What causes "Unknown position ${position} in AddDep operation" in stanfordnlp/CoreNLP?

Use a signed offset string: pass null for default placement, or values like "-1" / "+1" (and generally -N/+N) for relative positions.

stanfordnlp/CoreNLP · error · SsurgeonParseException

Unknown position in AddDep operation

Error message

Unknown position ${position} in AddDep operation

What it means

The AddDep Ssurgeon operation constructor validates its 'position' argument, which must be an offset string starting with '-' (insert before the governor) or '+' (insert after). Any other non-null position string is rejected at construction time with this SsurgeonParseException, before the operation ever runs.

Solutions

Use a signed offset string: pass null for default placement, or values like "-1" / "+1" (and generally -N/+N) for relative positions.
If you do not need a relative position, pass null for position — the null check is skipped and AddDep falls back to computing an index (maxIndex + 1).
Trim and normalize the position attribute when reading it from config before constructing AddDep.
Wrap construction in try/catch for SsurgeonParseException and surface the bad rule/element to the rule author.

Example fix

// before
new AddDep("gov", rel, attrs, "after"); // throws
// after
new AddDep("gov", rel, attrs, "+1"); // or null for default placement

Defensive patterns

Strategy: validation

Validate before calling

if (position != null && !(position.startsWith("-") || position.startsWith("+")))
  throw new IllegalArgumentException("position must start with '-' or '+' (or be null): " + position);

Try / catch

try { new AddDep(gov, rel, attrs, position); } catch (SsurgeonParseException e) { throw new IllegalArgumentException("Bad AddDep position: " + position, e); }

Prevention

Only pass signed offset strings or null for position
Normalize/trim the position attribute read from rule XML before constructing
Validate all AddDep constructor args (position, gov, relation) together in a rule loader

When it happens

Trigger: Constructing new AddDep(govNodeName, relation, attributes, position[, weight]) with a position string that does not start with '-' or '+', e.g. "after", "0", "before", or a stray space-prefixed value; also reached when Ssurgeon parses an AddDep element whose position attribute is misspelled or in the wrong format.

Common situations: Hand-editing Ssurgeon XML/rule files where the position attribute was written as a word instead of a signed offset; generated rules with a bad default; confusion between index-based insertion and the +/- relative-position convention.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/a97081de89fe4ffe. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/semgraph/semgrex/ssurgeon/AddDep.java:39

 * @author Eric Yeh
 *
 */
public class AddDep extends SsurgeonEdit {
  public static final String LABEL = "addDep";
  final Map<String, String> attributes;
  final GrammaticalRelation relation;
  final String govNodeName;
  final String position;
  final double weight;

  public AddDep(String govNodeName, GrammaticalRelation relation, Map<String, String> attributes, String position) {
    this(govNodeName, relation, attributes, position, 0.0);
  }

  public AddDep(String govNodeName, GrammaticalRelation relation, Map<String, String> attributes, String position, double weight) {
    if (position != null) {
      if (!position.startsWith("-") && !position.startsWith("+")) {
        throw new SsurgeonParseException("Unknown position " + position + " in AddDep operation");
      }
    }
    if (govNodeName == null) {
      throw new SsurgeonParseException("No governor given for an AddDep");
    }
    if (relation == null) {
      throw new SsurgeonParseException("No relation given for an AddDep");
    }
    checkIllegalAttributes(attributes);

    this.attributes = new TreeMap<>(attributes);
    this.relation = relation;
    this.govNodeName = govNodeName;
    this.position = position;
    this.weight = weight;
  }

  /**

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