ValueExpression.java :  » Database-DBMS » Quadcap-Embeddable-Database » com » quadcap » sql » Java Open Source

package com.quadcap.sql;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
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 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
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 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
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 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
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 * provided that the Software is free of defects, or fit for a
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 */

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

import java.sql.SQLException;

import com.quadcap.sql.types.Type;
import com.quadcap.sql.types.Value;

/**
 * Expression yielding a constant value.
 *
 * @author Stan Bailes
 */
public class ValueExpression extends Expression implements Externalizable {
    Value        value;

    public ValueExpression() {}
    
    public ValueExpression(Value value) {
  this.value = value;
    }

    public int rank() { return 0; }
    public Value getValue(Session session, Cursor cursor) { return value; }
    public Type getType(Session session, Cursor cursor) throws SQLException {
        return value.getType();
    }

    public void invert() {
  throw new RuntimeException(
      "invert not implemented for ValueExpression");
    }

    public void visitSubExpressions(ExpressionVisitor ev) {
    }

    public void readExternal(ObjectInput in)
  throws IOException, ClassNotFoundException
    {
  value = (Value)in.readObject();
    }
    
    public void writeExternal(ObjectOutput out) throws IOException {
  out.writeObject(value);
    }

    public String toString() {
  if (value == null) {
      return "<null>";
  } else {
      return value.toString();
  }
    }
}