@Override
public GroupBy optimize(final QueryContext qc, final VarScope scp) throws QueryException {
final int pl = preExpr.length;
for (int p = 0; p < pl; p++) {
final SeqType it = preExpr[p].seqType();
post[p].refineType(it.withOcc(it.mayBeZero() ? Occ.ZERO_MORE : Occ.ONE_MORE), qc);
}
return this;
}
@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 final Expr optimize(final QueryContext qc, final VarScope scp) throws QueryException {
final Value v = initial(qc);
if (v != null && v.isEmpty() || emptyPath(v)) return optPre(qc);
// merge descendant steps
Expr e = mergeSteps(qc);
if (e == this && v != null && v.type == NodeType.DOC) {
// check index access
e = index(qc, v);
// rewrite descendant to child steps
if (e == this) e = children(qc, v);
}
// recompile path if it has changed
if (e != this) return e.compile(qc, scp);
// set atomic type for single attribute steps to speed up predicate tests
if (root == null && steps.length == 1 && steps[0] instanceof Step) {
final Step curr = (Step) steps[0];
if (curr.axis == ATTR && curr.test.kind == Kind.URI_NAME) curr.seqType(SeqType.NOD_ZO);
}
// choose best path implementation and set type information
final Path path = get(info, root, steps);
path.size = path.size(qc);
path.seqType = SeqType.get(steps[steps.length - 1].seqType().type, size);
return path;
}
/**
* Returns an instance of a with the specified name and number of arguments, or {@code null}.
*
* @param name name of the function
* @param args optional arguments
* @param dyn compile-/run-time flag
* @param ctx query context
* @param ii input info
* @return function instance
* @throws QueryException query exception
*/
public static TypedFunc get(
final QNm name,
final Expr[] args,
final boolean dyn,
final QueryContext ctx,
final InputInfo ii)
throws QueryException {
// get namespace and local name
// parse data type constructors
if (eq(name.uri(), XSURI)) {
final byte[] ln = name.local();
final AtomType type = AtomType.find(name, false);
if (type == null) {
final Levenshtein ls = new Levenshtein();
for (final AtomType t : AtomType.values()) {
if (t.par != null
&& t != AtomType.NOT
&& t != AtomType.AAT
&& t != AtomType.BIN
&& ls.similar(lc(ln), lc(t.string()), 0))
FUNSIMILAR.thrw(ii, name.string(), t.string());
}
}
// no constructor function found, or abstract type specified
if (type == null || type == AtomType.NOT || type == AtomType.AAT) {
FUNCUNKNOWN.thrw(ii, name.string());
}
if (args.length != 1) FUNCTYPE.thrw(ii, name.string());
final SeqType to = SeqType.get(type, Occ.ZERO_ONE);
return TypedFunc.constr(new Cast(ii, args[0], to), to);
}
// pre-defined functions
final StandardFunc fun = Functions.get().get(name, args, ii);
if (fun != null) {
if (!ctx.sc.xquery3 && fun.xquery3()) FEATURE30.thrw(ii);
for (final Function f : Function.UPDATING) {
if (fun.sig == f) {
ctx.updating(true);
break;
}
}
return new TypedFunc(fun, fun.sig.type(args.length));
}
// user-defined function
final TypedFunc tf = ctx.funcs.get(name, args, ii);
if (tf != null) return tf;
// Java function (only allowed with administrator permissions)
final JavaMapping jf = JavaMapping.get(name, args, ctx, ii);
if (jf != null) return TypedFunc.java(jf);
// add user-defined function that has not been declared yet
if (!dyn && FuncType.find(name) == null) return ctx.funcs.add(name, args, ii, ctx);
// no function found
return null;
}
