Ejemplo n.º 1
0
 @Override
 public boolean accept(final ASTVisitor visitor) {
   for (final Expr e : preds) {
     visitor.enterFocus();
     if (!e.accept(visitor)) return false;
     visitor.exitFocus();
   }
   return root.accept(visitor);
 }
Ejemplo n.º 2
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;
 }
Ejemplo n.º 3
0
 @Override
 public Expr inline(final QueryContext ctx, final VarScope scp, final Var v, final Expr e)
     throws QueryException {
   final boolean pr = super.inline(ctx, scp, v, e) != null;
   final Expr rt = root == null ? null : root.inline(ctx, scp, v, e);
   if (rt != null) root = rt;
   return pr || rt != null ? optimize(ctx, scp) : null;
 }
Ejemplo n.º 4
0
  @Override
  public final Expr optimize(final QueryContext ctx, final VarScope scp) throws QueryException {
    // invalidate current context value (will be overwritten by filter)
    final Value cv = ctx.value;
    try {
      // return empty root
      if (root.isEmpty()) return optPre(null, ctx);
      // convert filters without numeric predicates to axis paths
      if (root instanceof AxisPath && !super.has(Flag.FCS))
        return ((AxisPath) root.copy(ctx, scp)).addPreds(ctx, scp, preds);

      // no predicates.. return root; otherwise, do some advanced compilations
      return preds.length == 0 ? root : opt(ctx);
    } finally {
      ctx.value = cv;
    }
  }
Ejemplo n.º 5
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;
  }
Ejemplo n.º 6
0
 @Override
 public final int exprSize() {
   int sz = 1;
   for (final Expr e : preds) sz += e.exprSize();
   return sz + root.exprSize();
 }
Ejemplo n.º 7
0
 @Override
 public final boolean removable(final Var v) {
   return root.removable(v) && super.removable(v);
 }
Ejemplo n.º 8
0
 @Override
 public final boolean has(final Flag flag) {
   return root.has(flag) || flag != Flag.CTX && super.has(flag);
 }