regular-state::process (config) {
        if (self->accepts) {                            # memo
            config->remember-accept-position
            config->remember-accept-type (self->type)
        }
        config->advance-input                           # advance
    }
    
    error-state::process (config) {
        push (output-queue, token {                     # token
            type = config->accepted-type
            value = config->accepted-string
        })
        config->rewind-input                            # rewind
    }
    
    error-state::transition-for (char) {
        return (start)                                  # restart-1
    }
    
    start-state::process (config) {
        config->remember-starting-position              # restart-2
    }    
    
    
    state = start
    
    while (config->has-more-input) {
        state->process (config)
        state = state->transition-for (config->current-input-char)
            || error-state                              # move
    }