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import patterns.request.*;

import hep.aida.IAnalysisFactory;
import hep.aida.ITree;

import java.util.MissingResourceException;

public class AidaLazyMakeTreeRequest extends AidaTreeRequest {

    String _treeName;
    String _treeType;

    ITree _cachedTree;

    public AidaLazyMakeTreeRequest(String treeName,
				   String treeType) {

	super();
	init(treeName, treeType);
    }

    public AidaLazyMakeTreeRequest(Object caller,
				   String treeName,
				   String treeType) {

	super(caller);
	init(treeName, treeType);
    }

    private void init(String treeName, String treeType) {

	_cachedTree = null;
	_treeName = treeName;
	_treeType = treeType;
    }

    public ITree getReturn() throws IllegalStateException, MissingResourceException {

	if (!wasExecuted()) { throw new IllegalStateException();}

	// returning the pre-cached tree
	if (getCachedTree() != null)
	    return getCachedTree();
	else 
	    throw new MissingResourceException("The cached tree turned out to be null");
    }
    
    protected void enterExecutedState() throws IllegalStateException {

	AidaAnalysisFactoryRequest afRequest = new AnalysisFactoryRequest();
	afRequest.execute();
	
	if (getTreeName() == null)
	    _cachedTree = afRequest.getReturn().createTreeFactory().create();
	else if (getTreeType() == null)
	    _cachedTree = afRequest.getReturn().createTreeFactory().create(getTreeName());
	else
	    _cachedTree = afRequest.getReturn().createTreeFactory().create(getTreeName(),
									   getTreeType());

	super.enterExecutedState();
    }

    // to un-execute, we just un-precache the tree
    protected void enterUnexecutedState() throws IllegalStateException {

	_cachedTree = null;
	super.enterUnexecutedState();
    }

    public boolean supportsUnexecution() { return true;}

    // accessor methods
    protected ITree getCachedTree() { return _cachedTree;}

    protected String getTreeName() { return _treeName;}
    protected String getTreeType() { return _treeType;}
}