
            final PsiStatement[] statements =
              codeBlock.getStatements();
            if (statements.length > 0) {
              parent.addRangeBefore(statements[0],
                                    statements[statements.length - 1], statement);
            }
            statement.delete();
          }
          else {
            statement.replace(blockStatement);
          }
        }
        else {
          statement.replace(thenBranch);
        }
      }
    }

    private static String buildOrExpressionText(PsiExpression expression1,
                                                PsiExpression expression2) {
      final StringBuilder result = new StringBuilder();
      if (expression1 != null) {
        result.append(expression1.getText());
      }
      result.append("||");
      if (expression2 != null) {
        result.append(expression2.getText());
      }
      return result.toString();
    }
  }

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

  private static class IfStatementWithIdenticalBranchesVisitor extends BaseInspectionVisitor {

    @Override
    public void visitIfStatement(@NotNull PsiIfStatement ifStatement) {
      super.visitIfStatement(ifStatement);
      final PsiStatement elseBranch = ifStatement.getElseBranch();
      final PsiStatement thenBranch = ifStatement.getThenBranch();
      if (thenBranch == null) {
        return;
      }
      final Project project = ifStatement.getProject();
      final InputVariables inputVariables =
        new InputVariables(Collections.emptyList(),
                           project, new LocalSearchScope(thenBranch), false);
      final DuplicatesFinder finder =
        new DuplicatesFinder(new PsiElement[]{thenBranch},
                             inputVariables, null,
                             Collections.emptyList());
      if (elseBranch instanceof PsiIfStatement) {
        final PsiIfStatement statement = (PsiIfStatement)elseBranch;
        final PsiStatement branch = statement.getThenBranch();
        if (branch == null) {
          return;
        }
        final Match match = finder.isDuplicate(branch, true);
        if (match != null) {
          final ReturnValue matchReturnValue = match.getReturnValue();
          if (matchReturnValue instanceof ConditionalReturnStatementValue &&
              !matchReturnValue.isEquivalent(buildReturnValue(thenBranch))) {
            return;
          }
          registerStatementError(ifStatement, statement);
          return;
        }
      }
      if (elseBranch == null) {
        checkIfStatementWithoutElseBranch(ifStatement);
      }
      else {
        final Match match = finder.isDuplicate(elseBranch, true);
        if (match != null) {
          final ReturnValue matchReturnValue = match.getReturnValue();
          if (matchReturnValue instanceof ConditionalReturnStatementValue &&
              !matchReturnValue.isEquivalent(buildReturnValue(thenBranch))) {
            return;
          }
          registerStatementError(ifStatement);
        }
      }
    }

    @Nullable
    private ReturnValue buildReturnValue(PsiElement element) {
      final Ref result = Ref.create(null);
      element.accept(new JavaRecursiveElementWalkingVisitor() {
        public void visitClass(PsiClass aClass) {}

        public void visitLambdaExpression(PsiLambdaExpression expression) {}

        @Override
        public void visitReturnStatement(PsiReturnStatement statement) {
          super.visitReturnStatement(statement);
          result.set(statement);
        }
      });
      final PsiReturnStatement returnStatement = result.get();
      if (returnStatement == null) {
        return null;
      }
      final PsiExpression expression = returnStatement.getReturnValue();
      if (expression == null) {
        return null;
      }
      return new ConditionalReturnStatementValue(expression);
    }

    private void checkIfStatementWithoutElseBranch(
      PsiIfStatement ifStatement) {
      final PsiStatement thenBranch = ifStatement.getThenBranch();
      if (ControlFlowUtils.statementMayCompleteNormally(thenBranch)) {
        return;
      }
      PsiStatement nextStatement = getNextStatement(ifStatement);
      if (thenBranch instanceof PsiBlockStatement) {
        final PsiBlockStatement blockStatement =
          (PsiBlockStatement)thenBranch;
        final PsiCodeBlock codeBlock = blockStatement.getCodeBlock();
        final PsiStatement[] statements = codeBlock.getStatements();
        final PsiStatement lastStatement =
          statements[statements.length - 1];
        for (PsiStatement statement : statements) {
          if (nextStatement == null) {
            if (statement == lastStatement &&
                statement instanceof PsiReturnStatement) {
              final PsiReturnStatement returnStatement =
                (PsiReturnStatement)statement;
              if (returnStatement.getReturnValue() == null) {
                registerStatementError(ifStatement);
              }
            }
            return;
          }
          else if (!EquivalenceChecker.statementsAreEquivalent(
            statement, nextStatement)) {
            return;
          }
          nextStatement = getNextStatement(nextStatement);
        }
      }
      else if (!EquivalenceChecker.statementsAreEquivalent(
        thenBranch, nextStatement)) {
        return;
      }
      registerStatementError(ifStatement);
    }

    @Nullable
    private static PsiStatement getNextStatement(PsiStatement statement) {
      PsiStatement nextStatement =
        PsiTreeUtil.getNextSiblingOfType(statement,
                                         PsiStatement.class);
      while (nextStatement == null) {
        //noinspection AssignmentToMethodParameter
        statement = PsiTreeUtil.getParentOfType(statement,
                                                PsiStatement.class);
        if (statement == null) {
          return null;
        }
        if (statement instanceof PsiLoopStatement) {
          // return in a loop statement is not the same as continuing
          // looping.
          return statement;
        }
        nextStatement = PsiTreeUtil.getNextSiblingOfType(statement,
                                                         PsiStatement.class);
        if (nextStatement == null) {
          continue;
        }
        final PsiElement statementParent = statement.getParent();
        if (!(statementParent instanceof PsiIfStatement)) {
          continue;
        }
        // nextStatement should not be the else part of an if statement
        final PsiElement nextStatementParent =
          nextStatement.getParent();
        if (statementParent.equals(nextStatementParent)) {
          nextStatement = null;
        }
      }
      return nextStatement;
    }
  }
}