/**
* Optimizes descendant-or-self steps and static types.
*
* @param ctx query context
*/
void optSteps(final QueryContext ctx) {
boolean opt = false;
Expr[] st = steps;
for (int l = 1; l < st.length; ++l) {
if (!(st[l - 1] instanceof Step && st[l] instanceof Step)) continue;
final Step prev = (Step) st[l - 1];
final Step curr = (Step) st[l];
if (!prev.simple(DESCORSELF, false)) continue;
if (curr.axis == CHILD && !curr.has(Flag.FCS)) {
// descendant-or-self::node()/child::X -> descendant::X
final int sl = st.length;
final Expr[] tmp = new Expr[sl - 1];
System.arraycopy(st, 0, tmp, 0, l - 1);
System.arraycopy(st, l, tmp, l - 1, sl - l);
st = tmp;
curr.axis = DESC;
opt = true;
} else if (curr.axis == ATTR && !curr.has(Flag.FCS)) {
// descendant-or-self::node()/@X -> descendant-or-self::*/@X
prev.test = new NameTest(false);
opt = true;
}
}
if (opt) ctx.compInfo(OPTDESC);
// set atomic type for single attribute steps to speedup predicate tests
if (root == null && st.length == 1 && st[0] instanceof Step) {
final Step curr = (Step) st[0];
if (curr.axis == ATTR && curr.test.mode == Mode.STD) curr.type = SeqType.NOD_ZO;
}
steps = st;
}
/**
* Gathers all declared variables.
*
* @param gs grouping specs
* @param vs non-grouping variables
* @return declared variables
*/
private static Var[] vars(final Spec[] gs, final Var[] vs) {
final int gl = gs.length, vl = vs.length;
final Var[] res = new Var[gl + vl];
for (int g = 0; g < gl; g++) res[g] = gs[g].var;
System.arraycopy(vs, 0, res, gl, vl);
return res;
}
/**
* Constructor.
*
* @param specs grouping specs
* @param pre references to pre-grouping variables
* @param post post-grouping variables
* @param info input info
*/
public GroupBy(final Spec[] specs, final VarRef[] pre, final Var[] post, final InputInfo info) {
super(info, vars(specs, post));
this.specs = specs;
this.post = post;
preExpr = new Expr[pre.length];
System.arraycopy(pre, 0, preExpr, 0, pre.length);
int n = 0;
for (final Spec spec : specs) if (!spec.occluded) n++;
nonOcc = n;
}