From 9c7883358a0d31d91e68f9a24bd7470e087096a9 Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Sun, 12 Apr 2020 20:52:30 -0400
Subject: [PATCH] Better error handling added to walkable

---
 src/bin.rs               | 35 ++++++++++++++++++++++++-----------
 src/renderer/renderer.rs | 25 +++++++++++++++----------
 2 files changed, 39 insertions(+), 21 deletions(-)

diff --git a/src/bin.rs b/src/bin.rs
index d334aef..7bad3b5 100644
--- a/src/bin.rs
+++ b/src/bin.rs
@@ -88,19 +88,32 @@ impl Renderable for serde_json::Value {
 impl Walkable for serde_json::Value {
     fn walk(&self, segment: &str) -> Result<&dyn ContextElement, RenderError> {
         match self {
-            serde_json::Value::Null => panic!("Attempted to walk to {} on a null value", segment),
-            serde_json::Value::Bool(_boolean) => {
-                panic!("Attempted to walk to {} on a boolean value", segment)
-            }
-            serde_json::Value::Number(_num) => {
-                panic!("Attempted to walk to {} on a number value", segment)
-            }
-            serde_json::Value::String(_string) => {
-                panic!("Attempted to walk to {} on a string value", segment)
-            }
+            serde_json::Value::Null => Err(RenderError::CantWalk {
+                segment: segment.to_string(),
+                elem: self,
+            }),
+            serde_json::Value::Bool(_boolean) => Err(RenderError::CantWalk {
+                segment: segment.to_string(),
+                elem: self,
+            }),
+            serde_json::Value::Number(_num) => Err(RenderError::CantWalk {
+                segment: segment.to_string(),
+                elem: self,
+            }),
+            serde_json::Value::String(_string) => Err(RenderError::CantWalk {
+                segment: segment.to_string(),
+                elem: self,
+            }),
             serde_json::Value::Array(_arr) => todo!("Arrays not supported yet"),
             // TODO: Handle this error better
-            serde_json::Value::Object(obj) => Ok(obj.get(segment).unwrap()),
+            serde_json::Value::Object(obj) => {
+                obj.get(segment)
+                    .map(|val| val as _)
+                    .ok_or(RenderError::WontWalk {
+                        segment: segment.to_string(),
+                        elem: self,
+                    })
+            }
         }
     }
 }
diff --git a/src/renderer/renderer.rs b/src/renderer/renderer.rs
index 80cd62e..b53b56c 100644
--- a/src/renderer/renderer.rs
+++ b/src/renderer/renderer.rs
@@ -139,24 +139,29 @@ mod tests {
 
         impl<I: ContextElement> Walkable for HashMap<&str, I> {
             fn walk(&self, segment: &str) -> Result<&dyn ContextElement, RenderError> {
-                Ok(self.get(segment).unwrap())
-                // TODO: Handle error here better
-                // self.get(segment).ok_or(RenderError::WontWalk {
-                //     segment: segment.to_string(),
-                //     elem: self,
-                // })
+                let child = self.get(segment).ok_or(RenderError::WontWalk {
+                    segment: segment.to_string(),
+                    elem: self,
+                })?;
+                Ok(child)
             }
         }
 
         impl Walkable for &str {
-            fn walk(&self, _segment: &str) -> Result<&dyn ContextElement, RenderError> {
-                panic!("Tried to walk down a str");
+            fn walk(&self, segment: &str) -> Result<&dyn ContextElement, RenderError> {
+                Err(RenderError::CantWalk {
+                    segment: segment.to_string(),
+                    elem: self,
+                })
             }
         }
 
         impl Walkable for u32 {
-            fn walk(&self, _segment: &str) -> Result<&dyn ContextElement, RenderError> {
-                panic!("Tried to walk down a str");
+            fn walk(&self, segment: &str) -> Result<&dyn ContextElement, RenderError> {
+                Err(RenderError::CantWalk {
+                    segment: segment.to_string(),
+                    elem: self,
+                })
             }
         }