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return persistent buffers from mb_str()/wc_str() to allow assigning the returned value to simple pointers

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git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@60116 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin 2009-04-12 19:49:45 +00:00
parent dbe31039f7
commit f54cb154d5
2 changed files with 232 additions and 188 deletions
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209
include/wx/string.h
View File

@ -246,8 +246,15 @@ public:
operator const void*() const { return AsChar(); }
// returns buffers that are valid as long as the associated wxString exists
inline const wxScopedCharBuffer AsCharBuf() const;
inline const wxScopedWCharBuffer AsWCharBuf() const;
const wxScopedCharBuffer AsCharBuf() const
{
return wxScopedCharBuffer::CreateNonOwned(AsChar());
}
const wxScopedWCharBuffer AsWCharBuf() const
{
return wxScopedWCharBuffer::CreateNonOwned(AsWChar());
}
inline wxString AsString() const;
@ -1786,21 +1793,34 @@ public:
// accepting the file names. The return value is always the same, but the
// type differs because a function may either return pointer to the buffer
// directly or have to use intermediate buffer for translation.
#if wxUSE_UNICODE
// this is an optimization: even though using mb_str(wxConvLibc) does the
// same thing (i.e. returns pointer to internal representation as locale is
// always an UTF-8 one) in wxUSE_UTF8_LOCALE_ONLY case, we can avoid the
// extra checks and the temporary buffer construction by providing a
// separate mb_str() overload
#if wxUSE_UTF8_LOCALE_ONLY
const char* mb_str() const { return wx_str(); }
const wxScopedCharBuffer mb_str(const wxMBConv& conv) const;
#else
const wxScopedCharBuffer mb_str(const wxMBConv& conv = wxConvLibc) const;
#endif
const wxScopedCharBuffer mb_str(const wxMBConv& conv) const
{
return AsCharBuf(conv);
}
#else // !wxUSE_UTF8_LOCALE_ONLY
const wxScopedCharBuffer mb_str(const wxMBConv& conv = wxConvLibc) const
{
return AsCharBuf(conv);
}
#endif // wxUSE_UTF8_LOCALE_ONLY/!wxUSE_UTF8_LOCALE_ONLY
const wxWX2MBbuf mbc_str() const { return mb_str(*wxConvCurrent); }
#if wxUSE_UNICODE_WCHAR
const wchar_t* wc_str() const { return wx_str(); }
#elif wxUSE_UNICODE_UTF8
const wxScopedWCharBuffer wc_str() const;
const wxScopedWCharBuffer wc_str() const
{ return AsWCharBuf(wxMBConvStrictUTF8()); }
#endif
// for compatibility with !wxUSE_UNICODE version
const wxWX2WCbuf wc_str(const wxMBConv& WXUNUSED(conv)) const
@ -1813,16 +1833,16 @@ public:
#endif // wxMBFILES/!wxMBFILES
#else // ANSI
const wxChar* mb_str() const { return wx_str(); }
const char* mb_str() const { return wx_str(); }
// for compatibility with wxUSE_UNICODE version
const char* mb_str(const wxMBConv& WXUNUSED(conv)) const { return wx_str(); }
const wxWX2MBbuf mbc_str() const { return mb_str(); }
#if wxUSE_WCHAR_T
const wxScopedWCharBuffer wc_str(const wxMBConv& conv = wxConvLibc) const;
#endif // wxUSE_WCHAR_T
const wxScopedWCharBuffer wc_str(const wxMBConv& conv = wxConvLibc) const
{ return AsWCharBuf(conv); }
const wxScopedCharBuffer fn_str() const
{ return wxConvFile.cWC2WX( wc_str( wxConvLibc ) ); }
#endif // Unicode/ANSI
@ -3421,36 +3441,105 @@ private:
wxStringImpl m_impl;
// buffers for compatibility conversion from (char*)c_str() and
// (wchar_t*)c_str():
// FIXME-UTF8: bechmark various approaches to keeping compatibility buffers
// (wchar_t*)c_str(): the pointers returned by these functions should remain
// valid until the string itself is modified for compatibility with the
// existing code and consistency with std::string::c_str() so returning a
// temporary buffer won't do and we need to cache the conversion results
// TODO-UTF8: benchmark various approaches to keeping compatibility buffers
template<typename T>
struct ConvertedBuffer
{
ConvertedBuffer() : m_buf(NULL) {}
// notice that there is no need to initialize m_len here as it's unused
// as long as m_str is NULL
ConvertedBuffer() : m_str(NULL) {}
~ConvertedBuffer()
{ free(m_buf); }
{ free(m_str); }
operator T*() const { return m_buf; }
ConvertedBuffer& operator=(T *str)
bool Extend(size_t len)
{
free(m_buf);
m_buf = str;
return *this;
// add extra 1 for the trailing NUL
void * const str = realloc(m_str, sizeof(T)*(len + 1));
if ( !str )
return false;
m_str = static_cast<T *>(str);
m_len = len;
return true;
}
T *m_buf;
const wxScopedCharTypeBuffer<T> AsScopedBuffer() const
{
return wxScopedCharTypeBuffer<T>::CreateNonOwned(m_str, m_len);
}
T *m_str; // pointer to the string data
size_t m_len; // length, not size, i.e. in chars and without last NUL
};
#if wxUSE_UNICODE && !wxUSE_UTF8_LOCALE_ONLY
#if wxUSE_UNICODE
// common mb_str() and wxCStrData::AsChar() helper: performs the conversion
// and returns either m_convertedToChar.m_str (in which case its m_len is
// also updated) or NULL if it failed
//
// there is an important exception: in wxUSE_UNICODE_UTF8 build if conv is a
// UTF-8 one, we return m_impl.c_str() directly, without doing any conversion
// as optimization and so the caller needs to check for this before using
// m_convertedToChar
//
// NB: AsChar() returns char* in any build, unlike mb_str()
const char *AsChar(const wxMBConv& conv) const;
// mb_str() implementation helper
wxScopedCharBuffer AsCharBuf(const wxMBConv& conv) const
{
#if wxUSE_UNICODE_UTF8
// avoid conversion if we can
if ( conv.IsUTF8() )
{
return wxScopedCharBuffer::CreateNonOwned(m_impl.c_str(),
m_impl.length());
}
#endif // wxUSE_UNICODE_UTF8
// call this solely in order to fill in m_convertedToChar as AsChar()
// updates it as a side effect: this is a bit ugly but it's a completely
// internal function so the users of this class shouldn't care or know
// about it and doing it like this, i.e. having a separate AsChar(),
// allows us to avoid the creation and destruction of a temporary buffer
// when using wxCStrData without duplicating any code
AsChar(conv);
return m_convertedToChar.AsScopedBuffer();
}
ConvertedBuffer<char> m_convertedToChar;
#endif
#endif // !wxUSE_UNICODE
#if !wxUSE_UNICODE_WCHAR
// common wc_str() and wxCStrData::AsWChar() helper for both UTF-8 and ANSI
// builds: converts the string contents into m_convertedToWChar and returns
// NULL if the conversion failed (this can only happen in ANSI build)
//
// NB: AsWChar() returns wchar_t* in any build, unlike wc_str()
const wchar_t *AsWChar(const wxMBConv& conv) const;
// wc_str() implementation helper
wxScopedWCharBuffer AsWCharBuf(const wxMBConv& conv) const
{
AsWChar(conv);
return m_convertedToWChar.AsScopedBuffer();
}
ConvertedBuffer<wchar_t> m_convertedToWChar;
#endif
#endif // !wxUSE_UNICODE_WCHAR
#if wxUSE_UNICODE_UTF8
// FIXME-UTF8: (try to) move this elsewhere (TLS) or solve differently
// assigning to character pointer to by wxString::interator may
// assigning to character pointer to by wxString::iterator may
// change the underlying wxStringImpl iterator, so we have to
// keep track of all iterators and update them as necessary:
struct wxStringIteratorNodeHead
@ -3994,45 +4083,53 @@ inline wxCStrData::~wxCStrData()
delete const_cast<wxString*>(m_str); // cast to silence warnings
}
// simple cases for AsChar() and AsWChar(), the complicated ones are
// in string.cpp
#if wxUSE_UNICODE_WCHAR
// AsChar() and AsWChar() implementations simply forward to wxString methods
inline const wchar_t* wxCStrData::AsWChar() const
{
return m_str->wx_str() + m_offset;
}
#endif // wxUSE_UNICODE_WCHAR
const wchar_t * const p =
#if wxUSE_UNICODE_WCHAR
m_str->wc_str();
#elif wxUSE_UNICODE_UTF8
m_str->AsWChar(wxMBConvStrictUTF8());
#else
m_str->AsWChar(wxConvLibc);
#endif
// in Unicode build the string always has a valid Unicode representation
// and even if a conversion is needed (as in UTF8 case) it can't fail
//
// but in ANSI build the string contents might be not convertible to
// Unicode using the current locale encoding so we do need to check for
// errors
#if !wxUSE_UNICODE
inline const char* wxCStrData::AsChar() const
{
return m_str->wx_str() + m_offset;
}
if ( !p )
{
// if conversion fails, return empty string and not NULL to avoid
// crashes in code written with either wxWidgets 2 wxString or
// std::string behaviour in mind: neither of them ever returns NULL
// from its c_str() and so we shouldn't neither
//
// notice that the same is done in AsChar() below and
// wxString::wc_str() and mb_str() for the same reasons
return L"";
}
#endif // !wxUSE_UNICODE
#if wxUSE_UTF8_LOCALE_ONLY
return p + m_offset;
}
inline const char* wxCStrData::AsChar() const
{
return wxStringOperations::AddToIter(m_str->wx_str(), m_offset);
}
#endif // wxUSE_UTF8_LOCALE_ONLY
#if wxUSE_UNICODE && !wxUSE_UTF8_LOCALE_ONLY
const char * const p = m_str->AsChar(wxConvLibc);
if ( !p )
return "";
#else // !wxUSE_UNICODE || wxUSE_UTF8_LOCALE_ONLY
const char * const p = m_str->mb_str();
#endif // wxUSE_UNICODE && !wxUSE_UTF8_LOCALE_ONLY
inline const wxScopedCharBuffer wxCStrData::AsCharBuf() const
{
#if !wxUSE_UNICODE || wxUSE_UTF8_LOCALE_ONLY
return wxScopedCharBuffer::CreateNonOwned(AsChar());
#else
return AsString().mb_str();
#endif
}
inline const wxScopedWCharBuffer wxCStrData::AsWCharBuf() const
{
#if wxUSE_UNICODE_WCHAR
return wxScopedWCharBuffer::CreateNonOwned(AsWChar());
#else
return AsString().wc_str();
#endif
return p + m_offset;
}
inline wxString wxCStrData::AsString() const

211
src/common/string.cpp
View File

@ -366,95 +366,6 @@ wxString::~wxString()
}
#endif
#if wxUSE_UNICODE && !wxUSE_UTF8_LOCALE_ONLY
const char* wxCStrData::AsChar() const
{
#if wxUSE_UNICODE_UTF8
if ( wxLocaleIsUtf8 )
return AsInternal();
#endif
// under non-UTF8 locales, we have to convert the internal UTF-8
// representation using wxConvLibc and cache the result
wxString *str = wxConstCast(m_str, wxString);
// convert the string:
//
// FIXME-UTF8: we'd like to do the conversion in the existing buffer (if we
// have it) but it's unfortunately not obvious to implement
// because we don't know how big buffer do we need for the
// given string length (in case of multibyte encodings, e.g.
// ISO-2022-JP or UTF-8 when internal representation is wchar_t)
//
// One idea would be to store more than just m_convertedToChar
// in wxString: then we could record the length of the string
// which was converted the last time and try to reuse the same
// buffer if the current length is not greater than it (this
// could still fail because string could have been modified in
// place but it would work most of the time, so we'd do it and
// only allocate the new buffer if in-place conversion returned
// an error). We could also store a bit saying if the string
// was modified since the last conversion (and update it in all
// operation modifying the string, of course) to avoid unneeded
// consequential conversions. But both of these ideas require
// adding more fields to wxString and require profiling results
// to be sure that we really gain enough from them to justify
// doing it.
wxScopedCharBuffer buf(str->mb_str());
// if it failed, return empty string and not NULL to avoid crashes in code
// written with either wxWidgets 2 wxString or std::string behaviour in
// mind: neither of them ever returns NULL and so we shouldn't neither
if ( !buf )
return "";
if ( str->m_convertedToChar &&
strlen(buf) == strlen(str->m_convertedToChar) )
{
// keep the same buffer for as long as possible, so that several calls
// to c_str() in a row still work:
strcpy(str->m_convertedToChar, buf);
}
else
{
str->m_convertedToChar = buf.release();
}
// and keep it:
return str->m_convertedToChar + m_offset;
}
#endif // wxUSE_UNICODE && !wxUSE_UTF8_LOCALE_ONLY
#if !wxUSE_UNICODE_WCHAR
const wchar_t* wxCStrData::AsWChar() const
{
wxString *str = wxConstCast(m_str, wxString);
// convert the string:
wxScopedWCharBuffer buf(str->wc_str());
// notice that here, unlike above in AsChar(), conversion can't fail as our
// internal UTF-8 is always well-formed -- or the string was corrupted and
// all bets are off anyhow
// FIXME-UTF8: do the conversion in-place in the existing buffer
if ( str->m_convertedToWChar &&
wxWcslen(buf) == wxWcslen(str->m_convertedToWChar) )
{
// keep the same buffer for as long as possible, so that several calls
// to c_str() in a row still work:
memcpy(str->m_convertedToWChar, buf, sizeof(wchar_t) * wxWcslen(buf));
}
else
{
str->m_convertedToWChar = buf.release();
}
// and keep it:
return str->m_convertedToWChar + m_offset;
}
#endif // !wxUSE_UNICODE_WCHAR
// ===========================================================================
// wxString class core
// ===========================================================================
@ -549,61 +460,97 @@ wxString::SubstrBufFromWC wxString::ConvertStr(const wchar_t *pwz, size_t nLengt
}
#endif // wxUSE_UNICODE_UTF8 || !wxUSE_UNICODE
// This std::string::c_str()-like method returns a wide char pointer to string
// contents. In wxUSE_UNICODE_WCHAR case it is trivial as it can simply return
// a pointer to the internal representation. Otherwise a conversion is required
// and it returns a temporary buffer.
//
// However for compatibility with c_str() and to avoid breaking existing code
// doing
//
// for ( const wchar_t *p = s.wc_str(); *p; p++ )
// ... use *p...
//
// we actually need to ensure that the returned buffer is _not_ temporary and
// so we use wxString::m_convertedToWChar to store the returned data
#if !wxUSE_UNICODE_WCHAR
#if wxUSE_UNICODE_WCHAR
//Convert wxString in Unicode mode to a multi-byte string
const wxScopedCharBuffer wxString::mb_str(const wxMBConv& conv) const
const wchar_t *wxString::AsWChar(const wxMBConv& conv) const
{
// NB: Length passed to cWC2MB() doesn't include terminating NUL, it's
// added by it automatically. If we passed length()+1 here, it would
// create a buffer with 2 trailing NULs of length one greater than
// expected.
return conv.cWC2MB(wx_str(), length(), NULL);
const char * const strMB = m_impl.c_str();
const size_t lenMB = m_impl.length();
// find out the size of the buffer needed
const size_t lenWC = conv.ToWChar(NULL, 0, strMB, lenMB);
if ( lenWC == wxCONV_FAILED )
return NULL;
// keep the same buffer if the string size didn't change: this is not only
// an optimization but also ensure that code which modifies string
// character by character (without changing its length) can continue to use
// the pointer returned by a previous wc_str() call even after changing the
// string
// TODO-UTF8: we could check for ">" instead of "!=" here as this would
// allow to save on buffer reallocations but at the cost of
// consuming (even) more memory, we should benchmark this to
// determine if it's worth doing
if ( !m_convertedToWChar.m_str || lenWC != m_convertedToWChar.m_len )
{
if ( !const_cast<wxString *>(this)->m_convertedToWChar.Extend(lenWC) )
return NULL;
}
// finally do convert
m_convertedToWChar.m_str[lenWC] = L'\0';
if ( conv.ToWChar(m_convertedToWChar.m_str, lenWC,
strMB, lenMB) == wxCONV_FAILED )
return NULL;
return m_convertedToWChar.m_str;
}
#elif wxUSE_UNICODE_UTF8
#endif // !wxUSE_UNICODE_WCHAR
const wxScopedWCharBuffer wxString::wc_str() const
{
// NB: Length passed to cMB2WC() doesn't include terminating NUL, it's
// added by it automatically. If we passed length()+1 here, it would
// create a buffer with 2 trailing NULs of length one greater than
// expected.
return wxMBConvStrictUTF8().cMB2WC
(
m_impl.c_str(),
m_impl.length(),
NULL
);
}
const wxScopedCharBuffer wxString::mb_str(const wxMBConv& conv) const
// Same thing for mb_str() which returns a normal char pointer to string
// contents: this always requires converting it to the specified encoding in
// non-ANSI build except if we need to convert to UTF-8 and this is what we
// already use internally.
#if wxUSE_UNICODE
const char *wxString::AsChar(const wxMBConv& conv) const
{
#if wxUSE_UNICODE_UTF8
if ( conv.IsUTF8() )
return wxScopedCharBuffer::CreateNonOwned(m_impl.c_str(), m_impl.length());
return m_impl.c_str();
wxScopedWCharBuffer wcBuf(wc_str());
if ( !wcBuf.length() )
return wxCharBuffer("");
const wchar_t * const strWC = AsWChar(wxMBConvStrictUTF8());
const size_t lenWC = m_convertedToWChar.m_len;
#else // wxUSE_UNICODE_WCHAR
const wchar_t * const strWC = m_impl.c_str();
const size_t lenWC = m_impl.length();
#endif // wxUSE_UNICODE_UTF8/wxUSE_UNICODE_WCHAR
return conv.cWC2MB(wcBuf.data(), wcBuf.length(), NULL);
const size_t lenMB = conv.FromWChar(NULL, 0, strWC, lenWC);
if ( lenMB == wxCONV_FAILED )
return NULL;
if ( !m_convertedToChar.m_str || lenMB != m_convertedToChar.m_len )
{
if ( !const_cast<wxString *>(this)->m_convertedToChar.Extend(lenMB) )
return NULL;
}
m_convertedToChar.m_str[lenMB] = '\0';
if ( conv.FromWChar(m_convertedToChar.m_str, lenMB,
strWC, lenWC) == wxCONV_FAILED )
return NULL;
return m_convertedToChar.m_str;
}
#else // ANSI
//Converts this string to a wide character string if unicode
//mode is not enabled and wxUSE_WCHAR_T is enabled
const wxScopedWCharBuffer wxString::wc_str(const wxMBConv& conv) const
{
// NB: Length passed to cMB2WC() doesn't include terminating NUL, it's
// added by it automatically. If we passed length()+1 here, it would
// create a buffer with 2 trailing NULs of length one greater than
// expected.
return conv.cMB2WC(wx_str(), length(), NULL);
}
#endif // Unicode/ANSI
#endif // wxUSE_UNICODE
// shrink to minimal size (releasing extra memory)
bool wxString::Shrink()