stanfordnlp/CoreNLP · error · SsurgeonParseException

SplitWord expected a -reln to represent the dependency to…

Error message

SplitWord expected a -reln to represent the dependency to use for the new words

What it means

The new words produced by a SplitWord operation must be connected by a grammatical relation; this is supplied via the -reln flag as a GrammaticalRelation. If relation is null after the headIndex check, the constructor throws SsurgeonParseException.

Solutions

Add a valid -reln flag, e.g. -reln dep or -reln compound, matching a Universal Dependencies relation name
Ensure GrammaticalRelation.valueOf for your relation name returns non-null before constructing SplitWord
Pass an explicit GrammaticalRelation instance as the fourth constructor argument

Example fix

// before
new SplitWord("w", pieces, 0, null, null, true);
// after
new SplitWord("w", pieces, 0, UniversalEnglishGrammaticalRelations.DEPENDENT, null, true);

Defensive patterns

Strategy: validation

Validate before calling

GrammaticalRelation reln = GrammaticalRelation.valueOf(lang, relnName);
if (reln == null) throw new IllegalArgumentException("-reln did not resolve to a GrammaticalRelation: " + relnName);

Try / catch

try { SplitWord sw = new SplitWord(node, pieces, headIndex, reln, names, exact); } catch (SsurgeonParseException e) { log.error("Missing -reln: " + e.getMessage()); }

Prevention

Always pass -reln with a valid UD relation name
Resolve the relation name via GrammaticalRelation.valueOf before constructing
Use IDE constants (e.g. UniversalEnglishGrammaticalRelations) instead of raw strings in Java code

When it happens

Trigger: Constructing SplitWord without -reln (or with a null GrammaticalRelation as the fourth constructor argument), such as when the relation name could not be resolved by GrammaticalRelation.valueOf.

Common situations: Omitting -reln in the ssurgeon rule; passing an invalid relation string so the parser yields null; building the operation in Java and forgetting the relation argument.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/29318ff5802ececa. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/semgraph/semgrex/ssurgeon/SplitWord.java:77

    }
    if (exactSplit) {
      this.exactPieces = new ArrayList<>(nodePieces);
      this.nodeRegex = null;
    } else {
      this.nodeRegex = new ArrayList<>();
      for (int i = 0; i < nodePieces.size(); ++i) {
        this.nodeRegex.add(Pattern.compile(nodePieces.get(i)));
      }
      this.exactPieces = null;
    }

    if (headIndex == null) {
      throw new SsurgeonParseException("SplitWord expected a -headIndex, 0-indexed for the word piece to use when chopping up the word");
    }
    this.headIndex = headIndex;

    if (relation == null) {
      throw new SsurgeonParseException("SplitWord expected a -reln to represent the dependency to use for the new words");
    }
    this.relation = relation;

    if (nodeNames != null) {
      String[] namePieces = nodeNames.split(",");
      this.nodeNames = new HashMap<>();
      for (String namePiece : namePieces) {
        String[] pieces = namePiece.split("=", 2);
        if (pieces.length < 2) {
          throw new SsurgeonParseException("SplitWord got a -name parameter which did not have a number for one of the names.  Should look like 0=foo,1=bar");
        }
        int idx = Integer.valueOf(pieces[0]);
        if (idx >= nodePieces.size()) {
          throw new SsurgeonParseException("SplitWord got an index in -name which was larger than the largest possible split piece, " + idx + " (this is 0-indexed)");
        }
        this.nodeNames.put(idx, pieces[1]);
      }
    } else {

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