/** * Invokes {@link #trimFields}, or the appropriate method for the type of the rel parameter, using * multi-method dispatch. * * @param rel Relational expression * @param fieldsUsed Bitmap of fields needed by the consumer * @return New relational expression and its field mapping */ protected final TrimResult dispatchTrimFields( RelNode rel, BitSet fieldsUsed, Set<RelDataTypeField> extraFields) { final TrimResult trimResult = trimFieldsDispatcher.invoke(rel, fieldsUsed, extraFields); final RelNode newRel = trimResult.left; final Mapping mapping = trimResult.right; final int fieldCount = rel.getRowType().getFieldCount(); assert mapping.getSourceCount() == fieldCount : "source: " + mapping.getSourceCount() + " != " + fieldCount; final int newFieldCount = newRel.getRowType().getFieldCount(); assert mapping.getTargetCount() + extraFields.size() == newFieldCount : "target: " + mapping.getTargetCount() + " + " + extraFields.size() + " != " + newFieldCount; if (Bug.TodoFixed) assert newFieldCount > 0 : "rel has no fields after trim: " + rel; if (newRel.equals(rel)) { return new TrimResult(rel, mapping); } return trimResult; }