Re: Infinity as index

[Dirk Laurie <dirk.laurie@...>]

2014-04-24 23:08 GMT+02:00 Lukas Prokop <admin@lukas-prokop.at>:
>   [[ Parsing recursive HTML5 tag structures ]]
>     1. Initialize "from, to = 1, 1/0"
>     2. Find first opening tag and set "from" to index after opening tag
>     3. Resolve recursive structure and find closing tag at equivalent depth
>     4. Set "to" to index before closing tag
>     5. Parse "source_code:sub(from, to)" recursively.
>
>     The point here is, that for empty tags I don't have to treat indices
>     in a special way. "to" keeps its infinity value and will return the
>     string until the end.
>
>     ... until I realized that infinity is unsupported.
>
> [You might want to argue that I could initialize "to" with "#source_code"
> but of course this algorithm is simplified. "#source_code" is more dynamic
> / more difficult to maintain in my real-world source code]

You could also initialize `to` to -1. By the time string.sub is hit, the
main argument must be a string, and -1 addresses its last bit.