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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
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 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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/*
 * Copyright (C) 2004-2011
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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 * THE SOFTWARE.
 */
package com.sun.xml.internal.rngom.binary;

final class PatternInterner {
    private static final int INIT_SIZE = 256;
    private static final float LOAD_FACTOR = 0.3f;
    private Pattern[] table;
    private int used;
    private int usedLimit;

    PatternInterner() {
        table = null;
        used = 0;
        usedLimit = 0;
    }

    PatternInterner(PatternInterner parent) {
        table = parent.table;
        if (table != null)
            table = (Pattern[]) table.clone();
        used = parent.used;
        usedLimit = parent.usedLimit;
    }

    @SuppressWarnings("empty-statement")
    Pattern intern(Pattern p) {
        int h;

        if (table == null) {
            table = new Pattern[INIT_SIZE];
            usedLimit = (int) (INIT_SIZE * LOAD_FACTOR);
            h = firstIndex(p);
        } else {
            for (h = firstIndex(p); table[h] != null; h = nextIndex(h)) {
                if (p.samePattern(table[h]))
                    return table[h];
            }
        }
        if (used >= usedLimit) {
            // rehash
            Pattern[] oldTable = table;
            table = new Pattern[table.length << 1];
            for (int i = oldTable.length; i > 0;) {
                --i;
                if (oldTable[i] != null) {
                    int j;
                    for (j = firstIndex(oldTable[i]);
                        table[j] != null;
                        j = nextIndex(j));
                    table[j] = oldTable[i];
                }
            }
            for (h = firstIndex(p); table[h] != null; h = nextIndex(h));
            usedLimit = (int) (table.length * LOAD_FACTOR);
        }
        used++;
        table[h] = p;
        return p;
    }

    private int firstIndex(Pattern p) {
        return p.patternHashCode() & (table.length - 1);
    }

    private int nextIndex(int i) {
        return i == 0 ? table.length - 1 : i - 1;
    }
}