1 /***********************************************************************
2 * *
3 * This software is part of the ast package *
4 * Copyright (c) 1985-2011 AT&T Intellectual Property *
5 * and is licensed under the *
6 * Eclipse Public License, Version 1.0 *
7 * by AT&T Intellectual Property *
8 * *
9 * A copy of the License is available at *
10 * http://www.eclipse.org/org/documents/epl-v10.html *
11 * (with md5 checksum b35adb5213ca9657e911e9befb180842) *
12 * *
13 * Information and Software Systems Research *
14 * AT&T Research *
15 * Florham Park NJ *
16 * *
17 * Glenn Fowler <gsf@research.att.com> *
18 * David Korn <dgk@research.att.com> *
19 * Phong Vo <kpv@research.att.com> *
20 * *
21 ***********************************************************************/
22 #pragma prototyped
23 /*
24 * Glenn Fowler
25 * AT&T Research
26 *
27 * _opt_infop_ context control
28 *
29 * allocate new context:
30 * new_context = optctx(0, 0);
31 * free new context:
32 * optctx(0, new_context);
33 * switch to new_context:
34 * old_context = optctx(new_context, 0);
35 * switch to old_context and free new_context:
36 * optctx(old_context, new_context);
37 */
38
39 #include <optlib.h>
40
41 static Opt_t* freecontext;
42
43 Opt_t*
optctx(Opt_t * p,Opt_t * o)44 optctx(Opt_t* p, Opt_t* o)
45 {
46 if (o)
47 {
48 if (freecontext)
49 free(o);
50 else
51 freecontext = o;
52 if (!p)
53 return 0;
54 }
55 if (p)
56 {
57 o = _opt_infop_;
58 _opt_infop_ = p;
59 }
60 else
61 {
62 if (o = freecontext)
63 freecontext = 0;
64 else if (!(o = newof(0, Opt_t, 1, 0)))
65 return 0;
66 memset(o, 0, sizeof(Opt_t));
67 o->state = _opt_infop_->state;
68 }
69 return o;
70 }
71