add breadth-first search function to find client nodes in a tree

util.c

@@ -50,9 +50,7 @@ void wm_nodearray_push(NodeArray *arr, TreeNode node)
 bool wm_nodearray_pop(NodeArray *arr, TreeNode *ret)
 {
     assert(arr);
-
+    assert(ret);
-    if (!ret || !arr)
-        return false;
     
     if (arr->size == 0)
         return false;
@@ -62,6 +60,21 @@ bool wm_nodearray_pop(NodeArray *arr, TreeNode *ret)
     return true;
 }
 
+bool wm_nodearray_pop_front(NodeArray *arr, TreeNode *ret)
+{
+    assert(arr);
+    assert(ret);
+
+    if (arr->size == 0)
+        return false;
+
+    *ret = arr->nodes[0];
+    arr->size--;
+    memcpy(arr->nodes, arr->nodes+1, arr->size * sizeof(TreeNode));
+
+    return true;
+}
+
 bool wm_nodearray_remove(NodeArray *arr, size_t index)
 {
     assert(arr);
@@ -91,6 +104,55 @@ void wm_nodearray_free(NodeArray *arr)
     free(arr->nodes);
 }
 
+// breadth-first search for finding client nodes in tree
+ClientArray wm_nodearray_find_clients(TreeNode *root)
+{
+    assert(root);
+
+    /* storing visited nodes in an array and searching is
+       not optimal, but this is not a performance-critical function. */
+    NodeArray visited = wm_nodearray_new();
+    wm_nodearray_push(&visited, *root);
+
+    NodeArray queue = wm_nodearray_new();
+    ClientArray clients = wm_clientarray_new();
+
+    wm_nodearray_push(&queue, *root);
+
+    while (queue.size > 0) {
+        TreeNode node;
+
+        if (!wm_nodearray_pop_front(&queue, &node))
+            goto ret;
+
+        if (node.type == NODE_CLIENT)
+            wm_clientarray_push(&clients, *node.client);
+
+        for (int i = 0; i < node.children.size; i++) {
+            TreeNode child_node = node.children.nodes[i];
+            bool _visited = false;
+
+            for (int j = 0; j < visited.size; j++) {
+                // this comparison may not work
+                if (visited.nodes[j].children.nodes == child_node.children.nodes) {
+                    _visited = true;
+                    break;
+                }
+            }
+
+            if (!_visited) {
+                wm_nodearray_push(&visited, child_node);
+                wm_nodearray_push(&queue, child_node);
+            }
+        }
+    }
+
+ret:
+    wm_nodearray_free(&visited);
+    wm_nodearray_free(&queue);
+    return clients;
+}
+
 ClientArray wm_clientarray_new()
 {
     ClientArray arr;

util.h

@@ -54,8 +54,10 @@ void wm_treenode_init(TreeNode *node, NodeType type, TreeNode *parent);
 NodeArray wm_nodearray_new();
 void wm_nodearray_push(NodeArray *arr, TreeNode node);
 bool wm_nodearray_pop(NodeArray *arr, TreeNode *ret);
+bool wm_nodearray_pop_front(NodeArray *arr, TreeNode *ret);
 bool wm_nodearray_remove(NodeArray *arr, size_t index);
 void wm_nodearray_free(NodeArray *arr);
+ClientArray wm_nodearray_find_clients(TreeNode *root);
 
 ClientArray wm_clientarray_new();
 void wm_clientarray_push(ClientArray *arr, Client node);