/** Return the clause to load. */
public ClauseInfo fetch() {
if (clauses == null) return null;
deunify(vars);
if (!checkCompatibility(goal)) return null;
ClauseInfo clause = (ClauseInfo) clauses.getHead();
clauses = clauses.getTail();
haveAlternatives = checkCompatibility(goal);
return clause;
}
public List<ClauseInfo> getClauses() {
List<ClauseInfo> l = new ArrayList<ClauseInfo>();
OneWayList<ClauseInfo> t = clauses;
while (t != null) {
l.add(t.getHead());
t = t.getTail();
}
return l;
}
/**
* Verify if a clause exists that is compatible with goal. As a side effect, clauses that are not
* compatible get discarded from the currently examined family.
*
* @param goal
*/
private boolean checkCompatibility(Term goal) {
if (clauses == null) return false;
ClauseInfo clause = null;
do {
clause = (ClauseInfo) clauses.getHead();
if (goal.match(clause.getHead())) return true;
clauses = clauses.getTail();
} while (clauses != null);
return false;
}
/**
* Load a clause family.
*
* @param familyClauses
*/
public static ClauseStore build(Term goal, List<Var> vars, List<ClauseInfo> familyClauses) {
ClauseStore clauseStore = new ClauseStore(goal, vars);
clauseStore.clauses = OneWayList.transform(familyClauses);
if (clauseStore.clauses == null || !clauseStore.existCompatibleClause()) return null;
return clauseStore;
}
