JRules Example

Back to PRD Logic Example

Execution results

When run, this programs displays:

Uncle or aunt of william is: edwardW
Uncle or aunt of william is: andrew
Uncle or aunt of william is: mark
Uncle or aunt of william is: anne

This result is correct.

JRules rule file, accompanied with a main function

function void ilrmain(Object ?arg)
{
    // JRules trick: do not care.
    // Initializations needed to assign distingushed values to each constant.
    constants.william = 0;
    constants.diana = 1;
    constants.charles = 2;
    constants.henry = 3;
    constants.elizabeth = 4;
    constants.philip = 5;
    constants.frances = 6;
    constants.edward = 7;
    constants.anne = 8;
    constants.andrew = 9;
    constants.mark = 10;
    constants.edwardW = 11;

    // Parents relationships fact basea
    insert parents() { p1=william; p2=diana; p3=charles; }
    insert parents() { p1=henry; p2=diana; p3=charles; }
    insert parents() { p1=charles; p2=elizabeth; p3=philip; }
    insert parents() { p1=diana; p2=frances; p3=edward; }

    insert parents() { p1=anne; p2=elizabeth; p3=philip; }
    insert parents() { p1=andrew; p2=elizabeth; p3=philip; }
    insert parents() { p1=edwardW; p2=elizabeth; p3=philip; }

    insert married() { p1=diana; p2=charles; }
    insert married() { p1=elizabeth; p2=philip; }
    insert married() { p1=frances; p2=edward; }
    insert married() { p1=anne; p2=mark; }

    execute();
}

/*
 * Rule: parent(C,M) <= parents(C,M,D).
 */
rule parent1
{
   when
   {
       parents(?C: p1; ?M: p2; ?D: p3);
   }
   then
   {
       insert parent() { p1=?C; p2=?M; }
   }
};

/*
 * parent(C,D) <= parents(C,M,D).
 */
rule parent2
{
   when
   {
       parents(?C: p1; ?M: p2; ?D: p3);
   }
   then
   {
       insert parent() { p1=?C; p2=?D; };
   }
};

/*
 * sibling(X,Y) <= parents(X,M,D) and parents(Y,M,D).
 */
rule sibling
{
   when
   {
       parents(?X: p1; ?M: p2; ?D: p3);
       parents(?Y: p1; p2 == ?M; p3 == ?D; ?X != ?Y);
   }
   then
   {
       insert sibling() { p1=?X; p2=?Y; };
   }
};

/*
 * aORuDirect(C, A) <= parent(C,P) and sibling(P,A).
 */
rule aORuDirect
{
   when
   {
       parent(?C: p1; ?P: p2);
       sibling(p1 == ?P; ?A: p2);
   }
   then
   {
       insert aORuDirect() { p1=?C; p2=?A; };
   }
};

/*
 * aORuMarr(C, A) <= aORuDirect(C,X) and married(X,A). 
 */
rule aORuMarriage1
{
   when
   {
       aORuDirect(?C: p1; ?X: p2);
       married(p1 == ?X; ?A: p2);
   }
   then
   {
       insert aORuMarriage() { p1=?C; p2=?A; };
   }
};

/*
 * aORuMarr(C, A) <= aORuDirect(C,X) and married(A,X).
 */
rule aORuMarriage2
{
   when
   {
       aORuDirect(?C: p1; ?X: p2);
       married(?A: p1; p2 == ?X);
   }
   then
   {
       insert aORuMarriage() { p1=?C; p2=?A; };
   }
};

/*
 * aORu(C,A) <= aORuDirect(C,A).
 */
rule aORu1
{
   when
   {
       aORuDirect(?C: p1; ?A: p2);
   }
   then
   {
       insert aORu() { p1=?C; p2=?A; };
   }
};

/*
 * aORu(C,A) <= aORuMarr(C,A).
 */
rule aORu2
{
   when
   {
       aORuMarriage(?C: p1; ?A: p2);
   }
   then
   {
       insert aORu() {p1=?C; p2=?A; };
   }
};

/*
 * ? aORu(william, A).
 */
rule queryRule
{
   when
   {
       aORu(p1==william; ?A: p2);
   }
   then
   {
       // ?A here is an int. We need to convert it into a string.
       String ?s = "";
       if (?A == 0) ?s = "william";
       else if (?A == 1) ?s = "diana";
       else if (?A == 2) ?s = "charles";
       else if (?A == 3) ?s = "henry";
       else if (?A == 4) ?s = "elizabeth";
       else if (?A == 5) ?s = "philip";
       else if (?A == 6) ?s = "frances";
       else if (?A == 7) ?s = "edward";
       else if (?A == 8) ?s = "anne";
       else if (?A == 9) ?s = "andrew";
       else if (?A == 10) ?s = "mark";
       else if (?A == 11) ?s = "edwardW";

       out.println("Uncle or aunt of william is: " + ?s);
   }
};

JRules Executable Object Model (XOM) file

JRules supports dynamic object model. This model has been generated on-the-fly to support the execution of these rules. While a developer can do this, it becomes much more challenging for an automatic translator. See my comments on this.

/*
 * ILOG JRules virtual classes used to implement the "parents" object model.
 */
public interface constants extends ilog.rules.factory.IlrHashObject
    property "ilog.rules.engine.driver" "ilog.rules.factory.IlrHashDriver"
{
    public static int william;
    public static int diana;
    public static int charles;
    public static int henry;
    public static int elizabeth;
    public static int philip;
    public static int frances;
    public static int edward;
    public static int anne;
    public static int andrew;
    public static int mark;
    public static int edwardW;
}

public class parents extends ilog.rules.factory.IlrHashObject, constants
       property "ilog.rules.engine.driver" "ilog.rules.factory.IlrHashDriver"
{
    public parents();
    public int p1;
    public int p2;
    public int p3;
}

public class parent extends ilog.rules.factory.IlrHashObject, constants
       property "ilog.rules.engine.driver" "ilog.rules.factory.IlrHashDriver"
{
    public parent();
    public int p1;
    public int p2;
}

public class sibling extends ilog.rules.factory.IlrHashObject, constants
       property "ilog.rules.engine.driver" "ilog.rules.factory.IlrHashDriver"
{
    public sibling();
    public int p1;
    public int p2;
}

public class married extends ilog.rules.factory.IlrHashObject, constants
       property "ilog.rules.engine.driver" "ilog.rules.factory.IlrHashDriver"
{
    public married();
    public int p1;
    public int p2;
}

public class aORuDirect extends ilog.rules.factory.IlrHashObject, constants
       property "ilog.rules.engine.driver" "ilog.rules.factory.IlrHashDriver"
{
    public aORuDirect();
    public int p1;
    public int p2;
}

public class aORuMarriage extends ilog.rules.factory.IlrHashObject, constants
       property "ilog.rules.engine.driver" "ilog.rules.factory.IlrHashDriver"
{
    public aORuMarriage();
    public int p1;
    public int p2;
}

public class aORu extends ilog.rules.factory.IlrHashObject, constants
       property "ilog.rules.engine.driver" "ilog.rules.factory.IlrHashDriver"
{
    public aORu();
    public int p1;
    public int p2;
}