Segment matcher for paths.
Seg provides two methods for consuming and capturing path segments.
A path is a string that starts with a slash and contains segments
separated by slashes, for example /foo/bar/baz or /users/42.
Consider this interactive session:
s = Seg.new("/users/42")
#=> #<Seg ...>
s.prev
#=> ""
s.curr
#=> "/users/42"
s.consume("users")
#=> true
s.prev
#=> "/users"
s.curr
#=> "/42"
s.consume("42")
#=> true
s.prev
#=> "/users/42"
s.curr
#=> ""The previous example shows how to walk the path by providing segments to consume. In the following example, we'll see what happens when we try to consume a segment with a string that doesn't match:
s = Seg.new("/users/42")
#=> #<Seg ...>
s.prev
#=> ""
s.curr
#=> "/users/42"
s.consume("admin")
#=> false
s.prev
#=> ""
s.curr
#=> "/users/42"As you can see, the command fails and the prev and
curr strings are not altered. Now we'll see
how to capture segment values:
s = Seg.new("/users/42")
#=> #<Seg ...>
captures = Hash(Symbol, String).new
#=> {}
s.prev
#=> ""
s.curr
#=> "/users/42"
s.capture(:foo, captures)
#=> true
s.prev
#=> "/users"
s.curr
#=> "/42"
s.capture(:bar, captures)
#=> true
s.prev
#=> "/users/42"
s.curr
#=> ""
captures
#=> {:foo=>"users", :bar=>42}It is also possible to extract the next segment from the path.
The method extract returns the next segment, if available, or nil
otherwise:
s = Seg.new("/users/42")
#=> #<Seg ...>
s.prev
#=> ""
s.curr
#=> "/users/42"
s.extract
#=> "users"
s.prev
#=> "/users"
s.curr
#=> "/42"
s.extract
#=> "42"
s.prev
#=> "/users/42"
s.curr
#=> ""You can also go back by using the methods retract and restore,
which are the antidote to extract and consume respectively.
Let's see how retract works:
s = Seg.new("/users/42")
#=> #<Seg ...>
s.prev
#=> ""
s.curr
#=> "/users/42"
s.extract
#=> "users"
s.prev
#=> "/users"
s.curr
#=> "/42"
s.retract
#=> "users"
s.prev
#=> ""
s.curr
#=> "/users/42"And now restore:
s = Seg.new("/users/42")
#=> #<Seg ...>
s.prev
#=> ""
s.curr
#=> "/users/42"
s.extract
#=> "users"
s.prev
#=> "/users"
s.curr
#=> "/42"
s.restore("foo")
#=> false
s.restore("users")
#=> true
s.prev
#=> ""
s.curr
#=> "/users/42"Add this to your application's shard.yml:
dependencies:
seg:
github: soveran/seg
branch: master
