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Business Document Validation Engine (BDVE)
There is a newer version: 5.2.11
/**
 * Copyright (C) 2014-2020 Philip Helger (www.helger.com)
 * philip[at]helger[dot]com
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.helger.bdve.executorset;

import java.io.Serializable;
import java.util.function.Predicate;
import java.util.function.Supplier;

import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.GuardedBy;
import javax.annotation.concurrent.ThreadSafe;

import com.helger.bdve.execute.IValidationExecutor;
import com.helger.commons.ValueEnforcer;
import com.helger.commons.annotation.ReturnsMutableCopy;
import com.helger.commons.collection.impl.CommonsHashMap;
import com.helger.commons.collection.impl.ICommonsList;
import com.helger.commons.collection.impl.ICommonsMap;
import com.helger.commons.concurrent.SimpleReadWriteLock;
import com.helger.commons.state.EChange;
import com.helger.commons.string.ToStringGenerator;

/**
 * A registry for {@link IValidationExecutorSet} objects. The default instance
 * can be accessed via {@link #INSTANCE}. This class is thread-safe and can
 * therefore be used as a singleton.

 * Initially all validation artefact providers need to register themselves via
 * {@link #registerValidationExecutorSet(IValidationExecutorSet)}. This needs to
 * be done only once upon initialization before usage.

 * For applying validation of rules onto an XML document,
 * {@link #getOfID(VESID)} needs to be invoked to find a matching VES
 * (Validation Executor Set - type `IValidationExecutorSet`). If the returned
 * value is non-null than some rules are registered.
 *
 * @author Philip Helger
 */
@ThreadSafe
public class ValidationExecutorSetRegistry implements Serializable
{
  public static final ValidationExecutorSetRegistry INSTANCE = new ValidationExecutorSetRegistry ();

  protected final SimpleReadWriteLock m_aRWLock = new SimpleReadWriteLock ();
  @GuardedBy ("m_aRWLock")
  protected final ICommonsMap  m_aMap = new CommonsHashMap <> ();

  public ValidationExecutorSetRegistry ()
  {}

  /**
   * Register a validation executor set into this registry.
   *
   * @param aVES
   *        The object to register. MAy not be null.
   * @return The passed parameter
   * @throws IllegalStateException
   *         If another object with the same ID is already registered in this
   *         registry.
   * @param 
   *        The {@link IValidationExecutorSet} implementation that is added and
   *        returned.
   */
  @Nonnull
  public  T registerValidationExecutorSet (@Nonnull final T aVES)
  {
    ValueEnforcer.notNull (aVES, "VES");

    final VESID aKey = aVES.getID ();
    m_aRWLock.writeLocked ( () -> {
      if (m_aMap.containsKey (aKey))
        throw new IllegalStateException ("Another validation executor set with the ID '" +
                                         aKey +
                                         "' is already registered!");
      m_aMap.put (aKey, aVES);
    });
    return aVES;
  }

  /**
   * @return A list of all contained validation executor sets in this registry.
   *         Never null but maybe empty.
   */
  @Nonnull
  @ReturnsMutableCopy
  public ICommonsList  getAll ()
  {
    return m_aRWLock.readLocked ((Supplier >) m_aMap::copyOfValues);
  }

  /**
   * Final all validation executor sets that match the provided filter.
   *
   * @param aFilter
   *        The filter to be used. May be null in which case the
   *        result is the same as {@link #getAll()}.
   * @return Never null but maybe empty.
   */
  @Nonnull
  @ReturnsMutableCopy
  public ICommonsList  findAll (@Nonnull final Predicate  aFilter)
  {
    return m_aRWLock.readLocked ( () -> m_aMap.copyOfValues (aFilter));
  }

  /**
   * Final all validation executor sets that match the provided filter.
   *
   * @param aFilter
   *        The filter to be used. May be null in which case the
   *        result is the same as {@link #getAll()}.
   * @return Never null but maybe empty.
   */
  @Nullable
  public IValidationExecutorSet findFirst (@Nonnull final Predicate  aFilter)
  {
    return m_aRWLock.readLocked ( () -> m_aMap.findFirstValue (e -> aFilter.test (e.getValue ())));
  }

  /**
   * Find the validation executor set with the specified ID.
   *
   * @param aID
   *        The ID to search. May be null.
   * @return null if no such validation executor set is registered.
   */
  @Nullable
  public IValidationExecutorSet getOfID (@Nullable final VESID aID)
  {
    if (aID == null)
      return null;

    return m_aRWLock.readLocked ( () -> m_aMap.get (aID));
  }

  /**
   * This is a cleanup method that frees all resources when they are no longer
   * needed. This may be helpful because some {@link IValidationExecutor}
   * implementations contained in the {@link IValidationExecutorSet} contained
   * in this registry might have strong references to {@link ClassLoader}
   * instances. By calling this method, you can clear the contained map and
   * invoke {@link ValidationExecutorSet#removeAllExecutors()} if applicable.
   *
   * @return {@link EChange}
   */
  @Nonnull
  public EChange removeAll ()
  {
    EChange ret = EChange.UNCHANGED;
    m_aRWLock.writeLock ().lock ();
    try
    {
      if (m_aMap.isNotEmpty ())
      {
        ret = EChange.CHANGED;
        for (final IValidationExecutorSet aVES : m_aMap.values ())
          if (aVES instanceof ValidationExecutorSet)
            ((ValidationExecutorSet) aVES).removeAllExecutors ();
        m_aMap.clear ();
      }
    }
    finally
    {
      m_aRWLock.writeLock ().unlock ();
    }
    return ret;
  }

  @Override
  public String toString ()
  {
    return new ToStringGenerator (this).append ("Map", m_aMap).getToString ();
  }
}