Пример #1
0
  /**
   * Computes the number of results.
   *
   * @param qc query context (may be @code null)
   * @return number of results
   */
  private long size(final QueryContext qc) {
    final Value rt = initial(qc);
    // skip computation if value is not a document node
    if (rt == null || rt.type != NodeType.DOC) return -1;
    final Data data = rt.data();
    // skip computation if no database instance is available, is out-of-date or
    // if context does not contain all database nodes
    if (data == null || !data.meta.uptodate || data.resources.docs().size() != rt.size()) return -1;

    ArrayList<PathNode> nodes = data.paths.root();
    long m = 1;
    final int sl = steps.length;
    for (int s = 0; s < sl; s++) {
      final Step curr = axisStep(s);
      if (curr != null) {
        nodes = curr.nodes(nodes, data);
        if (nodes == null) return -1;
      } else if (s + 1 == sl) {
        m = steps[s].size();
      } else {
        // stop if a non-axis step is not placed last
        return -1;
      }
    }

    long sz = 0;
    for (final PathNode pn : nodes) sz += pn.stats.count;
    return sz * m;
  }
Пример #2
0
  /**
   * 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;
  }
Пример #3
0
  /** Tests the specified instance. */
  @Test
  public void test() {
    final StringBuilder sb = new StringBuilder();
    int fail = 0;

    for (final Object[] qu : queries) {
      final boolean correct = qu.length == 3;
      final String query = qu[correct ? 2 : 1].toString();
      final Value cmp = correct ? (Value) qu[1] : null;

      final QueryProcessor qp = new QueryProcessor(query, context);
      try {
        final Value val = qp.value();
        if (!correct || !new DeepCompare().equal(val, cmp)) {
          sb.append("[" + qu[0] + "] " + query);
          String s = correct && cmp.size() != 1 ? "#" + cmp.size() : "";
          sb.append("\n[E" + s + "] ");
          if (correct) {
            final String cp = cmp.toString();
            sb.append('\'');
            sb.append(cp.length() > 1000 ? cp.substring(0, 1000) + "..." : cp);
            sb.append('\'');
          } else {
            sb.append("error");
          }
          final TokenBuilder types = new TokenBuilder();
          for (final Item it : val) types.add(it.type.toString()).add(" ");
          s = val.size() == 1 ? "" : "#" + val.size();
          sb.append("\n[F" + s + "] '" + val + "', " + types + details() + '\n');
          ++fail;
        }
      } catch (final Exception ex) {
        final String msg = ex.getMessage();
        if (correct || msg == null || msg.contains("mailman")) {
          final String cp = correct && cmp.data() != null ? cmp.toString() : "()";
          sb.append(
              "["
                  + qu[0]
                  + "] "
                  + query
                  + "\n[E] "
                  + cp
                  + "\n[F] "
                  + (msg == null ? Util.className(ex) : msg.replaceAll("\r\n?|\n", " "))
                  + ' '
                  + details()
                  + '\n');
          ex.printStackTrace();
          ++fail;
        }
      } finally {
        qp.close();
      }
    }
    if (fail != 0) fail(fail + " Errors. [E] = expected, [F] = found:\n" + sb.toString().trim());
  }
Пример #4
0
  /**
   * Returns the path nodes that will result from this path.
   *
   * @param qc query context
   * @return path nodes, or {@code null} if nodes cannot be evaluated
   */
  public final ArrayList<PathNode> pathNodes(final QueryContext qc) {
    final Value init = initial(qc);
    final Data data = init != null && init.type == NodeType.DOC ? init.data() : null;
    if (data == null || !data.meta.uptodate) return null;

    ArrayList<PathNode> nodes = data.paths.root();
    final int sl = steps.length;
    for (int s = 0; s < sl; s++) {
      final Step curr = axisStep(s);
      if (curr == null) return null;
      nodes = curr.nodes(nodes, data);
      if (nodes == null) return null;
    }
    return nodes;
  }
Пример #5
0
  /**
   * Returns a document test. This test will be called by {@link AxisPath#index} if the context
   * value only consists of database nodes.
   *
   * @param rt root value
   * @return document test
   */
  static Test get(final Value rt) {
    // use simple test if database contains only one document
    final Data data = rt.data();
    if (data.meta.ndocs == 1) return Test.DOC;

    // adopt nodes from existing sequence
    if (rt instanceof DBNodeSeq) {
      final DBNodeSeq seq = (DBNodeSeq) rt;
      return seq.all() ? Test.DOC : new InvDocTest(new IntList(seq.pres()), data);
    }

    // loop through all documents and add pre values of documents
    // not more than 2^31 documents supported
    final IntList il = new IntList((int) rt.size());
    for (final Item it : rt) il.add(((DBNode) it).pre());
    return new InvDocTest(il, data);
  }
Пример #6
0
  /**
   * Returns an equivalent expression which accesses an index. If the expression cannot be
   * rewritten, the original expression is returned.
   *
   * <p>The following types of queries can be rewritten (in the examples, the equality comparison is
   * used, which will be rewritten to {@link ValueAccess} instances):
   *
   * <pre>
   * 1. A[text() = '...']    -> IA('...')
   * 2. A[. = '...']         -> IA('...', A)
   * 3. text()[. = '...']    -> IA('...')
   * 4. A[B = '...']         -> IA('...', B)/parent::A
   * 1. A[B/text() = '...']  -> IA('...')/parent::B/parent::A
   * 2. A[B/C = '...']       -> IA('...', C)/parent::B/parent::A
   * 7. A[@a = '...']        -> IA('...', @a)/parent::A
   * 8. @a[. = '...']        -> IA('...', @a)</pre>
   *
   * Queries of type 1, 3, 5 will not yield any results if the string to be compared is empty.
   *
   * @param qc query context
   * @param rt root value
   * @return original or new expression
   * @throws QueryException query exception
   */
  private Expr index(final QueryContext qc, final Value rt) throws QueryException {
    // only rewrite paths with data reference
    final Data data = rt.data();
    if (data == null) return this;

    // cache index access costs
    IndexInfo index = null;
    // cheapest predicate and step
    int iPred = 0, iStep = 0;

    // check if path can be converted to an index access
    final int sl = steps.length;
    for (int s = 0; s < sl; s++) {
      // only accept descendant steps without positional predicates
      final Step step = axisStep(s);
      if (step == null || !step.axis.down || step.has(Flag.FCS)) break;

      // check if path is iterable (i.e., will be duplicate-free)
      final boolean iter = pathNodes(data, s) != null;
      final IndexContext ictx = new IndexContext(data, iter);

      // choose cheapest index access
      final int pl = step.preds.length;
      for (int p = 0; p < pl; p++) {
        final IndexInfo ii = new IndexInfo(ictx, qc, step);
        if (!step.preds[p].indexAccessible(ii)) continue;

        if (ii.costs == 0) {
          // no results...
          qc.compInfo(OPTNOINDEX, this);
          return Empty.SEQ;
        }
        if (index == null || index.costs > ii.costs) {
          index = ii;
          iPred = p;
          iStep = s;
        }
      }
    }

    // skip rewriting if no index access is possible, or if it is too expensive
    if (index == null || index.costs > data.meta.size) return this;

    // rewrite for index access
    qc.compInfo(index.info);

    // replace expressions for index access
    final Step indexStep = index.step;

    // collect remaining predicates
    final int pl = indexStep.preds.length;
    final ExprList newPreds = new ExprList(pl - 1);
    for (int p = 0; p < pl; p++) {
      if (p != iPred) newPreds.add(indexStep.preds[p]);
    }

    // invert steps that occur before index step and add them as predicate
    final Test test = InvDocTest.get(rt);
    final ExprList invSteps = new ExprList();
    if (test != Test.DOC || !data.meta.uptodate || predSteps(data, iStep)) {
      for (int s = iStep; s >= 0; s--) {
        final Axis ax = axisStep(s).axis.invert();
        if (s == 0) {
          // add document test for collections and axes other than ancestors
          if (test != Test.DOC || ax != Axis.ANC && ax != Axis.ANCORSELF)
            invSteps.add(Step.get(info, ax, test));
        } else {
          final Step prev = axisStep(s - 1);
          invSteps.add(Step.get(info, ax, prev.test, prev.preds));
        }
      }
    }
    if (!invSteps.isEmpty()) newPreds.add(get(info, null, invSteps.finish()));

    // create resulting expression
    final ExprList resultSteps = new ExprList();
    final Expr resultRoot;
    if (index.expr instanceof Path) {
      final Path p = (Path) index.expr;
      resultRoot = p.root;
      resultSteps.add(p.steps);
    } else {
      resultRoot = index.expr;
    }

    if (!newPreds.isEmpty()) {
      int ls = resultSteps.size() - 1;
      Step step;
      if (ls < 0 || !(resultSteps.get(ls) instanceof Step)) {
        // add at least one self axis step
        step = Step.get(info, Axis.SELF, Test.NOD);
        ls++;
      } else {
        step = (Step) resultSteps.get(ls);
      }
      // add remaining predicates to last step
      resultSteps.set(ls, step.addPreds(newPreds.finish()));
    }

    // add remaining steps
    for (int s = iStep + 1; s < sl; s++) resultSteps.add(steps[s]);
    return get(info, resultRoot, resultSteps.finish());
  }