/**
* Checks if the predicates are successful for the specified item.
*
* @param it item to be checked
* @param qc query context
* @return result of check
* @throws QueryException query exception
*/
protected final boolean preds(final Item it, final QueryContext qc) throws QueryException {
if (preds.length == 0) return true;
// set context value and position
final Value cv = qc.value;
try {
if (qc.scoring) {
double s = 0;
for (final Expr p : preds) {
qc.value = it;
final Item i = p.test(qc, info);
if (i == null) return false;
s += i.score();
}
it.score(Scoring.avg(s, preds.length));
} else {
for (final Expr p : preds) {
qc.value = it;
if (p.test(qc, info) == null) return false;
}
}
return true;
} finally {
qc.value = cv;
}
}
@Override
public Expr optimize(final QueryContext qc, final VarScope scp) throws QueryException {
// number of predicates may change in loop
for (int p = 0; p < preds.length; p++) {
final Expr pred = preds[p];
if (pred instanceof CmpG || pred instanceof CmpV) {
final Cmp cmp = (Cmp) pred;
if (cmp.exprs[0].isFunction(Function.POSITION)) {
final Expr e2 = cmp.exprs[1];
final SeqType st2 = e2.seqType();
// position() = last() -> last()
// position() = $n (numeric) -> $n
if (e2.isFunction(Function.LAST) || st2.one() && st2.type.isNumber()) {
if (cmp instanceof CmpG && ((CmpG) cmp).op == OpG.EQ
|| cmp instanceof CmpV && ((CmpV) cmp).op == OpV.EQ) {
qc.compInfo(OPTWRITE, pred);
preds[p] = e2;
}
}
}
} else if (pred instanceof And) {
if (!pred.has(Flag.FCS)) {
// replace AND expression with predicates (don't swap position tests)
qc.compInfo(OPTPRED, pred);
final Expr[] and = ((Arr) pred).exprs;
final int m = and.length - 1;
final ExprList el = new ExprList(preds.length + m);
for (final Expr e : Arrays.asList(preds).subList(0, p)) el.add(e);
for (final Expr a : and) {
// wrap test with boolean() if the result is numeric
el.add(Function.BOOLEAN.get(null, info, a).optimizeEbv(qc, scp));
}
for (final Expr e : Arrays.asList(preds).subList(p + 1, preds.length)) el.add(e);
preds = el.finish();
}
} else if (pred instanceof ANum) {
final ANum it = (ANum) pred;
final long i = it.itr();
if (i == it.dbl()) {
preds[p] = Pos.get(i, info);
} else {
qc.compInfo(OPTREMOVE, this, pred);
return Empty.SEQ;
}
} else if (pred.isValue()) {
if (pred.ebv(qc, info).bool(info)) {
qc.compInfo(OPTREMOVE, this, pred);
preds = Array.delete(preds, p--);
} else {
// handle statically known predicates
qc.compInfo(OPTREMOVE, this, pred);
return Empty.SEQ;
}
}
}
return this;
}
@Override
public Expr optimize(final QueryContext qc, final VarScope scp) throws QueryException {
final Expr c = super.optimize(qc, scp);
if (c != this) return c;
final int es = exprs.length;
final ExprList list = new ExprList(es);
for (int i = 0; i < es; i++) {
Expr e = exprs[i];
if (e instanceof CmpG) {
// merge adjacent comparisons
while (i + 1 < es && exprs[i + 1] instanceof CmpG) {
final Expr tmp = ((CmpG) e).union((CmpG) exprs[i + 1], qc, scp);
if (tmp != null) {
e = tmp;
i++;
} else {
break;
}
}
}
// expression will always return true
if (e == Bln.TRUE) return optPre(Bln.TRUE, qc);
// skip expression yielding false
if (e != Bln.FALSE) list.add(e);
}
// all arguments return false
if (list.isEmpty()) return optPre(Bln.FALSE, qc);
if (es != list.size()) {
qc.compInfo(OPTREWRITE_X, this);
exprs = list.finish();
}
compFlatten(qc);
boolean not = true;
for (final Expr expr : exprs) {
if (!expr.isFunction(Function.NOT)) {
not = false;
break;
}
}
if (not) {
qc.compInfo(OPTREWRITE_X, this);
final int el = exprs.length;
final Expr[] inner = new Expr[el];
for (int e = 0; e < el; e++) inner[e] = ((Arr) exprs[e]).exprs[0];
final Expr ex = new And(info, inner).optimize(qc, scp);
return Function.NOT.get(null, info, ex).optimize(qc, scp);
}
// return single expression if it yields a boolean
return exprs.length == 1 ? compBln(exprs[0], info) : this;
}
@Override
public Expr compile(final QueryContext qc, final VarScope scp) throws QueryException {
final Value init = qc.value;
// never compile predicates with empty sequence as context value (#1016)
if (init != null && init.isEmpty()) qc.value = null;
try {
final int pl = preds.length;
for (int p = 0; p < pl; ++p) preds[p] = preds[p].compile(qc, scp).optimizeEbv(qc, scp);
return this;
} finally {
qc.value = init;
}
}
@Override
public Value value(final QueryContext qc) throws QueryException {
if (seqType().zeroOrOne()) {
final Value v = item(qc, info);
return v == null ? Empty.SEQ : v;
}
return qc.iter(this).value();
}
@Override
public Value value(final QueryContext qc) throws QueryException {
// don't catch errors from error handlers
try {
return qc.value(expr);
} catch (final QueryException ex) {
if (!ex.isCatchable()) throw ex;
for (final Catch c : catches) if (c.matches(ex)) return c.value(qc, ex);
throw ex;
}
}
@Override
public Value value(final QueryContext qc) throws QueryException {
final Value val = qc.value(exprs[0]);
if (val.isEmpty()) throw ONEORMORE.get(info);
return val;
}
/**
* Adds an optimization info for pre-evaluating the specified expression.
*
* @param ex optimized expression
* @param qc query context
* @return optimized expression
*/
protected final Expr optPre(final Expr ex, final QueryContext qc) {
if (ex != this) qc.compInfo(OPTPRE_X, this);
return ex == null ? Empty.SEQ : ex;
}
/**
* Evaluates the specified function and creates a response.
*
* @throws Exception exception (including unexpected ones)
*/
void create() throws Exception {
// bind variables
final StaticFunc sf = function.function;
final Expr[] args = new Expr[sf.args.length];
function.bind(http, args, error);
// wrap function with a function call
final MainModule mm = new MainModule(sf, args);
// assign main module and http context and register process
query.mainModule(mm);
query.http(http);
query.context.register(query);
String redirect = null, forward = null;
RestXqRespBuilder resp = null;
try {
// compile and evaluate query
query.compile();
final Iter iter = query.iter();
Item item = iter.next();
// handle response element
if (item != null && item instanceof ANode) {
final ANode node = (ANode) item;
// send redirect to browser
if (REST_REDIRECT.eq(node)) {
final ANode ch = node.children().next();
if (ch == null || ch.type != NodeType.TXT) throw function.error(NO_VALUE, node.name());
redirect = string(ch.string()).trim();
return;
}
// server-side forwarding
if (REST_FORWARD.eq(node)) {
final ANode ch = node.children().next();
if (ch == null || ch.type != NodeType.TXT) throw function.error(NO_VALUE, node.name());
forward = string(ch.string()).trim();
return;
}
if (REST_RESPONSE.eq(node)) {
resp = new RestXqRespBuilder();
resp.build(node, function, iter, http);
return;
}
}
// HEAD method must return a single response element
if (function.methods.size() == 1 && function.methods.contains(HTTPMethod.HEAD.name()))
throw function.error(HEAD_METHOD);
// serialize result
final SerializerOptions sp = function.output;
http.sopts(sp);
http.initResponse();
final Serializer ser = Serializer.get(http.res.getOutputStream(), sp);
for (; item != null; item = iter.next()) ser.serialize(item);
ser.close();
} finally {
query.close();
query.context.unregister(query);
if (redirect != null) {
http.res.sendRedirect(redirect);
} else if (forward != null) {
http.req.getRequestDispatcher(forward).forward(http.req, http.res);
} else if (resp != null) {
if (resp.status != 0) http.status(resp.status, resp.message, resp.error);
http.res.getOutputStream().write(resp.cache.toArray());
}
}
}
