From 9baa669dea8e603b9dd6c48fbb3a539127ce70bf Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Sun, 10 May 2020 22:04:41 -0400
Subject: [PATCH] Separating out CastToAny.

---
 src/bin.rs                         |  6 ++++++
 src/renderer/context_element.rs    | 26 +++++++++++++++++---------
 src/renderer/parameters_context.rs | 17 ++++++++++++++++-
 3 files changed, 39 insertions(+), 10 deletions(-)

diff --git a/src/bin.rs b/src/bin.rs
index 661670d..47c977b 100644
--- a/src/bin.rs
+++ b/src/bin.rs
@@ -140,3 +140,9 @@ impl Loopable for serde_json::Value {
         }
     }
 }
+
+impl CompareContextElement for serde_json::Value {
+    fn equals(&self, other: &dyn ContextElement) -> bool {
+        false
+    }
+}
diff --git a/src/renderer/context_element.rs b/src/renderer/context_element.rs
index 29ca430..8701711 100644
--- a/src/renderer/context_element.rs
+++ b/src/renderer/context_element.rs
@@ -30,9 +30,11 @@ pub trait Loopable {
     fn get_loop_elements(&self) -> Vec<&dyn ContextElement>;
 }
 
-pub trait CompareContextElement {
+pub trait CastToAny {
     fn to_any(&self) -> &dyn Any;
+}
 
+pub trait CompareContextElement: CastToAny {
     fn equals(&self, other: &dyn ContextElement) -> bool;
 }
 
@@ -46,19 +48,25 @@ impl<C: 'static + ContextElement + Clone> CloneIntoBoxedContextElement for C {
     }
 }
 
-impl<C: 'static + ContextElement + PartialEq> CompareContextElement for C {
+impl<C: 'static + ContextElement + PartialEq> CastToAny for C {
     fn to_any(&self) -> &dyn Any {
         self
     }
-
-    fn equals(&self, other: &dyn ContextElement) -> bool {
-        other
-            .to_any()
-            .downcast_ref::<Self>()
-            .map_or(false, |a| self == a)
-    }
 }
 
+// impl<C: 'static + ContextElement + PartialEq> CompareContextElement for C {
+//     fn to_any(&self) -> &dyn Any {
+//         self
+//     }
+
+//     fn equals(&self, other: &dyn ContextElement) -> bool {
+//         other
+//             .to_any()
+//             .downcast_ref::<Self>()
+//             .map_or(false, |a| self == a)
+//     }
+// }
+
 impl<'a, 'b> PartialEq<&'b dyn ContextElement> for &'a dyn ContextElement {
     fn eq(&self, other: &&'b dyn ContextElement) -> bool {
         self.equals(*other)
diff --git a/src/renderer/parameters_context.rs b/src/renderer/parameters_context.rs
index f6045b7..6d525ca 100644
--- a/src/renderer/parameters_context.rs
+++ b/src/renderer/parameters_context.rs
@@ -1,5 +1,6 @@
 use crate::parser::KVPair;
 use crate::parser::{Filter, RValue};
+use crate::renderer::context_element::CastToAny;
 use crate::renderer::context_element::CloneIntoBoxedContextElement;
 use crate::renderer::context_element::CompareContextElement;
 use crate::renderer::context_element::ContextElement;
@@ -111,11 +112,13 @@ impl Clone for NewParametersContext {
     }
 }
 
-impl CompareContextElement for NewParametersContext {
+impl CastToAny for NewParametersContext {
     fn to_any(&self) -> &dyn Any {
         self
     }
+}
 
+impl CompareContextElement for NewParametersContext {
     fn equals(&self, other: &dyn ContextElement) -> bool {
         // TODO: Does this ever happen? perhaps I should have a panic here.
         false
@@ -197,3 +200,15 @@ impl Walkable for String {
         Err(WalkError::CantWalk)
     }
 }
+
+impl CompareContextElement for String {
+    fn equals(&self, other: &dyn ContextElement) -> bool {
+        // If its a String 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 => other.equals(self),
+            Some(other_string) => self == other_string,
+        }
+    }
+}