protected void explain_(RelNode rel, List<Pair<String, Object>> values) {
final Map<String, Object> map = jsonBuilder.map();
map.put("id", null); // ensure that id is the first attribute
map.put("relOp", relJson.classToTypeName(rel.getClass()));
for (Pair<String, Object> value : values) {
if (value.right instanceof RelNode) {
continue;
}
put(map, value.left, value.right);
}
// omit 'inputs: ["3"]' if "3" is the preceding rel
final List<Object> list = explainInputs(rel.getInputs());
if (list.size() != 1 || !list.get(0).equals(previousId)) {
map.put("inputs", list);
}
final String id = Integer.toString(relIdMap.size());
relIdMap.put(rel, id);
map.put("id", id);
relList.add(map);
previousId = id;
}
/** Returns a JSON string describing the relational expressions that were just explained. */
public String asString() {
final Map<String, Object> map = jsonBuilder.map();
map.put("rels", relList);
return jsonBuilder.toJsonString(map);
}