/**
* 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;
}
/**
* 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;
}