content: /*
   *    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 2 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, write to the Free Software
   *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  /*
   *    Arithmetic.java
   *    Copyright (C) 2008 University of Waikato, Hamilton, New Zealand
   *
   */
  
  package weka.core.pmml;
  
  import java.util.ArrayList;
  
  import weka.core.Attribute;
  
  /**
   * Built-in function for +, -, *, /.
   * 
   * @author Mark Hall (mhall{[at]}pentaho{[dot]}com)
   * @version $Revision 1.0 $
   */
  public class BuiltInArithmetic extends Function {
    
    /**
     * For serialization.
     */
    private static final long serialVersionUID = 2275009453597279459L;
  
    /**
     * Enumerated type for the operator.
     */
    enum Operator {
      ADDITION (" + ") {
        double eval(double a, double b) {
          return a + b;
        }
      },
      SUBTRACTION (" - ") {
        double eval(double a, double b) {
          return a - b;
        }
      },
      MULTIPLICATION (" * ") {
        double eval(double a, double b) {
          return a * b;
        }
      },
      DIVISION (" / ") {
        double eval(double a, double b) {
          return a / b;
        }
      };
      
      abstract double eval(double a, double b);
      
      private final String m_stringVal;
      
      Operator(String opName) {
        m_stringVal = opName;
      }
      
      public String toString() {
        return m_stringVal;
      }
    }
    
    /** The operator for this function */
    protected Operator m_operator = Operator.ADDITION;
    
    /**
     * Construct a new Arithmetic built-in pmml function.
     * @param op the operator to use.
     */
    public BuiltInArithmetic(Operator op) {
      m_operator = op;
      m_functionName = m_operator.toString();
    }
    
    /**
     * Set the structure of the parameters that are expected as input by
     * this function. This must be called before getOutputDef() is called.
     * 
     * @param paramDefs the structure of the input parameters
     * @throws Exception if the number or types of parameters are not acceptable by
     * this function
     */
    public void setParameterDefs(ArrayList<Attribute> paramDefs) throws Exception {
      m_parameterDefs = paramDefs;
      
      if (m_parameterDefs.size() != 2) {
        throw new Exception("[Arithmetic] wrong number of parameters. Recieved " 
            + m_parameterDefs.size() + ", expected 2.");
      }
    }
    
    /**
     * Returns an array of the names of the parameters expected
     * as input by this function
     * 
     * @return an array of the parameter names
     */
    public String[] getParameterNames() {
      String[] result = {"A", "B"};
      return result;
    }
    
    /**
     * Get the structure of the result produced by this function.
     * Subclasses must implement.
     * 
     * @return the structure of the result produced by this function.
     */
    public Attribute getOutputDef() {
      return new Attribute("BuiltInArithmeticResult:" + m_operator.toString());
    }
    
    /**
     * Get the result of applying this function.
     * 
     * @param incoming the arguments to this function (supplied in order to match that
     * of the parameter definitions
     * @return the result of applying this function. When the optype is
     * categorical or ordinal, an index into the values of the output definition
     * is returned.
     * @throws Exception if there is a problem computing the result of this function
     */
    public double getResult(double[] incoming) throws Exception {
      if (m_parameterDefs == null) {
        throw new Exception("[BuiltInArithmetic] incoming parameter structure has not been set!");
      }
      
      if (m_parameterDefs.size() != 2 || incoming.length != 2) {
        throw new Exception("[BuiltInArithmetic] wrong number of parameters!");
      }
      
      double result = m_operator.eval(incoming[0], incoming[1]);
      
      return result;
    }
    
    public String toString() {
      return toString("");
    }
    
    public String toString(String pad) {
      return pad + m_parameterDefs.get(0).name() + m_functionName
        + m_parameterDefs.get(1).name();
    }
  }
  