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Complete distribution for ANTLR 3
There is a newer version: 3.5.3
/*
 * [The "BSD license"]
 *  Copyright (c) 2010 Terence Parr
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *      derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.antlr.misc;

public class Utils {
	public static final int INTEGER_POOL_MAX_VALUE = 1000;
	static Integer[] ints = new Integer[INTEGER_POOL_MAX_VALUE+1];

	/** Integer objects are immutable so share all Integers with the
	 *  same value up to some max size.  Use an array as a perfect hash.
	 *  Return shared object for 0..INTEGER_POOL_MAX_VALUE or a new
	 *  Integer object with x in it.
	 */
	public static Integer integer(int x) {
		if ( x<0 || x>INTEGER_POOL_MAX_VALUE ) {
			return x;
		}
		if ( ints[x]==null ) {
			ints[x] = x;
		}
		return ints[x];
	}

	/** Given a source string, src,
		a string to replace, replacee,
		and a string to replace with, replacer,
		return a new string w/ the replacing done.
		You can use replacer==null to remove replacee from the string.

		This should be faster than Java's String.replaceAll as that one
		uses regex (I only want to play with strings anyway).
	*/
	public static String replace(String src, String replacee, String replacer) {
		StringBuilder result = new StringBuilder(src.length() + 50);
		int startIndex = 0;
		int endIndex = src.indexOf(replacee);
		while(endIndex != -1) {
			result.append(src.substring(startIndex,endIndex));
			if ( replacer!=null ) {
				result.append(replacer);
			}
			startIndex = endIndex + replacee.length();
			endIndex = src.indexOf(replacee,startIndex);
		}
		result.append(src.substring(startIndex,src.length()));
		return result.toString();
	}

//	/** mimic struct; like a non-iterable map. */
//	public static class Struct {
//		public Map fields = new HashMap();
//
//		@Override
//		public String toString() { return fields.toString(); }
//	}
//
//	public static Struct struct(String propNames, Object... values) {
//		String[] props = propNames.split(",");
//		int i=0;
//		Struct s = new Struct();
//		for (String p : props) s.fields.put(p, values[i++]);
//		return s;
//	}
}