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From scolebou...@apache.org
Subject cvs commit: jakarta-commons-sandbox/pattern/src/java/org/apache/commons/pattern/predicate Predicate.java PredicateException.java PredicateUtils.java
Date Sat, 29 Jun 2002 12:50:19 GMT
scolebourne    2002/06/29 05:50:19

  Added:       pattern/src/java/org/apache/commons/pattern/predicate
                        Predicate.java PredicateException.java
                        PredicateUtils.java
  Log:
  Initial checkin
  
  Revision  Changes    Path
  1.1                  jakarta-commons-sandbox/pattern/src/java/org/apache/commons/pattern/predicate/Predicate.java
  
  Index: Predicate.java
  ===================================================================
  /* ====================================================================
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 2002 The Apache Software Foundation.  All rights
   * reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution, if
   *    any, must include the following acknowlegement:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowlegement may appear in the software itself,
   *    if and wherever such third-party acknowlegements normally appear.
   *
   * 4. The names "The Jakarta Project", "Commons", and "Apache Software
   *    Foundation" must not be used to endorse or promote products derived
   *    from this software without prior written permission. For written
   *    permission, please contact apache@apache.org.
   *
   * 5. Products derived from this software may not be called "Apache"
   *    nor may "Apache" appear in their names without prior written
   *    permission of the Apache Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   */
  package org.apache.commons.pattern.predicate;
  
  /**
   * <code>Predicate</code> defines an interface implemented by classes that
   * perform a predicate test on an object. Predicate instances can be used
   * to implement queries or to do filtering. 
   * 
   * @author <a href="mailto:scolebourne@joda.org">Stephen Colebourne</a>
   * @version $Id: Predicate.java,v 1.1 2002/06/29 12:50:19 scolebourne Exp $
   */
  public interface Predicate {
      
      /**
       * Use the specified parameter to perform a test that returns true or false.
       *
       * @return true or false
       * @throws PredicateException (runtime) if the predicate encounters a problem
       */
      public boolean evaluate(Object object);
      
  }
  
  
  
  1.1                  jakarta-commons-sandbox/pattern/src/java/org/apache/commons/pattern/predicate/PredicateException.java
  
  Index: PredicateException.java
  ===================================================================
  /* ====================================================================
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 2002 The Apache Software Foundation.  All rights
   * reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution, if
   *    any, must include the following acknowlegement:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowlegement may appear in the software itself,
   *    if and wherever such third-party acknowlegements normally appear.
   *
   * 4. The names "The Jakarta Project", "Commons", and "Apache Software
   *    Foundation" must not be used to endorse or promote products derived
   *    from this software without prior written permission. For written
   *    permission, please contact apache@apache.org.
   *
   * 5. Products derived from this software may not be called "Apache"
   *    nor may "Apache" appear in their names without prior written
   *    permission of the Apache Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   */
  package org.apache.commons.pattern.predicate;
  
  import org.apache.commons.lang.exception.NestableRuntimeException;
  /**
   * Exception thrown when the a Predicate encounters a problem.
   * If required, a root cause error can be wrapped within this one.
   *
   * @author <a href="mailto:scolebourne@joda.org">Stephen Colebourne</a>
   * @version $Id: PredicateException.java,v 1.1 2002/06/29 12:50:19 scolebourne Exp $
   */
  public class PredicateException extends NestableRuntimeException {
  
      /**
       * Constructs a new <code>PredicateException</code> without specified
       * detail message.
       */
      public PredicateException() {
          super();
      }
  
      /**
       * Constructs a new <code>PredicateException</code> with specified
       * detail message.
       *
       * @param msg  the error message.
       */
      public PredicateException(String msg) {
          super(msg);
      }
  
      /**
       * Constructs a new <code>PredicateException</code> with specified
       * nested <code>Throwable</code> root cause.
       *
       * @param rootCause  the exception or error that caused this exception
       *                   to be thrown.
       */
      public PredicateException(Throwable rootCause) {
          super(rootCause);
      }
  
      /**
       * Constructs a new <code>PredicateException</code> with specified
       * detail message and nested <code>Throwable</code> root cause.
       *
       * @param msg        the error message.
       * @param rootCause  the exception or error that caused this exception
       *                   to be thrown.
       */
      public PredicateException(String msg, Throwable rootCause) {
          super(msg, rootCause);
      }
  
  }
  
  
  
  1.1                  jakarta-commons-sandbox/pattern/src/java/org/apache/commons/pattern/predicate/PredicateUtils.java
  
  Index: PredicateUtils.java
  ===================================================================
  /* =========/* ====================================================================
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 2002 The Apache Software Foundation.  All rights
   * reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution, if
   *    any, must include the following acknowlegement:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowlegement may appear in the software itself,
   *    if and wherever such third-party acknowlegements normally appear.
   *
   * 4. The names "The Jakarta Project", "Commons", and "Apache Software
   *    Foundation" must not be used to endorse or promote products derived
   *    from this software without prior written permission. For written
   *    permission, please contact apache@apache.org.
   *
   * 5. Products derived from this software may not be called "Apache"
   *    nor may "Apache" appear in their names without prior written
   *    permission of the Apache Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   */
  package org.apache.commons.pattern.predicate;
  
  import java.io.Serializable;
  import java.util.HashSet;
  import java.util.Set;
  /**
   * <code>PredicateUtils</code> provides reference implementations and utilities
   * for the Predicate pattern interface. The supplied predicates are:
   * <ul>
   * <li>True - always return true
   * <li>False - always return false
   * <li>And/All - true if all of the predicates are true
   * <li>Or/Any - true if any of the predicates is true
   * <li>Either/One - true if only one of the predicate is true
   * <li>Neither/None - true if none of the predicates are true
   * <li>Not - true if the predicate is false, and vice versa
   * <li>InstanceOf - true if the object is an instanceof a class
   * <li>Equal - true if the object equals() a specified object
   * <li>Identity - true if the object == a specified object
   * <li>Null - true if the object is null
   * <li>NotNull - true if the object is not null
   * <li>Unique - true if the object has not already been evaluated
   * </ul>
   * All the supplied predicates are Serializable.
   *
   * @author <a href="mailto:scolebourne@joda.org">Stephen Colebourne</a>
   * @version $Id: PredicateUtils.java,v 1.1 2002/06/29 12:50:19 scolebourne Exp $
   */
  public class PredicateUtils {
  
      /**
       * A predicate that always returns true
       */
      public static final Predicate TRUE_PREDICATE = new ConstantPredicate(true);
      /**
       * A predicate that always returns false
       */
      public static final Predicate FALSE_PREDICATE = new ConstantPredicate(false);
      /**
       * A predicate that returns true if the object is null
       */
      public static final Predicate NULL_PREDICATE = new IdentityPredicate(null);
      /**
       * A predicate that returns true if the object is not null
       */
      public static final Predicate NOT_NULL_PREDICATE = new NotPredicate(NULL_PREDICATE);
  
      /**
       * Restructive constructor
       */
      private PredicateUtils() {
          super();
      }
  
      /**
       * Gets a predicate that always returns true.
       * 
       * @return the predicate
       */
      public static Predicate truePredicate() {
          return TRUE_PREDICATE;
      }
  
      /**
       * Gets a predicate that always returns false.
       * 
       * @return the predicate
       */
      public static Predicate falsePredicate() {
          return FALSE_PREDICATE;
      }
  
      /**
       * Gets a predicate that checks if the object passed in is null.
       * 
       * @return the predicate
       */
      public static Predicate nullPredicate() {
          return NULL_PREDICATE;
      }
  
      /**
       * Gets a predicate that checks if the object passed in is not null.
       * 
       * @return the predicate
       */
      public static Predicate notNullPredicate() {
          return NOT_NULL_PREDICATE;
      }
  
      /**
       * Create a predicate that checks if the object passed in equals to the
       * specified object using equals().
       * 
       * @param value  the value to compare against
       * @return the predicate
       */
      public static Predicate equalPredicate(Object value) {
          if (value == null) {
              return NULL_PREDICATE;
          }
          return new EqualPredicate(value);
      }
  
      /**
       * Create a predicate that checks if the object passed in equals to the
       * specified object by identity.
       * 
       * @param value  the value to compare against
       * @return the predicate
       */
      public static Predicate identityPredicate(Object value) {
          if (value == null) {
              return NULL_PREDICATE;
          }
          return new IdentityPredicate(value);
      }
  
      /**
       * Create a new predicate that returns true only if both of the specified
       * predicates are true.
       * 
       * @param predicate1  the first predicate
       * @param predicate2  the second predicate
       * @return the predicate
       * @throws IllegalArgumentException if either predicate is null
       */
      public static Predicate andPredicate(Predicate predicate1, Predicate predicate2) {
          return allPredicate(new Predicate[] { predicate1, predicate2 });
      }
  
      /**
       * Create a new predicate that returns true only if all of the specified
       * predicates are true.
       * 
       * @param predicates  an array of predicates to check
       * @return the predicate
       * @throws IllegalArgumentException if the predicates array is null
       * @throws IllegalArgumentException if the predicates array has less than 2 elements
       * @throws IllegalArgumentException if any predicate in the array is null
       */
      public static Predicate allPredicate(Predicate[] predicates) {
          validate(predicates);
          return new AllPredicate(predicates);
      }
  
      /**
       * Create a new predicate that returns true if either of the specified
       * predicates are true.
       * 
       * @param predicate1  the first predicate
       * @param predicate2  the second predicate
       * @return the predicate
       * @throws IllegalArgumentException if either predicate is null
       */
      public static Predicate orPredicate(Predicate predicate1, Predicate predicate2) {
          return anyPredicate(new Predicate[] { predicate1, predicate2 });
      }
  
      /**
       * Create a new predicate that returns true if any of the specified
       * predicates are true.
       * 
       * @param predicates  an array of predicates to check
       * @return the predicate
       * @throws IllegalArgumentException if the predicates array is null
       * @throws IllegalArgumentException if the predicates array has less than 2 elements
       * @throws IllegalArgumentException if any predicate in the array is null
       */
      public static Predicate anyPredicate(Predicate[] predicates) {
          validate(predicates);
          return new AnyPredicate(predicates);
      }
  
      /**
       * Create a new predicate that returns true if one, but not both, of the
       * specified predicates are true.
       * 
       * @param predicate1  the first predicate
       * @param predicate2  the second predicate
       * @return the predicate
       * @throws IllegalArgumentException if either predicate is null
       */
      public static Predicate eitherPredicate(Predicate predicate1, Predicate predicate2)
{
          return onePredicate(new Predicate[] { predicate1, predicate2 });
      }
  
      /**
       * Create a new predicate that returns true if only one of the specified
       * predicates are true.
       * 
       * @param predicates  an array of predicates to check
       * @return the predicate
       * @throws IllegalArgumentException if the predicates array is null
       * @throws IllegalArgumentException if the predicates array has less than 2 elements
       * @throws IllegalArgumentException if any predicate in the array is null
       */
      public static Predicate onePredicate(Predicate[] predicates) {
          validate(predicates);
          return new OnePredicate(predicates);
      }
  
      /**
       * Create a new predicate that returns true if neither of the specified 
       * predicates are true.
       * 
       * @param predicate1  the first predicate
       * @param predicate2  the second predicate
       * @return the predicate
       * @throws IllegalArgumentException if either predicate is null
       */
      public static Predicate neitherPredicate(Predicate predicate1, Predicate predicate2)
{
          return nonePredicate(new Predicate[] { predicate1, predicate2 });
      }
  
      /**
       * Create a new predicate that returns true if none of the specified
       * predicates are true.
       * 
       * @param predicates  an array of predicates to check
       * @return the predicate
       * @throws IllegalArgumentException if the predicates array is null
       * @throws IllegalArgumentException if the predicates array has less than 2 elements
       * @throws IllegalArgumentException if any predicate in the array is null
       */
      public static Predicate nonePredicate(Predicate[] predicates) {
          validate(predicates);
          for (int i = 0; i < predicates.length; i++) {
              predicates[i] = notPredicate(predicates[i]);
          }
          return new AllPredicate(predicates);
      }
  
      /**
       * Create a new predicate that returns true if the specified predicate
       * returns false and vice versa.
       * 
       * @param predicate  the predicate to not
       * @return the predicate
       * @throws IllegalArgumentException if the predicate is null
       */
      public static Predicate notPredicate(Predicate predicate) {
          if (predicate == null) {
              throw new IllegalArgumentException("Predicate: The predicate must not be null");
          }
          return new NotPredicate(predicate);
      }
  
      /**
       * Create a new predicate that checks if the object passed in is of
       * a particular type, using instanceof.
       * 
       * @param type  the type to check for
       * @return the predicate
       * @throws IllegalArgumentException if the class is null
       */
      public static Predicate instanceofPredicate(Class type) {
          if (type == null) {
              throw new IllegalArgumentException("Predicate: The type to check instanceof
must not be null");
          }
          return new InstanceofPredicate(type);
      }
  
      /**
       * Gets a predicate that returns true the first time an object is
       * encoutered, and false if the same object is received 
       * again. The comparison is by equals().
       * 
       * @return the predicate
       */
      public static Predicate uniquePredicate() {
          return new UniquePredicate();
      }
  
      /**
       * Validate method shared amongst predicate implementations
       * 
       * @param predicates  the predicates to validate
       */
      private static void validate(Predicate[] predicates) {
          if (predicates == null) {
              throw new IllegalArgumentException("Predicate: The predicate array must not
be null");
          }
          if (predicates.length < 2) {
              throw new IllegalArgumentException(
                  "Predicate: At least 2 predicates must be specified in the predicate array,
size was "
                      + predicates.length);
          }
          for (int i = 0; i < predicates.length; i++) {
              if (predicates[i] == null) {
                  throw new IllegalArgumentException(
                      "Predicate: The predicate array must not contain a null predicate, index
"
                          + i
                          + " was null");
              }
          }
      }
  
      // ConstantPredicate
      //----------------------------------------------------------------------------------
  
      /**
       * ConstantPredicate returns the same instance each time.
       */
      private static class ConstantPredicate implements Predicate, Serializable {
  
          private final boolean iConstant;
  
          /**
           * Constructor to store constant
           */
          private ConstantPredicate(boolean constant) {
              super();
              iConstant = constant;
          }
  
          /**
           * Always return constant
           */
          public boolean evaluate(Object object) {
              return iConstant;
          }
      }
  
      // AndPredicate
      //----------------------------------------------------------------------------------
  
      /**
       * AndPredicate returns true if all predicates return true
       */
      private static class AllPredicate implements Predicate, Serializable {
          private final Predicate[] iPredicates;
  
          /**
           * Constructor
           */
          private AllPredicate(Predicate[] predicates) {
              super();
              iPredicates = predicates;
          }
  
          /**
           * Return true if all predicates return true
           */
          public boolean evaluate(Object object) {
              for (int i = 0; i < iPredicates.length; i++) {
                  if (iPredicates[i].evaluate(object) == false) {
                      return false;
                  }
              }
              return true;
          }
      }
  
      // OrPredicate
      //----------------------------------------------------------------------------------
  
      /**
       * OrPredicate returns true if one of the predicates return true
       */
      private static class AnyPredicate implements Predicate, Serializable {
          private final Predicate[] iPredicates;
  
          /**
           * Constructor
           */
          private AnyPredicate(Predicate[] predicates) {
              super();
              iPredicates = predicates;
          }
  
          /**
           * Return true if one of the predicates returns true
           */
          public boolean evaluate(Object object) {
              for (int i = 0; i < iPredicates.length; i++) {
                  if (iPredicates[i].evaluate(object)) {
                      return true;
                  }
              }
              return false;
          }
      }
  
      // OnePredicate
      //----------------------------------------------------------------------------------
  
      /**
       * OnePredicate returns true if only one of the predicates return true
       */
      private static class OnePredicate implements Predicate, Serializable {
          private final Predicate[] iPredicates;
  
          /**
           * Constructor
           */
          private OnePredicate(Predicate[] predicates) {
              super();
              iPredicates = predicates;
          }
  
          /**
           * Return true if only one of the predicates returns true
           */
          public boolean evaluate(Object object) {
              boolean match = false;
              for (int i = 0; i < iPredicates.length; i++) {
                  if (iPredicates[i].evaluate(object)) {
                      if (match) {
                          return false;
                      } 
                      match = true;
                  }
              }
              return match;
          }
      }
  
      // NotPredicate
      //----------------------------------------------------------------------------------
  
      /**
       * NotPredicate returns the opposite of the wrapped predicate
       */
      private static class NotPredicate implements Predicate, Serializable {
          private final Predicate iPredicate;
  
          /**
           * Constructor
           */
          private NotPredicate(Predicate predicate) {
              super();
              iPredicate = predicate;
          }
          
          /**
           * Return true if the wrapped predicate returns false, and vice versa
           */
          public boolean evaluate(Object object) {
              return !iPredicate.evaluate(object);
          }
      }
  
      // InstanceofPredicate
      //----------------------------------------------------------------------------------
  
      /**
       * InstanceofPredicate checks the type of an object
       */
      private static class InstanceofPredicate implements Predicate, Serializable {
          private final Class iType;
  
          /**
           * Constructor
           */
          public InstanceofPredicate(Class type) {
              super();
              iType = type;
          }
  
          /**
           * Return true if the object is an instanceof the type of the predicate.
           */
          public boolean evaluate(Object object) {
              return iType.isInstance(object);
          }
      }
  
      // EqualPredicate
      //----------------------------------------------------------------------------------
  
      /**
       * EqualPredicate that checks if the object is a particular value by equals().
       */
      private static class EqualPredicate implements Predicate, Serializable {
          private final Object iValue;
          
          /**
           * Constructor
           */
          public EqualPredicate(Object value) {
              super();
              iValue = value;
          }
  
          /**
           * Return true if the object is equals() to the value stored in the predicate.
           */
          public boolean evaluate(Object object) {
              return iValue.equals(object);
          }
      }
  
      // IdentityPredicate
      //----------------------------------------------------------------------------------
  
      /**
       * IdentityPredicate that checks if the object is a particular value by identity.
       */
      private static class IdentityPredicate implements Predicate, Serializable {
          private final Object iValue;
          
          /**
           * Constructor
           */
          public IdentityPredicate(Object value) {
              super();
              iValue = value;
          }
  
          /**
           * Return true if the object is equals() to the value stored in the predicate.
           */
          public boolean evaluate(Object object) {
              return iValue == object;
          }
      }
  
      // UniquePredicate
      //----------------------------------------------------------------------------------
  
      /**
       * UniquePredicate returns true the first time an object is
       * encoutered, and false if the same object is received 
       * again using equals().
       */
      private static class UniquePredicate implements Predicate, Serializable {
          private final Set iSet = new HashSet();
  
          /**
           * Constructor
           */
          public UniquePredicate() {
              super();
          }
  
          /**
           * Return true the first time, and false subsequant times
           * that an object is encountered, using equals().
           */
          public boolean evaluate(Object object) {
              return iSet.add(object);
          }
      }
  
  }
  
  
  

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