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Precedence.java

// $Id$

//  myexpr - My Service Expression Engine - Version 1.0 (www.mysvc.it)
//  Copyright (C) 2009 Davide Cucciniello <davide6169@gmail.com>
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program 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 General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.

/* **********************************************************************
 *
 *  ***   **        *** **  **  ****
 *   **  **        *  *  *  ** **  *
 *   *** **  **  * ***   *  *  *
 *   * ** *   * **   **   * *  *
 *   * *  *   * *  *  *   **   **
 *  ***  ***   **  ***     *    ****
 *             *
 *            *
 *
 *  My Service
 *
 * ***********************************************************************
 *
 *  ***   **       *****
 *   **  **         *  *
 *   *** **  **  *  ***  ***** ****  ****
 *   * ** *   * **  *     ***   *  *  * *
 *   * *  *   * *   *  *  ***   *  *  *
 *  ***  ***   **  ***** ** **  ***  ***
 *             *                *
 *            *                ***
 *
 *  My Service Expression Engine
 *
 *  File: Precedence.java
 *
 *  Description:
 *    class Precedence: represent an operator precedence table
 *    MyExpr: Java library implementing an advanced generic
 *    expression parser based on precedence operator
 *
 * ***********************************************************************
 *
 *  History:
 *    1.0               first version
 *
 * *********************************************************************** */

package it.mysvc.myexpr;

public class Precedence
{
  private Operators operators;
  private boolean[][] precedence;

  public Precedence(Operators operators)
  {
    this.operators = operators;

    int n = operators.getBinaryOperators();

    precedence = new boolean[n][n];

    for(int i=0;i<n;i++)
      for(int j=0;j<n;j++)
      {
        int p1 = operators.getPrecedence(i);
        int p2 = operators.getPrecedence(j);

        precedence[i][j] =
          (p1>p2)||((p1==p2)&&(operators.isLeftAssociative(i)));
      }
  }

  public boolean greaterThan(int binOp1,int binOp2)
  {
    return precedence[binOp1][binOp2];
  }
}

/* end of file */