@Override
public final Expr compile(final QueryContext qc, final VarScope scp) throws QueryException {
if (root != null) root = root.compile(qc, scp);
// no steps
if (steps.length == 0) return root == null ? new Context(info) : root;
final Value init = qc.value, cv = initial(qc);
final boolean doc = cv != null && cv.type == NodeType.DOC;
qc.value = cv;
try {
final int sl = steps.length;
for (int s = 0; s < sl; s++) {
Expr e = steps[s];
// axis step: if input is a document, its type is temporarily generalized
final boolean as = e instanceof Step;
if (as && s == 0 && doc) cv.type = NodeType.NOD;
e = e.compile(qc, scp);
if (e.isEmpty()) return optPre(qc);
steps[s] = e;
// no axis step: invalidate context value
if (!as) qc.value = null;
}
} finally {
if (doc) cv.type = NodeType.DOC;
qc.value = init;
}
// optimize path
return optimize(qc, scp);
}
@Override
public final Expr inline(final QueryContext ctx, final VarScope scp, final Var v, final Expr e)
throws QueryException {
final Value oldVal = ctx.value;
try {
ctx.value = root(ctx);
final Expr rt = root == null ? null : root.inline(ctx, scp, v, e);
if (rt != null) {
setRoot(ctx, rt);
ctx.value = oldVal;
ctx.value = root(ctx);
}
boolean change = rt != null;
for (int i = 0; i < steps.length; i++) {
final Expr nw = steps[i].inline(ctx, scp, v, e);
if (nw != null) {
steps[i] = nw;
change = true;
}
}
return change ? optimize(ctx, scp) : null;
} finally {
ctx.value = oldVal;
}
}
@Override
public final Expr compile(final QueryContext ctx, final VarScope scp) throws QueryException {
if (root != null) setRoot(ctx, root.compile(ctx, scp));
final Value v = ctx.value;
try {
ctx.value = root(ctx);
return compilePath(ctx, scp);
} finally {
ctx.value = v;
}
}