Method merge

basex-core/src/main/java/org/basex/query/expr/SimpleMap.java:117–249

(final Expr expr, final Expr next, final CompileContext cc)

  }

  @Override
  Expr merge(final Expr expr, final Expr next, final CompileContext cc) throws QueryException {
    final long size = expr.size();
    if(!expr.has(Flag.NDT) && !next.has(Flag.POS)) {
      // merge expressions if next expression does not rely on the context
      if(!next.has(Flag.CTX)) {
        Expr count = null;
        if(size != -1) {
          count = Itr.get(size);
        } else if(expr instanceof Range && expr.arg(0) == Itr.ONE &&
            expr.arg(1).seqType().instanceOf(Types.INTEGER_O)) {
          count = expr.arg(1);
        }
        // (1 to 2) ! <x/> → replicate(<x/>, 2, true())
        // (1 to $c) ! 'A' → replicate('A', $c, false())
        if(count != null) return cc.replicate(next, count, info);
      }

      if(next instanceof StandardFunc && !next.has(Flag.NDT)) {
        // next operand relies on context and is a deterministic function call
        final Expr[] args = next.args();
        if(REPLICATE.is(next) && ((FnReplicate) next).singleEval(true) &&
            args[0] instanceof ContextValue && !args[1].has(Flag.CTX)) {
          if(REPLICATE.is(expr) && ((FnReplicate) expr).singleEval(true)) {
            // replicate(E, C) ! replicate(., D) → replicate(E, C * D)
            final Expr cnt = new Arith(info, expr.arg(1), args[1], Calc.MULTIPLY).optimize(cc);
            return cc.function(REPLICATE, info, expr.arg(0), cnt);
          }
          if(expr instanceof final SingletonSeq ss && ss.singleItem()) {
            // SINGLETONSEQ ! replicate(., C) → replicate(SINGLETONSEQ, C)
            return cc.function(REPLICATE, info, expr, args[1]);
          }
        } else if(ITEMS_AT.is(next) && !args[0].has(Flag.CTX) && args[1] instanceof ContextValue) {
          if(expr instanceof final RangeSeq rs) {
            // (A to B) ! items-at(E, .) → util:range(E, A, B)
            // reverse(A to B) ! items-at(E, .) → reverse(util:range(E, A, B))
            final Expr func = cc.function(_UTIL_RANGE, info, args[0],
                Itr.get(rs.min()), Itr.get(rs.max()));
            return rs.ascending() ? func : cc.function(REVERSE, info, func);
          }
          if(expr instanceof Range) {
            // (START to END) ! items-at(X, .) → util:range(X, START, END)
            return cc.function(_UTIL_RANGE, info, args[0], expr.arg(0), expr.arg(1));
          }
          if(expr.seqType().instanceOf(Types.INTEGER_ZM)) {
            // INTEGERS ! items-at(X, .) → items-at(X, INTEGERS)
            return cc.function(ITEMS_AT, info, args[0], expr);
          }
        } else if(DATA.is(next) && (((FnData) next).contextAccess() ||
            args[0] instanceof ContextValue)) {
          // E ! data(.) → data(E)
          return cc.function(DATA, info, expr);
        } else if(STRING_TO_CODEPOINTS.is(expr) && CODEPOINTS_TO_STRING.is(next) &&
            args[0] instanceof ContextValue) {
          // string-to-codepoints(E) ! codepoints-to-string(.) → characters(E)
          return cc.function(CHARACTERS, info, expr.args());
        }
      }