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io.hh

// Copyright 2008, 2009, 2010 Martin C. Frith

// Generally useful input/output functions, mostly for binary reading
// and writing of vectors.

#ifndef IO_H
#define IO_H

#include <vector>
#include <string>
#include <stdexcept>
#include <fstream>
#include <cassert>

namespace cbrc{

// open an input file, but if the name is "-", just return cin
std::istream& openIn( const std::string& fileName, std::ifstream& ifs );

// open an output file, but if the name is "-", just return cout
std::ostream& openOut( const std::string& fileName, std::ofstream& ofs );

// read a file into a string, but if the name is "-", read cin
std::string slurp( const std::string& fileName );

template <typename T>  // T should be a vector-iterator or a pointer
void memoryFromStream( T beg, T end, std::istream& s ){
  assert( beg < end );
  enum { CHUNK_SIZE = 1073741824 };  // need to do big reads in chunks: why?
  char * b = reinterpret_cast<char*>(&(*beg));
  char * e = reinterpret_cast<char*>(&(*end));
  while( e - b > CHUNK_SIZE ){
    s.read( b, CHUNK_SIZE );
    b += CHUNK_SIZE;
  }
  s.read( b, e - b );
}

template<typename T>
void vectorFromStream( std::vector<T>& v, std::istream& s ){
  memoryFromStream( v.begin(), v.end(), s );
}

template<typename T>  // T should be a vector-iterator or a pointer
void memoryToStream( T beg, T end, std::ostream& s ){
  assert( beg < end );
  enum { CHUNK_SIZE = 1073741824 };  // need to do big writes in chunks: why?
  const char * b = (const char*)&(*beg);
  const char * e = (const char*)&(*end);
  while( e - b > CHUNK_SIZE ){
    s.write( b, CHUNK_SIZE );
    b += CHUNK_SIZE;
  }
  s.write( b, e - b );
}

template<typename T>
void vectorToStream( const std::vector<T>& v, std::ostream& s ){
  memoryToStream( v.begin(), v.end(), s );
}

template<typename T>  // T should be a vector-iterator or a pointer
void memoryFromBinaryFile( T beg, T end, const std::string& fileName ){
  if( beg == end ) return;
  std::ifstream file( fileName.c_str(), std::ios::binary );
  memoryFromStream( beg, end, file );
  if( !file ) throw std::runtime_error("can't read file: " + fileName);
}

template<typename T>
void vectorFromBinaryFile( std::vector<T>& v,
                     const std::string& fileName ){
  memoryFromBinaryFile( v.begin(), v.end(), fileName );
}

template<typename T>  // T should be a vector-iterator or a pointer
void memoryToBinaryFile( T beg, T end, const std::string& fileName ){
  if( beg == end ) return;
  std::ofstream file( fileName.c_str(), std::ios::binary );
  memoryToStream( beg, end, file );
  if( !file ) throw std::runtime_error("can't write file: " + fileName);
}

template<typename T>
void vectorToBinaryFile( const std::vector<T>& v,
                   const std::string& fileName ){
  memoryToBinaryFile( v.begin(), v.end(), fileName );
}

}  // end namespace cbrc
#endif  // IO_H

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