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

 // 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.coding;

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

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

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

 /**

  * Restricts the number of statements per line to one.

  * @author Alexander Jesse

  * @author Oliver Burn

  */

 public final class OneStatementPerLineCheck extends Check

 {

     /** hold the line-number where the last statement ended. */

     private int mLastStatementEnd = -1;

     /** tracks the depth of EXPR tokens. */

     private int mExprDepth;

     /**

      * The for-header usually has 3 statements on one line, but THIS IS OK.

      */

     private boolean mInForHeader;

     @Override

     public int[] getDefaultTokens()

     {

         return new int[] {

             TokenTypes.EXPR, TokenTypes.SEMI, TokenTypes.FOR_INIT,

             TokenTypes.FOR_ITERATOR,

         };

     }

     @Override

     public void beginTree(DetailAST aRootAST)

     {

         mExprDepth = 0;

         mInForHeader = false;

         mLastStatementEnd = -1;

     }

     @Override

     public void visitToken(DetailAST aAst)

     {

         switch (aAst.getType()) {

         case TokenTypes.EXPR:

             visitExpr(aAst);

             break;

         case TokenTypes.SEMI:

             visitSemi(aAst);

             break;

         case TokenTypes.FOR_INIT:

             mInForHeader = true;

             break;

         default:

             break;

         }

     }

     @Override

     public void leaveToken(DetailAST aAst)

     {

         switch (aAst.getType()) {

         case TokenTypes.FOR_ITERATOR:

             mInForHeader = false;

             break;

         case TokenTypes.EXPR:

             mExprDepth--;

             break;

         default:

             break;

         }

     }

     /**

      * Mark the state-change for the statement (entering) and remember the

      * first line of the last statement. If the first line of the new

      * statement is the same as the last line of the last statement and we are

      * not within a for-statement, then the rule is violated.

      * @param aAst token for the {@link TokenTypes#EXPR}.

      */

     private void visitExpr(DetailAST aAst)

     {

         mExprDepth++;

         if (mExprDepth == 1

                 && !mInForHeader

                 && (mLastStatementEnd == aAst.getLineNo()))

         {

             log(aAst, "multiple.statements.line");

         }

     }

     /**

      * Mark the state-change for the statement (leaving) and remember the last

      * line of the last statement.

      * @param aAst for the {@link TokenTypes#SEMI}.

      */

     private void visitSemi(DetailAST aAst)

     {

         if (mExprDepth == 0) {

             mLastStatementEnd = aAst.getLineNo();

         }

     }

 }