bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/NavigationHistoryEntry.java

/**********************************************************************
Copyright (c) 2000, 2002 IBM Corp. and others.
All rights reserved. This program and the accompanying materials
are made available under the terms of the Common Public License v1.0
which accompanies this distribution, and is available at
http://www.eclipse.org/legal/cpl-v10.html

Contributors:
    IBM Corporation - Initial implementation
**********************************************************************/

package org.eclipse.ui.internal;

import java.util.ArrayList;
import org.eclipse.ui.*;

/*
 * Wraps the INavigationLocation and keeps editor info.
 */
public class NavigationHistoryEntry {

	private IWorkbenchPage page;	
	NavigationHistoryEditorInfo editorInfo;
	String historyText;
	
	/* Both may be set at the same time. */
	INavigationLocation location;
	private IMemento locationMemento;
	
	/**
	 * Constructs a new HistoryEntry and intializes its editor input and editor id.
	 */
	public NavigationHistoryEntry(NavigationHistoryEditorInfo editorInfo, IWorkbenchPage page,IEditorPart part,INavigationLocation location) {
		this.editorInfo = editorInfo;
		this.page = page;
		this.location = location;
		if (location != null) {
			historyText = location.getText();
		}
		// ensure that the historyText is initialized to something
		if (historyText == null || historyText.length() == 0) {
			if(part != null)
				historyText = part.getTitle();
		}
	}
	/**
	 * Restores the state of the entry and the location if needed and then
	 * restores the location.
	 */
	void restoreLocation() {
		if (editorInfo.editorInput != null && editorInfo.editorID != null) {
			try {
				IEditorPart editor = page.openEditor(editorInfo.editorInput, editorInfo.editorID, true);
				if (location == null) {
					if(editor instanceof INavigationLocationProvider)
						location = ((INavigationLocationProvider)editor).createEmptyNavigationLocation();
				}
					
				if (location != null) {
					if (locationMemento != null) {
						location.setInput(editorInfo.editorInput);
						location.restoreState(locationMemento);
						locationMemento = null;
					}
					location.restoreLocation();
				}
			} catch (PartInitException e) {
				// ignore for now
			}
		}
	}
	/**
	 * Return the label to display in the history drop down list.  Use the
	 * history entry text if the location has not been restored yet.
	 */
	String getHistoryText() {
		if (location != null) {
			// location exists or has been restored, use its text.
			// Also update the historyText so that this value will
			// be saved.  Doing so handles cases where getText() value 
			// may be dynamic. 
			String text = location.getText();
			if ((text == null) || text.equals("")) { //$NON-NLS-1$
				text = historyText;
			} else {
				historyText = text;
			}
			return text;
		} else {		
			return historyText;
		}
	}
	/** 
	 * Saves the state of this entry and its location.
	 * Returns true if possible otherwise returns false.
	 */
	boolean handlePartClosed() {
		if(!editorInfo.isPersistable())
			return false;
		if (location != null) {
			locationMemento = XMLMemento.createWriteRoot(IWorkbenchConstants.TAG_POSITION);
			location.saveState(locationMemento);
			location.releaseState();
		}
		return true;
	}
	/**
	 * Saves the state of this entry and its location.
	 */
	void saveState(IMemento mem, ArrayList entries) {
		mem.putString(IWorkbenchConstants.TAG_HISTORY_LABEL, getHistoryText());
		if(locationMemento != null) {
			IMemento childMem = mem.createChild(IWorkbenchConstants.TAG_POSITION);
			childMem.putMemento(locationMemento);			
		} else if (location != null) {
			IMemento childMem = mem.createChild(IWorkbenchConstants.TAG_POSITION);
			location.saveState(childMem);
		}
	}
	/**
	 * Restore the state of this entry.
	 */
	void restoreState(IMemento mem) {
		historyText = mem.getString(IWorkbenchConstants.TAG_HISTORY_LABEL);
		locationMemento = mem.getChild(IWorkbenchConstants.TAG_POSITION);
	}

	/*
 	 * (non-Javadoc)
     * Method declared on Object.
     */	
	public String toString() {
		return "Input<" + editorInfo.editorInput + "> Details<" + location + ">"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
	}
	/**
	 * Disposes this entry and its location.
	 */
	void dispose() { 
		if (location != null)
			location.dispose();
		editorInfo = null;
	}
	/**
	 * Merges this entry into the current entry. Returns true
	 * if the merge was possible otherwise returns false.
	 */
	boolean mergeInto(NavigationHistoryEntry currentEntry) {
		if (editorInfo.editorInput != null && editorInfo.editorInput.equals(currentEntry.editorInfo.editorInput)) {
			if (location != null) {
				if (currentEntry.location == null) {
					currentEntry.location = location;
					return true;
				} else {
					return location.mergeInto(currentEntry.location);
				}
			}
		}
		return false; 
	}
};