# Gsub help **URL:** \ **Category:** Ruby\ **Created:** [August 29, 2007, 12:15am UTC](https://www.ruby-forum.com/t/gsub-help/113226 "2007-08-29T00:15:58Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![hurcan\_solter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/a88e4f/32.png) [@hurcan\_solter](https://www.ruby-forum.com/u/hurcan_solter)\ **Post date:** [August 29, 2007, 12:15am UTC](https://www.ruby-forum.com/t/gsub-help/113226/1 "2007-08-29T00:15:58Z")
Hi there; this is more of a regexp question but I’de be happy if you help me since i am doing it in ruby. i want to beautify some line by inserting or removing some space around the operators like = or == so i came up with an expression like; line.gsub!(/\s\*([=]+)\s\*/ ,’ \1 ') But it applies every = on the line ofc, but I want to exclude expressions between quotation marks (“sth=sth”) or regexp (/sth=sth/). I’ve tried negated character classes and such to no avail.How can I do this? Any help would be greatly appreciated… Hurcan ---
**Author:** ![hurcan\_solter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/a88e4f/32.png) [@hurcan\_solter](https://www.ruby-forum.com/u/hurcan_solter)\ **Post date:** [August 29, 2007, 1:17am UTC](https://www.ruby-forum.com/t/gsub-help/113226/2 "2007-08-29T01:17:03Z")
hurcan solter wrote: > expressions between quotation marks (“sth=sth”) or regexp (/sth=sth/). > I’ve tried negated character classes and such to no avail.How can I do > this? > Any help would be greatly appreciated… > Hurcan Hurcan, That’s a very hard problem. If you think creatively, you can probably come up with a decent algorithm, and then a handful of examples that break it. For each “=” or “==”, you need to decide whether it is between a pair of unescaped slashes, quotes, or other form of quoting (like %Q|| or %x{}). I doubt there is any way to do this with a regexp. You need to write some code that makes decisions about whether any of the following symbols has semantic meaning: |{}@^#() and any other that can be used in the % quoting construct Once you determine which ones have meaning (and which are escaped, or insignificant in their current context), you can decide whether some “=” should be re-spaced, based on its position relative to these characters. The more I think about it, the more I think you can’t do this without writing a ruby parser. puts (“this problem is nontrivial” == true) puts %q(“this problem is nontrivial” == true) puts %q(“this problem is nontrivial”, says a string == true) Good luck, Dan ---
**Author:** ![hurcan\_solter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/a88e4f/32.png) [@hurcan\_solter](https://www.ruby-forum.com/u/hurcan_solter)\ **Post date:** [August 29, 2007, 2:36am UTC](https://www.ruby-forum.com/t/gsub-help/113226/3 "2007-08-29T02:36:08Z")
On 8/28/07, hurcan solter [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > expressions between quotation marks (“sth=sth”) or regexp (/sth=sth/). > I’ve tried negated character classes and such to no avail.How can I do > this? > This is not a job for regexps. This is a job for a ruby parser. ---
**Author:** ![hurcan\_solter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/a88e4f/32.png) [@hurcan\_solter](https://www.ruby-forum.com/u/hurcan_solter)\ **Post date:** [August 29, 2007, 3:16am UTC](https://www.ruby-forum.com/t/gsub-help/113226/4 "2007-08-29T03:16:10Z")
On Aug 28, 5:11 pm, hurcan solter [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > expressions between quotation marks (“sth=sth”) or regexp (/sth=sth/). > I’ve tried negated character classes and such to no avail.How can I do > this? > Any help would be greatly appreciated… > Hurcan If " and / are the only wrappers you have to worry about, this may work. DATA.each{|line| line.chomp! array = line.scan( %r{ \G (?: [^“/]+ | " (?\> \. | [^”] ) \* " | / (?\> \. | [^/] ) \* / ) }xm ).map{|s| if s =~ %r{^[^"/]} s.gsub!( /\s\*(=+)\s\*/, ’ \1 ’ ) end s } puts array.join } **END** /x==9/ { print “x==9 and AWK is everywhere!”; x=9 } //x==9/ { print “x=="9”; x==9 } ---
**Author:** ![hurcan\_solter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/a88e4f/32.png) [@hurcan\_solter](https://www.ruby-forum.com/u/hurcan_solter)\ **Post date:** [August 29, 2007, 1:51pm UTC](https://www.ruby-forum.com/t/gsub-help/113226/5 "2007-08-29T13:51:14Z")
> This is not a job for regexps. This is a job for a ruby parser. Maybe parsing with [zenspider projects | software projects | by ryan davis](http://www.zenspider.com/ZSS/Products/ParseTree/) then regenerating the source from the parsed output could be good. (didn’t try myself - this is just a rough idea, and you would have to ensure nothing get missed by the parser!) Thibaut ---
**Author:** ![hurcan\_solter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/a88e4f/32.png) [@hurcan\_solter](https://www.ruby-forum.com/u/hurcan_solter)\ **Post date:** [August 29, 2007, 6:47am UTC](https://www.ruby-forum.com/t/gsub-help/113226/6 "2007-08-29T06:47:21Z")
From: hurcan solter [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)] # line.gsub!(/\s\*([=]+)\s\*/ ,’ \1 ') # # But it applies every = on the line ofc, but I want to exclude # expressions between quotation marks (“sth=sth”) or regexp (/sth=sth/). after reviewing WJames post (thanks james), i think you are not far to the solution. You just need to include the exceptions first, then gsub further to that. gsub accepts a block, so flexibility is unlimited, eg, > str > =\> “/x==9/ { print "x==9 and AWK is everywhere!"; x=9 }” let’s create our main regex sub and test if we can get back to the original str, > p str.gsub(/\S\*\s\*([=]+)\s\*\S\*/){|s| s } > “/x==9/ { print "x==9 and AWK is everywhere!"; x=9 }” > =\> nil ok. now let’s view our captures. let’s put some markers/tags. > p str.gsub(/\S\*\s\*([=]+)\s\*\S\*/){|s| “\<\<”+s+“\>\>” } > “\<\\> { print \<\<"x==9\>\> and AWK is everywhere!"; \<\\> }” > =\> nil ah, i think we’re capturing right for this case of str now let’s test the inner substitution. note the gsub inside the block. the expression gets simpler since we’ve already filtered thru the first/main regexp. > p str.gsub(/\S\*\s\*([=]+)\s\*\S\*/){|s| s.gsub(/(=+)/,’ \1 ') } > “/x == 9/ { print "x == 9 and AWK is everywhere!"; x = 9 }” > =\> nil ok. now, let us combine that one w the first one (the noop), using an inline if (i’m assumming you want a one-liner) filtering thru the exception you want, ie, no ["/] > p str.gsub(/\S\*\s\*([=]+)\s\*\S\*/){|s| s=~/["/]/ ? s : s.gsub(/(=+)/,’ \1 ') } > “/x==9/ { print "x==9 and AWK is everywhere!"; x = 9 }” > =\> nil is that ok? kind regards -botp ---
**Author:** ![hurcan\_solter](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/a88e4f/32.png) [@hurcan\_solter](https://www.ruby-forum.com/u/hurcan_solter)\ **Post date:** [August 29, 2007, 8:01pm UTC](https://www.ruby-forum.com/t/gsub-help/113226/7 "2007-08-29T20:01:31Z")
On Aug 28, 11:46 pm, Peña, Botp [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > =\> “/x==9/ { print "x==9 and AWK is everywhere!"; x=9 }” > > > p str.gsub(/\S\*\s\*([=]+)\s\*\S\*/){|s| “\<\<”+s+“\>\>” } > > “/x == 9/ { print "x == 9 and AWK is everywhere!"; x = 9 }” > > =\> nil > > ok. > now, let us combine that one w the first one (the noop), using an inline if (i’m assumming you want a one-liner) filtering thru the exception you want, ie, no ["/] > > > p str.gsub(/\S\*\s\*([=]+)\s\*\S\*/){|s| s=~/["/]/ ? s : s.gsub(/(=+)/,’ \1 ') } > > “/x==9/ { print "x==9 and AWK is everywhere!"; x = 9 }” > =\> nil > > irb --prompt xmp > > str=‘/x==9/ {print “so x=9 and AWK is everywhere!”; x=9 }’ > > ==\>“/x==9/ {print "so x=9 and AWK is everywhere!"; x=9 }” > > str.gsub(/\S\*\s\*([=]+)\s\*\S\*/){|s| > > s=~/[“/]/ ? s : s.gsub(/(=+)/,’ \1 ') } > > ==\>”/x==9/ {print "so x = 9 and AWK is everywhere!"; x = 9 }"