Further to the answers above there's presuf from the Regex::PreSuf module which is tailored specifically to solving this problem e.g

use Regex::PreSuf;

print presuf("1234", "ABCD", "HIGL", "TOOA", "COOLIE");

__output__

(?:1234|ABCD|COOLIE|HIGL|TOOA)
[download]

It also rather niftily 'optimizes' (or 'compresses', depending on your view) the regular expression for overlapping words. See. the Regex::PreSuf docs for more info.
HTH

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broquaint