buffered.cpp

   1 #include <cstring>
   2 #include <stdexcept>
   3 #include "buffered.h"
   4 #include "handle.h"
   5
   6 using namespace std;
   7
   8 namespace Msp {
   9 namespace IO {
  10
  11 Buffered::Buffered(Base &b, unsigned s):
  12         below(b),
  13         buf_size(s),
  14         buf(new char[buf_size]),
  15         begin(buf),
  16         end(buf),
  17         cur_op(M_NONE)
  18 {
  19         mode = below.get_mode();
  20         below.signal_flush_required.connect(sigc::mem_fun(this, &Buffered::flush));
  21 }
  22
  23 Buffered::~Buffered()
  24 {
  25         try
  26         {
  27                 flush();
  28         }
  29         catch(...)
  30         { }
  31
  32         delete[] buf;
  33 }
  34
  35 void Buffered::set_block(bool)
  36 {
  37         throw logic_error("Buffered::set_block");
  38 }
  39
  40 void Buffered::set_inherit(bool)
  41 {
  42         throw logic_error("Buffered::set_block");
  43 }
  44
  45 void Buffered::flush()
  46 {
  47         if(cur_op==M_WRITE)
  48         {
  49                 unsigned used = end-begin;
  50                 if(used)
  51                 {
  52                         unsigned len = below.write(begin, used);
  53
  54                         begin = end = buf;
  55
  56                         if(len<used)
  57                                 throw runtime_error("Couldn't flush all data");
  58                 }
  59         }
  60         else if(cur_op==M_READ)
  61                 begin = end = buf;
  62 }
  63
  64 unsigned Buffered::do_write(const char *data, unsigned size)
  65 {
  66         set_op(M_WRITE);
  67
  68         if(end+size<buf+buf_size)
  69         {
  70                 // All data fits in buffer with whatever is already there
  71                 memcpy(end, data, size);
  72                 end += size;
  73
  74                 return size;
  75         }
  76         else
  77         {
  78                 // Clear the buffer to make more room
  79                 flush();
  80
  81                 if(size<buf_size)
  82                 {
  83                         // Put new data in the buffer to wait for more
  84                         memcpy(end, data, size);
  85                         end += size;
  86
  87                         return size;
  88                 }
  89                 else
  90                         // New data still doesn't fit in the buffer, so write it directly
  91                         return below.write(data, size);
  92         }
  93 }
  94
  95 unsigned Buffered::do_read(char *data, unsigned size)
  96 {
  97         set_op(M_READ);
  98
  99         if(begin+size<=end)
 100         {
 101                 // The request can be served from the buffer
 102                 memcpy(data, begin, size);
 103                 begin += size;
 104
 105                 eof_flag = (below.eof() && begin==end);
 106
 107                 return size;
 108         }
 109         else
 110         {
 111                 // Give out whatever is in the buffer already
 112                 memcpy(data, begin, end-begin);
 113                 unsigned ret = end-begin;
 114                 begin = end = buf;
 115
 116                 data += ret;
 117                 size -= ret;
 118
 119                 if(size<buf_size)
 120                 {
 121                         // Fill the buffer and serve the rest of the request from it
 122                         unsigned len = below.read(end, buf+buf_size-end);
 123                         end += len;
 124
 125                         len = min(static_cast<unsigned>(end-begin), size);
 126                         memcpy(data, begin, len);
 127                         begin += len;
 128                         ret += len;
 129                 }
 130                 else
 131                         // Read the rest directly from the underlying object
 132                         ret += below.read(data, size);
 133
 134                 eof_flag = (below.eof() && begin==end);
 135
 136                 return ret;
 137         }
 138 }
 139
 140 unsigned Buffered::put(char c)
 141 {
 142         set_op(M_WRITE);
 143
 144         if(end<buf+buf_size)
 145         {
 146                 *end++ = c;
 147                 return 1;
 148         }
 149         else
 150                 return do_write(&c, 1);
 151 }
 152
 153 bool Buffered::getline(std::string &line)
 154 {
 155         set_op(M_READ);
 156
 157         for(char *i=begin; i!=end; ++i)
 158                 if(*i=='\n')
 159                 {
 160                         line.assign(begin, i-begin);
 161                         begin = i+1;
 162                         return true;
 163                 }
 164
 165         return Base::getline(line);
 166 }
 167
 168 int Buffered::get()
 169 {
 170         set_op(M_READ);
 171
 172         if(begin<end)
 173                 return static_cast<unsigned char>(*begin++);
 174
 175         char c;
 176         if(do_read(&c, 1)==0)
 177                 return -1;
 178         return static_cast<unsigned char>(c);
 179 }
 180
 181 const Handle &Buffered::get_handle(Mode)
 182 {
 183         throw logic_error("Buffered::get_handle");
 184 }
 185
 186 void Buffered::set_op(Mode op)
 187 {
 188         if(op!=cur_op)
 189                 flush();
 190         cur_op = op;
 191 }
 192
 193 unsigned Buffered::get_current_size() const
 194 {
 195         return end-begin;
 196 }
 197
 198 } // namespace IO
 199 } // namespace Msp