stanfordnlp/CoreNLP · error · RuntimeException

Error when parsing

Error message

Error when parsing 

What it means

TokenSequencePattern.compile wraps any exception from the token-sequence parser in RuntimeException('Error when parsing ' + string). It means the pattern string is not syntactically valid TokensRegex (or the environment/parser failed while compiling it); the original cause is attached as the exception cause.

Solutions

1. Read the getCause() of the RuntimeException — it contains the actual parser error and position.
2. Validate brackets, quotes, and case/quantifier syntax in the pattern string.
3. Ensure all variables/labels used by the pattern are registered in the Env before compile.
4. Test the pattern in isolation with a minimal compile call to isolate the failing fragment.
5. For TokenMgrError-style lexer failures, check for illegal characters in the string.

Example fix

// before
TokenSequencePattern p = TokenSequencePattern.compile("[ { word:/NN/ } "); // unbalanced
// after
TokenSequencePattern p = TokenSequencePattern.compile("[ { word:/NN/ } ]");

if (pattern == null || pattern.trim().isEmpty()) throw new IllegalArgumentException("empty TokensRegex pattern");
int depth = 0;
for (char c : pattern.toCharArray()) {
    if (c == '[') depth++;
    if (c == ']') depth--;
    if (depth < 0) throw new IllegalArgumentException("unbalanced brackets in: " + pattern);
}
if (depth != 0) throw new IllegalArgumentException("unbalanced brackets in: " + pattern);

try {
    TokenSequencePattern p = TokenSequencePattern.compile(env, pattern);
} catch (RuntimeException e) {
    // 'Error when parsing <string>' — inspect e.getCause() for the real parser error
    throw new InvalidPatternException("bad pattern: " + pattern, e.getCause());
}

When it happens

Trigger: TokenSequencePattern.compile(env, string) or compile(string) with a malformed pattern such as unbalanced brackets, illegal tokens, bad quantifier syntax, or references to undefined rules/variables in the Env.

Common situations: Hand-written TokensRegex rules in config files with typos; patterns copied from regex that use unsupported syntax; missing environment bindings after upgrading CoreNLP models/pipelines.

Related errors

• slurpFile IO problem
• slurpReader IO problem
• Invalid sequence pattern variable class:
• Invalid annotation key
• Unknown rule type:

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/5a37cd9c816148bf. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/ling/tokensregex/TokenSequencePattern.java:191

  }

  /**
   * Compiles a regular expression over tokens into a TokenSequencePattern
   * using the specified environment.
   *
   * @param env Environment to use
   * @param string Regular expression to be compiled
   * @return Compiled TokenSequencePattern
   */
  public static TokenSequencePattern compile(Env env, String string) {
    try {
//      SequencePattern.PatternExpr nodeSequencePattern = TokenSequenceParser.parseSequence(env, string);
//      return new TokenSequencePattern(string, nodeSequencePattern);
      // TODO: Check token sequence parser?
      Pair<PatternExpr, SequenceMatchAction<CoreMap>> p = env.parser.parseSequenceWithAction(env, string);
      return new TokenSequencePattern(string, p.first(), p.second());
    } catch (Exception ex) {
      throw new RuntimeException("Error when parsing " + string, ex);
    }
  }

  /**
   * Compiles a sequence of regular expressions into a TokenSequencePattern
   * using the default environment.
   *
   * @param strings List of regular expression to be compiled
   * @return Compiled TokenSequencePattern
   */
  public static TokenSequencePattern compile(String... strings)
  {
    return compile(DEFAULT_ENV, strings);
  }

  /**
   * Compiles a sequence of regular expressions into a TokenSequencePattern
   * using the specified environment.

View on GitHub (pinned to 1b7edd19c4)