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Merge pull request pocoproject#688 from martin-osborne/issue_297
Issue pocoproject#297 - Added implementation of seekoff to BasicMemoryStreamBuf
2 parents c05e56c + 683d7ce commit f440c4b

3 files changed

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‎Foundation/include/Poco/MemoryStream.h‎

Lines changed: 60 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -74,6 +74,66 @@ class BasicMemoryStreamBuf: public std::basic_streambuf<ch, tr>
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return char_traits::eof();
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}
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virtual pos_type seekoff(off_type off, std::ios_base::seekdir way, std::ios_base::openmode which = std::ios_base::in | std::ios_base::out)
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{
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const pos_type fail = off_type(-1);
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off_type newoff = off_type(-1);
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if ((which & std::ios_base::in) != 0)
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{
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if (this->gptr() == 0)
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return fail;
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switch (way)
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{
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case std::ios_base::beg:
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newoff = 0;
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break;
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case std::ios_base::cur:
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// cur is not valid if both in and out are specified (Condition 3)
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if ((which & std::ios_base::out) != 0)
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return fail;
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newoff = this->gptr() - this->eback();
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break;
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case std::ios_base::end:
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newoff = this->egptr() - this->eback();
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break;
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}
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if ((newoff + off) < 0 || (this->egptr() - this->eback()) < (newoff + off))
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return fail;
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this->setg(this->eback(), this->eback() + newoff + off, this->egptr());
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}
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if ((which & std::ios_base::out) != 0)
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{
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if (this->pptr() == 0)
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return fail;
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switch (way)
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{
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case std::ios_base::beg:
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newoff = 0;
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break;
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case std::ios_base::cur:
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// cur is not valid if both in and out are specified (Condition 3)
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if ((which & std::ios_base::in) != 0)
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return fail;
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newoff = this->pptr() - this->pbase();
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break;
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case std::ios_base::end:
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newoff = this->epptr() - this->pbase();
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break;
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}
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if (newoff + off < 0 || (this->epptr() - this->pbase()) < newoff + off)
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return fail;
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this->pbump((int)(newoff + off - (this->pptr() - this->pbase())));
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}
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return newoff;
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}
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virtual int sync()
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{
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return 0;

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