Implemented the json stringify and parse filters.

js/test_cases/filters/README.md

@@ -0,0 +1,8 @@
+HTML Escaping
+-------------
+
+Dust automatically applies the `|h` filter to html escape unless `|s` is applied to disable automatic html escaping. It seems that if you manually specify `|h` and `|s` in the same filter, then it still html escapes, so my theory on the logic is:
+
+Iterate over all filters  
+If `|s` or `|h` is not present append `|h`, otherwise, leave filters as-in  
+During render, `|s` does nothing, so we can just remove it on the dust side to prevent confusion.  

src/bin.rs

@@ -93,12 +93,30 @@ fn apply_filter(
     filter: &Filter,
 ) -> Result<serde_json::Value, RenderError> {
     match (json_value, filter) {
+        // Html escape filter
         (serde_json::Value::String(string), Filter::HtmlEncode) => {
             Ok(serde_json::Value::String(html_escape(string)))
         }
         (_, Filter::HtmlEncode) => Ok(serde_json::Value::String(html_escape(
             &json_value.render(&Vec::new())?,
         ))),
+        // Disable html escape filter
+        (_, Filter::DisableHtmlEncode) => panic!("The |s filter is automatically removed by the renderer since it is a no-op during rendering."),
+        // Parse JSON filter
+        (serde_json::Value::String(string), Filter::JsonParse) => {
+            serde_json::from_str(&string).or(Err(RenderError::InvalidJson(string.to_owned())))
+        }
+        (_, Filter::JsonParse) => {
+            let rendered_value = json_value.render(&Vec::new())?;
+            serde_json::from_str(&rendered_value).or(Err(RenderError::InvalidJson(rendered_value)))
+        }
+        // Json Stringify filter
+        (_, Filter::JsonStringify) => {
+            Ok(serde_json::Value::String(json_value.to_string()))
+        }
+        // TODO: javascript string escape
+        // TODO: EncodeUri
+        // TODO: EncodeUriComponent
         _ => panic!("Unimplemented"),
     }
 }
@@ -121,9 +139,9 @@ impl ContextElement for serde_json::Value {}
 impl Renderable for serde_json::Value {
     fn render(&self, _filters: &Vec<Filter>) -> Result<String, RenderError> {
         let after_apply = if _filters.is_empty() {
-            Some(apply_filters(self, _filters)?)
-        } else {
             None
+        } else {
+            Some(apply_filters(self, _filters)?)
         };
 
         match after_apply.as_ref().unwrap_or(self) {

src/renderer/errors.rs

@@ -8,6 +8,7 @@ use std::fmt;
 pub enum RenderError {
     Generic(String),
     TemplateNotFound(String),
+    InvalidJson(String),
 }
 
 #[derive(PartialEq)]
@@ -27,6 +28,11 @@ impl fmt::Display for RenderError {
             RenderError::TemplateNotFound(name) => {
                 write!(f, "No template named {} in context", name)
             }
+            RenderError::InvalidJson(invalid_json) => write!(
+                f,
+                "Attempted to parse the following invalid JSON: {}",
+                invalid_json
+            ),
         }
     }
 }
@@ -38,6 +44,11 @@ impl fmt::Debug for RenderError {
             RenderError::TemplateNotFound(name) => {
                 write!(f, "No template named {} in context", name)
             }
+            RenderError::InvalidJson(invalid_json) => write!(
+                f,
+                "Attempted to parse the following invalid JSON: {}",
+                invalid_json
+            ),
         }
     }
 }