Implement partial_compare for OwnedLiteral.

src/renderer/parameters_context.rs

@@ -204,8 +204,36 @@ impl CompareContextElement for OwnedLiteral {
     }
 
     fn partial_compare(&self, other: &dyn ContextElement) -> Option<Ordering> {
-        // TODO
-        None
+        println!("partial_compare literal {:?} | {:?}", self, other);
+        // If its an OwnedLiteral then compare them directly,
+        // otherwise defer to the other type's implementation of
+        // CompareContextElement since the end user could add any
+        // type.
+        match other.to_any().downcast_ref::<Self>() {
+            None => match other.partial_compare(self) {
+                None => None,
+                Some(ord) => match ord {
+                    Ordering::Equal => Some(Ordering::Equal),
+                    Ordering::Greater => Some(Ordering::Less),
+                    Ordering::Less => Some(Ordering::Greater),
+                },
+            },
+            Some(other_literal) => match (self, other_literal) {
+                (OwnedLiteral::LString(self_text), OwnedLiteral::LString(other_text)) => {
+                    self_text.partial_cmp(other_text)
+                }
+                (OwnedLiteral::LPositiveInteger(self_num), OwnedLiteral::LString(other_text)) => {
+                    self_num.to_string().partial_cmp(other_text)
+                }
+                (OwnedLiteral::LString(self_text), OwnedLiteral::LPositiveInteger(other_num)) => {
+                    self_text.partial_cmp(&other_num.to_string())
+                }
+                (
+                    OwnedLiteral::LPositiveInteger(self_num),
+                    OwnedLiteral::LPositiveInteger(other_num),
+                ) => self_num.partial_cmp(other_num),
+            },
+        }
     }
 }