protected override IPredicate BuildPredicate(XPathNavigator predicateElement, bool inHead, bool resolveImmediatly)
{
IPredicate predicate;
string predicateName = predicateElement.Name;
string predicateValue = predicateElement.Value;
switch(predicateName) {
// --------- IND predicates --------
case "Ind":
string predicateURI = predicateElement.GetAttribute("uri", String.Empty).ToLower();
switch(predicateURI) {
case "nxbre://expression":
if (inHead) {
if (resolveImmediatly) predicate = new Individual(Compilation.Evaluate(predicateValue));
else predicate = new Formula(Formula.FormulaResolutionType.NxBRE,
Binder,
predicateValue);
}
else {
predicate = new Function(Function.FunctionResolutionType.Binder,
predicateValue,
new ExpressionEvaluator(predicateValue),
String.Empty,
String.Empty);
}
break;
case "nxbre://operator":
// NxBRE operators must follow this pattern: operator(uniqueargument)
ObjectPair operatorCall = Parameter.ParseOperatorCall(predicateValue);
predicate = new Function(Function.FunctionResolutionType.NxBRE,
predicateValue,
null,
(string)operatorCall.First,
(string)operatorCall.Second);
break;
case "nxbre://binder":
if (Binder == null) throw new BREException("No binder available for Individual: " + predicateValue);
if (inHead) predicate = new Formula(Formula.FormulaResolutionType.Binder,
Binder,
predicateValue);
else predicate = Binder.AnalyzeIndividualPredicate(new Individual(predicateValue));
break;
case "":
predicate = new Individual(predicateValue);
break;
default:
// there is a predicateURI but it is not recognized by the engine so we assimilate it as
// a web reference
predicate = new Individual(new HyperLink(predicateValue, predicateURI));
break;
}
break;
// --------- VAR predicates --------
case "Var":
predicate = new Variable(predicateValue);
break;
// --------- DATA predicates --------
case "Data":
string schemaType = predicateElement.GetAttribute("type", "http://www.w3.org/2001/XMLSchema-instance");
if (schemaType != String.Empty) {
// remove any preceding namespace, like in "xs:string"
if (schemaType.IndexOf(':')>=0) schemaType = schemaType.Split(':')[1];
// this is a strongly typed individual
predicate = new Individual(Xml.ToClr(predicateValue, schemaType), schemaType);
}
else {
// this is just a string based predicate, using Data was not so wise...
predicate = new Individual(predicateValue);
}
break;
// --------- SLOT predicates --------
case "slot":
// the first child must be an Ind, we do not support other slot name holders
if (predicateElement.MoveToFirstChild()) {
if (predicateElement.Name != "Ind") throw new BREException("Only Ind is accepted as a slot name holder");
string slotName = predicateElement.Value;
if (!predicateElement.MoveToNext()) throw new BREException("A slot should contain two children");
predicate = new Slot(slotName, BuildPredicate(predicateElement, inHead, resolveImmediatly));
}
else {
throw new BREException("A slot can not be empty");
}
break;
// --------- UNKNOWN predicates --------
default:
throw new BREException("Unsupported predicate type: " + predicateName);
}
return predicate;
}
protected override IPredicate BuildPredicate(XPathNavigator predicateElement, bool inHead, bool resolveImmediatly)
{
IPredicate predicate;
string predicateName = predicateElement.Name;
string predicateValue = predicateElement.Value;
switch(predicateName) {
// --------- IND predicates --------
case "ind":
if (predicateValue.ToLower().StartsWith("expr:")) {
if (inHead) {
if (resolveImmediatly) predicate = new Individual(Compilation.Evaluate(predicateValue));
else predicate = new Formula(Formula.FormulaResolutionType.NxBRE,
Binder,
predicateValue);
}
else {
predicate = new Function(Function.FunctionResolutionType.Binder,
predicateValue,
new ExpressionEvaluator(predicateValue),
String.Empty,
String.Empty);
}
}
else if (predicateValue.ToLower().StartsWith("nxbre:")) {
// NxBRE functions must follow this pattern: NxBRE:Function(uniqueargument)
ObjectPair operatorCall = Parameter.ParseOperatorCall(predicateValue);
predicate = new Function(Function.FunctionResolutionType.NxBRE,
predicateValue,
null,
(string)operatorCall.First,
(string)operatorCall.Second);
}
else if (Binder == null) {
predicate = new Individual(predicateValue);
}
else if ((inHead) && (predicateValue.ToLower().StartsWith("binder:"))) {
predicate = new Formula(Formula.FormulaResolutionType.Binder,
Binder,
predicateValue);
}
else if ((inHead) && (predicateValue.EndsWith("()"))) {
predicate = new Formula(Formula.FormulaResolutionType.Binder,
Binder,
predicateValue);
}
else {
predicate = Binder.AnalyzeIndividualPredicate(new Individual(predicateValue));
}
break;
// --------- VAR predicates --------
case "var":
predicate = new Variable(predicateValue);
break;
// --------- UNKNOWN predicates --------
default:
throw new BREException("Unsupported predicate type: " + predicateName);
}
return predicate;
}