Copyright (c) 2005, 2015 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM - Initial API and implementation
/*******************************************************************************
 * Copyright (c) 2005, 2015 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM - Initial API and implementation
 *******************************************************************************/
package org.eclipse.core.internal.preferences;

import java.util.HashMap;

A string pool is used for sharing strings in a way that eliminates duplicate
equal strings.  A string pool instance can be maintained over a long period
of time, or used as a temporary structure during a string sharing pass over
a data structure.

This class is not intended to be subclassed by clients.

Note: This class is copied from org.eclipse.core.resources
Since:
3.1/**
 * A string pool is used for sharing strings in a way that eliminates duplicate
 * equal strings.  A string pool instance can be maintained over a long period
 * of time, or used as a temporary structure during a string sharing pass over
 * a data structure.
 * <p>
 * This class is not intended to be subclassed by clients.
 * </p>
 *
 * Note: This class is copied from org.eclipse.core.resources
 *
 * @since 3.1
 */
public final class StringPool {
	private int savings;
	private final HashMap<String, String> map = new HashMap<>();

	
Adds a String to the pool.  Returns a String
that is equal to the argument but that is unique within this pool.
Params:
string – The string to add to the pool
Returns:
A string that is equal to the argument./**
	 * Adds a <code>String</code> to the pool.  Returns a <code>String</code>
	 * that is equal to the argument but that is unique within this pool.
	 * @param string The string to add to the pool
	 * @return A string that is equal to the argument.
	 */
	public String add(String string) {
		if (string == null)
			return string;
		Object result = map.get(string);
		if (result != null) {
			if (result != string)
				savings += 44 + 2 * string.length();
			return (String) result;
		}
		map.put(string, string);
		return string;
	}

	
Returns an estimate of the size in bytes that was saved by sharing strings in
the pool.  In particular, this returns the size of all strings that were added to the
pool after an equal string had already been added.  This value can be used
to estimate the effectiveness of a string sharing operation, in order to
determine if or when it should be performed again.
In some cases this does not precisely represent the number of bytes that
were saved.  For example, say the pool already contains string S1.  Now
string S2, which is equal to S1 but not identical, is added to the pool five
times. This method will return the size of string S2 multiplied by the
number of times it was added, even though the actual savings in this case
is only the size of a single copy of S2.
/**
	 * Returns an estimate of the size in bytes that was saved by sharing strings in
	 * the pool.  In particular, this returns the size of all strings that were added to the
	 * pool after an equal string had already been added.  This value can be used
	 * to estimate the effectiveness of a string sharing operation, in order to
	 * determine if or when it should be performed again.
	 *
	 * In some cases this does not precisely represent the number of bytes that
	 * were saved.  For example, say the pool already contains string S1.  Now
	 * string S2, which is equal to S1 but not identical, is added to the pool five
	 * times. This method will return the size of string S2 multiplied by the
	 * number of times it was added, even though the actual savings in this case
	 * is only the size of a single copy of S2.
	 */
	public int getSavedStringCount() {
		return savings;
	}
}