[binary_tree] add BST_NODE_EXTRA to define additional properties on nodes

Author: albarrentine

src/binary_tree.h

@@ -25,6 +25,9 @@ typedef struct BST_TYPED(node) {
     BST_KEY_TYPE key;
     struct BST_TYPED(node) *left;
     struct BST_TYPED(node) *right;
+#ifdef BST_NODE_EXTRA
+    BST_NODE_EXTRA
+#endif
 } BST_TYPED(node_t);
 
 #define BST_NODE_TYPE BST_TYPED(node_t)

test.c

@@ -9,6 +9,8 @@
 #define BST_NAME binary_tree
 #define BST_KEY_TYPE uint32_t
 #define BST_VALUE_TYPE char *
+#define BST_NODE_EXTRA \
+    uint8_t height;
 #include "binary_tree.h"
 #undef BST_NAME
 #undef BST_KEY_TYPE