content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one or more
   *  contributor license agreements.  See the NOTICE file distributed with
   *  this work for additional information regarding copyright ownership.
   *  The ASF licenses this file to You 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
   *
   *      https://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 org.apache.tools.ant.types.resources;
  
  import java.io.File;
  import java.util.Iterator;
  import java.util.Stack;
  import java.util.stream.Collectors;
  
  import org.apache.tools.ant.BuildException;
  import org.apache.tools.ant.Project;
  import org.apache.tools.ant.types.DataType;
  import org.apache.tools.ant.types.Resource;
  import org.apache.tools.ant.types.ResourceCollection;
  
  /**
   * Base class for a ResourceCollection that wraps a single nested
   * ResourceCollection.
   * @since Ant 1.8.2
   */
  public abstract class AbstractResourceCollectionWrapper
      extends DataType implements ResourceCollection, Cloneable {
      private static final String ONE_NESTED_MESSAGE
          = " expects exactly one nested resource collection.";
  
      private ResourceCollection rc;
      private boolean cache = true;
  
      /**
       * Set whether to cache collections.
       * @param b boolean cache flag.
       */
      public synchronized void setCache(boolean b) {
          cache = b;
      }
  
      /**
       * Learn whether to cache collections. Default is <code>true</code>.
       * @return boolean cache flag.
       */
      public synchronized boolean isCache() {
          return cache;
      }
  
      /**
       * Add a ResourceCollection to the container.
       * @param c the ResourceCollection to add.
       * @throws BuildException on error.
       */
      public synchronized void add(ResourceCollection c) throws BuildException {
          if (isReference()) {
              throw noChildrenAllowed();
          }
          if (c == null) {
              return;
          }
          if (rc != null) {
              throw oneNested();
          }
          rc = c;
          if (Project.getProject(rc) == null) {
              Project p = getProject();
              if (p != null) {
                  p.setProjectReference(rc);
              }
          }
          setChecked(false);
      }
  
      /**
       * Fulfill the ResourceCollection contract.
       * @return an Iterator of Resources.
       */
      @Override
      public final synchronized Iterator<Resource> iterator() {
          if (isReference()) {
              return getRef().iterator();
          }
          dieOnCircularReference();
          return new FailFast(this, createIterator());
      }
  
      /**
       * Do create an iterator on the resource collection. The creation
       * of the iterator is allowed to not be thread safe whereas the iterator
       * itself should. The returned iterator will be wrapped into the FailFast
       * one.
       *
       * @return the iterator on the resource collection
       */
      protected abstract Iterator<Resource> createIterator();
  
      /**
       * Fulfill the ResourceCollection contract.
       * @return number of elements as int.
       */
      @Override
      public synchronized int size() {
          if (isReference()) {
              return getRef().size();
          }
          dieOnCircularReference();
          return getSize();
      }
  
      /**
       * Do compute the size of the resource collection. The implementation of
       * this function is allowed to be not thread safe.
       *
       * @return size of resource collection.
       */
      protected abstract int getSize();
  
      /**
       * Fulfill the ResourceCollection contract.
       * @return whether this is a filesystem-only resource collection.
       */
      public synchronized boolean isFilesystemOnly() {
          if (isReference()) {
              return getRef().isFilesystemOnly();
          }
          dieOnCircularReference();
  
          if (rc == null || rc.isFilesystemOnly()) {
              return true;
          }
          /* now check each Resource in case the child only
             lets through files from any children IT may have: */
          for (Resource r : this) {
              if (r.as(FileProvider.class) == null) {
                  return false;
              }
          }
          return true;
      }
  
      /**
       * Overrides the version of DataType to recurse on all DataType
       * child elements that may have been added.
       * @param stk the stack of data types to use (recursively).
       * @param p   the project to use to dereference the references.
       * @throws BuildException on error.
       */
      protected synchronized void dieOnCircularReference(Stack<Object> stk, Project p)
          throws BuildException {
          if (isChecked()) {
              return;
          }
          if (isReference()) {
              super.dieOnCircularReference(stk, p);
          } else {
              if (rc instanceof DataType) {
                  pushAndInvokeCircularReferenceCheck((DataType) rc, stk, p);
              }
              setChecked(true);
          }
      }
  
      /**
       * Get the nested ResourceCollection.
       * @return a ResourceCollection.
       * @throws BuildException if no nested ResourceCollection has been provided.
       */
      protected final synchronized ResourceCollection getResourceCollection() {
          dieOnCircularReference();
          if (rc == null) {
              throw oneNested();
          }
          return rc;
      }
  
      /**
       * Format this AbstractResourceCollectionWrapper as a String.
       * @return a descriptive <code>String</code>.
       */
      @Override
      public synchronized String toString() {
          if (isReference()) {
              return getRef().toString();
          }
          if (isEmpty()) {
              return "";
          }
          return stream().map(Object::toString)
              .collect(Collectors.joining(File.pathSeparator));
      }
  
      private AbstractResourceCollectionWrapper getRef() {
          return getCheckedRef(AbstractResourceCollectionWrapper.class);
      }
  
      private BuildException oneNested() {
          return new BuildException(super.toString() + ONE_NESTED_MESSAGE);
      }
  
  }
  