src/SBufStream.h

   1 /*
   2  * Copyright (C) 1996-2014 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 #ifndef SQUID_SBUFSTREAM_H
  10 #define SQUID_SBUFSTREAM_H
  11
  12 #include "SBuf.h"
  13
  14 #include <ostream>
  15
  16 /** streambuf class for a SBuf-backed stream interface.
  17  *
  18  * Auxiliary class to be able to leverage an ostream generating SBuf's
  19  * analogous to std::ostrstream.
  20  */
  21 class SBufStreamBuf : public std::streambuf
  22 {
  23 public:
  24     /// initialize streambuf; use supplied SBuf as backing store
  25     explicit SBufStreamBuf(SBuf aBuf) : theBuf(aBuf) {}
  26
  27     /// get a copy of the stream's contents
  28     SBuf getBuf() {
  29         return theBuf;
  30     }
  31
  32     /// clear the stream's store
  33     void clearBuf() {
  34         theBuf.clear();
  35     }
  36
  37 protected:
  38     virtual int_type overflow(int_type aChar = traits_type::eof()) {
  39         std::streamsize pending(pptr() - pbase());
  40
  41         if (pending && sync())
  42             return traits_type::eof();
  43
  44         if (aChar != traits_type::eof()) {
  45             char chars[1] = {static_cast<char>(aChar)};
  46
  47             if (aChar != traits_type::eof())
  48                 theBuf.append(chars, 1);
  49         }
  50
  51         pbump(-pending);  // Reset pptr().
  52         return aChar;
  53     }
  54
  55     /// push the streambuf to the backing SBuf
  56     virtual int sync() {
  57         std::streamsize pending(pptr() - pbase());
  58
  59         if (pending)
  60             theBuf.append(pbase(), pending);
  61
  62         return 0;
  63     }
  64
  65     /** write multiple characters to the store entry
  66      * \note this is an optimisation consistent with std::streambuf API
  67      */
  68     virtual std::streamsize xsputn(const char * chars, std::streamsize number) {
  69         if (number)
  70             theBuf.append(chars, number);
  71
  72         return number;
  73     }
  74
  75 private:
  76     SBuf theBuf;
  77     SBufStreamBuf(); // no default constructor
  78 };
  79
  80 /** Stream interface to write to a SBuf.
  81  *
  82  * Data is appended using standard operator << semantics, and extracted
  83  * using the buf() method, in analogy with std::strstream .
  84  */
  85 class SBufStream : public std::ostream
  86 {
  87 public:
  88     /** Create a SBufStream preinitialized with the contents of a SBuf
  89      *
  90      * The supplied SBuf copied: in order to retrieve the written-to contents
  91      * they must be later fetched using the buf() class method.
  92      */
  93     SBufStream(SBuf aBuf): std::ostream(0), theBuffer(aBuf) {
  94         rdbuf(&theBuffer); // set the buffer to now-initialized theBuffer
  95         clear(); //clear badbit set by calling init(0)
  96     }
  97
  98     /// Create an empty SBufStream
  99     SBufStream(): std::ostream(0), theBuffer(SBuf()) {
 100         rdbuf(&theBuffer); // set the buffer to now-initialized theBuffer
 101         clear(); //clear badbit set by calling init(0)
 102     }
 103
 104     /// Retrieve a copy of the current stream status
 105     SBuf buf() {
 106         flush();
 107         return theBuffer.getBuf();
 108     }
 109
 110     /// Clear the stream's backing store
 111     SBufStream& clearBuf() {
 112         flush();
 113         theBuffer.clearBuf();
 114         return *this;
 115     }
 116
 117 private:
 118     SBufStreamBuf theBuffer;
 119 };
 120
 121 #endif /* SQUID_SBUFSTREAM_H */