@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;
}
/**
* Returns the root of the current context or {@code null}.
*
* @param ctx query context
* @return root
*/
final Value root(final QueryContext ctx) {
final Value v = ctx != null ? ctx.value : null;
// no root specified: return context, if it does not reference a document
// as e.g. happens in //a(b|c)
if (root == null) return v == null || v.type != NodeType.DOC ? v : null;
// root is value: return root
if (root.isValue()) return (Value) root;
// no root reference, no context: return null
if (!(root instanceof Root) || v == null) return null;
// return context sequence or root of current context
return v.size() == 1 ? Root.root(v) : v;
}
@Override
public Expr compile(final QueryContext qc, final VarScope scp) throws QueryException {
ts = ts.compile(qc, scp);
// static condition: return branch in question
if (ts.isValue()) {
final Value val = ts.value(qc);
for (final TypeCase tc : cases) {
if (tc.matches(val)) return optPre(tc.compile(qc, scp, (Value) ts).expr, qc);
}
}
// compile branches
for (final TypeCase tc : cases) tc.compile(qc, scp);
return optimize(qc, scp);
}
/**
* Returns the initial context value of a path or {@code null}.
*
* @param qc query context (may be @code null)
* @return root
*/
private Value initial(final QueryContext qc) {
// current context value
final Value v = qc != null ? qc.value : null;
// no root or context expression: return context
if (root == null || root instanceof Context) return v;
// root reference
if (root instanceof Root) return v != null && v instanceof Item ? Root.root(v) : v;
// root is value: return root
if (root.isValue()) return (Value) root;
// data reference
final Data d = root.data();
if (d != null) return new DBNode(d, 0, Data.ELEM);
// otherwise, return null
return null;
}
@Override
public FTWords compile(final QueryContext qc, final VarScope scp) throws QueryException {
if (occ != null) {
final int ol = occ.length;
for (int o = 0; o < ol; ++o) occ[o] = occ[o].compile(qc, scp);
}
// compile only once
if (tokens == null) {
query = query.compile(qc, scp);
if (query.isValue()) tokens = tokens(qc);
// choose fast evaluation for default settings
fast = mode == FTMode.ANY && tokens != null && occ == null;
if (ftt == null) ftt = new FTTokenizer(this, qc);
}
return this;
}
/**
* Compiles the filter expression, excluding the root node.
*
* @param ctx query context
* @return compiled expression
*/
private Expr opt(final QueryContext ctx) {
// evaluate return type
final SeqType t = root.type();
// determine number of results and type
final long s = root.size();
if (s != -1) {
if (pos != null) {
size = Math.max(0, s + 1 - pos.min) - Math.max(0, s - pos.max);
} else if (last) {
size = s > 0 ? 1 : 0;
}
// no results will remain: return empty sequence
if (size == 0) return optPre(null, ctx);
type = SeqType.get(t.type, size);
} else {
type = SeqType.get(t.type, t.zeroOrOne() ? Occ.ZERO_ONE : Occ.ZERO_MORE);
}
// no numeric predicates.. use simple iterator
if (!super.has(Flag.FCS)) return new IterFilter(this);
// one single position() or last() function specified: return single value
if (preds.length == 1
&& (last || pos != null)
&& root.isValue()
&& t.one()
&& (last || pos.min == 1 && pos.max == 1)) return optPre(root, ctx);
// only choose deterministic and context-independent offsets; e.g., skip:
// (1 to 10)[random:integer(10)] or (1 to 10)[.]
boolean off = false;
if (preds.length == 1) {
final Expr p = preds[0];
final SeqType st = p.type();
off = st.type.isNumber() && st.zeroOrOne() && !p.has(Flag.CTX) && !p.has(Flag.NDT);
if (off) type = SeqType.get(type.type, Occ.ZERO_ONE);
}
// iterator for simple numeric predicate
return off || useIterator() ? new IterPosFilter(this, off) : this;
}
/**
* Returns true if all arguments are values.
*
* @return result of check
*/
protected final boolean allAreValues() {
for (final Expr e : exprs) if (!e.isValue()) return false;
return true;
}
