/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jena.sparql.algebra.op;

import org.apache.jena.atlas.io.IndentedWriter ;
import org.apache.jena.sparql.algebra.Op ;
import org.apache.jena.sparql.serializer.SerializationContext ;
import org.apache.jena.sparql.sse.writers.WriterOp ;
import org.apache.jena.sparql.util.NodeIsomorphismMap ;
import org.apache.jena.sparql.util.PrintSerializableBase ;

public abstract class OpBase extends PrintSerializableBase implements Op
{
    @Override
    public abstract int hashCode() ;
    @Override
    public abstract boolean equalTo(Op other, NodeIsomorphismMap labelMap) ;

    @Override
    final public boolean equals(Object other)
    { 
        if ( other == null ) return false;
        if ( this == other ) return true ;

        if ( ! ( other instanceof Op ) )
            return false ;
        return equalTo((Op)other, null) ;
    }

    @Override
    public void output(IndentedWriter out)
    {
        output(out, null) ;
    }

    @Override
    public void output(IndentedWriter out, SerializationContext sCxt)
    {
        int line = out.getRow() ;
        WriterOp.output(out, this, sCxt) ;
        if ( line != out.getRow() )
            out.ensureStartOfLine() ;
    }

    // Constants used in hashing to stop an element and it's sub-element
    // (if just one) having the same hash.  That isn't usually any problem but
    // it's easy to avoid so we do.
    
    static final int HashBasicGraphPattern      = 0xB1 ;
//    static final int HashGroup                = 0xB2 ;
//    static final int HashUnion                = 0xB3 ;
//    static final int HashLeftJoin             = 0xB4 ;
    static final int HashDistinct               = 0xB5 ;
    static final int HashReduced                = 0xB5 ;
    static final int HashToList                 = 0xB6 ;
    static final int HashNull                   = 0xB7 ;
    static final int HashSequence               = 0xB8 ;
    static final int HashLabel                  = 0xB9 ;
    static final int HashTriple                 = 0xBA ;
    static final int HashQuad                   = 0xBB ;
    static final int HashQuadBlock              = 0xBC ;


}