The structure is all there, just need to implement owned_walk_path and clone on NewParametersContext.

src/renderer/parameters_context.rs

@@ -3,6 +3,7 @@ use crate::parser::{Filter, RValue};
 use crate::renderer::context_element::CloneIntoBoxedContextElement;
 use crate::renderer::context_element::CompareContextElement;
 use crate::renderer::context_element::ContextElement;
+use crate::renderer::walking::owned_walk_path;
 use crate::renderer::walking::walk_path;
 use crate::renderer::Loopable;
 use crate::renderer::RenderError;
@@ -94,7 +95,7 @@ impl Walkable for NewParametersContext {
     fn walk(&self, segment: &str) -> Result<&dyn ContextElement, WalkError> {
         let rval = self.params.get(segment).ok_or(WalkError::CantWalk)?;
         match rval {
-            OwnedRValue::RVPath(path) => walk_path(self.breadcrumbs, &path.keys),
+            OwnedRValue::RVPath(path) => owned_walk_path(&self.breadcrumbs, &path.keys),
             OwnedRValue::RVString(text) => Ok(text),
         }
     }
@@ -102,8 +103,11 @@ impl Walkable for NewParametersContext {
 
 impl Clone for NewParametersContext {
     fn clone(&self) -> Self {
-        // TODO: What is this doing, really?
+        // TODO: Implement clone
-        *self
+        NewParametersContext {
+            params: HashMap::new(),
+            breadcrumbs: Vec::new(),
+        }
     }
 }
 

src/renderer/walking.rs

@@ -51,3 +51,11 @@ pub fn walk_path<'a>(
     }
     Err(WalkError::CantWalk)
 }
+
+pub fn owned_walk_path<'a>(
+    breadcrumbs: &Vec<Box<dyn ContextElement>>,
+    path: &Vec<String>,
+) -> Result<&'a dyn ContextElement, WalkError> {
+    // TODO: Implement owned_walk_path
+    Err(WalkError::CantWalk)
+}