antlr/antlr4 · error · Exception

Missing path element at end of path

Error message

Missing path element at end of path

What it means

Raised by XPath.getXPathElement() in the Python3 runtime when the element token is EOF, i.e. the path ends where an element (rule name, token name, wildcard, or string) is required. It is the internal counterpart of the 'Missing element after' checks.

Solutions

1. Terminate the path with a concrete element instead of a separator or bang
2. Validate assembled paths end with an identifier, '*', or quoted string
3. Strip trailing separator/bang characters before evaluation

Example fix

# before
nodes = XPath.findAll(tree, "//expr/", parser)

# after
nodes = XPath.findAll(tree, "//expr", parser)

import re
if not re.search(r"([A-Za-z_][A-Za-z0-9_]*|\*|'[^']*')\s*$", xpath.rstrip()):
    raise ValueError('XPath must end with an element')

try:
    nodes = XPath.findAll(tree, xpath, parser)
except Exception as e:
    if 'Missing path element' in str(e):
        # fix trailing separator/bang
        ...

When it happens

Trigger: A path whose last meaningful token is a separator or '!', so the element slot receives EOF; commonly reached through getXPathElement directly or edge cases in splitToTokens.

Common situations: Paths ending in '/', '//', or '!', especially dynamically assembled ones.

Related errors

• Missing element after
• at index isn't a valid rule name
• at index isn't a valid token name
• Unknown path element
• Invalid tokens or characters at index

AI-assisted analysis of antlr/antlr4@7d5770395b (2026-08-14). Data as JSON: /api/errors/0185620c917402af. Report an issue: GitHub.

Appendix: source

Thrown at runtime/Python3/src/antlr4/xpath/XPath.py:135

            # Add searched element
            if el.type in [XPathLexer.TOKEN_REF, XPathLexer.RULE_REF, XPathLexer.WILDCARD, XPathLexer.STRING]:
                element = self.getXPathElement(el, anywhere)
                element.invert = invert
                elements.append(element)
            elif el.type==Token.EOF:
                break
            else:
                raise Exception("Unknown path element %s" % lexer.symbolicNames[el.type])
        return elements

    #
    # Convert word like {@code#} or {@code ID} or {@code expr} to a path
    # element. {@code anywhere} is {@code true} if {@code //} precedes the
    # word.
    #
    def getXPathElement(self, wordToken:Token, anywhere:bool):
        if wordToken.type==Token.EOF:
            raise Exception("Missing path element at end of path")

        word = wordToken.text
        if wordToken.type==XPathLexer.WILDCARD :
            return XPathWildcardAnywhereElement() if anywhere else XPathWildcardElement()

        elif wordToken.type in [XPathLexer.TOKEN_REF, XPathLexer.STRING]:
            tsource = self.parser.getTokenStream().tokenSource

            ttype = Token.INVALID_TYPE
            if wordToken.type == XPathLexer.TOKEN_REF:
                if word in tsource.ruleNames:
                    ttype = tsource.ruleNames.index(word) + 1
            else:
                if word in tsource.literalNames:
                    ttype = tsource.literalNames.index(word)

            if ttype == Token.INVALID_TYPE:
                raise Exception("%s at index %d isn't a valid token name" % (word, wordToken.tokenIndex))

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