[libstdc++] Partial implementation of DR 60.

Phil Edwards phil@jaj.com
Wed Apr 23 07:20:00 GMT 2003


On Mon, Apr 21, 2003 at 11:06:06AM -0500, Benjamin Kosnik wrote:
> 
> >DR 60 makes changes to which functions affect, or do not affect, subsequent
> >calls to gcount().  Easily implemented as below.  I'd actually noticed
> >these back when doxygenating the I/O library, but never checked them in.  (?)
> >
> >DR 60 also changes other things, not done here.
> 
> Ouch!!!! I had just changed some of this behavior when the testsuites
> got re-packaged. I was sure that I had added tests for some of this
> stuff.

You did, for putback and unget.  And the behavior was already correct
for tellg, this will just add a comment there.  It correct sync and
both forms of seekg, and adds tests.

Mark, this fixes some inconsistent behavior that we'd really like to
get right in 3.3, and is a very stable change.  It's always been broken,
I believe.


2003-04-23  Phil Edwards  <pme@gcc.gnu.org>

	* docs/html/ext/howto.html ('LWG Issues'):  Add issue 60, partial
	implementation only.
	* include/bits/istream.tcc (putback, unget, sync, tellg, seekg):
	Comment and change to comply with DR 60 and the effect on gcount().
	* include/std/std_istream.h:  Update comments.
	* testsuite/27_io/basic_istream/putback/char/1.cc (test01):  Add
	comments about reasons for tests.  Test sync() against gcount().
	* testsuite/27_io/basic_istream/seekg/char/2.cc:  New file, test
	for effect on gcount().
	* testsuite/27_io/basic_istream/tellg/char/2.cc:  New file, test
	for effect on gcount().


Index: docs/html/ext/howto.html
===================================================================
RCS file: /cvs/gcc/gcc/libstdc++-v3/docs/html/ext/howto.html,v
retrieving revision 1.27
diff -u -3 -p -r1.27 howto.html
--- docs/html/ext/howto.html	20 Apr 2003 22:18:49 -0000	1.27
+++ docs/html/ext/howto.html	23 Apr 2003 07:01:19 -0000
@@ -464,6 +464,13 @@
         "copying stream state" was deemed too complicated.
     </dd>
 
+    <dt><a href="lwg-defects.html#60">60</a>:
+        <em>What is a formatted input function?</em>
+    </dt>
+    <dd>This DR made many widespread changes to <code>basic_istream</code>,
+        not all of which have been implemented.
+    </dd>
+
     <dt><a href="lwg-defects.html#68">68</a>:
         <em>Extractors for char* should store null at end</em>
     </dt>
Index: include/bits/istream.tcc
===================================================================
RCS file: /cvs/gcc/gcc/libstdc++-v3/include/bits/istream.tcc,v
retrieving revision 1.43
diff -u -3 -p -r1.43 istream.tcc
--- include/bits/istream.tcc	18 Apr 2003 03:46:43 -0000	1.43
+++ include/bits/istream.tcc	23 Apr 2003 07:01:19 -0000
@@ -841,7 +841,10 @@ namespace std 
     basic_istream<_CharT, _Traits>::
     putback(char_type __c)
     {
+#ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS
+// 60. What is a formatted input function?
       _M_gcount = 0;
+#endif
       sentry __cerb(*this, true);
       if (__cerb) 
 	{
@@ -872,7 +875,10 @@ namespace std 
     basic_istream<_CharT, _Traits>::
     unget(void)
     {
+#ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS
+// 60. What is a formatted input function?
       _M_gcount = 0;
+#endif
       sentry __cerb(*this, true);
       if (__cerb) 
 	{
@@ -903,8 +909,8 @@ namespace std 
     basic_istream<_CharT, _Traits>::
     sync(void)
     {
+      // DR60.  Do not change _M_gcount.
       int __ret = -1;
-      _M_gcount = 0;
       sentry __cerb(*this, true);
       if (__cerb) 
 	{
@@ -948,7 +954,7 @@ namespace std 
     basic_istream<_CharT, _Traits>::
     seekg(pos_type __pos)
     {
-      _M_gcount = 0;
+      // DR60.  Do not change _M_gcount.
       if (!this->fail())
 	{
 #ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS
@@ -968,7 +974,7 @@ namespace std 
     basic_istream<_CharT, _Traits>::
     seekg(off_type __off, ios_base::seekdir __dir)
     {
-      _M_gcount = 0;
+      // DR60.  Do not change _M_gcount.
       if (!this->fail())
 	{
 #ifdef _GLIBCPP_RESOLVE_LIB_DEFECTS
Index: include/std/std_istream.h
===================================================================
RCS file: /cvs/gcc/gcc/libstdc++-v3/include/std/std_istream.h,v
retrieving revision 1.8
diff -u -3 -p -r1.8 std_istream.h
--- include/std/std_istream.h	28 Mar 2003 19:45:44 -0000	1.8
+++ include/std/std_istream.h	23 Apr 2003 07:01:19 -0000
@@ -476,10 +476,6 @@ namespace std
        *
        *  @note  Since no characters are extracted, the next call to
        *         @c gcount() will return 0, as required by DR 60.
-       *
-       *  @if maint
-       *  FIXME We don't comply with DR 60 here, _M_gcount is untouched.
-       *  @endif
       */
       __istream_type& 
       putback(char_type __c);
@@ -513,9 +509,6 @@ namespace std
        *  @note  This function does not count the number of characters
        *         extracted, if any, and therefore does not affect the next
        *         call to @c gcount().
-       *  @if maint
-       *  FIXME We don't comply with DR 60 here, _M_gcount is zeroed.
-       *  @endif
       */
       int 
       sync();
@@ -545,9 +538,6 @@ namespace std
        *  @note  This function does not count the number of characters
        *         extracted, if any, and therefore does not affect the next
        *         call to @c gcount().
-       *  @if maint
-       *  FIXME We don't comply with DR 60 here, _M_gcount is zeroed.
-       *  @endif
       */
       __istream_type& 
       seekg(pos_type);
@@ -564,9 +554,6 @@ namespace std
        *  @note  This function does not count the number of characters
        *         extracted, if any, and therefore does not affect the next
        *         call to @c gcount().
-       *  @if maint
-       *  FIXME We don't comply with DR 60 here, _M_gcount is zeroed.
-       *  @endif
       */
       __istream_type& 
       seekg(off_type, ios_base::seekdir);
Index: testsuite/27_io/basic_istream/putback/char/1.cc
===================================================================
RCS file: /cvs/gcc/gcc/libstdc++-v3/testsuite/27_io/basic_istream/putback/char/1.cc,v
retrieving revision 1.1
diff -u -3 -p -r1.1 1.cc
--- testsuite/27_io/basic_istream/putback/char/1.cc	10 Apr 2003 07:15:31 -0000	1.1
+++ testsuite/27_io/basic_istream/putback/char/1.cc	23 Apr 2003 07:01:20 -0000
@@ -39,8 +39,9 @@ test01()
 
   std::stringbuf isbuf_03(str_02, std::ios_base::in);
   std::stringbuf isbuf_04(str_02, std::ios_base::in);
+  std::stringbuf isbuf_05(str_02, std::ios_base::in);
 
-  std::istream is_00(NULL);
+  std::istream is_00(&isbuf_05);
   std::istream is_03(&isbuf_03);
   std::istream is_04(&isbuf_04);
   std::ios_base::iostate state1, state2, statefail, stateeof;
@@ -54,7 +55,7 @@ test01()
   is_04.clear();
   state1 = is_04.rdstate();
   is_04.putback('|');
-  VERIFY( is_04.gcount() == 0 );
+  VERIFY( is_04.gcount() == 0 );  // DR 60
   state2 = is_04.rdstate();
   VERIFY( state1 == state2 );
   VERIFY( is_04.peek() == '|' );
@@ -63,13 +64,17 @@ test01()
   is_04.clear();
   state1 = is_04.rdstate();
   is_04.unget();
-  VERIFY( is_04.gcount() == 0 );
+  VERIFY( is_04.gcount() == 0 );  // DR 60
   state2 = is_04.rdstate();
   VERIFY( state1 == state2 );
   VERIFY( is_04.peek() == 'r' );
   
   // int sync()
+  is_00.ignore(10);
+  int count1 = is_00.gcount();
   int i = is_00.sync();
+  int count2 = is_00.gcount();
+  VERIFY (count1 == count2 );     // DR 60
 }
 
 int 
Index: testsuite/27_io/basic_istream/seekg/char/2.cc
===================================================================
RCS file: testsuite/27_io/basic_istream/seekg/char/2.cc
diff -N testsuite/27_io/basic_istream/seekg/char/2.cc
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/27_io/basic_istream/seekg/char/2.cc	23 Apr 2003 07:01:20 -0000
@@ -0,0 +1,48 @@
+// 2003-04-22 pme
+
+// Copyright (C) 2003 Free Software Foundation
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 2, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING.  If not, write to the Free
+// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+// USA.
+
+// 27.6.1.3 unformatted input functions
+// DR 60 -- seekg does not effect calls to gcount
+
+#include <istream>
+#include <sstream>
+#include <testsuite_hooks.h>
+
+void test01()
+{
+  using namespace std;
+  bool test = true;
+
+  istringstream ist("the lamb lies down on broadway");
+  ios::pos_type pos = ist.tellg();
+  ist.ignore(4);
+  int count1 = ist.gcount();
+  ist.seekg(pos);
+  int count2 = ist.gcount();
+  ist.seekg(pos, ios::beg);
+  count2 = ist.gcount();
+  VERIFY( count1 == count2 );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}
Index: testsuite/27_io/basic_istream/tellg/char/2.cc
===================================================================
RCS file: testsuite/27_io/basic_istream/tellg/char/2.cc
diff -N testsuite/27_io/basic_istream/tellg/char/2.cc
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/27_io/basic_istream/tellg/char/2.cc	23 Apr 2003 07:01:20 -0000
@@ -0,0 +1,45 @@
+// 2003-04-22 pme
+
+// Copyright (C) 2003 Free Software Foundation
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 2, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING.  If not, write to the Free
+// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+// USA.
+
+// 27.6.1.3 unformatted input functions
+// DR 60 -- tellg does not effect calls to gcount
+
+#include <istream>
+#include <sstream>
+#include <testsuite_hooks.h>
+
+void test01()
+{
+  using namespace std;
+  bool test = true;
+
+  istringstream ist("three sides live");
+  ist.ignore(4);
+  int count1 = ist.gcount();
+  ist.tellg();
+  int count2 = ist.gcount();
+  VERIFY( count1 == count2 );
+}
+
+int main()
+{
+  test01();
+  return 0;
+}



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