| package jp.ac.kobe_u.cs.prolog.builtin; |
| import jp.ac.kobe_u.cs.prolog.lang.*; |
| /** |
| <code>'$get_instances'/2</code><br> |
| @author Mutsunori Banbara (banbara@kobe-u.ac.jp) |
| @author Naoyuki Tamura (tamura@kobe-u.ac.jp) |
| @version 1.1 |
| */ |
| class PRED_$get_instances_2 extends Predicate { |
| public Term arg1, arg2; |
| public static SymbolTerm COMMA = SymbolTerm.makeSymbol(",", 2); |
| |
| public PRED_$get_instances_2(Term a1, Term a2, Predicate cont) { |
| arg1 = a1; |
| arg2 = a2; |
| this.cont = cont; |
| } |
| |
| public PRED_$get_instances_2(){} |
| |
| public void setArgument(Term[] args, Predicate cont) { |
| arg1 = args[0]; |
| arg2 = args[1]; |
| this.cont = cont; |
| } |
| |
| public int arity() { return 2; } |
| |
| public String toString() { |
| return "$get_instances(" + arg1 + "," + arg2 + ")"; |
| } |
| |
| public Predicate exec(Prolog engine) { |
| engine.setB0(); |
| Term a1, a2; |
| a1 = arg1; |
| a2 = arg2; |
| int idx; |
| |
| a1 = a1.dereference(); |
| if (a1.isNil()) |
| return engine.fail(); |
| if (! a1.isList()) |
| throw new IllegalTypeException(this, 1, "list", a1); |
| Term x = Prolog.Nil; |
| Term tmp = a1; |
| while(! tmp.isNil()) { |
| if (! tmp.isList()) |
| throw new IllegalTypeException(this, 1, "list", a1); |
| Term car = ((ListTerm)tmp).car().dereference(); |
| if (car.isVariable()) |
| throw new PInstantiationException(this, 1); |
| if (! car.isInteger()) |
| throw new RepresentationException(this, 1, "integer"); |
| // car is an integer |
| int i = ((IntegerTerm)car).intValue(); |
| Term e = engine.internalDB.get(i); |
| if (e != null) { |
| Term[] arg = {e, car}; |
| x = new ListTerm(new StructureTerm(COMMA, arg), x); |
| } |
| // else { |
| // System.out.println("index " + i + " is deleted."); |
| // } |
| |
| // if (e == null) |
| // throw new SystemException("invalid index"); |
| // Term[] arg = {e, car}; |
| // x = new ListTerm(new StructureTerm(COMMA, arg), x); |
| tmp = ((ListTerm)tmp).cdr().dereference(); |
| } |
| if (! a2.unify(x, engine.trail)) |
| return engine.fail(); |
| return cont; |
| } |
| } |