Reenable routes with optional portions

[timriley]

All the following examples from spec/integration/hanami/router/generation_spec.rb are skipped.

I think these were most likely disabled when we first introduced the trie structure for 2.0, and then we did not reintroduce this behaviour afterwards.

I think this is useful to have. We should have a look to see whether we can achieve it again.

context "variable with optional format" do
  let(:router) do
    described_class.new do
      get "/:var(.:format)", as: :a, to: -> {}
    end
  end

  it "generates relative and absolute URLs" do
    runner.run!([
      [:a, "/test.html", {var: "test", format: "html"}],
      [:a, "/test", {var: "test"}]
    ])
  end
end

context "variable with optional variable" do
  let(:router) do
    described_class.new do
      get "/:var1(/:var2)", as: :a, to: -> {}
    end
  end

  xit "generates relative and absolute URLs" do
    runner.run!([
      [:a, "/foo/bar", {var1: "foo", var2: "bar"}],
      [:a, "/foo", {var1: "foo"}]
    ])
  end
end

context "variable with optional variable and format" do
  let(:router) do
    described_class.new do
      get "/:var1(/:var2.:format)", as: :a, to: -> {}
    end
  end

  xit "generates relative and absolute URLs" do
    runner.run!([
      [:a, "/test/test2.html", {var1: "test", var2: "test2", format: "html"}]
    ])
  end
end

context "variable with optional nested variables" do
  let(:router) do
    described_class.new do
      get "/:var1(/:var2(/:var3))", as: :a, to: -> {}
    end
  end

  xit "generates relative and absolute URLs" do
    runner.run!([
      [:a, "/var/fooz/baz", {var1: "var", var2: "fooz", var3: "baz"}],
      [:a, "/var/fooz", {var1: "var", var2: "fooz"}],
      [:a, "/var", {var1: "var"}]
    ])
  end
end

[dcr8898]

There is no reason this can't be done with the current trie implementation. It would just require parsing the route specification containing optional segments, and then adding all of the possible route permutations to the trie.

If optional segments are used a lot, especially multiple optional segments in the same route, the proliferation of routes could lead to slower start times (see #278 for related issue).

I would be happy to work on this when I have a little more time.