It's not specifically related to just whitespace, but have you looked at Perl::Tidy? It will beautify and format your code for you.

Cleaning up whitespace in Perl code just with regexps is problematic since Perl's code can include both nonessential whitespace, and essential whitespace. For example, unless you're using a real parser, it's difficult to tell the difference between a HERE doc (which presumably has significant whitespace) and code (which presumably has some insignificant whitespace).

If this is what you mean, there's still the question of what you want to do with comments in the source code (remove them entirely, or just normalize whitespace?); presumably, you'll need to be able to identify the beginnings and endings of quoted strings, so you can leave the enclosed whitespace as is (assuming you don't want to change the output of the program as a side effect of "cleaning" the source code). In any case, you're probably going to need something like Parse::RecDescent, which is, effectively, the perl version of "yacc".

It'll be a challenge, and I wish you luck, but once you work out how the rules are stated, and figure out the rules you need for each language, switching from one rule set to another should be pretty trivial.

If you mean something else by "cleaning whitespace", it would be hard for me to guess what that might be.

Parser, smarser. Just use a simple regex. As a start:

    s{
      (                         # $1 for whole match
         ' (?: \\. | [^']+ )* ' # 'string'
       | " (?: \\. | [^"]+ )* " # "string"
       | (?:^|\r*\n)[^\S\n]*    # leading spaces
       | ([^\S\n]+)             # $2 is trivial spaces
      )
    }{
        $2 ? ' ' : $1
    }gsex
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- tye        

As already stated above, it is unclear exactly what you trying to achieve.

The following is probably too simplistic as a complete solution but the two methods described may be useful in parts of your final script.

• $/ is used here to remove duplicate blank lines
• y/// (alias tr///) is used here to remove duplicate spaces

(These are not their only uses.)

[ ~/tmp ] $ cat spacey_text 
1 12  23   32  21 1
a b  c   d    e
1 blank:

2 blanks:


3 blanks:



end_blanks
[ ~/tmp ] $ perl -we 'use strict; { local $/ = ""; while (<>) { $_ =~ 
+y/ / /s; print $_; } }' spacey_text 
1 12 23 32 21 1
a b c d e
1 blank:

2 blanks:

3 blanks:

end_blanks
[ ~/tmp ] $
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Not perl, but many flavours of *NIX come with a program indent which reformats C code. If it's not available out of the box on your particular platform there's also a GNU version.

Basically for perl use perltidy, for c use indent, for c++ use bcpp, and htmltidy for html. What I have is a little perl script that strips all leading whitespace( and possibly leading line numbers followed by zero or 1 colon(or semi-colon typo) , then I run it thru the above mentioned beautifiers. And yes, occasionally I need to manually fix something, when the thing breaks on an odd line or 2.

perltidy -dws yourscript.pl
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See "perltidy -h" or "man perltidy" for more usefull options

kind regards