There's a FAQ entry (no, not on this site, but there is Perl life outside of it, too, you know :): How can I split a [character] delimited string except when inside [character]? (Comma-separated files)

Anyway, aside from that, my first though would be along these lines:

  @tokens = /(?:".*?"|\S)+/g;
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which, with the string

  $_ = 'Here we have u"a quoted string" and a .';
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produces, with each item of @tokens on a separate line:

Here
we
have
u"a quoted string"
and
a
.

Looks fine to me.