Iron and Tera: how can I get the current url in the master layout?

I'm using Iron and Tera. And I have a master html layout and several child html templates. I want to get access to the current url in a layout. How can I do that?

Or is there a way to get the current url in rust code -- main.rs -- and pass it as a variable to my layout? Not to each of child templates, but straight to the layout.

In other words, I want to pass a variable to the mater layout.