operators

1.  Moperator



/**
 *
 * MonadicOperator
 * Part of Mbase implemented in Java
 * @author Paul Cockshott
  Started Aug 1997
  Copyright (c) University of strathclyde
 */
package strathclyde.cs.relational.operators;
import strathclyde.cs.relational.*;
public abstract class Moperator 
{  

        public abstract Universal apply(Universal b);
    public static final Moperator IDENTITY = new Identity();
    public static final Moperator LOAD = new LoadRelation();

   
}

2.  LoadRelation


LoadRelation1 is a monadic operator whose syntactic representation in K is the dollar sign and whose signiture is given as follows:

Syntax Type Meaning
$ x (String® relation)x is a filename
containing ',' separated
fields to be loaded as a relation
$ [x,[i,j,...]]([String,*int]® relation) x as above
i,j,.. key fields
is a



package strathclyde.cs.relational.operators;
import java.io.*;
import java.util.*;
import strathclyde.cs.relational.*;
import strathclyde.cs.relational.structured.*;
import strathclyde.cs.relational.atomic.*;




public class LoadRelation extends Moperator

{
  
     public Universal apply(Universal b){

If the parameter is a text string interpret this as the name of a comma separated file of text to be loaded with no primary key


}
}

/*StreamTokenizer tokens= new StreamTokenizer (inputFile);
tokens.quoteChar((int)'"');
tokens.eolIsSignificant(true);
Vector v=new Vector();
while(tokens.nextToken()!=tokens.TT_EOF){
String line=tokens.sval;

  if (tokens.nextToken()==tokens.TT_EOL){}
  else{}
  v.addElement(line);
System.out.println(v);*/

3.  Doperator



/*
 *
 * Doperator
 *Part of Mbase implemented in Java
  Author Paul Cockshott
  Started Aug 1997
  Copyright (c) University of strathclyde

 */

package strathclyde.cs.relational.operators;

import  strathclyde.cs.relational.*;

public abstract class Doperator 
{}

4.  Subscript


/**
 *
 * Subscript
 ** Part of Mbase implemented in Java
 * @author Paul Cockshott
  Started Sept 1997
  Copyright (c) University of strathclyde
 */

package strathclyde.cs.relational.operators;
import strathclyde.cs.relational.*;


public class Subscript extends Doperator
{}

5.  Select

package strathclyde.cs.relational.operators;
import strathclyde.cs.relational.*;
import strathclyde.cs.relational.structured.*;
/*
 *
 * Select
 *
 implements the selection operator on sets
 */
public class Select extends Moperator
{}

6.  Plus

//package operator;



/*
 *
 * plus
 * Part of Mbase implemented in Java
  Author Paul Cockshott
  Started Aug 1997
  Copyright (c) University of strathclyde
 */

package strathclyde.cs.relational.operators;
import strathclyde.cs.relational.*;
public class Plus extends Doperator
{}


Footnotes:

1 Part of MdBase implemented in Java Author Nikolaos Kotsis Started September 1997 Copyright © University of Strathclyde


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