Class AggFinder

core/src/main/java/org/apache/calcite/sql/validate/AggFinder.java:34–120

Visitor that looks for an aggregate function inside a tree of SqlNode objects and throws Util.FoundOne when it finds one.

 * {@link SqlNode} objects and throws {@link Util.FoundOne} when it finds
 * one. */
class AggFinder extends AggVisitor {
  /**
   * Creates an AggFinder.
   *
   * @param opTab Operator table
   * @param over Whether to find windowed function calls {@code agg(x) OVER
   *             windowSpec}
   * @param aggregate Whether to find non-windowed aggregate calls
   * @param group Whether to find group functions (e.g. {@code TUMBLE})
   * @param delegate Finder to which to delegate when processing the arguments
   * @param nameMatcher Whether to match the agg function case-sensitively
   */
  AggFinder(SqlOperatorTable opTab, boolean over, boolean aggregate,
      boolean group, @Nullable AggFinder delegate, SqlNameMatcher nameMatcher) {
    super(opTab, over, aggregate, group, delegate, nameMatcher);
  }

  //~ Methods ----------------------------------------------------------------

  /**
   * Finds an aggregate.
   *
   * @param node Parse tree to search
   * @return First aggregate function in parse tree, or null if not found
   */
  public @Nullable SqlCall findAgg(SqlNode node) {
    try {
      node.accept(this);
      return null;
    } catch (Util.FoundOne e) {
      Util.swallow(e, null);
      return (SqlCall) e.getNode();
    }
  }

  // SqlNodeList extends SqlNode and implements List<SqlNode>, so this method
  // disambiguates
  public @Nullable SqlCall findAgg(SqlNodeList nodes) {
    return findAgg((List<SqlNode>) nodes);
  }

  public @Nullable SqlCall findAgg(List<SqlNode> nodes) {
    try {
      for (SqlNode node : nodes) {
        node.accept(this);
      }
      return null;
    } catch (Util.FoundOne e) {
      Util.swallow(e, null);
      return (SqlCall) e.getNode();
    }
  }

  @Override protected Void found(SqlCall call) {
    throw new Util.FoundOne(call);
  }

  /** Creates a copy of this finder that has the same parameters as this,