Imported Upstream version 93u+upstream

1 files changed, 70 insertions, 0 deletions

diff --git a/src/lib/libast/misc/optctx.c b/src/lib/libast/misc/optctx.c
new file mode 100644
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+++ b/src/lib/libast/misc/optctx.c
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+/***********************************************************************
+*                                                                      *
+*               This software is part of the ast package               *
+*          Copyright (c) 1985-2011 AT&T Intellectual Property          *
+*                      and is licensed under the                       *
+*                 Eclipse Public License, Version 1.0                  *
+*                    by AT&T Intellectual Property                     *
+*                                                                      *
+*                A copy of the License is available at                 *
+*          http://www.eclipse.org/org/documents/epl-v10.html           *
+*         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
+*                                                                      *
+*              Information and Software Systems Research               *
+*                            AT&T Research                             *
+*                           Florham Park NJ                            *
+*                                                                      *
+*                 Glenn Fowler <gsf@research.att.com>                  *
+*                  David Korn <dgk@research.att.com>                   *
+*                   Phong Vo <kpv@research.att.com>                    *
+*                                                                      *
+***********************************************************************/
+#pragma prototyped
+/*
+ * Glenn Fowler
+ * AT&T Research
+ *
+ * _opt_infop_ context control
+ *
+ * allocate new context:
+ *	new_context = optctx(0, 0);
+ * free new context:
+ *	optctx(0, new_context);
+ * switch to new_context:
+ *	old_context = optctx(new_context, 0);
+ * switch to old_context and free new_context:
+ *	optctx(old_context, new_context);
+ */
+
+#include <optlib.h>
+
+static Opt_t*	freecontext;
+
+Opt_t*
+optctx(Opt_t* p, Opt_t* o)
+{
+	if (o)
+	{
+		if (freecontext)
+			free(o);
+		else
+			freecontext = o;
+		if (!p)
+			return 0;
+	}
+	if (p)
+	{
+		o = _opt_infop_;
+		_opt_infop_ = p;
+	}
+	else
+	{
+		if (o = freecontext)
+			freecontext = 0;
+		else if (!(o = newof(0, Opt_t, 1, 0)))
+			return 0;
+		memset(o, 0, sizeof(Opt_t));
+		o->state = _opt_infop_->state;
+	}
+	return o;
+}