ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/persistence/PersistenceHelper.java

/*=============================================================================#
 # Copyright (c) 2012, 2021 Dirk Fauth and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0
 # 
 # Contributors:
 #     Dirk Fauth - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.ecommons.waltable.persistence;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Properties;
import java.util.Set;

import org.eclipse.statet.ecommons.waltable.persistence.gui.PersistenceDialog;


/**
 * Helper class for dealing with persistence of NatTable states.
 */
public class PersistenceHelper {

	/**
	 * Deletes the keys for a state that is identified by given prefix out
	 * of the given properties. 
	 * 
	 * @param prefix The prefix for the keys the state consists of.
	 * 				Can be interpreted as state configuration name.
	 * @param properties The properties containing the state configuration.
	 */
	public static void deleteState(final String prefix, final Properties properties) {
		if (properties != null) {
			//build the key prefix to search for
			//always add the dot as states without a prefix are stored with a leading dot
			//and for named states it might be possible that there are some starting with
			//the same prefix, so the dot clarifies the prefix
			final String keyPrefix= prefix + IPersistable.DOT;
			
			//collect the keys to remove
			final List<Object> keysToRemove= new ArrayList<>();
			for (final Object key : properties.keySet()) {
				if (key.toString().startsWith(keyPrefix)) {
					keysToRemove.add(key);
				}
			}
			
			//remove the keys
			for (final Object toRemove : keysToRemove) {
				properties.remove(toRemove);
			}
		}
	}
	
	/**
	 * As one Properties instance can contain several stored states of a NatTable instance,
	 * this method can be used to retrieve the names of the containing states. In terms
	 * of NatTable states, you may also call the names prefixes.
	 * 
	 * @param properties The Properties to retrieve the containing states of
	 * @return Collection of all state prefixes that are contained in the given properties.
	 */
	public static Collection<String> getAvailableStates(final Properties properties) {
		final Set<String> stateNames= new HashSet<>();
		if (properties != null && !properties.isEmpty()) {
			for (final Object key : properties.keySet()) {
				final String keyString= key.toString();
				if (!PersistenceDialog.ACTIVE_VIEW_CONFIGURATION_KEY.equals(keyString))
				 {
					stateNames.add(keyString.split("\\.")[0]); //$NON-NLS-1$
				}
			}
		}
		return stateNames;
	}
}