Class DataConfigNode

solr/core/src/java/org/apache/solr/util/DataConfigNode.java:41–145

ConfigNode impl that applies property substitutions on access. This class wraps another ConfigNode and applies property substitution immediately when the #txt or #attributes methods are called. Because property substition is based on ThreadLocal values, These methods

 * @see PropertiesUtil#substitute
 */
public class DataConfigNode implements ConfigNode {
  private final String name;
  private final Map<String, String> rawAttributes;
  private final Map<String, List<ConfigNode>> kids;
  private final String rawTextData;

  public DataConfigNode(ConfigNode root) {
    Map<String, List<ConfigNode>> kids = new LinkedHashMap<>();
    name = root.name();
    rawAttributes = root.attributes();
    rawTextData = root.txt();
    root.forEachChild(
        it -> {
          List<ConfigNode> nodes = kids.computeIfAbsent(it.name(), k -> new ArrayList<>());
          nodes.add(new DataConfigNode(it));
          return Boolean.TRUE;
        });
    for (Map.Entry<String, List<ConfigNode>> e : kids.entrySet()) {
      if (e.getValue() != null) {
        e.setValue(List.copyOf(e.getValue()));
      }
    }
    this.kids = Map.copyOf(kids);
  }

  private static String substituteVal(String s) {
    return PropertiesUtil.substitute(s, SUBSTITUTES.get());
  }

  @Override
  public String name() {
    return name;
  }

  /** Each call to this method returns a (new) copy of the original txt with substitions applied. */
  @Override
  public String txt() {
    return substituteVal(rawTextData);
  }

  /**
   * Each call to this method returns a (new) copy of the original Map with substitions applied to
   * the values.
   */
  @Override
  public Map<String, String> attributes() {
    if (rawAttributes.isEmpty()) return rawAttributes; // avoid unnecessary object creation

    // Note: using the 4 arg toMap to force LinkedHashMap.
    // Duplicate keys should be impossible, but toMap makes us specify a mergeFunction
    return rawAttributes.entrySet().stream()
        .collect(
            Collectors.toMap(
                Map.Entry::getKey,
                e -> {
                  return substituteVal(e.getValue());
                },
                (v, vv) -> {