1 /*********************************************************************** 2 * * 3 * This software is part of the ast package * 4 * Copyright (c) 1985-2010 AT&T Intellectual Property * 5 * and is licensed under the * 6 * Common Public License, Version 1.0 * 7 * by AT&T Intellectual Property * 8 * * 9 * A copy of the License is available at * 10 * http://www.opensource.org/licenses/cpl1.0.txt * 11 * (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) * 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* 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