Description
3 Problem statement
Consider the following Java program:
public interface Behavior {
public String act();
public String reason();
}
public class Human implements Behavior {
public String type = “HUMAN.”;
public boolean empathy = true;
public String act() {
return “I am an human and I can act.”;
}
public String reason() {
return “I am a human and I can reason.”;
}
public boolean hasEmpathy() {return empathy;}}
public class Bladerunner extends Human {
public String type = “BLADERUNNER.”;
public String rank;
Bladerunner(){}
Bladerunner (String r) {
this.rank = r;
String rank = “OFFICER.”;
System.out.println(rank);
}
public String reason() {
return “I am bladerunner and I can reason.”;
} }
3
public abstract class Machine implements Behavior {
public static String type = “MACHINE.”;
}
public class Android extends Machine {
public int version;
Android (int version) {
this.version = version;
}
public String whatIhave() {
return “I have physical power.”;
}
public static String whatIneed() {
return “I need more time.”;
}
public String act() {
return “I am an android and I can act.”;
}
public String reason() {
return “I am an android and I can reason.”;
}
}
public interface Behavior2 {
public boolean empathy = true;
public boolean memories = true;
public boolean hasEmpathy();
public boolean hasMemories();
}
4
public class Android2 extends Android implements Behavior2 {
Android2 (int version) {
super(version);
}
Android2() {
super(8);
}
public String whatIhave() {
return “I have an infinite time.”;
}
public boolean hasEmpathy() {
return empathy;
}
public boolean hasMemories() {
return memories;
}
}
5
4 Your assignment
Your assignment consists of the following activities:
4.1 Construct a declarative database
Transform the Java program into a declarative database (facts.pl), with the following
facts:
• class(Type): Type is defined as a class.
• construction(Type, Signature): Type is instantiated by a constructor defines by
Signature. In the case of a default constructor, use the keyword default. Consider
the following example:
?- construction(’Bladerunner’, ConstructorSignature).
ConstructorSignature = default ;
ConstructorSignature = ’(String)’ ;
false.
• interface(Type): Type is defined as an interface.
• defines(Type, FeatureName, Kind, AccessType): Class Type defines feature FeatureName
with access control AccessType, where Kind can be either one of method, or attribute.
• extends(Subclass, SuperClass): Class Subclass directly extends class SuperClass.
• implements(Type, Interface): Type directly implements Interface.
6
4.2 Executing queries (12 pts)
Execute the following queries and record your interaction into a file:
1. What classes, if any, are present in the program?
2. What methods, if any, does class ’Human’ define?
3. Does class ’Android’ define an attribute named ’version’?
4. Does class ’Machine’ define a method named ’hasMemories()’?
5. Which class, if any, extends class ’Human’?
6. Which type, if any, implements interface ’Behavior2’?
For each query, write down its type (ground, non-ground).
7
4.3 Extend the database with rules (48 pts)
Extend your database by preparing a separate file to contain all rules described below. The
first line should contain the statement
:- consult(facts).
This will enable your rules file to read (import) your facts file while keeping the two separate.
1. empty class/1: Succeeds when a type defines no features.
2. lazy class/1: Succeeds when a type defines only one method.
3. data type/1: Succeeds when a type defines attributes, but does not define any methods.
4. child/1 Succeeds by finding a set of direct subtype-supertype pairs.
5. child/2: Succeeds when it finds a subtype relationship
6. ancestor/2: Succeeds when it finds all ancestors of a given type
(Hint: Uses child/2).
7. state of/2: Succeeds by obtaining the state of a given type. Recall that the state of
a class consists of all attributes defined or inherited.
8. interface of/2 Succeeds when List contains a list of all messages (method calls)
that make up the interface of class Type.
9. siblings/1: Succeeds by obtaining a pair of sibling types.
10. instantiated polymorphically /1: Succeeds when a type is instantiated using polymorphism.
11. root/1: Succeeds by finding a type with no ancestors. Uses is type/1 which succeeds
when a type is either a class or an interface.
12. provides interface/2: Succeeds by obtaining a list of all classes that implement a
given interface.
8
5 Expected output
?- empty_class(Empty).
false.
?- lazy_class(Lazy).
Lazy = ’Bladerunner’ ;
false.
?- data_type(Type).
Type = ’Machine’ ;
false.
?- child(Set).
Set = [[’Bladerunner’, ’Human’], [’Android’, ’Machine’],
[’Android2’, ’Android’], [’Human’, ’Behavior’],
[’Machine’, ’Behavior’]] .
?- child(’Bladerunner’, ’Machine’).
false.
?- child(’Android’, Parent).
Parent = ’Machine’ ;
false.
?- ancestor(A, ’Android2’).
A = ’Android’ ;
A = ’Behavior2’ ;
A = ’Machine’ ;
A = ’Behavior’ ;
9
false.
?- state_of(’Bladerunner’, State).
State = [type, rank, type, empathy] .
?- interface_of(’Android2’, Interface).
Interface = [’whatIhave()’, ’hasEmpathy()’, hasMemories(),
’whatIneed()’, ’act()’, ’reason()’] .
?- siblings(ListofSiblings).
ListofSiblings = [[’Human’, ’Machine’], [’Machine’, ’Human’]] .
?- instantiated_polymorphically(’Human’).
false.
?- root(R).
R = ’Behavior’ ;
R = ’Behavior2’ ;
false.
?- provides_interface(’Behavior2’, L).
L = [’Android2’] ;
false.
?- provides_interface(’Behavior’, L).
L = [’Human’, ’Machine’, ’Bladerunner’, ’Android’, ’Android2’] ;
false.
10
6 What to submit
You must submit a zip file containing the following two files:
1. File README.txt that contains the names and id’s of all contributing members of your
team.
2. A text file (named after your team, e.g. team1-interaction.txt), containing the
interaction with the system while executing the queries of Section 4.2.
3. A prolog file (named after your team, e.g. team1-rules.pl) with your rules defined
in 4.3.
Name the zip file after your team e.g. team1.zip and submit it at the Electronic Assignment
Submission portal
(https://fis.encs.concordia.ca/eas)
under Programming Assignment 1.
END OF ASSIGNMENT
11
