private boolean matchFunctionCompletion(EventCompletionContext context, Node clean) {
        if (context.triggerCharacter.equals('.')) return false;
        return (clean.getLanguageType() == LanguageType.RANK_EXPRESSION || (
            clean.getParent() != null && (
                clean.getParent().isASTInstance(expressionElm.class) 
             || clean.getParent().isASTInstance(featureListElm.class)
             )
        ));
    }
Compute completion snippets for all the builtin ranking features using the signatures
in {@link BuiltInFunctions}.
integration/schema-language-server/language-server/src/main/java/ai/vespa/schemals/lsp/schema/completion/provider/RankingExpressionCompletion.java