Method mergeSteps

basex-core/src/main/java/org/basex/query/expr/path/Path.java:950–980

Merges adjacent steps. @param cc compilation context @return original or new expression @throws QueryException query exception

(final CompileContext cc)

   * @throws QueryException query exception
   */
  private Expr mergeSteps(final CompileContext cc) throws QueryException {
    final int sl = steps.length;
    final ExprList stps = new ExprList(sl);
    return cc.ok(root, true, () -> {
      boolean chngd = false;
      for(int s = 0; s < sl; s++) {
        Expr curr = steps[s];
        if(curr instanceof final Step crr) {
          Expr next = s < sl - 1 ? steps[s + 1] : null;
          if(crr.test == NodeTest.NODE && next instanceof final Step stp && stp.axis == ATTRIBUTE) {
            // rewrite node test before attribute step: node()/@* → */@*
            next = Step.get(cc, null, crr.info(), crr.axis, NodeTest.ELEMENT, crr.exprs);
            curr = cc.replaceWith(curr, next);
            chngd = true;
          } else if(next != null) {
            // merge steps: //* → /descendant::*
            next = mergeStep(crr, next, s > 0 ? steps[s - 1] : root, cc);
            if(next != null) {
              cc.info(QueryText.OPTMERGE_X, next);
              curr = next;
              chngd = true;
              s++;
            }
          }
        }
        stps.add(curr);
        cc.updateFocus(curr, true);
      }
      return chngd;
    }) ? get(info, root, stps.finish()) : this;
  }

  /**
   * Moves predicates downward.