Refactor XML visitor to visit on entry/exit (#26)

lib/src/converter/mod.rs

@@ -102,7 +102,7 @@ impl<'a, 'input: 'a> ConversionVisitor<'a, PreprocessTurtle> {
 }
 
 impl<'a, T: Turtle> visit::XmlVisitor for ConversionVisitor<'a, T> {
-    fn visit(&mut self, node: Node) {
+    fn visit_enter(&mut self, node: Node) {
         if node.tag_name().name() == CLIP_PATH_TAG_NAME {
             warn!("Clip paths are not supported: {:?}", node);
         }
@@ -217,26 +217,12 @@ impl<'a, T: Turtle> visit::XmlVisitor for ConversionVisitor<'a, T> {
             }
         }
 
-        if node.first_element_child().is_some() {
-            self.name_stack.push(node_name(&node));
-        } else {
-            // Pop transform since this is the only element that has it
-            self.terrarium.pop_transform();
-
-            let mut parent = Some(node);
-            while let Some(p) = parent {
-                if p.next_sibling_element().is_some()
-                    || p.is_root()
-                    || p.tag_name().name() == SVG_TAG_NAME
-                {
-                    break;
-                }
-                // Pop the parent transform since this is the last child
-                self.terrarium.pop_transform();
-                self.name_stack.pop();
-                parent = p.parent_element();
-            }
-        }
+        self.name_stack.push(node_name(&node));
+    }
+
+    fn visit_exit(&mut self, _node: Node) {
+        self.terrarium.pop_transform();
+        self.name_stack.pop();
     }
 }
 

lib/src/converter/visit.rs

@@ -1,22 +1,29 @@
 use roxmltree::{Document, Node};
 
 pub trait XmlVisitor {
-    fn visit(&mut self, node: Node);
+    fn visit_enter(&mut self, node: Node);
+    fn visit_exit(&mut self, node: Node);
 }
 
-pub fn is_valid_node(node: &Node) -> bool {
-    return node.is_element() && !node.attribute("style").unwrap_or_default().contains("display:none");
+pub fn is_valid_node(node: Node) -> bool {
+    return node.is_element()
+        && !node
+            .attribute("style")
+            .unwrap_or_default()
+            .contains("display:none");
 }
 
 pub fn depth_first_visit(doc: &Document, visitor: &mut impl XmlVisitor) {
-    let mut stack = doc
-        .root()
-        .children()
-        .rev()
-        .filter(|x| is_valid_node(x))
-        .collect::<Vec<_>>();
-    while let Some(node) = stack.pop() {
-        visitor.visit(node);
-        stack.extend(node.children().rev().filter(|x| is_valid_node(x)));
+    fn visit_node(node: Node, visitor: &mut impl XmlVisitor) {
+        if !is_valid_node(node) {
+            return;
+        }
+        visitor.visit_enter(node);
+        node.children().for_each(|child| visit_node(child, visitor));
+        visitor.visit_exit(node);
     }
+
+    doc.root()
+        .children()
+        .for_each(|child| visit_node(child, visitor));
 }