# Splitting a string with escapable separator? **URL:** \ **Category:** ruby-talk\ **Created:** [27 September 2005 23:46 UTC](https://rubytalk.org/t/splitting-a-string-with-escapable-separator/21156 "2005-09-27T23:46:44Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Michael\_Schuerig](https://avatars.discourse-cdn.com/v4/letter/m/54ee81/32.png) [@Michael\_Schuerig](https://rubytalk.org/u/Michael_Schuerig)\ **Post date:** [27 September 2005 23:46 UTC](https://rubytalk.org/t/splitting-a-string-with-escapable-separator/21156/1 "2005-09-27T23:46:44Z")
I'm trying to come up with an \*elegant\* way to split a string into an array at a separator with the additional feature that the separators can be escaped. It should work like this   "Hello\, World,Hi".split\_escapable(',' '\')   # =\> ["Hello, World", "Hi"] Through a number of permutations with regexps, scan and the rest of the family, I was unable to find a solution. I could parse the given string myself, going though it character by character, but I'd prefer a less pedestrian approach. Michael > **···** > > -- > Michael Schuerig All good people read good books > [mailto:michael@schuerig.de](mailto:michael@schuerig.de) Now your conscience is clear > [http://www.schuerig.de/michael/](http://www.schuerig.de/michael/) --Tanita Tikaram, Twist In My Sobriety ---
**Author:** ![Gavin\_Kistner2](https://avatars.discourse-cdn.com/v4/letter/g/b9e5f3/32.png) [@Gavin\_Kistner2](https://rubytalk.org/u/Gavin_Kistner2)\ **Post date:** [28 September 2005 05:00 UTC](https://rubytalk.org/t/splitting-a-string-with-escapable-separator/21156/2 "2005-09-28T05:00:37Z")
Your above example is missing a couple of \, but I assume I know what you meant. Is the following elegant or not? class String      def split\_escapable( separator, escape\_char=nil )          results =          re = /(.+?)(?:#{escape\_char ? "([^\\#{escape\_char}])" : ''}#{separator}|$)/          self.scan( re ){ |str,last\_char|              results \<\< str + last\_char.to\_s          }          results      end end p "Hello\\, World,Hi".split\_escapable( ',', '\\' ) #=\> ["Hello\\, World", "Hi"] Note that the above does not account for the case of: Hello \\,World (where an escaped backslash is intended to end the first entry) but if that was important, that's just a matter of a bit of odd/even backslash counting. Something like (untested): re = /(.+?)(?:#{escape\_char ? "([^\\#{escape\_char}](\\#{escape\_char}\\#{escape\_char})\*)" : ''}#{separator}|$)/ > **···** > > On Sep 27, 2005, at 5:46 PM, Michael Schuerig wrote: > > > I'm trying to come up with an \*elegant\* way to split a string into an > > array at a separator with the additional feature that the separators > > can be escaped. It should work like this > > > >   "Hello\, World,Hi".split\_escapable(',' '\') > >   # =\> ["Hello, World", "Hi"] > > > > Through a number of permutations with regexps, scan and the rest of the > > family, I was unable to find a solution. ---
**Author:** ![W\_James](https://avatars.discourse-cdn.com/v4/letter/w/e274bd/32.png) [@W\_James](https://rubytalk.org/u/W_James)\ **Post date:** [28 September 2005 10:26 UTC](https://rubytalk.org/t/splitting-a-string-with-escapable-separator/21156/3 "2005-09-28T10:26:44Z")
Michael Schuerig wrote: > I'm trying to come up with an \*elegant\* way to split a string into an > array at a separator with the additional feature that the separators > can be escaped. It should work like this > >   "Hello\, World,Hi".split\_escapable(',' '\') >   # =\> ["Hello, World", "Hi"] > > Through a number of permutations with regexps, scan and the rest of the > family, I was unable to find a solution. I could parse the given string > myself, going though it character by character, but I'd prefer a less > pedestrian approach. class String   def split\_escapable( splitter, escaper )     escaper = escaper\*2 if escaper=='\\'     re = %r{ \G              # Make sure at least 1 character remains.              (?= . )              (                (?:                  [^#{ splitter }#{ escaper }]                  \>                  (?: #{ escaper } . )                ) \*              )              (?:                #{ splitter }                \>                \Z              )            }xm     scan( re ).map{|x| x.first.gsub( /#{escaper}(.)/, '\1' ) }   end end s = \<\ **Author:** ![Jason\_Sweat](https://avatars.discourse-cdn.com/v4/letter/j/53a042/32.png) [@Jason\_Sweat](https://rubytalk.org/u/Jason_Sweat)\ **Post date:** [28 September 2005 11:02 UTC](https://rubytalk.org/t/splitting-a-string-with-escapable-separator/21156/4 "2005-09-28T11:02:43Z") > I'm trying to come up with an \*elegant\* way to split a string into an > array at a separator with the additional feature that the separators > can be escaped. It should work like this > >   "Hello\, World,Hi".split\_escapable(',' '\') >   # =\> ["Hello, World", "Hi"] > > Through a number of permutations with regexps, scan and the rest of the > family, I was unable to find a solution. I could parse the given string > myself, going though it character by character, but I'd prefer a less > pedestrian approach. > > Michael With the new Regex engine in cvs ruby you can use a negative lookback assertion in your split: > > s = "Hello\\, World, Hi" =\> "Hello\\, World, Hi" > > s.split /(?\ ["Hello\\, World", " Hi"] $ ruby --v ruby 1.9.0 (2005-09-08) [i686-linux] Regards, Jason [http://blog.casey-sweat.us/](http://blog.casey-sweat.us/) > **···** > > On 9/27/05, Michael Schuerig \ wrote: ---
**Author:** ![Han\_Holl](https://avatars.discourse-cdn.com/v4/letter/h/d2c977/32.png) [@Han\_Holl](https://rubytalk.org/u/Han_Holl)\ **Post date:** [29 September 2005 10:18 UTC](https://rubytalk.org/t/splitting-a-string-with-escapable-separator/21156/5 "2005-09-29T10:18:35Z")
None of the offerings so far had support for the second argument for split. The following is probably quite efficent if the chance of an occurrence of an escaped character is low. (I haven't benchmarked anything, though). Also, it's not suitable for binary strings. class String def split\_escapable(separator, escape\_char, \*args) istr = dup impossible = "\x01" replace = "#{escape\_char}#{separator}" changed = istr.gsub!(replace, impossible) fields = istr.split(separator, \*args) if changed fields.each do |f| f.gsub!(impossible, separator) end end fields end end a = "Hello\\, World,Hi" puts a.split\_escapable( ',', '\\' ) Cheers, Han Holl > **···** > > On 9/28/05, Michael Schuerig \ wrote: > > > I'm trying to come up with an \*elegant\* way to split a string into an > > array at a separator with the additional feature that the separators > > can be escaped. It should work like this > > > > "Hello\, World,Hi".split\_escapable(',' '\') > > # =\> ["Hello, World", "Hi"] ---
**Author:** ![David\_Tran1](https://avatars.discourse-cdn.com/v4/letter/d/51bf81/32.png) [@David\_Tran1](https://rubytalk.org/u/David_Tran1)\ **Post date:** [4 October 2005 14:56 UTC](https://rubytalk.org/t/splitting-a-string-with-escapable-separator/21156/6 "2005-10-04T14:56:49Z")
Without 1.9 lookback, you could try: 'Hello\,World,Hi'.scan(/(?:\\,|[^,])+/).map {|e| e.tr('\\','')} =\> ["Hello,World", "Hi"] Michael Schuerig wrote: > **···** > > > I'm trying to come up with an \*elegant\* way to split a string into an > > array at a separator with the additional feature that the separators > > can be escaped. It should work like this > > > >   "Hello\, World,Hi".split\_escapable(',' '\') > >   # =\> ["Hello, World", "Hi"] > > > > Through a number of permutations with regexps, scan and the rest of the > > family, I was unable to find a solution. I could parse the given string > > myself, going though it character by character, but I'd prefer a less > > pedestrian approach. > > > > Michael > > > > -- > > Michael Schuerig All good people read good books > > [mailto:michael@schuerig](mailto:michael@schuerig).de Now your conscience is clear > > [Michael Schürig | Sentenced to making sense](http://www.schuerig.de/michael/) --Tanita Tikaram, Twist In My Sobriety ---
**Author:** ![Michael\_Schuerig](https://avatars.discourse-cdn.com/v4/letter/m/54ee81/32.png) [@Michael\_Schuerig](https://rubytalk.org/u/Michael_Schuerig)\ **Post date:** [28 September 2005 14:56 UTC](https://rubytalk.org/t/splitting-a-string-with-escapable-separator/21156/7 "2005-09-28T14:56:44Z")
Jason Sweat wrote: > **···** > > > On 9/27/05, Michael Schuerig \ wrote: > > > > > I'm trying to come up with an \*elegant\* way to split a string into an > > > array at a separator with the additional feature that the separators > > > can be escaped. It should work like this > > > > > >   "Hello\, World,Hi".split\_escapable(',' '\') > > >   # =\> ["Hello, World", "Hi"] > > > > > > Through a number of permutations with regexps, scan and the rest of > > > the family, I was unable to find a solution. I could parse the given > > > string myself, going though it character by character, but I'd prefer > > > a less pedestrian approach. > > > > > > Michael > > > > With the new Regex engine in cvs ruby you can use a negative lookback > > assertion in your split: > > > > > > s = "Hello\\, World, Hi" > > > > =\> "Hello\\, World, Hi" > > > > > > s.split /(?\ > > > =\> ["Hello\\, World", " Hi"] > > That must be the most elegant solution. Unfortunately I can't use cvs > ruby and can't wait for it either. > > Michael > > -- > Michael Schuerig Airtight arguments have > [mailto:michael@schuerig](mailto:michael@schuerig).de vacuous conclusions. > [Michael Schürig | Sentenced to making sense](http://www.schuerig.de/michael/) --A.O. Rorty, Explaining Emotions ---
**Author:** ![Michael\_Schuerig](https://avatars.discourse-cdn.com/v4/letter/m/54ee81/32.png) [@Michael\_Schuerig](https://rubytalk.org/u/Michael_Schuerig)\ **Post date:** [28 September 2005 15:16 UTC](https://rubytalk.org/t/splitting-a-string-with-escapable-separator/21156/8 "2005-09-28T15:16:44Z")
William James wrote: > Michael Schuerig wrote: > > > I'm trying to come up with an \*elegant\* way to split a string into an > > array at a separator with the additional feature that the separators > > can be escaped. [snip] > class String >   def split\_escapable( splitter, escaper ) [snip] >   end > end Thanks, that appears to work indeed, although I can't claim to understand how or why. Michae. > **···** > > -- > Michael Schuerig The more it stays the same, > [mailto:michael@schuerig](mailto:michael@schuerig).de The less it changes! > [Michael Schürig | Sentenced to making sense](http://www.schuerig.de/michael/) --Spinal Tap, The Majesty of Rock ---
**Author:** ![Michael\_Schuerig](https://avatars.discourse-cdn.com/v4/letter/m/54ee81/32.png) [@Michael\_Schuerig](https://rubytalk.org/u/Michael_Schuerig)\ **Post date:** [28 September 2005 15:16 UTC](https://rubytalk.org/t/splitting-a-string-with-escapable-separator/21156/9 "2005-09-28T15:16:45Z")
Gavin Kistner wrote: [snip] > Note that the above does not account for the case of: > Hello \\,World > (where an escaped backslash is intended to end the first entry) > but if that was important, that's just a matter of a bit of odd/even > backslash counting. That's a thing I'd need. Opportunistically, I'll go with William's suggestion from a sibling post. > Something like (untested): > re = /(.+?)(?:#{escape\_char ? "([^\\#{escape\_char}](\\#{escape\_char}\ > \#{escape\_char})\*)" : ''}#{separator}|$)/ Thanks. Michael > **···** > > -- > Michael Schuerig The more it stays the same, > [mailto:michael@schuerig](mailto:michael@schuerig).de The less it changes! > [Michael Schürig | Sentenced to making sense](http://www.schuerig.de/michael/) --Spinal Tap, The Majesty of Rock