From e261a7b5189e893e0d5c3eac7fe269f45c87cd23 Mon Sep 17 00:00:00 2001
From: Akos Horvath <koma@koma.sh>
Date: Sun, 7 Apr 2024 13:43:43 +0200
Subject: [PATCH] simplify wm_postorder_traversal

---
 src/util.c | 64 ++++++++++--------------------------------------------
 1 file changed, 12 insertions(+), 52 deletions(-)

diff --git a/src/util.c b/src/util.c
index 6adaef1..51ca8e9 100644
--- a/src/util.c
+++ b/src/util.c
@@ -384,61 +384,21 @@ UIntArray* wm_treenode_all_lmds_index(TreeNode *node)
     return ret;
 }
 
+static void traversal(TreeNode *node, NodeArray *arr)
+{
+    if (!node) return;
+
+    for (size_t i = 0; i < node->children->size; i++)
+        traversal(node->children->nodes[i], arr);
+
+    wm_nodearray_push(arr, node);
+}
+
 NodeArray* wm_postorder_traversal(TreeNode *tree)
 {
-    assert(tree);
+    NodeArray *ret = wm_nodearray_new();
 
-    TreeNode *root = tree;
-
-    typedef struct {
-        TreeNode *node;
-        size_t index;
-    } NodeWithIndex;
-
-    int root_index = 0;
-
-    NodeArray* stack = wm_nodearray_new();
-    NodeArray* ret = wm_nodearray_new();
-
-    while (root != NULL || stack->size > 0) {
-        if (root != NULL) {
-            NodeWithIndex *n = malloc(sizeof(NodeWithIndex));
-            assert(n);
-            n->node = root;
-            n->index = root_index;
-            wm_nodearray_push(stack, (void*)n);
-            root_index = 0;
-
-            if (root->children->size >= 1)
-                root = root->children->nodes[0];
-            else root = NULL;
-
-            continue;
-        }
-
-        NodeWithIndex *nptr;
-        wm_nodearray_pop(stack, (TreeNode**)(void**)&nptr);
-        NodeWithIndex n = *nptr;
-        free(nptr);
-        wm_nodearray_push(ret, n.node);
-
-        while (stack->size > 0 && n.index == ((NodeWithIndex**)stack->nodes)
-               [stack->size-1]->node->children->size - 1) {
-            wm_nodearray_pop(stack, (TreeNode**)(void**)&nptr);
-            n = *nptr;
-            free(nptr);
-
-            wm_nodearray_push(ret, n.node);
-        }
-
-        if (stack->size > 0) {
-            root = ((NodeWithIndex**)stack->nodes)[stack->size-1]->node
-                   ->children->nodes[n.index + 1];
-            root_index = n.index + 1;
-        }
-    }
-
-    wm_nodearray_free(stack);
+    traversal(tree, ret);
 
     return ret;
 }