Method simplify

basex-core/src/main/java/org/basex/query/expr/Expr.java:345–359

Simplifies the expression. @param mode mode of simplification @param cc compilation context @return simplified or original expression @see Simplify @throws QueryException query exception

(final Simplify mode, final CompileContext cc)

   * @throws QueryException query exception
   */
  public final Expr simplify(final Simplify mode, final CompileContext cc) throws QueryException {
    Expr expr = this;
    if(mode.oneOf(Simplify.EBV, Simplify.PREDICATE)) {
      // boolean(<a/>) → true()
      // E[()] → E[false()]
      final SeqType st = seqType();
      final boolean nodes = st.instanceOf(Types.NODE_OM);
      if((nodes || st.zero()) && !has(Flag.NDT)) expr = Bln.get(nodes);
    } else if(mode == Simplify.COUNT && !(this instanceof Value)) {
      // count(db:get('db')//with-known-result-size) → replicate('', size)
      final long size = size();
      if(size != -1 && !has(Flag.NDT)) expr = SingletonSeq.get(Str.EMPTY, size);
    }
    return expr != this ? cc.simplify(this, expr, mode) : this;
  }

  /**
   * Returns the static type of the resulting value.