/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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

 * or visit www.oracle.com if you need additional information or have any

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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

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

package com.sun.xml.internal.rngom.binary;

public class PatternBuilder {

  private final EmptyPattern empty;

  protected final NotAllowedPattern notAllowed;

  protected final PatternInterner interner;

  public PatternBuilder() {

    empty = new EmptyPattern();

    notAllowed = new NotAllowedPattern();

    interner = new PatternInterner();

  }

  public PatternBuilder(PatternBuilder parent) {

    empty = parent.empty;

    notAllowed = parent.notAllowed;

    interner = new PatternInterner(parent.interner);

  }

  Pattern makeEmpty() {

    return empty;

  }

  Pattern makeNotAllowed() {

    return notAllowed;

  }

  Pattern makeGroup(Pattern p1, Pattern p2) {

    if (p1 == empty)

      return p2;

    if (p2 == empty)

      return p1;

    if (p1 == notAllowed || p2 == notAllowed)

      return notAllowed;

    if (false && p1 instanceof GroupPattern) {

      GroupPattern sp = (GroupPattern)p1;

      return makeGroup(sp.p1, makeGroup(sp.p2, p2));

    }

    Pattern p = new GroupPattern(p1, p2);

    return interner.intern(p);

  }

  Pattern makeInterleave(Pattern p1, Pattern p2) {

    if (p1 == empty)

      return p2;

    if (p2 == empty)

      return p1;

    if (p1 == notAllowed || p2 == notAllowed)

      return notAllowed;

    if (false && p1 instanceof InterleavePattern) {

      InterleavePattern ip = (InterleavePattern)p1;

      return makeInterleave(ip.p1, makeInterleave(ip.p2, p2));

    }

    if (false) {

    if (p2 instanceof InterleavePattern) {

      InterleavePattern ip = (InterleavePattern)p2;

      if (p1.hashCode() > ip.p1.hashCode())

        return makeInterleave(ip.p1, makeInterleave(p1, ip.p2));

    }

    else if (p1.hashCode() > p2.hashCode())

      return makeInterleave(p2, p1);

    }

    Pattern p = new InterleavePattern(p1, p2);

    return interner.intern(p);

  }

  Pattern makeChoice(Pattern p1, Pattern p2) {

    if (p1 == empty && p2.isNullable())

      return p2;

    if (p2 == empty && p1.isNullable())

      return p1;

    Pattern p = new ChoicePattern(p1, p2);

    return interner.intern(p);

  }

  Pattern makeOneOrMore(Pattern p) {

    if (p == empty

        || p == notAllowed

        || p instanceof OneOrMorePattern)

      return p;

    Pattern p1 = new OneOrMorePattern(p);

    return interner.intern(p1);

  }

  Pattern makeOptional(Pattern p) {

    return makeChoice(p, empty);

  }

  Pattern makeZeroOrMore(Pattern p) {

    return makeOptional(makeOneOrMore(p));

  }

}