87 #define __TREE_DFS_PUSH(scratch, var) \  argument
89 	 *(++((scratch)->sp)) = (var))
93 #define TREE_DFS_FOREACH(var, root, scratch, field) \  argument
95 		(var) = (root); (var); \
96 		(var) = (var)->field.tn_first \
97 		? ((((var)->field.tn_younger && (var) != (root)) \
98 			? __TREE_DFS_PUSH(scratch, (var)->field.tn_younger) : 0), \
99 		   (var)->field.tn_first) \
100 		: ((var)->field.tn_younger && (var) != (root)) \
101 			? (var)->field.tn_younger : __TREE_DFS_POP(scratch))
103 #define TREE_DFS_FOREACH_SELECTIVE(var, root, scratch, field, sel) \  argument
105 		(var) = (root); (sel = true, var); \
106 		(var) = ((sel) && (var)->field.tn_first) \
107 		? ((((var)->field.tn_younger && (var) != (root)) \
108 			? __TREE_DFS_PUSH(scratch, (var)->field.tn_younger) : 0), \
109 		   (var)->field.tn_first) \
110 		: ((var)->field.tn_younger && (var) != (root)) \
111 			? (var)->field.tn_younger : __TREE_DFS_POP(scratch))
113 #define __TREE_BFS_ENQUEUE(scratch, var) \  argument
114 	(*(((scratch)->tail)++) = (var))
118 #define TREE_BFS_FOREACH(var, root, scratch, field) \  argument
120 		(var) = (root); (var); \
121 		(var) = (var)->field.tn_first \
122 		? (var)->field.tn_younger \
124 			  (__TREE_BFS_ENQUEUE(scratch, (var)->field.tn_first), \
125 			   (var)->field.tn_younger) \
128 				  (__TREE_BFS_ENQUEUE(scratch, (var)->field.tn_first), \
131 				  (var)->field.tn_first \
132 		: (var)->field.tn_younger \
134 			  (var)->field.tn_younger \
140 #define TREE_BFS_FOREACH_SELECTIVE(var, root, scratch, field, sel) \  argument
142 		(var) = (root); (sel = true, var); \
143 		(var) = ((sel) && (var)->field.tn_first) \
144 		? (var)->field.tn_younger \
146 			  (__TREE_BFS_ENQUEUE(scratch, (var)->field.tn_first), \
147 			   (var)->field.tn_younger) \
150 				  (__TREE_BFS_ENQUEUE(scratch, (var)->field.tn_first), \
153 				  (var)->field.tn_first \
154 		: (var)->field.tn_younger \
156 			  (var)->field.tn_younger \