Function format_expected_element

tests/test-chat.cpp:145–216

Helper to format expected element from grammar stack

// Helper to format expected element from grammar stack
static std::string format_expected_element(const llama_grammar_rules & /* rules*/, const llama_grammar_element * elem) {
    if (!elem) {
        return "<end>";
    }

    switch (elem->type) {
        case LLAMA_GRETYPE_END:
            return "<end of rule>";
        case LLAMA_GRETYPE_ALT:
            return "<alternative>";
        case LLAMA_GRETYPE_RULE_REF:
            {
                // Find rule name - just show rule ID for now
                return "<rule-" + std::to_string(elem->value) + ">";
            }
        case LLAMA_GRETYPE_CHAR:
            {
                std::string                   result;
                const llama_grammar_element * pos   = elem;
                bool                          first = true;

                do {
                    if (!first) {
                        result += " | ";
                    }
                    first = false;

                    if (pos[1].type == LLAMA_GRETYPE_CHAR_RNG_UPPER) {
                        // Range like [a-z]
                        result += "[" + format_codepoint(pos->value) + "-" + format_codepoint(pos[1].value) + "]";
                        pos += 2;
                    } else {
                        result += format_codepoint(pos->value);
                        pos += 1;
                    }
                } while (pos->type == LLAMA_GRETYPE_CHAR_ALT);

                return result;
            }
        case LLAMA_GRETYPE_CHAR_NOT:
            {
                std::string                   result = "[^";
                const llama_grammar_element * pos    = elem;
                bool                          first  = true;

                do {
                    if (!first) {
                        result += " ";
                    }
                    first = false;

                    if (pos[1].type == LLAMA_GRETYPE_CHAR_RNG_UPPER) {
                        result += format_codepoint(pos->value) + "-" + format_codepoint(pos[1].value);
                        pos += 2;
                    } else {
                        result += format_codepoint(pos->value);
                        pos += 1;
                    }