--- ray/src/common/calprnt.c	1991/08/14 16:26:34	1.2
+++ ray/src/common/calprnt.c	2021/07/30 00:22:32	2.7
@@ -1,28 +1,50 @@
-/* Copyright (c) 1991 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char	RCSid[] = "$Id: calprnt.c,v 2.7 2021/07/30 00:22:32 greg Exp $";
 #endif
-
 /*
  *  calprint.c - routines for printing calcomp expressions.
- *
- *     1/29/87
  */
 
+#include "copyright.h"
+
 #include  <stdio.h>
+#include  <string.h>
 
+#include  "rterror.h"
 #include  "calcomp.h"
 
 
-eprint(ep, fp)			/* print a parse tree */
-register EPNODE  *ep;
-FILE  *fp;
+/* is child binary operation lower precedence than parent? */
+static int
+lower_precedent_binop(int typ, EPNODE *ekid)
 {
+    if (ekid == NULL)
+	return(0);
+    switch (typ) {
+	case '+':
+		return(0);
+	case '-':
+		return(ekid->type == '+');
+	case '*':
+		return(strchr("+-", ekid->type) != NULL);
+	case '/':
+		return(strchr("+-*", ekid->type) != NULL);
+	case '^':
+		return(strchr("+-*/^", ekid->type) != NULL);
+	}
+    return(0);			/* child not binary op */
+}
+
+void
+eprint(				/* print a parse tree */
+	EPNODE  *ep,
+	FILE  *fp
+)
+{
     static EPNODE  *curdef = NULL;
-    register EPNODE  *ep1;
+    EPNODE  *ep1 = NULL;
 
-    switch (ep->type) {
+    switch (ep==NULL ? -1 : ep->type) {
 
 	case VAR:
 	    fputs(ep->v.ln->name, fp);
@@ -34,14 +56,14 @@ FILE  *fp;
 
 	case FUNC:
 	    eprint(ep->v.kid, fp);
-	    fputs("(", fp);
+	    fputc('(', fp);
 	    ep1 = ep->v.kid->sibling;
 	    while (ep1 != NULL) {
 		eprint(ep1, fp);
 		if ((ep1 = ep1->sibling) != NULL)
 		    fputs(", ", fp);
 	    }
-	    fputs(")", fp);
+	    fputc(')', fp);
 	    break;
 
 	case ARG:
@@ -57,11 +79,6 @@ FILE  *fp;
 	    fprintf(fp, "%.9g", ep->v.num);
 	    break;
 
-	case UMINUS:
-	    fputs("-", fp);
-	    eprint(ep->v.kid, fp);
-	    break;
-
 	case CHAN:
 	    fprintf(fp, "$%d", ep->v.chan);
 	    break;
@@ -71,25 +88,46 @@ FILE  *fp;
 	    ep1 = curdef;
 	    curdef = ep;
 	    eprint(ep->v.kid, fp);
-	    putc(' ', fp);
-	    putc(ep->type, fp);
-	    putc(' ', fp);
+	    fputc(' ', fp);
+	    fputc(ep->type, fp);
+	    fputc(' ', fp);
 	    eprint(ep->v.kid->sibling, fp);
 	    curdef = ep1;
 	    break;
-	    
+
+	case UMINUS:
+	    fputc('-', fp);
+	    if (ep->v.kid != NULL && strchr("+-*/^", ep->v.kid->type)) {
+		fputc('(', fp);
+		eprint(ep->v.kid, fp);
+		fputc(')', fp);
+	    } else
+		eprint(ep->v.kid, fp);
+	    break;
+
 	case '+':
 	case '-':
 	case '*':
 	case '/':
 	case '^':
-	    fputs("(", fp);
-	    eprint(ep->v.kid, fp);
-	    putc(' ', fp);
-	    putc(ep->type, fp);
-	    putc(' ', fp);
-	    eprint(ep->v.kid->sibling, fp);
-	    fputs(")", fp);
+	    if (lower_precedent_binop(ep->type, ep->v.kid)) {
+		fputc('(', fp);
+		eprint(ep->v.kid, fp);
+		fputc(')', fp);
+	    } else
+		eprint(ep->v.kid, fp);
+	    if (ep->type != '^') {
+		fputc(' ', fp);
+		fputc(ep->type, fp);
+		fputc(' ', fp);
+	    } else
+		fputc(ep->type, fp);
+	    if (lower_precedent_binop(ep->type, ep->v.kid->sibling)) {
+		fputc('(', fp);
+		eprint(ep->v.kid->sibling, fp);
+		fputc(')', fp);
+	    } else
+		eprint(ep->v.kid->sibling, fp);
 	    break;
 
 	default:
@@ -97,15 +135,16 @@ FILE  *fp;
 	    quit(1);
 
     }
-
 }
 
 
-dprint(name, fp)		/* print a definition (all if no name) */
-char  *name;
-FILE  *fp;
+void
+dprint(			/* print a definition (all if no name) */
+	char  *name,
+	FILE  *fp
+)
 {
-    register EPNODE  *ep;
+    EPNODE  *ep;
     
     if (name == NULL)
 	for (ep = dfirst(); ep != NULL; ep = dnext()) {