--- ray/src/common/caldefn.c	1992/11/21 21:42:42	2.5
+++ ray/src/common/caldefn.c	1997/02/12 17:38:03	2.11
@@ -1,4 +1,4 @@
-/* Copyright (c) 1992 Regents of the University of California */
+/* Copyright (c) 1997 Regents of the University of California */
 
 #ifndef lint
 static char SCCSid[] = "$SunId$ LBL";
@@ -42,10 +42,12 @@ extern char  *ecalloc(), *emalloc(), *savestr(), *strc
 
 static double  dvalue();
 
-long  eclock = -1;			/* value storage timer */
+unsigned long  eclock = 0;		/* value storage timer */
 
-static char  context[MAXWORD+1];	/* current context path */
+#define  MAXCNTX	1023		/* maximum context length */
 
+static char  context[MAXCNTX+1];	/* current context path */
+
 static VARDEF  *hashtbl[NHASH];		/* definition list */
 static int  htndx;			/* index for */		
 static VARDEF  *htpos;			/* ...dfirst() and */
@@ -55,7 +57,7 @@ static EPNODE  *outchan;
 #endif
 
 #ifdef	FUNCTION
-EPNODE	*curfunc;
+EPNODE	*curfunc = NULL;
 #define	 dname(ep)	((ep)->v.kid->type == SYM ? \
 			(ep)->v.kid->v.name : \
 			(ep)->v.kid->v.kid->v.name)
@@ -189,15 +191,16 @@ register char  *ctx;
 
     if (ctx == NULL)
 	return(context);		/* just asking */
+    while (*ctx == CNTXMARK)
+	ctx++;				/* skip past marks */
     if (!*ctx) {
-	context[0] = '\0';		/* clear context */
+	context[0] = '\0';		/* empty means clear context */
 	return(context);
     }
-    cpp = context;			/* else copy it (carefully!) */
-    if (*ctx != CNTXMARK)
-	*cpp++ = CNTXMARK;		/* make sure there's a mark */
-    do {
-	if (cpp >= context+MAXWORD)
+    cpp = context;			/* start context with mark */
+    *cpp++ = CNTXMARK;
+    do {				/* carefully copy new context */
+	if (cpp >= context+MAXCNTX)
 	    break;			/* just copy what we can */
 	if (isid(*ctx))
 	    *cpp++ = *ctx++;
@@ -205,12 +208,51 @@ register char  *ctx;
 	    *cpp++ = '_'; ctx++;
 	}
     } while (*ctx);
+    while (cpp[-1] == CNTXMARK)		/* cannot end in context mark */
+	cpp--;
     *cpp = '\0';
     return(context);
 }
 
 
 char *
+pushcontext(ctx)		/* push on another context */
+char  *ctx;
+{
+    extern char  *strncpy(), *strcpy();
+    char  oldcontext[MAXCNTX+1];
+    register int  n;
+
+    strcpy(oldcontext, context);	/* save old context */
+    setcontext(ctx);			/* set new context */
+    n = strlen(context);		/* tack on old */
+    if (n+strlen(oldcontext) > MAXCNTX) {
+	strncpy(context+n, oldcontext, MAXCNTX-n);
+	context[MAXCNTX] = '\0';
+    } else
+	strcpy(context+n, oldcontext);
+    return(context);
+}
+
+
+char *
+popcontext()			/* pop off top context */
+{
+    register char  *cp1, *cp2;
+
+    if (!context[0])			/* nothing left to pop */
+	return(context);
+    cp2 = context;			/* find mark */
+    while (*++cp2 && *cp2 != CNTXMARK)
+	;
+    cp1 = context;			/* copy tail to front */
+    while (*cp1++ = *cp2++)
+	;
+    return(context);
+}
+
+
+char *
 qualname(nam, lvl)		/* get qualified name */
 register char  *nam;
 int  lvl;
@@ -259,6 +301,8 @@ toolong:
 incontext(qn)			/* is qualified name in current context? */
 register char  *qn;
 {
+    if (!context[0])			/* global context accepts all */
+	return(1);
     while (*qn && *qn != CNTXMARK)	/* find context mark */
 	qn++;
     return(!strcmp(qn, context));
@@ -287,7 +331,7 @@ int  lvl;
 				/* if context is global, clear all */
     for (i = 0; i < NHASH; i++)
 	for (vp = hashtbl[i]; vp != NULL; vp = vp->next)
-	    if (!context[0] || incontext(vp->name))
+	    if (incontext(vp->name))
 		if (lvl >= 2)
 		    dremove(vp->name);
 		else
@@ -516,7 +560,7 @@ getstatement()			/* get next statement */
 	qname = qualname(dname(ep), 0);
 #ifdef	REDEFW
 	if ((vdef = varlookup(qname)) != NULL)
-	    if (vdef->def != NULL) {
+	    if (vdef->def != NULL && epcmp(ep, vdef->def)) {
 		wputs(qname);
 		if (vdef->def->type == ':')
 		    wputs(": redefined constant expression\n");
@@ -578,8 +622,7 @@ getdefn()			/* A -> SYM = E1 */
 	    syntax("')' expected");
 	scan();
 	curfunc = ep1;
-    } else
-	curfunc = NULL;
+    }
 #endif
 
     if (nextc != '=' && nextc != ':')
@@ -598,13 +641,17 @@ getdefn()			/* A -> SYM = E1 */
 	    ep1->sibling->type != NUM) {
 	ep1 = newnode();
 	ep1->type = TICK;
-	ep1->v.tick = -1;
+	ep1->v.tick = 0;
 	addekid(ep2, ep1);
 	ep1 = newnode();
 	ep1->type = NUM;
 	addekid(ep2, ep1);
     }
 
+#ifdef  FUNCTION
+    curfunc = NULL;
+#endif
+
     return(ep2);
 }
 
@@ -659,8 +706,8 @@ EPNODE	*d;
     if (ep1->type == NUM)
 	return(ep1->v.num);			/* return if number */
     ep2 = ep1->sibling;				/* check time */
-    if (ep2->v.tick < 0 || ep2->v.tick < eclock) {
-	ep2->v.tick = d->type == ':' ? 1L<<30 : eclock;
+    if (ep2->v.tick == 0 || ep2->v.tick < eclock) {
+	ep2->v.tick = d->type == ':' ? ~0L : eclock;
 	ep2 = ep2->sibling;
 	ep2->v.num = evalue(ep1);		/* needs new value */
     } else