2 * Copyright (c) 2016, Olivier MATZ <zer0@droids-corp.org>
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are met:
7 * * Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * * Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * * Neither the name of the University of California, Berkeley nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
16 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
17 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY
20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 #ifndef ECOLI_NODE_WEAKREF_
29 #define ECOLI_NODE_WEAKREF_
31 #include <ecoli_node.h>
33 /* A node that just behaves like its child and that does not free
34 * its child when freed. **The child has to be freed manually**.
36 * useful to create cyclic graphs of nodes:
37 * creating a loop (with clones) result in something that is not
38 * freeable, due to reference counters
44 * seq = seq(clone(op), clone(expr))
45 * expr.add(clone(seq))
46 * expr.add(clone(val))
51 * FAIL: expr cannot be freed due to cyclic refs
52 * The references are like this:
57 * $user ---> expr ---> seq ---> op
65 * seq = seq(clone(op), clone(weak))
66 * expr.add(clone(seq))
67 * expr.add(clone(val))
77 * $user ---> expr ---------------> seq ---> op
80 * The node expr can be freed.
83 /* on error, child is *not* freed */
84 struct ec_node *ec_node_weakref(const char *id, struct ec_node *child);
86 /* on error, child is *not* freed */
87 int ec_node_weakref_set(struct ec_node *node, struct ec_node *child);