test/interactive-helper/teestream.h

   1 #ifndef APT_HELPER_TEESTREAM_H
   2 #define APT_HELPER_TEESTREAM_H
   3
   4 /* 'basic' implementation of a streambuf which passes the output
   5    to two 'real' streambufs emulating '| tee' on the shell
   6
   7    The main use is streaming debug output to std::clog as well as
   8    a logfile easily, so don't expect that to be a bulletproof
   9    implementation. */
  10
  11 #include <iostream>
  12 #include <apt-pkg/macros.h>
  13
  14 template <typename CharT, typename Traits = std::char_traits<CharT>
  15 > class basic_teebuf: public std::basic_streambuf<CharT, Traits>
  16 {
  17 public:
  18    basic_teebuf(std::basic_streambuf<CharT, Traits> * const sb1,
  19          std::basic_streambuf<CharT, Traits> * const sb2)
  20       : s1(sb1), s2(sb2) {}
  21 protected:
  22    virtual std::streamsize xsputn(const CharT* s, std::streamsize c) APT_OVERRIDE
  23    {
  24       return s2->sputn(s, s1->sputn(s, c));
  25    }
  26    // overflow is the fallback of sputc which is non-virtual
  27    typedef typename Traits::int_type int_type;
  28    virtual int_type overflow(int_type ch = Traits::eof()) APT_OVERRIDE
  29    {
  30       auto const eof = Traits::eof();
  31       if (Traits::eq_int_type(ch, Traits::eof()) == true)
  32          return eof;
  33
  34       auto const r1 = s1->sputc(Traits::to_char_type(ch));
  35       auto const r2 = s2->sputc(Traits::to_char_type(ch));
  36       return Traits::eq_int_type(r1, eof) ? r1: r2;
  37    }
  38    virtual void imbue(const std::locale& loc) APT_OVERRIDE
  39    {
  40       s1->pubimbue(loc);
  41       s2->pubimbue(loc);
  42    }
  43    virtual int sync() APT_OVERRIDE
  44    {
  45       auto const r1 = s1->pubsync();
  46       auto const r2 = s2->pubsync();
  47       return r1 == 0 ? r2 : r1;
  48    }
  49 private:
  50    std::basic_streambuf<CharT, Traits> * const s1;
  51    std::basic_streambuf<CharT, Traits> * const s2;
  52 };
  53 template <typename CharT, typename Traits = std::char_traits<CharT>
  54 > class basic_teeostream: public std::basic_ostream<CharT, Traits>
  55 {
  56 public:
  57     basic_teeostream(std::basic_ostream<CharT, Traits> &o1, std::basic_ostream<CharT, Traits> &o2) :
  58        std::basic_ostream<CharT, Traits>(&tbuf), tbuf(o1.rdbuf(), o2.rdbuf()) {}
  59 private:
  60     basic_teebuf<CharT, Traits> tbuf;
  61 };
  62 #endif