[PATCH] Support stateful encodings in basic_filebuf

[Pétur Runólfsson]

Hi,

This patch adds support for stateful encodings to basic_filebuf.

Two changes were needed to make this work:
1) Call codecvt::unshift() from close(), seekoff and seekpos iff
   _M_writing is true. Note that this is not what the standard says,
   but it has the benefit that the written file can actually be read
   again.
2) Store the current state in the return values of seekoff and seekpos,
   restore the state from the pos_type parameter in seekpos.

Both cause changes that affect stateless encodings also: 1) means that
sync must not modify _M_writing, and 2) means that pos_type::state() is
now used, so pos_type must be fpos<state_type>.

Since codecvt<wchar_t, char, mbstate_t> doesn't handle stateful
encodings, and none of the encodings supported by glibc-2.3 is simple
enough for testing anyway, I created a simple encoding to do the
testing. This is in testsuite/testsuite_character.h.

Regards,
Petur


2003-10-31  Petur Runolfsson  <peturr02@ru.is>

	PR libstdc++/12790
	* include/bits/fstream.tcc: Delete _M_last_overflowed.
	(basic_filebuf::basic_filebuf): Initialize _M_state_last.
	(basic_filebuf::open, basic_filebuf::close): Assign
	_M_state_beg to _M_state_cur and _M_state_last.
	(basic_filebuf::close): Call _M_terminate_output to handle
	unshift and flushing.
	(basic_filebuf::underflow): Assign _M_state_last, throw
	exception instead of calling abort when codecvt::max_length()
	is bad.
	(basic_filebuf::seekoff): Use _M_state_last when calling
	codecvt::length(), pass correct state to _M_seek.
	(basic_filebuf::seekpos): Pass __pos.state() to _M_seek.
	(basic_filebuf::_M_seek): Add __state_type parameter,
	set _M_state_cur correctly, store the resulting state in
	the return value and use _M_terminate output to handle
	flushing and unshift.
	(basic_filebuf::_M_terminate_output): Flush contents of
	output buffer, if any, then call codecvt::unshift as
	needed and output the result.
	(basic_filebuf::sync): Move here, don't modify _M_writing
	or _M_reading.
	
	* include/std/std_fstream.h
	(basic_filebuf::_M_state_last): Declare it.
	(basic_filebuf::_M_last_overflowed): Delete.
	(basic_filebuf::_M_seek): Add __state_type parameter.
	(basic_filebuf::sync): Declare only.
	(basic_filebuf::_M_output_unshift): Delete.
	(basic_filebuf::_M_terminate_output): Declare it.
	
	* testsuite/testsuite_character.h:
	Define character class and state class plus char_traits and
	codecvt specializations for same for testing support for
	stateful encodings.
	
	* testsuite/27_io/basic_filebuf/close/12790-1.cc,
	* testsuite/27_io/basic_filebuf/close/char/12790-1.cc,
	* testsuite/27_io/basic_filebuf/close/char/12790-2.cc,
	* testsuite/27_io/basic_filebuf/close/char/12790-3.cc,
	* testsuite/27_io/basic_filebuf/close/char/12790-4.cc,
	* testsuite/27_io/basic_filebuf/close/wchar_t/12790-1.cc,
	* testsuite/27_io/basic_filebuf/close/wchar_t/12790-2.cc,
	* testsuite/27_io/basic_filebuf/close/wchar_t/12790-3.cc,
	* testsuite/27_io/basic_filebuf/close/wchar_t/12790-4.cc,
	* testsuite/27_io/basic_filebuf/open/12790-1.cc,
	* testsuite/27_io/basic_filebuf/seekoff/12790-1.cc,
	* testsuite/27_io/basic_filebuf/seekoff/12790-2.cc,
	* testsuite/27_io/basic_filebuf/seekoff/12790-3.cc,
	* testsuite/27_io/basic_filebuf/seekoff/12790-4.cc,
	* testsuite/27_io/basic_filebuf/seekoff/char/12790-1.cc,
	* testsuite/27_io/basic_filebuf/seekoff/char/12790-2.cc,
	* testsuite/27_io/basic_filebuf/seekoff/char/12790-3.cc,
	* testsuite/27_io/basic_filebuf/seekoff/char/12790-4.cc,
	* testsuite/27_io/basic_filebuf/seekoff/wchar_t/12790-1.cc,
	* testsuite/27_io/basic_filebuf/seekoff/wchar_t/12790-2.cc,
	* testsuite/27_io/basic_filebuf/seekoff/wchar_t/12790-3.cc,
	* testsuite/27_io/basic_filebuf/seekoff/wchar_t/12790-4.cc,
	* testsuite/27_io/basic_filebuf/seekoff/wchar_t/3.cc,
	* testsuite/27_io/basic_filebuf/seekpos/12790-1.cc,
	* testsuite/27_io/basic_filebuf/seekpos/12790-2.cc,
	* testsuite/27_io/basic_filebuf/seekpos/12790-3.cc,
	* testsuite/27_io/basic_filebuf/seekpos/char/12790-1.cc,
	* testsuite/27_io/basic_filebuf/seekpos/char/12790-2.cc,
	* testsuite/27_io/basic_filebuf/seekpos/char/12790-3.cc,
	* testsuite/27_io/basic_filebuf/seekpos/char/12790-4.cc,
	* testsuite/27_io/basic_filebuf/seekpos/wchar_t/1.cc,
	* testsuite/27_io/basic_filebuf/seekpos/wchar_t/12790-1.cc,
	* testsuite/27_io/basic_filebuf/seekpos/wchar_t/12790-2.cc,
	* testsuite/27_io/basic_filebuf/seekpos/wchar_t/12790-3.cc,
	* testsuite/27_io/basic_filebuf/seekpos/wchar_t/12790-4.cc,
	* testsuite/27_io/basic_filebuf/sync/char/1.cc,
	* testsuite/27_io/basic_filebuf/sync/wchar_t/1.cc:
	New tests.

	* testsuite/27_io/basic_filebuf/3.cc,
	* testsuite/27_io/basic_filebuf/seekoff/10132-2.cc,
	* testsuite/27_io/basic_filebuf/seekpos/10132-3.cc,
	* testsuite/27_io/basic_fstream/3.cc,
	* testsuite/27_io/basic_ifstream/3.cc,
	* testsuite/27_io/basic_ofstream/3.cc:
	Use streamoff as off_type and fpos<state_type> as pos_type.

	* testsuite/27_io/basic_filebuf/seekpos/char/1-io.cc,
	* testsuite/27_io/basic_filebuf/seekpos/char/1-out.cc:
	Check that sync does *not* set _M_writing to false.

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