PatternReplaceFilterFactory -- what does this regex do?

[Eric Wilson <wi...@gmail.com>]

I'm using the Solr Suggester for autocompletion with WFSTLookup suggest
component, and a text file with phrases and weights. (
http://wiki.apache.org/solr/Suggester)

I found that the following filter made it impossible to match on
ampersands. So I removed it. But I'm sure it was there for a reason. What
was this suppose to do?

<filter class="solr.PatternReplaceFilterFactory" pattern=
"([^\p{L}\p{M}\p{N}\p{Cs}]*[\p{L}\p{M}\p{N}\p{Cs}\_]+:)|([^\p{L}\p{M}\p{N}\p{Cs}])+"
replacement=" " replace="all"/>

Thanks,

Eric Wilson