Function JsonValue

eval/CIPO_evaluation/common/gason.h:51–53

    double fval;

    JsonValue(double x)
        : fval(x) {
    }
    JsonValue(JsonTag tag = JSON_NULL, void *payload = nullptr) {
        assert((uintptr_t)payload <= JSON_VALUE_PAYLOAD_MASK);
        ival = JSON_VALUE_NAN_MASK | ((uint64_t)tag << JSON_VALUE_TAG_SHIFT) | (uintptr_t)payload;