net.sf.staccatocommons.lang.predicate.Predicates Maven / Gradle / Ivy

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/**
 *  Copyright (c) 2011, The Staccato-Commons Team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation; version 3 of the License.
 *
 *  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.
 */

package net.sf.staccatocommons.lang.predicate;

import java.util.Arrays;
import java.util.Collection;

import net.sf.staccatocommons.defs.Evaluable;
import net.sf.staccatocommons.defs.NullSafe;
import net.sf.staccatocommons.defs.predicate.Predicate;
import net.sf.staccatocommons.lang.predicate.internal.All;
import net.sf.staccatocommons.lang.predicate.internal.Any;
import net.sf.staccatocommons.lang.predicate.internal.Equals;
import net.sf.staccatocommons.lang.predicate.internal.EvaluablePredicate;
import net.sf.staccatocommons.lang.predicate.internal.False;
import net.sf.staccatocommons.lang.predicate.internal.InPredicate;
import net.sf.staccatocommons.lang.predicate.internal.NullPredicates;
import net.sf.staccatocommons.lang.predicate.internal.Same;
import net.sf.staccatocommons.lang.predicate.internal.True;
import net.sf.staccatocommons.restrictions.Constant;
import net.sf.staccatocommons.restrictions.check.NonNull;

/**
 * Factory methods for common predicates
 * 
 * @author flbulgarelli
 */
public class Predicates {

  private Predicates() {}

  /**
   * @param 
   * @return A {@link AbstractPredicate} that always returns true
   */
  @Constant
  @NullSafe
  public static  Predicate true_() {
    return True.getInstance();
  }

  /**
   * @param 
   * @return A {@link AbstractPredicate} that always returns false
   */
  @Constant
  @NullSafe
  public static  Predicate false_() {
    return False.getInstance();
  }

  /*
   * Object predicates
   */

  /**
   * Returns a preficate that tests if its argument is not null
   * 
   * @param 
   * @return A constant {@link AbstractPredicate}
   */
  @Constant
  @NullSafe
  public static  Predicate notNull() {
    return NullPredicates.notNull();
  }

  /**
   * Returns a predicate that tests if its argument is null
   * 
   * @param 
   * @return A singleton {@link AbstractPredicate}
   */
  @Constant
  @NullSafe
  public static  Predicate null_() {
    return NullPredicates.null_();
  }

  /**
   * Returns a predicate that tests if the given value is equal to its argument:
   * value.equals(argument).
   * 
   * @param 
   * @param value
   * @return Equiv.equal().apply(value)
   */
  public static  Predicate equal(@NonNull T value) {
    return new Equals(value);
  }

  /**
   * Returns a predicate that tests if its argument is the same that the given
   * value
   * 
   * @param 
   * @param value
   * @return Equiv.same().apply(value)
   */
  @NullSafe
  public static  Predicate same(T value) {
    return new Same(value);
  }

  /**
   * Returns a predicate that tests if its argument is instance of the given
   * class
   * 
   * @param 
   * @param clazz
   * @return a new {@link AbstractPredicate}
   */
  public static  Predicate isInstanceOf(@NonNull final Class clazz) {
    return new AbstractPredicate() {
      public boolean eval(T argument) {
        return clazz.isAssignableFrom(argument.getClass());
      }
    };
  }

  /**
   * Returns a predicate that tests if its argument is equal to any of the given
   * values
   * 
   * @param 
   * @param values
   * @return a new {@link Predicate}
   */
  public static  Predicate in(@NonNull T... values) {
    return new InPredicate(values);
  }

  /**
   * Returns a predicate that tests if its argument is equal to any of the
   * values in the given collection
   * 
   * @param 
   * @param values
   * @return a new {@link AbstractPredicate}
   */
  public static  Predicate in(@NonNull Collection values) {
    return new InPredicate(values);
  }

  /*
   * String predicates
   */

  /**
   * Returns a predicate that evaluates to true if and only if all the given
   * predicates evaluate true
   * 
   * @param 
   * @param predicates
   * @return the all predicate
   */
  public static  Predicate all(@NonNull Evaluable... predicates) {
    return all(Arrays.asList(predicates));
  }

  /**
   * Returns a predicate that evaluates to true if and only if all the given
   * predicates evaluate true
   * 
   * @param 
   * @param predicates
   * @return the all predicate
   */
  public static  Predicate all(@NonNull Iterable> predicates) {
    return new All(predicates);
  }

  /**
   * Returns a predicate that evaluates to false if and only if all the given
   * predicates evaluate false
   * 
   * @param 
   * @param predicates
   * @return the any predicate
   */
  public static  Predicate any(@NonNull Evaluable... predicates) {
    return any(Arrays.asList(predicates));
  }

  /**
   * Returns a predicate that evaluates to false if and only if all the given
   * predicates evaluate false
   * 
   * @param 
   * @param predicates
   * @return the any predicate
   */
  public static  Predicate any(@NonNull Iterable> predicates) {
    return new Any(predicates);
  }

  /*
   * Comparable predicates
   */

  /**
   * Converts the given {@link Evaluable} into a {@link AbstractPredicate}. If
   * it is already a Predicate, returns it.
   * 
   * @param evaluable
   * @param 
   * @return a {@link AbstractPredicate} view of the given evaluable, or the
   *         evaluable, it is a {@link AbstractPredicate} already
   */
  public static  Predicate from(@NonNull Evaluable evaluable) {
    if (evaluable instanceof AbstractPredicate)
      return (Predicate) evaluable;
    return new EvaluablePredicate(evaluable);
  }

}