Integrated new_breadcrumbs into exists and not exists, and partially integrated it into partials.

src/renderer/renderer.rs

@@ -250,29 +250,58 @@ impl<'a> DustRenderer<'a> {
                 }
             }
             DustTag::DTExists(container) => {
+                let new_breadcrumbs =
+                    Self::new_breadcrumbs(breadcrumbs, None, &container.explicit_context, None);
                 let val = walk_path(breadcrumbs, &container.path.keys);
                 return if val.map(|v| v.is_truthy()).unwrap_or(false) {
-                    self.render_maybe_body(&container.contents, breadcrumbs, blocks)
+                    self.render_maybe_body(
+                        &container.contents,
+                        new_breadcrumbs.as_ref().unwrap_or(breadcrumbs),
+                        blocks,
+                    )
                 } else {
-                    self.render_maybe_body(&container.else_contents, breadcrumbs, blocks)
+                    self.render_maybe_body(
+                        &container.else_contents,
+                        new_breadcrumbs.as_ref().unwrap_or(breadcrumbs),
+                        blocks,
+                    )
                 };
             }
             DustTag::DTNotExists(container) => {
+                let new_breadcrumbs =
+                    Self::new_breadcrumbs(breadcrumbs, None, &container.explicit_context, None);
                 let val = walk_path(breadcrumbs, &container.path.keys);
                 return if !val.map(|v| v.is_truthy()).unwrap_or(false) {
-                    self.render_maybe_body(&container.contents, breadcrumbs, blocks)
+                    self.render_maybe_body(
+                        &container.contents,
+                        new_breadcrumbs.as_ref().unwrap_or(breadcrumbs),
+                        blocks,
+                    )
                 } else {
-                    self.render_maybe_body(&container.else_contents, breadcrumbs, blocks)
+                    self.render_maybe_body(
+                        &container.else_contents,
+                        new_breadcrumbs.as_ref().unwrap_or(breadcrumbs),
+                        blocks,
+                    )
                 };
             }
             DustTag::DTPartial(partial) => {
                 let partial_name = self.render_partial_name(&partial.name, breadcrumbs, blocks)?;
                 if partial.params.is_empty() {
-                    let rendered_content =
-                        self.render_template(&partial_name, breadcrumbs, Some(blocks))?;
+                    let new_breadcrumbs =
+                        Self::new_breadcrumbs(breadcrumbs, None, &partial.explicit_context, None);
+                    let rendered_content = self.render_template(
+                        &partial_name,
+                        new_breadcrumbs.as_ref().unwrap_or(breadcrumbs),
+                        Some(blocks),
+                    )?;
                     return Ok(rendered_content);
                 } else {
                     let injected_context = ParametersContext::new(breadcrumbs, &partial.params);
+                    // TODO: need to add a special case where the
+                    // injected context is added 1 behind the existing
+                    // breadcrumbs when new_context_element does not
+                    // exist.
                     let mut new_breadcrumbs = breadcrumbs.clone();
                     new_breadcrumbs.insert(new_breadcrumbs.len() - 1, &injected_context);
                     let rendered_content =