From 9e2087d37770e4201db1975a051d3287b93b6bc3 Mon Sep 17 00:00:00 2001
From: Otto Moerbeek <otto@cvs.openbsd.org>
Date: Sun, 19 Oct 2003 19:21:49 +0000
Subject: Allow the expressions in for (E ; E ; E ) to be empty.

---
 usr.bin/bc/bc.1 |  8 +++++---
 usr.bin/bc/bc.y | 26 +++++++++++++++++++++-----
 2 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/usr.bin/bc/bc.1 b/usr.bin/bc/bc.1
index d6734a810fc..26ed11be713 100644
--- a/usr.bin/bc/bc.1
+++ b/usr.bin/bc/bc.1
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: bc.1,v 1.6 2003/10/18 19:57:10 otto Exp $
+.\"	$OpenBSD: bc.1,v 1.7 2003/10/19 19:21:48 otto Exp $
 .\"
 .\" Copyright (C) Caldera International Inc.  2001-2002.
 .\" All rights reserved.
@@ -125,6 +125,10 @@ quit
 a string of characters, enclosed in double quotes
 .Ed
 .Pp
+The E's in a for statement may all three be empty.
+This is a non-portable extension.
+The continue statement also is a non-portable extension.
+.Pp
 Function definitions
 .Bd -unfilled -offset indent -compact
 define L ( L ,..., L ) {
@@ -232,8 +236,6 @@ or
 .Sq \&!
 operators.
 .Pp
-.Ql For
-statements must have all three E's.
 .Pp
 .Ql Quit
 is interpreted when read, not when executed.
diff --git a/usr.bin/bc/bc.y b/usr.bin/bc/bc.y
index c97fbeb803a..e0f876f8a00 100644
--- a/usr.bin/bc/bc.y
+++ b/usr.bin/bc/bc.y
@@ -1,5 +1,5 @@
 %{
-/*	$OpenBSD: bc.y,v 1.12 2003/10/18 20:35:36 otto Exp $	*/
+/*	$OpenBSD: bc.y,v 1.13 2003/10/19 19:21:48 otto Exp $	*/
 
 /*
  * Copyright (c) 2003, Otto Moerbeek <otto@drijf.net>
@@ -31,7 +31,7 @@
  */
 
 #ifndef lint
-static const char rcsid[] = "$OpenBSD: bc.y,v 1.12 2003/10/18 20:35:36 otto Exp $";
+static const char rcsid[] = "$OpenBSD: bc.y,v 1.13 2003/10/19 19:21:48 otto Exp $";
 #endif /* not lint */
 
 #include <ctype.h>
@@ -138,6 +138,8 @@ extern char *__progname;
 %type <node>	function_header
 %type <node>	input_item
 %type <node>	opt_argument_list
+%type <node>	opt_expression
+%type <node>	opt_relational_expression
 %type <node>	opt_statement
 %type <node>	relational_expression
 %type <node>	return_expression
@@ -278,9 +280,9 @@ statement	: expression
 				}
 				$$ = $3;
 			}
-		| FOR LPAR alloc_macro expression SEMICOLON
-		     relational_expression SEMICOLON
-		     expression RPAR opt_statement pop_nesting
+		| FOR LPAR alloc_macro opt_expression SEMICOLON
+		     opt_relational_expression SEMICOLON
+		     opt_expression RPAR opt_statement pop_nesting
 			{
 				ssize_t n;
 
@@ -443,6 +445,13 @@ argument_list	: expression
 			}
 		;
 
+opt_relational_expression
+		: /* empty */
+			{
+				$$ = cs(" 0 0=");
+			}
+		| relational_expression
+		;
 
 relational_expression
 		: expression
@@ -490,6 +499,13 @@ return_expression
 		;
 
 
+opt_expression : /* empty */
+			{
+				$$ = cs(" 0");
+			}
+		| expression
+		;
+
 expression	: named_expression
 			{
 				$$ = node($1.load, END_NODE);
-- 
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