Example #1
0
  @Override
  public Expr optimize(final QueryContext qc, final VarScope scp) throws QueryException {
    final Expr c = super.optimize(qc, scp);
    if (c != this) return c;

    final int es = exprs.length;
    final ExprList list = new ExprList(es);
    for (int i = 0; i < es; i++) {
      Expr e = exprs[i];
      if (e instanceof CmpG) {
        // merge adjacent comparisons
        while (i + 1 < es && exprs[i + 1] instanceof CmpG) {
          final Expr tmp = ((CmpG) e).union((CmpG) exprs[i + 1], qc, scp);
          if (tmp != null) {
            e = tmp;
            i++;
          } else {
            break;
          }
        }
      }
      // expression will always return true
      if (e == Bln.TRUE) return optPre(Bln.TRUE, qc);
      // skip expression yielding false
      if (e != Bln.FALSE) list.add(e);
    }

    // all arguments return false
    if (list.isEmpty()) return optPre(Bln.FALSE, qc);

    if (es != list.size()) {
      qc.compInfo(OPTREWRITE_X, this);
      exprs = list.finish();
    }
    compFlatten(qc);

    boolean not = true;
    for (final Expr expr : exprs) {
      if (!expr.isFunction(Function.NOT)) {
        not = false;
        break;
      }
    }

    if (not) {
      qc.compInfo(OPTREWRITE_X, this);
      final int el = exprs.length;
      final Expr[] inner = new Expr[el];
      for (int e = 0; e < el; e++) inner[e] = ((Arr) exprs[e]).exprs[0];
      final Expr ex = new And(info, inner).optimize(qc, scp);
      return Function.NOT.get(null, info, ex).optimize(qc, scp);
    }

    // return single expression if it yields a boolean
    return exprs.length == 1 ? compBln(exprs[0], info) : this;
  }
Example #2
0
  @Override
  public Expr optimize(final QueryContext qc, final VarScope scp) throws QueryException {
    super.optimize(qc, scp);

    final ExprList el = new ExprList(exprs.length);
    for (final Expr ex : exprs) {
      if (ex.isEmpty()) {
        // remove empty operands (return empty sequence if first value is empty)
        if (el.isEmpty()) return optPre(qc);
        qc.compInfo(OPTREMOVE_X_X, this, ex);
      } else {
        el.add(ex);
      }
    }
    // ensure that results are always sorted
    if (el.size() == 1 && iterable) return el.get(0);
    // replace expressions with optimized list
    exprs = el.finish();
    return this;
  }