Section 2.40. Wrapping Lines of Text

2.39. Expanding and Compressing Tab Characters

Occasionally we have a string with tabs in it and we want to convert them to spaces (or vice versa). The two methods shown here do these operations.

class String   def detab(ts=8)     str = self.dup     while (leftmost = str.index("\t")) != nil       space = " "*(ts-(leftmost%ts))       str[leftmost]=space     end     str   end   def entab(ts=8)     str = self.detab     areas = str.length/ts     newstr = ""     for a in 0..areas       temp = str[a*ts..a*ts+ts-1]       if temp.size==ts         if temp =~ / +/           match=Regexp.last_match[0]           endmatch = Regexp.new(match+"$")           if match.length>1             temp.sub!(endmatch,"\t")           end         end       end       newstr += temp     end     newstr   end end foo = "This       is        only   a     test.          " puts foo puts foo.entab(4) puts foo.entab(4).dump

Note that this code is not smart enough to handle backspaces.