Exemplo n.º 1
0
 @Override
 public VarUsage count(final Var v) {
   final VarUsage inPreds = super.count(v), inRoot = root.count(v);
   if (inPreds == VarUsage.NEVER) return inRoot;
   final long sz = root.size();
   return sz >= 0 && sz <= 1 || root.type().zeroOrOne()
       ? inRoot.plus(inPreds)
       : VarUsage.MORE_THAN_ONCE;
 }
Exemplo n.º 2
0
  @Override
  public Expr compile(final QueryContext ctx) throws QueryException {
    for (int e = 0; e < expr.length; e++) expr[e] = expr[e].compile(ctx);

    // compute number of results
    size = 0;
    for (final Expr e : expr) {
      final long c = e.size();
      if (c == -1) {
        size = c;
        break;
      }
      size += c;
    }

    // evaluate sequence type
    type = SeqType.EMP;
    Value[] val = new Value[expr.length];
    for (int v = 0; v < expr.length; v++) {
      final Expr e = expr[v];
      // check if all expressions are values
      if (val != null) {
        if (e.isValue()) val[v] = (Value) e;
        else val = null;
      }
      // skip expression that will not add any results
      if (e.isEmpty()) continue;
      // evaluate sequence type
      final SeqType et = e.type();
      type =
          type == SeqType.EMP
              ? et
              : SeqType.get(
                  et.type == type.type ? et.type : AtomType.ITEM,
                  et.mayBeZero() && type.mayBeZero() ? Occ.ZERO_MORE : Occ.ONE_MORE);
    }

    // return cached integer sequence, cached values or self reference
    Expr e = this;
    final int s = (int) size;
    if (val != null && size <= Integer.MAX_VALUE) {
      if (type.type == AtomType.STR) e = StrSeq.get(val, s);
      else if (type.type == AtomType.BLN) e = BlnSeq.get(val, s);
      else if (type.type == AtomType.FLT) e = FltSeq.get(val, s);
      else if (type.type == AtomType.DBL) e = DblSeq.get(val, s);
      else if (type.type == AtomType.DEC) e = DecSeq.get(val, s);
      else if (type.type == AtomType.BYT) e = BytSeq.get(val, s);
      else if (type.type.instanceOf(AtomType.ITR)) e = IntSeq.get(val, s, type.type);
      else {
        final ValueBuilder vb = new ValueBuilder(s);
        for (final Value v : val) vb.add(v);
        e = vb.value();
      }
    }
    return optPre(e, ctx);
  }
Exemplo n.º 3
0
  /**
   * Compiles the filter expression, excluding the root node.
   *
   * @param ctx query context
   * @return compiled expression
   */
  private Expr opt(final QueryContext ctx) {
    // evaluate return type
    final SeqType t = root.type();

    // determine number of results and type
    final long s = root.size();
    if (s != -1) {
      if (pos != null) {
        size = Math.max(0, s + 1 - pos.min) - Math.max(0, s - pos.max);
      } else if (last) {
        size = s > 0 ? 1 : 0;
      }
      // no results will remain: return empty sequence
      if (size == 0) return optPre(null, ctx);
      type = SeqType.get(t.type, size);
    } else {
      type = SeqType.get(t.type, t.zeroOrOne() ? Occ.ZERO_ONE : Occ.ZERO_MORE);
    }

    // no numeric predicates.. use simple iterator
    if (!super.has(Flag.FCS)) return new IterFilter(this);

    // one single position() or last() function specified: return single value
    if (preds.length == 1
        && (last || pos != null)
        && root.isValue()
        && t.one()
        && (last || pos.min == 1 && pos.max == 1)) return optPre(root, ctx);

    // only choose deterministic and context-independent offsets; e.g., skip:
    // (1 to 10)[random:integer(10)]  or  (1 to 10)[.]
    boolean off = false;
    if (preds.length == 1) {
      final Expr p = preds[0];
      final SeqType st = p.type();
      off = st.type.isNumber() && st.zeroOrOne() && !p.has(Flag.CTX) && !p.has(Flag.NDT);
      if (off) type = SeqType.get(type.type, Occ.ZERO_ONE);
    }

    // iterator for simple numeric predicate
    return off || useIterator() ? new IterPosFilter(this, off) : this;
  }