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/*******************************************************************************
* Copyright (c) 2009, 2011 Mountainminds GmbH & Co. KG and Contributors
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Brock Janiczak - analysis and concept
* Marc R. Hoffmann - initial API and implementation
*
*******************************************************************************/
package org.jacoco.core.analysis;
import java.util.HashMap;
import java.util.Map;
/**
* Utility to normalize {@link String} instances in a way that if
* <code>equals()</code> is <code>true</code> for two strings they will be
* represented the same instance. While this is exactly what
* {@link String#intern()} does, this implementation avoids VM specific side
* effects and is supposed to be faster, as neither native code is called nor
* synchronization is required for concurrent lookup.
*
* @author Marc R. Hoffmann
* @version $qualified.bundle.version$
*/
public final class StringPool {
private static final String[] EMPTY_ARRAY = new String[0];
private final Map<String, String> pool = new HashMap<String, String>(1024);
/**
* Returns a normalized instance that is equal to the given {@link String} .
*
* @param s
* any string or <code>null</code>
* @return normalized instance or <code>null</code>
*/
public String get(final String s) {
if (s == null) {
return null;
}
final String norm = pool.get(s);
if (norm == null) {
pool.put(s, s);
return s;
}
return norm;
}
/**
* Returns a modified version of the array with all string slots normalized.
* It is up to the implementation to replace strings in the array instance
* or return a new array instance.
*
* @param arr
* String array or <code>null</code>
* @return normalized instance or <code>null</code>
*/
public String[] get(final String[] arr) {
if (arr == null) {
return null;
}
if (arr.length == 0) {
return EMPTY_ARRAY;
}
for (int i = 0; i < arr.length; i++) {
arr[i] = get(arr[i]);
}
return arr;
}
}
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