/libformula-1.1.3/source/org/pentaho/reporting/libraries/formula/FormulaContext.java

/*
 * 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 - 2009 Pentaho Corporation and Contributors.  All rights reserved.
 */

package org.pentaho.reporting.libraries.formula;

import org.pentaho.reporting.libraries.formula.function.FunctionRegistry;
import org.pentaho.reporting.libraries.formula.operators.OperatorFactory;
import org.pentaho.reporting.libraries.formula.typing.Type;
import org.pentaho.reporting.libraries.formula.typing.TypeRegistry;
import org.pentaho.reporting.libraries.base.config.Configuration;

/**
 * The formula-context connects the formula functions with the outside world. The context can be used to resolve
 * external references, to query the configuration or to retrieve information about the formula-evaluation system.
 *
 * @author Thomas Morgner
 */
public interface FormulaContext
{
  /**
   * Checks whether the external object referenced by <code>name</code> has changed.
   *
   * @param name the name that identifies the reference.
   * @return true, if the reference has changed, false otherwise.
   * @throws ContextEvaluationException if an error occurs.
   */
  public boolean isReferenceDirty(Object name) throws ContextEvaluationException;

  /**
   * Resolves the given reference. How the name is interpreted by the outside system is an implementation detail.
   *
   * @param name the name that identifies the reference.
   * @return the resolved object.
   * @throws ContextEvaluationException if an error occurs.
   */
  public Object resolveReference(Object name) throws ContextEvaluationException;

  /**
   * Queries the type of the given reference. How the name is interpreted by the outside system is an implementation
   * detail. This return a LibFormula type object matching the type of the object that would be returned by
   * resolveReference.
   *
   * @param name the name that identifies the reference.
   * @return the type of the resolved object.
   * @throws ContextEvaluationException if an error occurs.
   */
  public Type resolveReferenceType(Object name) throws ContextEvaluationException;

  /**
   * Returns the localization context of this formula. The localization context can be used to query locale specific
   * configuration settings.
   *
   * @return the localization context.
   */
  public LocalizationContext getLocalizationContext();

  /**
   * Returns the local configuration of the formula.
   *
   * @return the local configuration.
   */
  public Configuration getConfiguration();

  /**
   * Returns the function registry. The function registry grants access to all formula-function implementations.
   *
   * @return the function registry.
   */
  public FunctionRegistry getFunctionRegistry();

  /**
   * Returns the type registry. The type registry contains all type information and allows to convert values between
   * different types.
   *
   * @return the function registry.
   */
  public TypeRegistry getTypeRegistry();

  /**
   * Returns the operator registry. The Operator-registry contains all operator-implementations.
   *
   * @return the operator registry.
   */
  public OperatorFactory getOperatorFactory();
}