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/**
* Copyright (C) 2006-2015 phloc systems
* http://www.phloc.com
* office[at]phloc[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.phloc.commons.tree.utils.walk;
import javax.annotation.Nonnull;
import javax.annotation.concurrent.Immutable;
import com.phloc.commons.ValueEnforcer;
import com.phloc.commons.annotations.PresentForCodeCoverage;
import com.phloc.commons.hierarchy.DefaultHierarchyWalkerDynamicCallback;
import com.phloc.commons.hierarchy.EHierarchyCallbackReturn;
import com.phloc.commons.hierarchy.IHierarchyWalkerDynamicCallback;
import com.phloc.commons.parent.IChildrenProvider;
import com.phloc.commons.parent.impl.ChildrenProviderHasChildren;
import com.phloc.commons.tree.IBasicTree;
import com.phloc.commons.tree.IBasicTreeItem;
/**
* A specialized walker that iterates all elements in a tree and calls a
* callback method. Compared to {@link TreeWalker} the callbacks used in this
* class allow to stop iteration or to skip all siblings.
*
* @author Philip Helger
*/
@Immutable
public final class TreeWalkerDynamic
{
@PresentForCodeCoverage
@SuppressWarnings ("unused")
private static final TreeWalkerDynamic s_aInstance = new TreeWalkerDynamic ();
private TreeWalkerDynamic ()
{}
@Nonnull
private static > EHierarchyCallbackReturn _walkTree (@Nonnull final ITEMTYPE aTreeItem,
@Nonnull final IChildrenProvider aChildrenProvider,
@Nonnull final IHierarchyWalkerDynamicCallback aCallback)
{
// prefix insertion
final EHierarchyCallbackReturn eRetPrefix = aCallback.onItemBeforeChildren (aTreeItem);
// call children only if mode is continue
EHierarchyCallbackReturn eRetChildren = EHierarchyCallbackReturn.CONTINUE;
if (eRetPrefix == EHierarchyCallbackReturn.CONTINUE && aChildrenProvider.hasChildren (aTreeItem))
{
// iterate children
aCallback.onLevelDown ();
try
{
for (final ITEMTYPE aChildItem : aChildrenProvider.getChildren (aTreeItem))
{
// recursive call
eRetChildren = _walkTree (aChildItem, aChildrenProvider, aCallback);
if (eRetChildren == EHierarchyCallbackReturn.USE_PARENTS_NEXT_SIBLING)
{
// If we don't want the children to be enumerated, break this loop
// and continue as normal
eRetChildren = EHierarchyCallbackReturn.CONTINUE;
break;
}
if (eRetChildren == EHierarchyCallbackReturn.STOP_ITERATION)
{
// stop iterating and propagate the return code to the root
break;
}
}
}
finally
{
// callback
aCallback.onLevelUp ();
}
}
// postfix insertion even if prefix iteration failed
final EHierarchyCallbackReturn eRetPostfix = aCallback.onItemAfterChildren (aTreeItem);
// most stringent first
if (eRetPrefix == EHierarchyCallbackReturn.STOP_ITERATION ||
eRetChildren == EHierarchyCallbackReturn.STOP_ITERATION ||
eRetPostfix == EHierarchyCallbackReturn.STOP_ITERATION)
{
// stop complete iteration
return EHierarchyCallbackReturn.STOP_ITERATION;
}
if (eRetPrefix == EHierarchyCallbackReturn.USE_PARENTS_NEXT_SIBLING ||
eRetChildren == EHierarchyCallbackReturn.USE_PARENTS_NEXT_SIBLING ||
eRetPostfix == EHierarchyCallbackReturn.USE_PARENTS_NEXT_SIBLING)
{
// skip children and siblings
return EHierarchyCallbackReturn.USE_PARENTS_NEXT_SIBLING;
}
// continue
return EHierarchyCallbackReturn.CONTINUE;
}
public static > void walkTree (@Nonnull final IBasicTree aTree,
@Nonnull final IHierarchyWalkerDynamicCallback aCallback)
{
walkTree (aTree, new ChildrenProviderHasChildren (), aCallback);
}
public static > void walkTree (@Nonnull final IBasicTree aTree,
@Nonnull final IChildrenProvider aChildrenResolver,
@Nonnull final IHierarchyWalkerDynamicCallback aCallback)
{
ValueEnforcer.notNull (aTree, "Tree");
walkSubTree (aTree.getRootItem (), aChildrenResolver, aCallback);
}
public static > void walkTreeData (@Nonnull final IBasicTree aTree,
@Nonnull final IHierarchyWalkerDynamicCallback aDataCallback)
{
walkTreeData (aTree, new ChildrenProviderHasChildren (), aDataCallback);
}
public static > void walkTreeData (@Nonnull final IBasicTree aTree,
@Nonnull final IChildrenProvider aChildrenProvider,
@Nonnull final IHierarchyWalkerDynamicCallback aDataCallback)
{
ValueEnforcer.notNull (aTree, "Tree");
walkSubTreeData (aTree.getRootItem (), aChildrenProvider, aDataCallback);
}
public static > void walkSubTree (@Nonnull final ITEMTYPE aTreeItem,
@Nonnull final IHierarchyWalkerDynamicCallback aCallback)
{
walkSubTree (aTreeItem, new ChildrenProviderHasChildren (), aCallback);
}
public static > void walkSubTree (@Nonnull final ITEMTYPE aTreeItem,
@Nonnull final IChildrenProvider aChildrenProvider,
@Nonnull final IHierarchyWalkerDynamicCallback aCallback)
{
ValueEnforcer.notNull (aTreeItem, "TreeItem");
ValueEnforcer.notNull (aChildrenProvider, "ChildrenProvider");
ValueEnforcer.notNull (aCallback, "Callback");
aCallback.begin ();
try
{
if (aChildrenProvider.hasChildren (aTreeItem))
for (final ITEMTYPE aChildItem : aChildrenProvider.getChildren (aTreeItem))
_walkTree (aChildItem, aChildrenProvider, aCallback);
}
finally
{
aCallback.end ();
}
}
public static > void walkSubTreeData (@Nonnull final ITEMTYPE aTreeItem,
@Nonnull final IHierarchyWalkerDynamicCallback aDataCallback)
{
walkSubTreeData (aTreeItem, new ChildrenProviderHasChildren (), aDataCallback);
}
public static > void walkSubTreeData (@Nonnull final ITEMTYPE aTreeItem,
@Nonnull final IChildrenProvider aChildrenProvider,
@Nonnull final IHierarchyWalkerDynamicCallback aDataCallback)
{
ValueEnforcer.notNull (aDataCallback, "DataCallback");
// Wrap callback
walkSubTree (aTreeItem, aChildrenProvider, new DefaultHierarchyWalkerDynamicCallback ()
{
@Override
public void begin ()
{
aDataCallback.begin ();
}
@Override
public void onLevelDown ()
{
super.onLevelDown ();
aDataCallback.onLevelDown ();
}
@Override
public void onLevelUp ()
{
super.onLevelUp ();
aDataCallback.onLevelUp ();
}
@Override
public void end ()
{
aDataCallback.end ();
}
@Override
@Nonnull
public EHierarchyCallbackReturn onItemBeforeChildren (@Nonnull final ITEMTYPE aItem)
{
return aDataCallback.onItemBeforeChildren (aItem.getData ());
}
@Override
@Nonnull
public EHierarchyCallbackReturn onItemAfterChildren (@Nonnull final ITEMTYPE aItem)
{
return aDataCallback.onItemAfterChildren (aItem.getData ());
}
});
}
}
