What causes "Not a valid dashes style: " in stanfordnlp/CoreNLP?

Use a valid LexerUtils.DashesEnum constant name (check LexerUtils for allowed values), e.g. 'dashes=short' or whichever constant exists

stanfordnlp/CoreNLP · error · IllegalArgumentException

Not a valid dashes style:

Error message

Not a valid dashes style:

What it means

FrenchLexer option parsing validates the 'dashes' option value by converting it to LexerUtils.DashesEnum via valueOf; if the string is not an enum constant name (case-insensitive) it rethrows an IllegalArgumentException. This guard ensures the lexer is only configured with a supported dashes style.

Solutions

Use a valid LexerUtils.DashesEnum constant name (check LexerUtils for allowed values), e.g. 'dashes=short' or whichever constant exists
Fix typos or casing (case is normalized via toUpperCase, so check spelling not case)
Inspect LexerUtils.DashesEnum.values() to list valid values
Validate the options string before constructing the lexer

Example fix

// before
new FrenchLexer("dashes=em-dash");
// after
new FrenchLexer("dashes=short");

Defensive patterns

Strategy: validation

Validate before calling

boolean dashesOk = java.util.Arrays.stream(LexerUtils.DashesEnum.values()).anyMatch(e -> e.name().equalsIgnoreCase(value));
if (!dashesOk) throw new IllegalArgumentException("Bad dashes option: " + value);

Type guard

boolean isValidDashesStyle(String v) { return v != null && java.util.Arrays.stream(LexerUtils.DashesEnum.values()).anyMatch(e -> e.name().equalsIgnoreCase(v)); }

Try / catch

try { lexer = new FrenchLexer(optionsString); } catch (IllegalArgumentException e) { log.error("Bad lexer option: " + e.getMessage()); throw new ConfigurationException(e); }

Prevention

List DashesEnum values before building the options string
Copy option values from library docs/tests, not memory
Centralize lexer option strings as constants

When it happens

Trigger: Calling the FrenchLexer(String) options constructor with 'dashes' set to a value not matching a DashesEnum constant, e.g. options string 'dashes=em-dash' or 'dashes=' (empty).

Common situations: Typo in option value, copying options from English PTBTokenizer that supports different styles, passing an empty or null value in the comma/semicolon-delimited options string.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/6d0a4209155ed830. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/international/french/process/FrenchLexer.java:12416

        } else if ("normalizeAmpersandEntity".equals(key)) {
          normalizeAmpersandEntity = val;
        } else if ("normalizeFractions".equals(key)) {
          normalizeFractions = val;
        } else if ("normalizeParentheses".equals(key)) {
          normalizeParentheses = val;
        } else if ("normalizeOtherBrackets".equals(key)) {
          normalizeOtherBrackets = val;
        } else if ("ellipses".equals(key)) {
          try {
            ellipsisStyle = LexerUtils.EllipsesEnum.valueOf(value.trim().toUpperCase(Locale.ROOT));
          } catch (IllegalArgumentException iae) {
            throw new IllegalArgumentException ("Not a valid ellipses style: " + value);
          }
        } else if ("dashes".equals(key)) {
          try {
            dashesStyle = LexerUtils.DashesEnum.valueOf(value.trim().toUpperCase(Locale.ROOT));
          } catch (IllegalArgumentException iae) {
            throw new IllegalArgumentException ("Not a valid dashes style: " + value);
          }
        } else if ("escapeForwardSlashAsterisk".equals(key)) {
          escapeForwardSlashAsterisk = val;
        } else if ("untokenizable".equals(key)) {
          switch (value) {
            case "noneDelete":
              untokenizable = UntokenizableOptions.NONE_DELETE;
              break;
            case "firstDelete":
              untokenizable = UntokenizableOptions.FIRST_DELETE;
              break;
            case "allDelete":
              untokenizable = UntokenizableOptions.ALL_DELETE;
              break;
            case "noneKeep":
              untokenizable = UntokenizableOptions.NONE_KEEP;
              break;
            case "firstKeep":

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