Why does free-run mode stop the negative appearance from working?

Question

Consider the following Ruby code:

/(?<!big )dog/.match('I have a big dog.')        # => nil

Now I turn on the free space mode:

/(?x)(?<!big )dog/.match('I have a big dog.')        # => #<MatchData "dog">

Why is this happening, and how can I turn on the free space mode without violating my negative distortions?

Answer 1

/(?x)(?<!big )dog/.match('I have a big dog.')
#           ^

Please note that after bigyou have a space. Since this is an advanced mode, spaces are ignored.

You have several options :

• Use a pattern, for example, \sor \p{Space}.
• Use escaped whitespace e.g. \e.g. space preceded by backslash.
• , [ ].

:

/(?x)(?<!big\s)dog/.match('I have a big dog.')
# => nil