The history of luaTEX 2006–2009 / v 0.50 - Pragma ADE

Collecting tokens can take place inside the callback but also outside. This also gives you
the opportunity to collect them in efcient ways and keep an eye on the memory demands.
Of course using TEX directly takes less code:
\def\SwapChars#1#2{#2#1}
The example shown here involves so little tokens that running it takes no noticeable time.
Here we show this denition in tokenized form:
cmd chr id name
def 0 706 def
undefined_cs 0 636553 SwapChars
mac_param 35
other_char 49 1
mac_param 35
other_char 50 2
left_brace 123
mac_param 35
other_char 50 2
mac_param 35
other_char 49 1
right_brace 125
64 How about performance