Implemented syntree.

src/syntree.rs

@@ -14,15 +14,22 @@ pub struct Syntree<T> {
 // Hint: Start with seek_node_mut
 impl<'a, T> Syntree<T> {
     pub fn new(value: T, id: ID) -> Syntree<T> {
-        todo!()
+        let children = Vec::new();
+        Syntree{id, value, children}
     }
-
-    pub fn push_node(&mut self, parent_id: ID, new_node: Syntree<T>) -> Result<(), String> {
-        todo!()
+    
+    pub fn push_node(&mut self, parent_id: ID, new_node: Syntree<T>) -> Result<(), &str> {
+        let current_node = self.seek_node_mut(&parent_id);
+        if current_node.is_none() {
+            return Result::Err("The listed node does not exist.");
+        }
+        let current_node = current_node.unwrap();
+        current_node.children.push(new_node);
+        return Result::Ok(());
     }
 
-    pub fn prepend_node(&mut self, parent_id: ID, new_node: Syntree<T>) -> Result<(), String> {
-        todo!()
+    pub fn prepend_node(&mut self, parent_id: ID, new_node: Syntree<T>) -> Result<(), &str> {
+        self.insert_node(parent_id, 0, new_node)
     }
 
     pub fn insert_node(
@@ -30,8 +37,14 @@ impl<'a, T> Syntree<T> {
         parent_id: ID,
         index: usize,
         new_node: Syntree<T>,
-    ) -> Result<(), String> {
-        todo!()
+    ) -> Result<(), &str> {
+        let current_node = self.seek_node_mut(&parent_id);
+        if current_node.is_none() {
+            return Result::Err("The listed node does not exist.");
+        }
+        let current_node = current_node.unwrap();
+        current_node.children.insert(index, new_node);
+        return Result::Ok(());
     }
 
     // Anmerkung: `'a` Is ein Lebenszeit angabe für die Referenzen
@@ -50,7 +63,16 @@ impl<'a, T> Syntree<T> {
     }
 
     pub fn seek_node_mut(&'a mut self, id: &ID) -> Option<&'a mut Syntree<T>> {
-        todo!()
+        if self.id == *id {
+            Some(self)
+        } else {
+            for child in &mut self.children {
+                if let Some(result) = child.seek_node_mut(id) {
+                    return Some(result);
+                }
+            }
+            None
+        }
     }
 }