Package org.antlr.analysis

Source Code of org.antlr.analysis.LookaheadSet

/*
* [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.analysis;

import org.antlr.misc.IntSet;
import org.antlr.misc.IntervalSet;
import org.antlr.tool.Grammar;

/** An LL(1) lookahead set; contains a set of token types and a "hasEOF"
*  condition when the set contains EOF.  Since EOF is -1 everywhere and -1
*  cannot be stored in my BitSet, I set a condition here.  There may be other
*  reasons in the future to abstract a LookaheadSet over a raw BitSet.
*/
public class LookaheadSet {
  public IntervalSet tokenTypeSet;

  public LookaheadSet() {
    tokenTypeSet = new IntervalSet();
  }

  public LookaheadSet(IntSet s) {
    this();
    tokenTypeSet.addAll(s);
  }

  public LookaheadSet(int atom) {
    tokenTypeSet = IntervalSet.of(atom);
  }

    public LookaheadSet(LookaheadSet other) {
        this();
        this.tokenTypeSet.addAll(other.tokenTypeSet);
    }

    public void orInPlace(LookaheadSet other) {
    this.tokenTypeSet.addAll(other.tokenTypeSet);
  }

  public LookaheadSet or(LookaheadSet other) {
    return new LookaheadSet(tokenTypeSet.or(other.tokenTypeSet));
  }

  public LookaheadSet subtract(LookaheadSet other) {
    return new LookaheadSet(this.tokenTypeSet.subtract(other.tokenTypeSet));
  }

  public boolean member(int a) {
    return tokenTypeSet.member(a);
  }

  public LookaheadSet intersection(LookaheadSet s) {
    IntSet i = this.tokenTypeSet.and(s.tokenTypeSet);
    LookaheadSet intersection = new LookaheadSet(i);
    return intersection;
  }

  public boolean isNil() {
    return tokenTypeSet.isNil();
  }

  public void remove(int a) {
    tokenTypeSet = tokenTypeSet.subtract(IntervalSet.of(a));
  }

  @Override
  public int hashCode() {
    return tokenTypeSet.hashCode();
  }

  @Override
  public boolean equals(Object other) {
    return tokenTypeSet.equals(((LookaheadSet)other).tokenTypeSet);
  }

  public String toString(Grammar g) {
    if ( tokenTypeSet==null ) {
      return "";
    }
    String r = tokenTypeSet.toString(g);
    return r;
  }

  @Override
  public String toString() {
    return toString(null);
  }
}
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