FindFunction.java example

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/*
* This program is free software; you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
* Foundation.
*
* You should have received a copy of the GNU Lesser General Public License along with this
* program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
* or from the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* 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 Lesser General Public License for more details.
*
* Copyright (c) 2006 - 2013 Pentaho Corporation and Contributors.  All rights reserved.
*/

package org.pentaho.reporting.libraries.formula.function.text;

import org.pentaho.reporting.libraries.formula.EvaluationException;
import org.pentaho.reporting.libraries.formula.FormulaContext;
import org.pentaho.reporting.libraries.formula.LibFormulaErrorValue;
import org.pentaho.reporting.libraries.formula.function.Function;
import org.pentaho.reporting.libraries.formula.function.ParameterCallback;
import org.pentaho.reporting.libraries.formula.lvalues.TypeValuePair;
import org.pentaho.reporting.libraries.formula.typing.Type;
import org.pentaho.reporting.libraries.formula.typing.TypeRegistry;
import org.pentaho.reporting.libraries.formula.typing.coretypes.NumberType;

import java.math.BigDecimal;

/**
 * This function returns the starting position of a given text in the given text.
 *
 * @author Cedric Pronzato
 */
public class FindFunction implements Function {
  private static final long serialVersionUID = -6581390286475368968L;

  public FindFunction() {
  }

  public TypeValuePair evaluate( final FormulaContext context, final ParameterCallback parameters )
    throws EvaluationException {
    final int parameterCount = parameters.getParameterCount();
    if ( parameterCount < 2 || parameterCount > 3 ) {
      throw EvaluationException.getInstance( LibFormulaErrorValue.ERROR_ARGUMENTS_VALUE );
    }
    final TypeRegistry typeRegistry = context.getTypeRegistry();

    final Type searchType = parameters.getType( 0 );
    final Object searchValue = parameters.getValue( 0 );
    final Type textType = parameters.getType( 1 );
    final Object textValue = parameters.getValue( 1 );
    Type indexType = null;
    Object indexValue = null;

    if ( parameterCount == 3 ) {
      indexType = parameters.getType( 2 );
      indexValue = parameters.getValue( 2 );

      if ( indexType == null || indexValue == null ) {
        throw EvaluationException.getInstance( LibFormulaErrorValue.ERROR_MISSING_ARGUMENT_VALUE );
      }
    }

    final String search = typeRegistry.convertToText( searchType, searchValue );
    final String text = typeRegistry.convertToText( textType, textValue );

    if ( search == null || text == null ) {
      throw EvaluationException.getInstance( LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE );
    }
    int indexFrom = 0;

    if ( indexType != null ) {
      final Number n = typeRegistry.convertToNumber( indexType, indexValue );
      if ( n.intValue() >= 1 ) {
        indexFrom = n.intValue() - 1;
      } else {
        throw EvaluationException.getInstance( LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE );
      }
    }

    final int index = text.indexOf( search, indexFrom );
    if ( index < 0 ) {
      throw EvaluationException.getInstance( LibFormulaErrorValue.ERROR_NOT_FOUND_VALUE );
    }

    return new TypeValuePair( NumberType.GENERIC_NUMBER, new BigDecimal( index + 1 ) );
  }

  public String getCanonicalName() {
    return "FIND";
  }

}