How to split a string in Ruby?

Question

I have special strings like name1="value1" name2='value2'. Values can contain whitespaces and are delimited by either single quotes or double quotes. Names never contain whitespaces. name/value pairs are separated by whitespaces.

I want to parse them into a list of name-value pairs like this

string.magic_split() => { "name1"=>"value1", "name2"=>"value2" }

If Ruby understood lookaround assertions, I could do this by

string.split(/[\'\"](?=\s)/).each do |element|
    element =~ /(\w+)=[\'\"](.*)[\'\"]/
    hash[$1] = $2
end

but Ruby does not understand lookaround assertions, so I am somewhat stuck.

However, I am sure that there are much more elegant ways to solve this problem anyway, so I turn to you. Do you have a good idea for solving this problem?

Answer 1

This is not a complete answer, but Oniguruma, the standard regexp library in 1.9 supports lookaround assertions. It can be installed as a gem if you are using Ruby 1.8.x.

That said, and as Sorpigal has commented, instead of using a regexp I would be inclined to iterate through the string one character at a time keeping track of whether you are in a name portion, when you reach the equals sign, when you are within quotes and when you reach a matched closing quote. On reaching a closing quote you can put the name and value into the hash and proceed to the next entry.

Answer 2

Have a try with : /[='"] ?/

I don't know Ruby syntax but here is a Perl script you could translate

#!/usr/bin/perl 
use 5.10.1;
use warnings;
use strict;
use Data::Dumper;

my $str =  qq/name1="val ue1" name2='va lue2'/;

my @list = split/[='"] ?/,$str;
my %hash;
for (my $i=0; $i<@list;$i+=3) {
  $hash{$list[$i]} = $list[$i+2];
}
say Dumper \%hash;

Output :

$VAR1 = {
          'name2' => 'va lue2',
          'name1' => 'val ue1'
        };

Answer 3

class String

  def magic_split
    str = self.gsub('"', '\'').gsub('\' ', '\'\, ').split('\, ').map{ |str| str.gsub("'", "").split("=") }
    Hash[str]
  end

end

Answer 4

This fails on values like '"hi" she said', but it might be good enough.

str = %q(name1="value1" name2='value 2')
p Hash[ *str.chop.split( /' |" |='|="/ ) ]
#=> {"name1"=>"value1", "name2"=>"value 2"}

Answer 5

This should do it for you.

 class SpecialString
   def self.parse(string)
     string.split.map{|s| s.split("=") }.inject({}) {|h, a| h[a[0]] = a[1].gsub(/"|'/, ""); h }
   end
 end