General ⇒ Switch statement performance

[toberthanner]

Hello,
I am facing performance issues when using switch statements with a large number of cases.
Defining a new command with an single argument (type int) and returning different content is working as expected BUT the compilation time is depending on the argument:
\tablexy{100} is fast but
\tablexy{6000} takes more than 30 seconds (i guess because it is at the very end of the switch statement)

Code: Select all

\newcommand{\tablexy}[1]{
\int_case:nnF{#1}{
{100}{some content}
{101}{some other content}
...
{6000}{again something different}
}

I also tried \IfStrEqCase with almost the same result.

I was first thinking of having a single command for each number like \tablexy100 ... \tablexy6000 but that is not possible because of the numbers in the command name.

The latex code is generated with c# from am Dictionary<int,string> (where the string contains latex code for tables) and i am open to other approaches. Just need to pick content out of this list based on the key (int).

[Ijon Tichy]

TeX itself does not provide a case-statement. So the \int_case:nnF results in a sequence of comparisons that stops if the true state is reached. So early true cases (= early true state) need more comparisons and more time than late true cases (= late true state).

With \@namedef and \@nameuse (\csname …\endcsname or the expl3 synonyms \cs:w…\cs:end: or \use:c) you can indeed define and use code sequences with Arabic numbers. Instead you could also use roman numbers instead of Arabic to be able to use them as macro names.

Another alternative would be to use luaTeX and implement such things using lua.

[toberthanner]

Thank you very much for pointing me in the right direction.

Code: Select all

\documentclass{article}

\makeatletter
% define each table
\@namedef{table1}#1{#1 content of table 1}%
\@namedef{table2}#1{#1 content of table 2}%

% helper function to access tables
\def\mytable#1#2{
  \@nameuse{table#1}{#2}%
}
\makeatother


\begin{document}
\mytable{1}{\section{table1}}
\mytable{2}{\section{table2}}
\end{document}