@Override
public List getTerm() {
if (immutable) {
return this;
} else {
Term newHead = head.getTerm();
Term newTail = tail.getTerm();
if (newHead == head && newTail == tail) {
return this;
} else {
return new List(newHead, newTail, newHead.isImmutable() && newTail.isImmutable());
}
}
}
public boolean char_code_2(Term arg0, Term arg1) throws PrologError {
arg0 = arg0.getTerm();
arg1 = arg1.getTerm();
if (arg1 instanceof Var) {
if (arg0.isAtom()) {
String st = ((Struct) arg0).getName();
if (st.length() <= 1) return unify(arg1, new Int(st.charAt(0)));
else throw PrologError.type_error(engine.getEngineManager(), 1, "character", arg0);
} else throw PrologError.type_error(engine.getEngineManager(), 1, "character", arg0);
} else if ((arg1 instanceof Int) || (arg1 instanceof alice.tuprolog.Long)) {
char c = (char) ((Number) arg1).intValue();
return unify(arg0, new Struct("" + c));
} else throw PrologError.type_error(engine.getEngineManager(), 2, "integer", arg1);
}
public boolean atom_length_2(Term arg0, Term len) throws PrologError {
arg0 = arg0.getTerm();
if (arg0 instanceof Var) throw PrologError.instantiation_error(engine.getEngineManager(), 1);
if (!arg0.isAtom()) throw PrologError.type_error(engine.getEngineManager(), 1, "atom", arg0);
Struct atom = (Struct) arg0;
return unify(len, new Int(atom.getName().length()));
}
/**
* var unification.
*
* <p>First, verify the Term eventually already unified with the same Var if the Term exist, unify
* var with that term, in order to handle situation as (A = p(X) , A = p(1)) which must produce
* X/1.
*
* <p>If instead the var is not already unified, then:
*
* <p>if the Term is a var bound to X, then try unification with X so for example if A=1, B=A then
* B is unified to 1 and not to A (note that it's coherent with chronological backtracking: the
* eventually backtracked A unification is always after backtracking of B unification.
*
* <p>if are the same Var, unification must succeed, but without any new bindings (to avoid cycles
* for extends in A = B, B = A)
*
* <p>if the term is a number, then it's a success and new link is created (retractable by means
* of a code)
*
* <p>if the term is a compound, then occur check test is executed: the var must not appear in the
* compound ( avoid X=p(X), or p(X,X)=p(Y,f(Y)) ); if occur check is ok then it's success and a
* new link is created (retractable by a code)
*/
boolean unify(List vl1, List vl2, Term t) {
Term tt = getTerm();
if (tt == this) {
t = t.getTerm();
if (t instanceof Var) {
if (this == t) {
try {
vl1.add(this);
} catch (NullPointerException e) {
/* vl1==null mean nothing intresting for the caller */
}
return true;
}
} else if (t instanceof Struct) {
// occur-check
if (occurCheck(vl2, (Struct) t)) {
return false;
}
} else if (!(t instanceof Number)) {
return false;
}
link = t;
try {
vl1.add(this);
} catch (NullPointerException e) {
/* vl1==null mean nothing intresting for the caller */
}
// System.out.println("VAR "+name+" BOUND to "+link+" - time: "+time+" - mark: "+mark);
return true;
} else {
return (tt.unify(vl1, vl2, t));
}
}
// Updates indexes, deleting informations about the last removed clause
public void unregister(ClauseInfo ci) {
Term clause = ci.getHead();
if (clause instanceof Struct) {
Struct g = (Struct) clause.getTerm();
if (g.getArity() == 0) {
return;
}
Term t = g.getArg(0).getTerm();
if (t instanceof Var) {
numCompClausesIndex.removeShared(ci);
constantCompClausesIndex.removeShared(ci);
structCompClausesIndex.removeShared(ci);
listCompClausesList.remove(ci);
} else if (t.isAtomic()) {
if (t instanceof Number) {
numCompClausesIndex.delete((Number) t, ci);
} else if (t instanceof Struct) {
constantCompClausesIndex.delete(((Struct) t).getName(), ci);
}
} else if (t instanceof Struct) {
if (t.isList()) {
listCompClausesList.remove(ci);
} else {
structCompClausesIndex.delete(((Struct) t).getPredicateIndicator(), ci);
}
}
}
}
public boolean isEqual(Term t) {
Term tt = getTerm();
if (tt == this) {
t = t.getTerm();
return (t instanceof Var && timestamp == ((Var) t).timestamp);
} else {
return tt.isEqual(t);
}
}
public boolean atom_chars_2(Term arg0, Term arg1) throws PrologError {
arg0 = arg0.getTerm();
arg1 = arg1.getTerm();
if (arg0 instanceof Var) {
if (!arg1.isList()) {
throw PrologError.type_error(engine.getEngineManager(), 2, "list", arg1);
}
Struct list = (Struct) arg1;
if (list.isEmptyList()) {
return unify(arg0, new Struct(""));
}
String st = "";
while (!(list.isEmptyList())) {
String st1 = list.getTerm(0).toString();
try {
if (st1.startsWith("'") && st1.endsWith("'")) {
st1 = st1.substring(1, st1.length() - 1);
}
} catch (Exception ex) {
}
;
st = st.concat(st1);
list = (Struct) list.getTerm(1);
}
return unify(arg0, new Struct(st));
} else {
if (!arg0.isAtom()) {
throw PrologError.type_error(engine.getEngineManager(), 1, "atom", arg0);
}
String st = ((Struct) arg0).getName();
Term[] tlist = new Term[st.length()];
for (int i = 0; i < st.length(); i++) {
tlist[i] = new Struct(new String(new char[] {st.charAt(i)}));
}
Struct list = new Struct(tlist);
/*
* for (int i=0; i<st.length(); i++){ Struct ch=new Struct(new
* String(new char[]{ st.charAt(st.length()-i-1)} )); list=new
* Struct( ch, list); }
*/
return unify(arg1, list);
}
}
/**
* Retrieves a sublist of all the clauses of the same family as the goal and which, in all
* probability, could match with the given goal
*
* @param goal The goal to be resolved
* @return The list of goal-compatible predicates
*/
public List<ClauseInfo> get(Term goal) {
// Gets the correct list and encapsulates it in ReadOnlyLinkedList
if (goal instanceof Struct) {
Struct g = (Struct) goal.getTerm();
/*
* If no arguments no optimization can be applied
* (and probably no optimization is needed)
*/
if (g.getArity() == 0) {
return new ReadOnlyLinkedList<>(this);
}
/* Retrieves first argument and checks type */
Term t = g.getArg(0).getTerm();
if (t instanceof Var) {
/*
* if first argument is an unbounded variable,
* no reasoning is possible, all family must be returned
*/
return new ReadOnlyLinkedList<>(this);
} else if (t.isAtomic()) {
if (t instanceof Number) {
/* retrieves clauses whose first argument is numeric (or Var)
* and same as goal's first argument, if no clauses
* are retrieved, all clauses with a variable
* as first argument
*/
return new ReadOnlyLinkedList<>(numCompClausesIndex.get((Number) t));
} else if (t instanceof Struct) {
/* retrieves clauses whose first argument is a constant (or Var)
* and same as goal's first argument, if no clauses
* are retrieved, all clauses with a variable
* as first argument
*/
return new ReadOnlyLinkedList<>(constantCompClausesIndex.get(((Struct) t).getName()));
}
} else if (t instanceof Struct) {
if (isAList((Struct) t)) {
/* retrieves clauses which has a list (or Var) as first argument */
return new ReadOnlyLinkedList<>(listCompClausesList);
} else {
/* retrieves clauses whose first argument is a struct (or Var)
* and same as goal's first argument, if no clauses
* are retrieved, all clauses with a variable
* as first argument
*/
return new ReadOnlyLinkedList<>(
structCompClausesIndex.get(((Struct) t).getPredicateIndicator()));
}
}
}
/* Default behaviour: no optimization done */
return new ReadOnlyLinkedList<>(this);
}
public boolean isGreater(Term t) {
Term tt = getTerm();
if (tt == this) {
t = t.getTerm();
if (!(t instanceof Var)) return false;
return timestamp > ((Var) t).timestamp;
} else {
return tt.isGreater(t);
}
}
// Updates indexes, storing informations about the last added clause
private void register(ClauseInfo ci, boolean first) {
// See FamilyClausesList.get(Term): same concept
Term clause = ci.getHead();
if (clause instanceof Struct) {
Struct g = (Struct) clause.getTerm();
if (g.getArity() == 0) {
return;
}
Term t = g.getArg(0).getTerm();
if (t instanceof Var) {
numCompClausesIndex.insertAsShared(ci, first);
constantCompClausesIndex.insertAsShared(ci, first);
structCompClausesIndex.insertAsShared(ci, first);
if (first) {
listCompClausesList.addFirst(ci);
} else {
listCompClausesList.addLast(ci);
}
} else if (t.isAtomic()) {
if (t instanceof Number) {
numCompClausesIndex.insert((Number) t, ci, first);
} else if (t instanceof Struct) {
constantCompClausesIndex.insert(((Struct) t).getName(), ci, first);
}
} else if (t instanceof Struct) {
if (isAList((Struct) t)) {
if (first) {
listCompClausesList.addFirst(ci);
} else {
listCompClausesList.addLast(ci);
}
} else {
structCompClausesIndex.insert(((Struct) t).getPredicateIndicator(), ci, first);
}
}
}
}
public boolean sub_atom_guard_5(Term arg0, Term arg1, Term arg2, Term arg3, Term arg4)
throws PrologError {
arg0 = arg0.getTerm();
if (!arg0.isAtom()) throw PrologError.type_error(engine.getEngineManager(), 1, "atom", arg0);
return true;
}
private void javaException(Engine e) {
Term exceptionTerm = e.currentContext.currentGoal.getArg(0);
e.currentContext = e.currentContext.fatherCtx;
if (e.currentContext == null) {
// passo nello stato HALT se l?errore non pu? essere gestito (sono
// arrivato alla radice dell'albero di risoluzione)
e.nextState = c.END_HALT;
return;
}
while (true) {
// visito all'indietro l'albero di risoluzione alla ricerca di un
// subgoal java_catch/3 che abbia un catcher unificabile con
// l'argomento dell'eccezione lanciata
if (e.currentContext.currentGoal.match(javaCatchTerm)
&& javaMatch(e.currentContext.currentGoal.getArg(1), exceptionTerm)) {
// ho identificato l?ExecutionContext con il corretto subgoal
// java_catch/3
// taglio tutti i punti di scelta generati da JavaGoal
c.cut();
// unifico l'argomento di java_throw/1 con il catcher
// appropriato e recupero l'handler corrispondente
List<Var> unifiedVars = e.currentContext.trailingVars.getHead();
Term handlerTerm =
javaUnify(e.currentContext.currentGoal.getArg(1), exceptionTerm, unifiedVars);
if (handlerTerm == null) {
e.nextState = c.END_FALSE;
return;
}
// inserisco il gestore e il finally (se presente) in testa alla
// lista dei subgoal da eseguire. I due predicati devono inoltre
// essere preparati per l?esecuzione, mantenendo le sostituzioni
// effettuate durante il processo di unificazione tra
// l'eccezione e il catcher
Term curHandlerTerm = handlerTerm.getTerm();
if (!(curHandlerTerm instanceof Struct)) {
e.nextState = c.END_FALSE;
return;
}
Term finallyTerm = e.currentContext.currentGoal.getArg(2);
Term curFinallyTerm = finallyTerm.getTerm();
// verifico se c'? il blocco finally
boolean isFinally = true;
if (curFinallyTerm instanceof Int) {
Int finallyInt = (Int) curFinallyTerm;
if (finallyInt.intValue() == 0) isFinally = false;
else {
// errore di sintassi, esco
e.nextState = c.END_FALSE;
return;
}
} else if (!(curFinallyTerm instanceof Struct)) {
e.nextState = c.END_FALSE;
return;
}
// Code inserted to allow evaluation of meta-clause
// such as p(X) :- X. When evaluating directly terms,
// they are converted to execution of a call/1 predicate.
// This enables the dynamic linking of built-ins for
// terms coming from outside the demonstration context.
if (handlerTerm != curHandlerTerm) handlerTerm = new Struct("call", curHandlerTerm);
if (finallyTerm != curFinallyTerm) finallyTerm = new Struct("call", curFinallyTerm);
Struct handler = (Struct) handlerTerm;
c.identify(handler);
SubGoalTree sgt = new SubGoalTree();
sgt.addChild(handler);
if (isFinally) {
Struct finallyStruct = (Struct) finallyTerm;
c.identify(finallyStruct);
sgt.addChild(finallyStruct);
}
c.pushSubGoal(sgt);
e.currentContext.currentGoal = handler;
// passo allo stato GOAL_SELECTION
e.nextState = c.GOAL_SELECTION;
return;
} else {
// passo all'ExecutionContext successivo
e.currentContext = e.currentContext.fatherCtx;
if (e.currentContext == null) {
// passo nello stato HALT se l?errore non pu? essere gestito
// (sono arrivato alla radice dell'albero di risoluzione)
e.nextState = c.END_HALT;
return;
}
}
}
}
private void prologError(Engine e) {
Term errorTerm = e.currentContext.currentGoal.getArg(0);
e.currentContext = e.currentContext.fatherCtx;
if (e.currentContext == null) {
// passo nello stato HALT se l?errore non pu? essere gestito (sono
// arrivato alla radice dell'albero di risoluzione)
e.nextState = c.END_HALT;
return;
}
while (true) {
// visito all'indietro l'albero di risoluzione alla ricerca di un
// subgoal catch/3 il cui secondo argomento unifica con l?argomento
// dell?eccezione lanciata
if (e.currentContext.currentGoal.match(catchTerm)
&& e.currentContext.currentGoal.getArg(1).match(errorTerm)) {
// ho identificato l?ExecutionContext con il corretto subgoal
// catch/3
// taglio tutti i punti di scelta generati da Goal
c.cut();
// unifico l'argomento di throw/1 con il secondo argomento di
// catch/3
List<Var> unifiedVars = e.currentContext.trailingVars.getHead();
e.currentContext.currentGoal.getArg(1).unify(unifiedVars, unifiedVars, errorTerm);
// inserisco il gestore dell?errore in testa alla lista dei
// subgoal da eseguire, come definito dal terzo argomento di
// catch/3. Il gestore deve inoltre essere preparato per
// l?esecuzione, mantenendo le sostituzioni effettuate durante
// il processo di unificazione tra l?argomento di throw/1 e il
// secondo argomento di catch/3
Term handlerTerm = e.currentContext.currentGoal.getArg(2);
Term curHandlerTerm = handlerTerm.getTerm();
if (!(curHandlerTerm instanceof Struct)) {
e.nextState = c.END_FALSE;
return;
}
// Code inserted to allow evaluation of meta-clause
// such as p(X) :- X. When evaluating directly terms,
// they are converted to execution of a call/1 predicate.
// This enables the dynamic linking of built-ins for
// terms coming from outside the demonstration context.
if (handlerTerm != curHandlerTerm) handlerTerm = new Struct("call", curHandlerTerm);
Struct handler = (Struct) handlerTerm;
c.identify(handler);
SubGoalTree sgt = new SubGoalTree();
sgt.addChild(handler);
c.pushSubGoal(sgt);
e.currentContext.currentGoal = handler;
// passo allo stato GOAL_SELECTION
e.nextState = c.GOAL_SELECTION;
return;
} else {
// passo all'ExecutionContext successivo
e.currentContext = e.currentContext.fatherCtx;
if (e.currentContext == null) {
// passo nello stato HALT se l?errore non pu? essere gestito
// (sono arrivato alla radice dell'albero di risoluzione)
e.nextState = c.END_HALT;
return;
}
}
}
}
