PLearn 0.1
PStreamBuf.cc
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00001 // -*- C++ -*-
00002 
00003 // PStreamBuf.cc
00004 // 
00005 // Copyright (C) 2003 Pascal Vincent
00006 // 
00007 // Redistribution and use in source and binary forms, with or without
00008 // modification, are permitted provided that the following conditions are met:
00009 // 
00010 //  1. Redistributions of source code must retain the above copyright
00011 //     notice, this list of conditions and the following disclaimer.
00012 // 
00013 //  2. Redistributions in binary form must reproduce the above copyright
00014 //     notice, this list of conditions and the following disclaimer in the
00015 //     documentation and/or other materials provided with the distribution.
00016 // 
00017 //  3. The name of the authors may not be used to endorse or promote
00018 //     products derived from this software without specific prior written
00019 //     permission.
00020 // 
00021 // THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
00022 // IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00023 // OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
00024 // NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
00025 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
00026 // TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
00027 // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
00028 // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
00029 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
00030 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00031 // 
00032 // This file is part of the PLearn library. For more information on the PLearn
00033 // library, go to the PLearn Web site at www.plearn.org
00034 
00035 /* *******************************************************      
00036  * $Id: PStreamBuf.cc 9199 2008-07-03 15:00:12Z nouiz $ 
00037  ******************************************************* */
00038 
00040 #include "PStreamBuf.h"
00041 #include <plearn/io/pl_log.h>
00042 
00043 #define PSTREAMBUF_NO_GET (-1000)
00044 
00045 namespace PLearn {
00046 using namespace std;
00047 
00048 PStreamBuf::PStreamBuf(bool is_readable_, bool is_writable_,
00049                        streamsize inbuf_capacity, streamsize outbuf_capacity, 
00050                        streamsize unget_capacity)
00051     :is_readable(is_readable_),
00052      is_writable(is_writable_),
00053      last_get(PSTREAMBUF_NO_GET),
00054      ungetsize(0),
00055      inbuf_chunksize(0),
00056      inbuf(0), inbuf_p(0), inbuf_end(0),
00057      outbuf_chunksize(0),
00058      outbuf(0), outbuf_p(0), outbuf_end(0)
00059 {
00060     setBufferCapacities(inbuf_capacity, outbuf_capacity, unget_capacity);
00061 }
00062 
00063 PStreamBuf::~PStreamBuf() 
00064 {
00065     if (inbuf)
00066         delete[] inbuf;
00067     if (outbuf)
00068         delete[] outbuf;
00069 }
00070 
00071 void PStreamBuf::setBufferCapacities(streamsize inbuf_capacity,
00072                                      streamsize outbuf_capacity, streamsize unget_capacity)
00073 {
00074     if (inbuf_capacity < 1)
00075         inbuf_capacity = 1;
00076     if (unget_capacity < 1)
00077         unget_capacity = 1;
00078     ungetsize = unget_capacity;
00079     inbuf_chunksize = inbuf_capacity;
00080     outbuf_chunksize = outbuf_capacity;
00081     
00082     if (inbuf)
00083         delete[] inbuf;
00084     if (ungetsize + inbuf_chunksize <= 0)
00085         inbuf = inbuf_p = inbuf_end = 0;
00086     else
00087     {
00088         inbuf = new char[ungetsize+inbuf_chunksize];
00089         inbuf_p = inbuf+ungetsize;
00090         inbuf_end = inbuf_p;
00091     }
00092 
00093     if (outbuf)
00094     {
00095         flush();
00096         delete[] outbuf;
00097     }
00098     if (outbuf_chunksize <= 0)
00099         outbuf = outbuf_p = outbuf_end = 0;
00100     else
00101     {
00102         outbuf = new char[outbuf_chunksize];
00103         outbuf_p = outbuf;
00104         outbuf_end = outbuf+outbuf_chunksize;
00105     }
00106 }
00107 
00108 PStreamBuf::streamsize PStreamBuf::read_(char* p, streamsize n)
00109 {
00110     PLERROR("read_ not implemented for this PStreamBuf");
00111     return 0;
00112 }
00113 
00116 void PStreamBuf::write_(const char* p, streamsize n)
00117 {
00118     PLERROR("write_ not implemented for this PStreamBuf");
00119 }
00120  
00121 PStreamBuf::streamsize PStreamBuf::refill_in_buf()
00122 {
00123 #ifdef BOUNDCHECK
00124     if(!isReadable())
00125         PLERROR("Called PStreamBuf::refill_in_buf on a buffer not marked as readable");
00126 #endif
00127 
00128     inbuf_p = inbuf + ungetsize;
00129     inbuf_end= inbuf_p; //buf empty until read_ finished
00130     streamsize n = read_(inbuf_p, inbuf_chunksize);
00131     inbuf_end = inbuf_p + n;
00132     return n;
00133 }
00134 
00135 PStreamBuf::streamsize PStreamBuf::read(char* p, streamsize n)
00136 {
00137 #ifdef BOUNDCHECK
00138     if(!isReadable())
00139         PLERROR("Called PStreamBuf::read on a buffer not marked as readable");
00140 #endif
00141 
00142     streamsize nleft = n;
00143 
00144     streamsize inbuf_n = (streamsize)(inbuf_end-inbuf_p);
00145     if(inbuf_n) // First copy what's left in the buffer
00146     {
00147         streamsize k = nleft<inbuf_n ?nleft :inbuf_n;
00148         memcpy(p,inbuf_p,k);
00149         inbuf_p += k;
00150         p += k;
00151         nleft -= k;
00152     }
00153 
00154     if(nleft) // need some more ?
00155     {
00156         if(nleft>=inbuf_chunksize) // large block: read it directly
00157         {
00158             streamsize nr= read_(p,nleft);
00159             nleft-= nr;
00160             p+= nr;
00161             while(nleft > 0 && nr > 0) // need some more and not eof?
00162             {
00163                 nr= read_(p,nleft);
00164                 nleft-= nr;
00165                 p+= nr;
00166             }
00167         }
00168         else // small block: read it in the buffer first
00169         {
00170             inbuf_n = refill_in_buf();
00171             while(nleft > 0 && inbuf_n > 0) // need some more and not eof?
00172             {
00173                 streamsize k = nleft<inbuf_n ?nleft :inbuf_n;
00174                 memcpy(p,inbuf_p,k);
00175                 inbuf_p += k;
00176                 nleft -= k;
00177                 p+= k;
00178                 if(nleft > 0)
00179                     inbuf_n = refill_in_buf();
00180             }
00181         }
00182     }
00183 
00184     streamsize nread = n-nleft;
00185 
00186     if (nread > 0)
00187         last_get = (unsigned char) p[-1];//p has advanced and now points one after the end
00188     else
00189         last_get = EOF;
00190 
00191     return nread;
00192 }
00193 
00194 void PStreamBuf::unread(const char* p, streamsize n)
00195 {
00196     if(streamsize(inbuf_p-inbuf)<n)
00197         PLERROR("Cannot unread that many characters: %ld, input buffer bound reached (you may want to increase the unget_capacity)", long(n));
00198   
00199     inbuf_p -= n;
00200     memcpy(inbuf_p,p,n);
00201 }
00202 
00203 void PStreamBuf::putback(char c)
00204 {
00205     if(inbuf_p<=inbuf)
00206         PLERROR("Cannot putback('%c') Input buffer bound reached (you may want to increase the unget_capacity)",c);
00207   
00208     inbuf_p--;
00209     *inbuf_p = c;
00210 }
00211 
00212 void PStreamBuf::unget()
00213 {
00214     if (last_get == PSTREAMBUF_NO_GET)
00215         PLERROR("In PStreamBuf::unget - You called unget() more than once or you did not call get() first");
00216     if (last_get != EOF)
00217         putback((char) last_get);
00218     last_get = PSTREAMBUF_NO_GET;
00219 }
00220 
00221 
00222 void PStreamBuf::flush()
00223 {
00224     streamsize n = (streamsize)(outbuf_p-outbuf);
00225     if(n)
00226     {
00227         write_(outbuf, n);
00228         outbuf_p = outbuf;
00229     }
00230 }
00231 
00232 
00233 void PStreamBuf::write(const char* p, streamsize n)
00234 {
00235 #ifdef BOUNDCHECK
00236     if(!isWritable())
00237         PLERROR("Called PStreamBuf::write on a buffer not marked as writable");
00238 #endif
00239     if(outbuf_chunksize>0) // buffered
00240     {
00241         streamsize bufrem = (streamsize)(outbuf_end-outbuf_p);
00242         if(n<=bufrem)
00243         {
00244             memcpy(outbuf_p, p, n);
00245             outbuf_p += n;
00246         }
00247         else // n>bufrem
00248         {
00249             memcpy(outbuf_p, p, bufrem);
00250             outbuf_p += bufrem;
00251             flush();
00252             p += bufrem;
00253             n -= bufrem;
00254             if(n>outbuf_chunksize)
00255                 write_(p, n);
00256             else
00257             {
00258                 memcpy(outbuf_p, p, n);
00259                 outbuf_p += n;
00260             }
00261         }
00262     }
00263     else // unbuffered
00264         write_(p,n);
00265 }
00266 
00267 bool PStreamBuf::good() const
00268 {
00269     if (is_readable)
00270         return !eof();
00271     else
00272         return is_writable;
00273 }
00274 
00275 
00276 } // end of namespace PLearn
00277 
00278 
00279 /*
00280   Local Variables:
00281   mode:c++
00282   c-basic-offset:4
00283   c-file-style:"stroustrup"
00284   c-file-offsets:((innamespace . 0)(inline-open . 0))
00285   indent-tabs-mode:nil
00286   fill-column:79
00287   End:
00288 */
00289 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=79 :
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