plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/controlflow/SwitchStatementsWithoutDefaultInspection.java

/*
 * Copyright 2003-2013 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.ui.SingleCheckboxOptionsPanel;
import com.intellij.psi.*;
import com.siyeh.InspectionGadgetsBundle;
import com.siyeh.ig.BaseInspection;
import com.siyeh.ig.BaseInspectionVisitor;
import org.jetbrains.annotations.NotNull;

import javax.swing.*;

public class SwitchStatementsWithoutDefaultInspection extends BaseInspection {

  @SuppressWarnings("PublicField")
  public boolean m_ignoreFullyCoveredEnums = true;

  @Override
  @NotNull
  public String getDisplayName() {
    return InspectionGadgetsBundle.message("switch.statements.without.default.display.name");
  }

  @Override
  @NotNull
  public String getID() {
    return "SwitchStatementWithoutDefaultBranch";
  }

  @Override
  @NotNull
  protected String buildErrorString(Object... infos) {
    return InspectionGadgetsBundle.message("switch.statements.without.default.problem.descriptor");
  }

  @Override
  public JComponent createOptionsPanel() {
    return new SingleCheckboxOptionsPanel(InspectionGadgetsBundle.message("switch.statement.without.default.ignore.option"),
                                          this, "m_ignoreFullyCoveredEnums");
  }

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

  private class SwitchStatementsWithoutDefaultVisitor extends BaseInspectionVisitor {

    @Override
    public void visitSwitchStatement(@NotNull PsiSwitchStatement statement) {
      super.visitSwitchStatement(statement);
      if (switchStatementHasDefault(statement)) {
        return;
      }
      if (m_ignoreFullyCoveredEnums && switchStatementIsFullyCoveredEnum(statement)) {
        return;
      }
      registerStatementError(statement);
    }

    private boolean switchStatementHasDefault(PsiSwitchStatement statement) {
      final PsiCodeBlock body = statement.getBody();
      if (body == null) {
        return true; // do not warn about incomplete code
      }
      final PsiStatement[] statements = body.getStatements();
      if (statements.length == 0) {
        return true; // do not warn when no switch branches are present at all
      }
      for (final PsiStatement child : statements) {
        if (!(child instanceof PsiSwitchLabelStatement)) {
          continue;
        }
        final PsiSwitchLabelStatement switchLabelStatement = (PsiSwitchLabelStatement)child;
        if (switchLabelStatement.isDefaultCase()) {
          return true;
        }
      }
      return false;
    }

    private boolean switchStatementIsFullyCoveredEnum(PsiSwitchStatement statement) {
      final PsiExpression expression = statement.getExpression();
      if (expression == null) {
        return false;
      }
      final PsiType type = expression.getType();
      if (!(type instanceof PsiClassType)) {
        return false;
      }
      final PsiClassType classType = (PsiClassType)type;
      final PsiClass aClass = classType.resolve();
      if (aClass == null || !aClass.isEnum()) {
        return false;
      }
      final PsiCodeBlock body = statement.getBody();
      if (body == null) {
        return false;
      }
      final PsiStatement[] statements = body.getStatements();
      int numCases = 0;
      for (final PsiStatement child : statements) {
        if (child instanceof PsiSwitchLabelStatement) {
          numCases++;
        }
      }
      final PsiField[] fields = aClass.getFields();
      int numEnums = 0;
      for (final PsiField field : fields) {
        final PsiType fieldType = field.getType();
        if (fieldType.equals(type)) {
          numEnums++;
        }
      }
      return numEnums == numCases;
    }
  }
}