Add tests and a Sizable trait for ContextElement.

src/bin.rs

@@ -15,6 +15,7 @@ use renderer::Loopable;
 use renderer::MathNumber;
 use renderer::RenderError;
 use renderer::Renderable;
+use renderer::Sizable;
 use renderer::Truthiness;
 use renderer::WalkError;
 use renderer::Walkable;
@@ -313,6 +314,12 @@ impl Loopable for serde_json::Value {
     }
 }
 
+impl Sizable for serde_json::Value {
+    fn get_size<'a>(&'a self) -> Option<IceResult<'a>> {
+        todo!()
+    }
+}
+
 impl Castable for serde_json::Value {
     fn cast_to_type<'a>(&'a self, target: &str) -> Option<IceResult<'a>> {
         match (self, target) {

src/renderer/context_element.rs

@@ -22,6 +22,7 @@ pub trait ContextElement:
     + FromContextElement
     + IntoRcIce
     + Castable
+    + Sizable
 {
 }
 
@@ -63,6 +64,10 @@ pub trait Castable {
     fn cast_to_type<'a>(&'a self, target: &str) -> Option<IceResult<'a>>;
 }
 
+pub trait Sizable {
+    fn get_size<'a>(&'a self) -> Option<IceResult<'a>>;
+}
+
 pub trait CastToAny {
     fn to_any(&self) -> &dyn Any;
 }

src/renderer/mod.rs

@@ -18,6 +18,7 @@ pub use context_element::IceResult;
 pub use context_element::IntoContextElement;
 pub use context_element::Loopable;
 pub use context_element::Renderable;
+pub use context_element::Sizable;
 pub use context_element::Truthiness;
 pub use context_element::Walkable;
 pub use errors::CompileError;

src/renderer/parameters_context.rs

@@ -14,6 +14,7 @@ use crate::renderer::DustRenderer;
 use crate::renderer::Loopable;
 use crate::renderer::RenderError;
 use crate::renderer::Renderable;
+use crate::renderer::Sizable;
 use crate::renderer::Truthiness;
 use crate::renderer::WalkError;
 use crate::renderer::Walkable;
@@ -189,6 +190,12 @@ impl Walkable for OwnedLiteral {
     }
 }
 
+impl Sizable for OwnedLiteral {
+    fn get_size<'a>(&'a self) -> Option<IceResult<'a>> {
+        todo!()
+    }
+}
+
 impl Castable for OwnedLiteral {
     fn cast_to_type<'a>(&'a self, target: &str) -> Option<IceResult<'a>> {
         match (self, target) {