/**
* Converts descendant to child steps.
*
* @param qc query context
* @param rt root value
* @return original or new expression
*/
private Expr children(final QueryContext qc, final Value rt) {
// skip if index does not exist or is out-dated, or if several namespaces occur in the input
final Data data = rt.data();
if (data == null || !data.meta.uptodate || data.nspaces.globalNS() == null) return this;
Path path = this;
final int sl = steps.length;
for (int s = 0; s < sl; s++) {
// don't allow predicates in preceding location steps
final Step prev = s > 0 ? axisStep(s - 1) : null;
if (prev != null && prev.preds.length != 0) break;
// ignore axes other than descendant, or numeric predicates
final Step curr = axisStep(s);
if (curr == null || curr.axis != DESC || curr.has(Flag.FCS)) continue;
// check if child steps can be retrieved for current step
ArrayList<PathNode> nodes = pathNodes(data, s);
if (nodes == null) continue;
// cache child steps
final ArrayList<QNm> qnm = new ArrayList<>();
while (nodes.get(0).parent != null) {
QNm nm = new QNm(data.elemNames.key(nodes.get(0).name));
// skip children with prefixes
if (nm.hasPrefix()) return this;
for (final PathNode p : nodes) {
if (nodes.get(0).name != p.name) nm = null;
}
qnm.add(nm);
nodes = PathSummary.parent(nodes);
}
qc.compInfo(OPTCHILD, steps[s]);
// build new steps
int ts = qnm.size();
final Expr[] stps = new Expr[ts + sl - s - 1];
for (int t = 0; t < ts; t++) {
final Expr[] preds = t == ts - 1 ? ((Preds) steps[s]).preds : new Expr[0];
final QNm nm = qnm.get(ts - t - 1);
final NameTest nt =
nm == null ? new NameTest(false) : new NameTest(nm, Kind.NAME, false, null);
stps[t] = Step.get(info, CHILD, nt, preds);
}
while (++s < sl) stps[ts++] = steps[s];
path = get(info, root, stps);
break;
}
// check if all steps yield results; if not, return empty sequence
final ArrayList<PathNode> nodes = pathNodes(qc);
if (nodes != null && nodes.isEmpty()) {
qc.compInfo(OPTPATH, path);
return Empty.SEQ;
}
return path;
}
/**
* Returns all summary path nodes for the specified location step or {@code null} if nodes cannot
* be retrieved or are found on different levels.
*
* @param data data reference
* @param last last step to be checked
* @return path nodes
*/
private ArrayList<PathNode> pathNodes(final Data data, final int last) {
// skip request if no path index exists or might be out-of-date
if (!data.meta.uptodate) return null;
ArrayList<PathNode> nodes = data.paths.root();
for (int s = 0; s <= last; s++) {
// only follow axis steps
final Step curr = axisStep(s);
if (curr == null) return null;
final boolean desc = curr.axis == DESC;
if (!desc && curr.axis != CHILD || curr.test.kind != Kind.NAME) return null;
final int name = data.elemNames.id(curr.test.name.local());
final ArrayList<PathNode> tmp = new ArrayList<>();
for (final PathNode node : PathSummary.desc(nodes, desc)) {
if (node.kind == Data.ELEM && name == node.name) {
// skip test if an element name occurs on different levels
if (!tmp.isEmpty() && tmp.get(0).level() != node.level()) return null;
tmp.add(node);
}
}
if (tmp.isEmpty()) return null;
nodes = tmp;
}
return nodes;
}
/** Finishes the index creation. */
void finish() {
if (reorder == null) return;
for (int i = 1; i < reorder.size(); i++) {
if (reorder.get(i)) Arrays.sort(idsList.get(i), 0, lenList.get(i));
}
reorder = null;
}
@Override
public IndexIterator iter(final IndexToken token) {
final int id = values.id(token.get());
if (id == 0) return IndexIterator.EMPTY;
final int len = lenList.get(id);
final int[] ids = idsList.get(id), pres;
if (data.meta.updindex) {
final IntList tmp = new IntList();
for (int i = 0; i < len; ++i) tmp.add(data.pre(ids[i]));
pres = tmp.sort().finish();
} else {
pres = ids;
}
return new IndexIterator() {
int p;
@Override
public boolean more() {
return p < len;
}
@Override
public int pre() {
return pres[p++];
}
@Override
public int size() {
return len;
}
};
}
/**
* Returns all summary path nodes for the specified location step or {@code null} if nodes cannot
* be retrieved or are found on different levels.
*
* @param data data reference
* @param l last step to be checked
* @return path nodes
*/
ArrayList<PathNode> pathNodes(final Data data, final int l) {
// skip request if no path index exists or might be out-of-date
if (!data.meta.uptodate) return null;
ArrayList<PathNode> in = data.paths.root();
for (int s = 0; s <= l; ++s) {
final Step curr = axisStep(s);
if (curr == null) return null;
final boolean desc = curr.axis == DESC;
if (!desc && curr.axis != CHILD || curr.test.mode != Mode.LN) return null;
final int name = data.tagindex.id(curr.test.name.local());
final ArrayList<PathNode> al = new ArrayList<>();
for (final PathNode pn : PathSummary.desc(in, desc)) {
if (pn.kind == Data.ELEM && name == pn.name) {
// skip test if a tag is found on different levels
if (!al.isEmpty() && al.get(0).level() != pn.level()) return null;
al.add(pn);
}
}
if (al.isEmpty()) return null;
in = al;
}
return in;
}
/**
* Removes values from the index.
*
* @param key key
* @param vals sorted values
*/
void delete(final byte[] key, final int... vals) {
final int id = values.id(key), vl = vals.length, l = lenList.get(id), s = l - vl;
final int[] ids = idsList.get(id);
for (int i = 0, n = 0, v = 0; i < l; i++) {
if (v == vl || ids[i] != vals[v]) ids[n++] = ids[i];
else v++;
}
lenList.set(id, s);
if (s == 0) idsList.set(id, null);
}
/**
* Checks if steps before index step need to be inverted and traversed.
*
* @param data data reference
* @param iStep index step
* @return result of check
*/
private boolean predSteps(final Data data, final int iStep) {
for (int s = iStep; s >= 0; s--) {
final Step step = axisStep(s);
// ensure that the index step does not use wildcard
if (step.test.kind == Kind.WILDCARD && s != iStep) continue;
// consider child steps with name test and without predicates
if (step.test.kind != Kind.NAME
|| step.axis != Axis.CHILD
|| s != iStep && step.preds.length > 0) return true;
// support only unique paths with nodes on the correct level
final ArrayList<PathNode> pn = data.paths.desc(step.test.name.local());
if (pn.size() != 1 || pn.get(0).level() != s + 1) return true;
}
return false;
}
/**
* Adds values to the index.
*
* @param key key to be indexed
* @param vals sorted values
*/
void add(final byte[] key, final int... vals) {
// token index: add values. otherwise, reference existing values
final int id = type == IndexType.TOKEN ? values.put(key) : values.id(key), vl = vals.length;
// updatable index: if required, resize existing arrays
while (idsList.size() < id + 1) idsList.add(null);
if (lenList.size() < id + 1) lenList.set(id, 0);
final int len = lenList.get(id), size = len + vl;
int[] ids = idsList.get(id);
if (ids == null) {
ids = vals;
} else {
if (ids.length < size) ids = Arrays.copyOf(ids, Array.newSize(size));
System.arraycopy(vals, 0, ids, len, vl);
if (ids[len - 1] > vals[0]) {
if (reorder == null) reorder = new BoolList(values.size());
reorder.set(id, true);
}
}
idsList.set(id, ids);
lenList.set(id, size);
}
/**
* Returns a string representation of the index structure.
*
* @param all include database contents in the representation. During updates, database lookups
* must be avoided, as the data structures will be inconsistent.
* @return string
*/
public String toString(final boolean all) {
final TokenBuilder tb = new TokenBuilder();
tb.addExt(type).add(" INDEX, '").add(data.meta.name).add("':\n");
final int s = lenList.size();
for (int m = 1; m < s; m++) {
final int len = lenList.get(m);
if (len == 0) continue;
final int[] ids = idsList.get(m);
tb.add(" ").addInt(m);
if (all)
tb.add(", key: \"").add(data.text(data.pre(ids[0]), type == IndexType.TEXT)).add('"');
tb.add(", ids");
if (all) tb.add("/pres");
tb.add(": ");
for (int n = 0; n < len; n++) {
if (n != 0) tb.add(",");
tb.addInt(ids[n]);
if (all) tb.add('/').addInt(data.pre(ids[n]));
}
tb.add("\n");
}
return tb.toString();
}
/**
* Converts descendant to child steps.
*
* @param ctx query context
* @param data data reference
* @return path
*/
Expr children(final QueryContext ctx, final Data data) {
// skip path check if no path index exists, or if it is out-of-date
if (!data.meta.uptodate || data.nspaces.globalNS() == null) return this;
Path path = this;
for (int s = 0; s < steps.length; ++s) {
// don't allow predicates in preceding location steps
final Step prev = s > 0 ? axisStep(s - 1) : null;
if (prev != null && prev.preds.length != 0) break;
// ignore axes other than descendant, or numeric predicates
final Step curr = axisStep(s);
if (curr == null || curr.axis != DESC || curr.has(Flag.FCS)) continue;
// check if child steps can be retrieved for current step
ArrayList<PathNode> pn = pathNodes(data, s);
if (pn == null) continue;
// cache child steps
final ArrayList<QNm> qnm = new ArrayList<>();
while (pn.get(0).par != null) {
QNm nm = new QNm(data.tagindex.key(pn.get(0).name));
// skip children with prefixes
if (nm.hasPrefix()) return this;
for (final PathNode p : pn) {
if (pn.get(0).name != p.name) nm = null;
}
qnm.add(nm);
pn = PathSummary.parent(pn);
}
ctx.compInfo(OPTCHILD, steps[s]);
// build new steps
int ts = qnm.size();
final Expr[] stps = new Expr[ts + steps.length - s - 1];
for (int t = 0; t < ts; ++t) {
final Expr[] preds = t == ts - 1 ? ((Preds) steps[s]).preds : new Expr[0];
final QNm nm = qnm.get(ts - t - 1);
final NameTest nt =
nm == null ? new NameTest(false) : new NameTest(nm, Mode.LN, false, null);
stps[t] = Step.get(info, CHILD, nt, preds);
}
while (++s < steps.length) stps[ts++] = steps[s];
path = get(info, root, stps);
break;
}
// check if the all children in the path exist; don't test with namespaces
if (data.nspaces.size() == 0) {
LOOP:
for (int s = 0; s < path.steps.length; ++s) {
// only verify child steps; ignore namespaces
final Step st = path.axisStep(s);
if (st == null || st.axis != CHILD) break;
if (st.test.mode == Mode.ALL || st.test.mode == null) continue;
if (st.test.mode != Mode.LN) break;
// check if one of the addressed nodes is on the correct level
final int name = data.tagindex.id(st.test.name.local());
for (final PathNode pn : data.paths.desc(name, Data.ELEM)) {
if (pn.level() == s + 1) continue LOOP;
}
ctx.compInfo(OPTPATH, path);
return Empty.SEQ;
}
}
return path;
}