Do you want all rules to be performed simultanuously? Or sequentially? That is, if I have "foo{space}{tab}{space}bar" should that result in "foo{space}{space}bar", or in "foo{space}bar"? Rule 2 says repeating spaces should be collapsed, but the original string doesn't have repeated spaces - they only repeat after rule 1 has been applied.

Assuming rules should be applied in order: 

    no warnings "uninitialized";
    s/([ \n])|\s/$1/g;
    s/(\s)\K\1+//g;

[download]
If they apply all at once: 
    no warnings "uninitialized";
    s/([ \n])\1+|\s/$1/g;

[download]
(None of the snippets above were tested).

In reply to Re: regexp: removing extra whitespace by JavaFan
in thread regexp: removing extra whitespace by perlmax

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