@Override
public boolean has(final Flag flag) {
for (final Expr pred : preds) {
if (flag == Flag.FCS && pred.seqType().mayBeNumber() || pred.has(flag)) return true;
}
return false;
}
/**
* Ensures that none of the specified expressions performs an update. Otherwise, throws an
* exception.
*
* @param exprs expressions (may be {@code null}, and may contain {@code null} references)
* @throws QueryException query exception
*/
protected final void checkNoneUp(final Expr... exprs) throws QueryException {
if (exprs == null) return;
checkAllUp(exprs);
for (final Expr expr : exprs) {
if (expr != null && expr.has(Flag.UPD)) throw UPNOT_X.get(info, description());
}
}
/**
* 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 inline(final QueryContext qc, final VarScope scp, final Var var, final Expr ex)
throws QueryException {
boolean change = false;
try {
final Expr sub = expr.inline(qc, scp, var, ex);
if (sub != null) {
if (sub.isValue()) return optPre(sub, qc);
expr = sub;
change = true;
}
} catch (final QueryException qe) {
if (!qe.isCatchable()) throw qe;
for (final Catch c : catches) {
if (c.matches(qe)) {
// found a matching clause, inline variable and error message
final Catch nw = c.inline(qc, scp, var, ex);
return optPre((nw == null ? c : nw).asExpr(qe, qc, scp), qc);
}
}
throw qe;
}
for (final Catch c : catches) change |= c.inline(qc, scp, var, ex) != null;
return change ? this : null;
}
@Override
protected Expr opt(final QueryContext qc, final VarScope scp) {
final Expr e = exprs[0];
final SeqType st = e.seqType();
if (!st.mayBeZero()) return e;
seqType = SeqType.get(st.type, seqType.occ);
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;
}
/**
* Ensures that all specified expressions are vacuous or either updating or non-updating.
* Otherwise, throws an exception.
*
* @param exprs expressions to be checked
* @throws QueryException query exception
*/
void checkAllUp(final Expr... exprs) throws QueryException {
// updating state: 0 = initial state, 1 = updating, -1 = non-updating
int s = 0;
for (final Expr expr : exprs) {
expr.checkUp();
if (expr.isVacuous()) continue;
final boolean u = expr.has(Flag.UPD);
if (u && s == -1 || !u && s == 1) throw UPALL.get(info, description());
s = u ? 1 : -1;
}
}
/**
* Prepares this expression for iterative evaluation. The expression can be iteratively evaluated
* if no predicate or only the first is positional.
*
* @return result of check
*/
protected final boolean posIterator() {
// check if first predicate is numeric
if (preds.length == 1) {
Expr p = preds[0];
if (p instanceof Int) p = Pos.get(((Int) p).itr(), info);
pos = p instanceof Pos ? (Pos) p : null;
last = p.isFunction(Function.LAST);
preds[0] = p;
}
return pos != null || last;
}
@Override
public Item item(final QueryContext qc, final InputInfo ii) throws QueryException {
final QNm name = toQNm(exprs[0], qc, sc, false);
final long arity = toLong(exprs[1], qc);
if (arity < 0 || arity > Integer.MAX_VALUE) throw FUNCUNKNOWN_X.get(ii, name);
try {
final Expr lit = Functions.getLiteral(name, (int) arity, qc, sc, ii);
return lit == null ? null : lit.item(qc, ii);
} catch (final QueryException e) {
// function not found (in most cases: XPST0017)
return null;
}
}
/**
* Merges a single predicate with the root expression and returns the resulting expression, or
* returns a self reference if the expression cannot be merged. This function is e.g. called by
* {@link Where#optimize}.
*
* @param qc query context
* @param scp variable scope
* @param root root expression
* @return expression
* @throws QueryException query exception
*/
public Expr merge(final Expr root, final QueryContext qc, final VarScope scp)
throws QueryException {
// only one predicate can be rewritten; root expression must yield nodes
if (preds.length != 1 || !(root.seqType().type instanceof NodeType)) return this;
final Expr pred = preds[0];
// a[.] -> a
if (pred instanceof Context) return root;
if (!pred.seqType().mayBeNumber()) {
// a[b] -> a/b
if (pred instanceof Path) return Path.get(info, root, pred).optimize(qc, scp);
if (pred instanceof CmpG) {
final CmpG cmp = (CmpG) pred;
final Expr expr1 = cmp.exprs[0], expr2 = cmp.exprs[1];
// only first operand can depend on context
if (!expr2.has(Flag.CTX)) {
Expr path = null;
// a[. = 'x'] -> a = 'x'
if (expr1 instanceof Context) path = root;
// a[text() = 'x'] -> a/text() = 'x'
if (expr1 instanceof Path) path = Path.get(info, root, expr1).optimize(qc, scp);
if (path != null) return new CmpG(path, expr2, cmp.op, cmp.coll, cmp.sc, cmp.info);
}
}
if (pred instanceof FTContains) {
final FTContains cmp = (FTContains) pred;
final FTExpr ftexpr = cmp.ftexpr;
// only first operand can depend on context
if (!ftexpr.has(Flag.CTX)) {
final Expr expr = cmp.expr;
Expr path = null;
// a[. contains text 'x'] -> a contains text 'x'
if (expr instanceof Context) path = root;
// [text() contains text 'x'] -> a/text() contains text 'x'
if (expr instanceof Path) path = Path.get(info, root, expr).optimize(qc, scp);
if (path != null) return new FTContains(path, ftexpr, cmp.info);
}
}
}
return this;
}
@Override
public boolean indexAccessible(final IndexInfo ii) throws QueryException {
int costs = 0;
final ExprList el = new ExprList(exprs.length);
for (final Expr expr : exprs) {
// check if expression can be rewritten, and if access is not sequential
if (!expr.indexAccessible(ii)) return false;
// skip expressions without results
if (ii.costs == 0) continue;
costs += ii.costs;
el.add(ii.expr);
}
// use summarized costs for estimation
ii.costs = costs;
// no expressions means no costs: expression will later be ignored
ii.expr = el.size() == 1 ? el.get(0) : new Union(info, el.finish());
return true;
}
@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 Item item(final QueryContext qc, final InputInfo ii) throws QueryException {
// compute scoring
if (qc.scoring) {
double s = 0;
boolean f = false;
for (final Expr expr : exprs) {
final Item it = expr.ebv(qc, info);
f |= it.bool(ii);
s += it.score();
}
return Bln.get(f, Scoring.avg(s, exprs.length));
}
// standard evaluation
for (final Expr expr : exprs) {
if (expr.ebv(qc, info).bool(ii)) return Bln.TRUE;
}
return Bln.FALSE;
}
/**
* Ensures that the specified expression performs no updates. Otherwise, throws an exception.
*
* @param expr expression (may be {@code null})
* @throws QueryException query exception
*/
protected void checkNoUp(final Expr expr) throws QueryException {
if (expr == null) return;
expr.checkUp();
if (expr.has(Flag.UPD)) throw UPNOT_X.get(info, description());
}
/**
* Returns a boolean equivalent for the specified expression. If the specified expression yields a
* boolean value anyway, it will be returned as is. Otherwise, it will be wrapped into a boolean
* function.
*
* @param ex expression to be rewritten
* @param info input info
* @param sc static context
* @return expression
*/
protected static Expr compBln(final Expr ex, final InputInfo info, final StaticContext sc) {
return ex.seqType().eq(SeqType.BLN) ? ex : Function.BOOLEAN.get(sc, info, ex);
}
/**
* Checks if the specified expression yields a QName. Returns the item or throws an exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @param empty allow empty result
* @return QNm item
* @throws QueryException query exception
*/
protected final QNm toQNm(final Expr ex, final QueryContext qc, final boolean empty)
throws QueryException {
return toQNm(ex.atomItem(qc, info), empty);
}
/**
* Checks if the specified expression yields an item of the specified atomic type. Returns the
* item or throws an exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @param type type to be checked
* @return item
* @throws QueryException query exception
*/
protected Item checkAtomic(final Expr ex, final QueryContext qc, final Type type)
throws QueryException {
return checkType(ex.atomItem(qc, info), type);
}
/**
* Checks if the specified expression yields a binary item. Returns the binary item or throws an
* exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @return binary item
* @throws QueryException query exception
*/
protected final Bin toBin(final Expr ex, final QueryContext qc) throws QueryException {
return toBin(ex.atomItem(qc, info));
}
/**
* Checks if the specified expression yields a string or binary item.
*
* @param ex expression to be evaluated
* @param qc query context
* @return byte array
* @throws QueryException query exception
*/
protected final byte[] toBytes(final Expr ex, final QueryContext qc) throws QueryException {
return toBytes(ex.atomItem(qc, info));
}
/**
* Checks if the evaluated expression yields a non-empty item. Returns the atomized item or throws
* an exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @return atomized item
* @throws QueryException query exception
*/
protected final Item toAtomItem(final Expr ex, final QueryContext qc) throws QueryException {
return checkNoEmpty(ex.atomItem(qc, info));
}
/**
* Checks if the specified expression yields a double. Returns the double or throws an exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @return double
* @throws QueryException query exception
*/
protected final double toDouble(final Expr ex, final QueryContext qc) throws QueryException {
return toDouble(ex.atomItem(qc, info));
}
/**
* Checks if the specified expression yields a node or {@code null}. Returns the node, {@code
* null}, or throws an exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @return node or {@code null}
* @throws QueryException query exception
*/
protected final ANode toEmptyNode(final Expr ex, final QueryContext qc) throws QueryException {
final Item it = ex.item(qc, info);
return it == null ? null : toNode(it);
}
/**
* Checks if the specified expression yields a non-empty item. Returns the item or throws an
* exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @param type expected type
* @return item
* @throws QueryException query exception
*/
private Item toItem(final Expr ex, final QueryContext qc, final Type type) throws QueryException {
return checkNoEmpty(ex.item(qc, info), type);
}
/**
* Checks if the specified expression yields a node. Returns the boolean or throws an exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @return node
* @throws QueryException query exception
*/
protected final ANode toNode(final Expr ex, final QueryContext qc) throws QueryException {
return toNode(checkNoEmpty(ex.item(qc, info), NodeType.NOD));
}
/**
* Checks if the specified expression yields a float. Returns the float or throws an exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @return float
* @throws QueryException query exception
*/
protected final float toFloat(final Expr ex, final QueryContext qc) throws QueryException {
final Item it = ex.atomItem(qc, info);
if (checkNoEmpty(it, AtomType.FLT).type.isNumberOrUntyped()) return it.flt(info);
throw numberError(this, it);
}
/**
* Checks if the specified expression yields a string. Returns a value as token or throws an
* exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @return token
* @throws QueryException query exception
*/
protected final byte[] toToken(final Expr ex, final QueryContext qc) throws QueryException {
final Item it = ex.atomItem(qc, info);
if (it == null) throw EMPTYFOUND_X.get(info, AtomType.STR);
return toToken(it);
}
@Override
public void plan(final FElem plan) {
for (final Expr p : preds) p.plan(plan);
}
/**
* Checks if the specified expression yields an element. Returns the element or throws an
* exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @return binary item
* @throws QueryException query exception
*/
protected final ANode toElem(final Expr ex, final QueryContext qc) throws QueryException {
return (ANode) checkType(ex.item(qc, info), NodeType.ELM);
}
/**
* Checks if the specified expression yields a number or {@code null}. Returns the number, {@code
* null}, or throws an exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @return double
* @throws QueryException query exception
*/
protected final ANum toNumber(final Expr ex, final QueryContext qc) throws QueryException {
final Item it = ex.atomItem(qc, info);
return it == null ? null : toNumber(it);
}
/**
* Checks if the specified expression yields a string or an empty sequence. Returns a value as
* token or throws an exception.
*
* @param ex expression to be evaluated
* @param qc query context
* @return token (empty string if result is an empty sequence)
* @throws QueryException query exception
*/
protected final byte[] toEmptyToken(final Expr ex, final QueryContext qc) throws QueryException {
final Item it = ex.atomItem(qc, info);
return it == null ? EMPTY : toToken(it);
}
