From 80888fdb8d67e3e974fc9368aae0e581fdae0e71 Mon Sep 17 00:00:00 2001
From: servostar <sven.vogel123@web.de>
Date: Fri, 10 May 2024 13:49:04 +0200
Subject: [PATCH] added function for removing and detaching a node

---
 src/ast/ast.c | 35 +++++++++++++++++++++++++++++++++++
 src/ast/ast.h | 20 ++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/src/ast/ast.c b/src/ast/ast.c
index 7bae47b..ca2442c 100644
--- a/src/ast/ast.c
+++ b/src/ast/ast.c
@@ -134,6 +134,33 @@ struct AST_Node_t *AST_get_node(struct AST_Node_t *owner, size_t idx) {
   return child;
 }
 
+struct AST_Node_t* AST_remove_child(struct AST_Node_t* owner, const size_t idx) {
+
+  struct AST_Node_t* child = owner->children[idx];
+
+  child->parent = NULL;
+
+  owner->child_count--;
+
+  // shift back every following element by one
+  for (size_t i = idx; i < owner->child_count; i++) {
+    owner->children[i] = owner->children[i + 1];
+  }
+
+  return child;
+}
+
+struct AST_Node_t* AST_detach_child(struct AST_Node_t* owner, const struct AST_Node_t* child) {
+  for (size_t i = 0; i < owner->child_count; i++) {
+    if (owner->children[i] == child) {
+      return AST_remove_child(owner, i);
+    }
+  }
+
+  PANIC("Child to detach not a child of parent");
+  return NULL;
+}
+
 void AST_delete_node(struct AST_Node_t *node) {
   DEBUG("Deleting AST node: %p", node);
 
@@ -145,9 +172,17 @@ void AST_delete_node(struct AST_Node_t *node) {
     return;
   }
 
+  if (node->parent != NULL) {
+    AST_detach_child(node->parent, node);
+  }
+
   for (size_t i = 0; i < node->child_count; i++) {
+    // prevent detach of children node
+    node->children[i]->parent = NULL;
     AST_delete_node(node->children[i]);
   }
+
+  free(node);
 }
 
 static void __AST_visit_nodes_recurse2(struct AST_Node_t *root,
diff --git a/src/ast/ast.h b/src/ast/ast.h
index 767388b..40c9af2 100644
--- a/src/ast/ast.h
+++ b/src/ast/ast.h
@@ -130,6 +130,26 @@ void AST_delete_node(struct AST_Node_t * node);
  */
 void AST_push_node(struct AST_Node_t *owner, struct AST_Node_t *child);
 
+/**
+ * @brief Remove the specified child from the owner.
+ * @attention The parent of the removed node is set to NULL.
+ *            The returned pointer is still valid. It must be freed at some pointer later.
+ * @param owner Node to remove the child from
+ * @param idx the index of the child to remove
+ * @return a pointer to the child which was removed
+ */
+struct AST_Node_t* AST_remove_child(struct AST_Node_t* owner, size_t idx);
+
+/**
+ * @brief Detach a child from its parent. This involves removing the child from its parent
+ *        and marking the parent of the child as NULL.
+ * @attention The returned pointer is still valid. It must be freed at some pointer later.
+ * @param owner the owner to remove the child from
+ * @param child the child to detach
+ * @return a pointer to child detached
+ */
+struct AST_Node_t* AST_detach_child(struct AST_Node_t* owner, const struct AST_Node_t* child);
+
 /**
  * @brief Return a pointer to the n-th child of a node
  * @attention Pointer to childen nodes will never change.