\n \n Current stack

Error message

${warning}\n    ${fullExpression(startToken)}\n    Current stack: ${trace}

What it means

SemgrexParser.jj (JavaCC-generated parser) has a helper that logs a warning containing the offending semgrex expression (fullExpression(startToken)) and the current parser stack trace. When semantic warnings occur during pattern parsing, this builds "<warning>\n <expr>\n Current stack: <trace>" and logs it — the pattern may still parse or may be subtly wrong.

Solutions

Read the logged warning text and the echoed expression to see which part of the pattern is flagged
Update the pattern to current semgrex syntax (check SemgrexPattern documentation for the relation you used)
Test the pattern with a small SemanticGraph to confirm intended matches after fixing
Keep patterns under version control and re-validate them when upgrading the Stanford CoreNLP version

Example fix

// before
SemgrexPattern p = SemgrexPattern.compile("{} >nsubj {}<<deprecated-syntax");
// after
SemgrexPattern p = SemgrexPattern.compile("{}=src >nsubj {}"); // current syntax

Defensive patterns

Strategy: validation

Validate before calling

// Java: pre-check pattern for balanced delimiters before compiling
static boolean balanced(String p) {
  int d = 0;
  for (char c : p.toCharArray()) {
    if (c == '[' || c == '{' || c == '(') d++;
    if (c == ']' || c == '}' || c == ')') d--;
    if (d < 0) return false;
  }
  return d == 0;
}

Try / catch

// Compile may still warn; catch parse failures to fail fast
try {
  SemgrexPattern p = SemgrexPattern.compile(expr);
} catch (RuntimeException e) {
  throw new IllegalArgumentException("Bad semgrex: " + expr, e);
}

Prevention

Keep semgrex patterns in reviewed version-controlled files
Re-validate all stored patterns after upgrading CoreNLP versions
Read the logged expression + stack to pinpoint the offending fragment
Test patterns against a small sample SemanticGraph

When it happens

Trigger: Parsing a semgrex pattern string via SemgrexPattern.compile that triggers a parser warning hook — e.g., deprecated or suspicious syntax the grammar recognizes but flags.

Common situations: Migrating old semgrex syntax to a newer parser version; typos in relation patterns like {} node specs; copy-pasted patterns from older papers/code.

Understand the failure class

Background: "is deprecated and will be removed" — deprecation warnings for old API names, keywords, and options, and how to migrate before the removal release — this error's family across 29 libraries.

Related errors

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/18f7c4580c4f7000. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/semgraph/semgrex/SemgrexParser.jj:52

  private String fullExpression(Token startToken) {
    StringBuilder result = new StringBuilder();
    for (Token p = startToken; p != null; p = p.next) {
      if (p.specialToken != null) {
        result.append(p.specialToken.image);
      }
      result.append(p.image);
    }
    return result.toString();
  }

  private void warnDeprecated(String warning, Token startToken) {
    StringWriter sw = new StringWriter();
    PrintWriter pw = new PrintWriter(sw);
    (new RuntimeException()).printStackTrace(pw);
    String trace = sw.toString();
    trace = trace.substring(trace.lastIndexOf("SemgrexParser"));
    trace = trace.substring(trace.indexOf("at "));
    log.warn(warning + "\n    " + fullExpression(startToken) + "\n    Current stack: " + trace);
  }
}

PARSER_END(SemgrexParser)

SPECIAL_TOKEN:
{
	< WHITESPACE: (" " | "\r" | "\t")+ >
}

TOKEN:
{
        < UNIQ: "uniq" >
}

TOKEN:
{
	< RELATION: "<" | ">" | ">>" | "<<" | "<>" | "==" | "$+" | "$-" | "$++" | "$--" | "." | ".." | "-" | "--" | ">++" | ">--" | "<++" | "<--" >

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