From 65445cc8fcbb456e85f4adf9f7fb62516533858a Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Sun, 31 May 2020 16:16:21 -0400
Subject: [PATCH] Finished implementing the new tree walking.

---
 src/renderer/tree_walking.rs | 65 ++++++++++++++++++++++++++++++------
 1 file changed, 54 insertions(+), 11 deletions(-)

diff --git a/src/renderer/tree_walking.rs b/src/renderer/tree_walking.rs
index 65f6cbd..4cb2c41 100644
--- a/src/renderer/tree_walking.rs
+++ b/src/renderer/tree_walking.rs
@@ -10,22 +10,44 @@ enum WalkResult<'a> {
     FullyWalked(&'a dyn IntoContextElement),
 }
 
-fn walk_path_from_single_level<'a, P, C>(context: &'a C, path: &[P]) -> WalkResult<'a>
+fn walk_path_from_single_level<'a, P>(
+    context: &'a dyn IntoContextElement,
+    path: &[P],
+) -> WalkResult<'a>
 where
     P: Borrow<str>,
-    C: Borrow<dyn IntoContextElement + 'a>,
 {
-    todo!()
+    if path.is_empty() {
+        return WalkResult::FullyWalked(context);
+    }
+
+    let mut walk_failure = WalkResult::NoWalk;
+    let mut output = context;
+    for elem in path.iter() {
+        match output.walk(elem.borrow()) {
+            Err(WalkError::CantWalk { .. }) => {
+                return walk_failure;
+            }
+            Ok(new_val) => {
+                walk_failure = WalkResult::PartialWalk;
+                output = new_val;
+            }
+        }
+    }
+
+    WalkResult::FullyWalked(output)
 }
 
 fn get_first_non_pseudo_element<'a, B>(
     breadcrumbs: &'a BreadcrumbTreeNode<B>,
-) -> Option<&'a dyn IntoContextElement>
+) -> Option<&'a dyn BreadcrumbTree>
 where
     B: IntoContextElement,
 {
-    todo!()
-    // breadcrumbs.iter().filter(|b| b.is_pseudo_element()).next()
+    breadcrumbs
+        .breadcrumb_iter()
+        .filter(|b| b.get_ice().is_pseudo_element())
+        .next()
 }
 
 pub fn walk_path<'a, B, P>(
@@ -41,12 +63,33 @@ where
         (Some(breadcrumbs), None) => return Ok(breadcrumbs.get_ice()),
         (Some(breadcrumbs), Some(path_first)) if path_first.borrow() == "." => {
             let first_non_pseudo_element = get_first_non_pseudo_element(breadcrumbs);
-            // return match first_non_pseudo_element {
-            //     None => Err(WalkError::CantWalk),
-            //     Some(current_context)
-            // }
+            return match first_non_pseudo_element {
+                None => Err(WalkError::CantWalk),
+                Some(current_context) => {
+                    match walk_path_from_single_level(current_context.get_ice(), &path[1..]) {
+                        // If no walking was done at all or we partially walked
+                        // then stop trying to find anything because '.' restricts
+                        // us to the current scope
+                        WalkResult::NoWalk | WalkResult::PartialWalk => Err(WalkError::CantWalk),
+                        WalkResult::FullyWalked(new_context) => Ok(new_context),
+                    }
+                }
+            };
+        }
+        (Some(breadcrumbs), Some(path_first)) => {
+            for context in breadcrumbs.ice_iter() {
+                match walk_path_from_single_level(context, path) {
+                    // If no walking was done at all, keep looping
+                    WalkResult::NoWalk => {}
+                    // If we partially walked then stop trying to find
+                    // anything
+                    WalkResult::PartialWalk => {
+                        return Err(WalkError::CantWalk);
+                    }
+                    WalkResult::FullyWalked(new_context) => return Ok(new_context),
+                }
+            }
         }
-        (Some(breadcrumbs), Some(path_first)) => (),
     }
 
     Err(WalkError::CantWalk)