Make distinction between prefix and postfix unary operators in trees.

src/tree.c

@@ -3,7 +3,7 @@
 
 int libab_tree_has_vector(libab_tree_variant variant) {
     return variant == TREE_BASE || variant == TREE_OP ||
-            variant == TREE_UNARY_OP || variant == TREE_BLOCK ||
+            variant == TREE_PREFIX_OP || variant == TREE_POSTFIX_OP || variant == TREE_BLOCK ||
             variant == TREE_IF || variant == TREE_CALL || variant == TREE_WHILE ||
             variant == TREE_DOWHILE || variant == TREE_FUN ||
             variant == TREE_RETURN || variant == TREE_RESERVED_OP;
@@ -11,7 +11,7 @@ int libab_tree_has_vector(libab_tree_variant variant) {
 
 int libab_tree_has_string(libab_tree_variant variant) {
     return variant == TREE_ID || variant == TREE_NUM ||
-            variant == TREE_OP || variant == TREE_UNARY_OP ||
+            variant == TREE_OP || variant == TREE_PREFIX_OP || variant == TREE_POSTFIX_OP ||
             variant == TREE_FUN || variant == TREE_FUN_PARAM ||
             variant == TREE_RESERVED_OP;
 }