use handbar::*; fn ifcond<'reg, 'rc>( h: &Helper<'rc>, handle: &'reg Handbar, ctx: &'rc Context, render_ctx: &mut RenderContext<'reg, 'rc>, out: &mut dyn Output, ) -> Result<(), RenderError> { let cond = h .param(0) .and_then(|ref v| v.value().as_bool()) .ok_or(RenderError::new("Ifcond takes a boolean !"))? as bool; let temp = if cond { h.template() } else { h.inverse() }; match temp { Some(t) => t.render(handle, ctx, render_ctx, out), None => Ok(()), } } #[test] fn test_helper() { let mut handbar = Handbar::new(); // register some custom helpers handbar.register_helper("ifcond", Box::new(ifcond)); // make data and render it let data = true; assert_eq!( "yes", handbar .render_template("{{#ifcond this}}yes{{/ifcond}}", &data) .unwrap() ); }