I need to create a regular expression that will remove all extra whitespace from a text document with the exception of spaces and new lines. The document is read into a variable and I then perform a search and replace using regexp. Unfortunately I haven't been able to remove all of the extra whitespace with a single regexp command. Is it possible to use a single regexp statement to accomplish all of the following tasks?

* remove all whitespace other than spaces and new lines
* remove any repeating spaces that appear one after another
* limit number of new lines that appear one after another to a total of 2 (double spaced)

EXAMPLE:
"this is an {space}{space}example\n\n\t\nthis is line two"

In the example above I would need to remove the two extra spaces, the tab, and one of the new lines. The simplest way to remove extra whitespace would be to use something like this /[\t\v\f\r]|\s(?=\s)/ and then just replace the occurrences with an empty string. However, I need to preserve some spaces and new lines so I'm unable to use \s and the statement above doesn't catch all unicode whitespace characters.

In reply to regexp: removing extra whitespace by perlmax

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