////////////////////////////////////////////////////////////////////////////////

 // checkstyle: Checks Java source code for adherence to a set of rules.

 // Copyright (C) 2001-2014  Oliver Burn

 //

 // This library is free software; you can redistribute it and/or

 // modify it under the terms of the GNU Lesser General Public

 // License as published by the Free Software Foundation; either

 // version 2.1 of the License, or (at your option) any later version.

 //

 // This library is distributed in the hope that it will be useful,

 // but WITHOUT ANY WARRANTY; without even the implied warranty of

 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 // Lesser General Public License for more details.

 //

 // You should have received a copy of the GNU Lesser General Public

 // License along with this library; if not, write to the Free Software

 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 ////////////////////////////////////////////////////////////////////////////////

 package com.puppycrawl.tools.checkstyle.checks.design;

 import com.puppycrawl.tools.checkstyle.api.Check;

 import com.puppycrawl.tools.checkstyle.api.TokenTypes;

 import com.puppycrawl.tools.checkstyle.api.DetailAST;

 /**

  * Implements Bloch, Effective Java, Item 17 -

  * Use Interfaces only to define types.

  *

  * <p>

  * An interface should describe a <em>type</em>, it is therefore

  * inappropriate to define an interface that does not contain any methods

  * but only constants.

  * </p>

  *

  * <p>

  * The check can be configured to also disallow marker interfaces like

  * <code>java.io.Serializable</code>, that do not contain methods or

  * constants at all.

  * </p>

  *

  * @author lkuehne

  */

 public final class InterfaceIsTypeCheck

         extends Check

 {

     /** flag to control whether marker interfaces are allowed. */

     private boolean mAllowMarkerInterfaces = true;

     @Override

     public int[] getDefaultTokens()

     {

         return new int[] {TokenTypes.INTERFACE_DEF};

     }

     @Override

     public int[] getRequiredTokens()

     {

         return getDefaultTokens();

     }

     @Override

     public void visitToken(DetailAST aAST)

     {

         final DetailAST objBlock =

                 aAST.findFirstToken(TokenTypes.OBJBLOCK);

         final DetailAST methodDef =

                 objBlock.findFirstToken(TokenTypes.METHOD_DEF);

         final DetailAST variableDef =

                 objBlock.findFirstToken(TokenTypes.VARIABLE_DEF);

         final boolean methodRequired =

                 !mAllowMarkerInterfaces || (variableDef != null);

         if ((methodDef == null) && methodRequired) {

             log(aAST.getLineNo(), "interface.type");

         }

     }

     /**

      * Controls whether marker interfaces like Serializable are allowed.

      * @param aFlag whether to allow marker interfaces or not

      */

     public void setAllowMarkerInterfaces(boolean aFlag)

     {

         mAllowMarkerInterfaces = aFlag;

     }

 }