linesource.h

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#pragma once
 
// Inc Libray
#include <iostream>
#include <fstream>
#include <string>
 
// Inc HAA
#include "error.h"
 
// Inc Medium
#include "counter.h"
 
// IDEA: a class for reading a file and another class for reading from stdin. A third to read interactively?
 
class LineSource : public Counter<LineSource> {
  std::string fn_;             
  std::ifstream * inFile_{};   
  bool fromcin_;               
public:
  explicit LineSource( const std::string & p_fn ) : fn_(p_fn), fromcin_(p_fn=="-") {}
 
  LineSource( const LineSource& ) = delete;
 
  LineSource( LineSource&& ) = delete;
 
  LineSource& operator=( const LineSource& ) = delete;
 
  LineSource& operator=( LineSource&& ) = delete;
 
  ~LineSource() { delete inFile_; }
 
  bool getLine( std::string & p_line ) {
    if( fromcin_ )
      return static_cast<bool>( std::getline( std::cin, p_line ) );
    if( inFile_ == nullptr ) {
      inFile_ = new (std::nothrow) std::ifstream( fn_, std::ios::in );
      if( inFile_ == nullptr )
        panicExit();                   /* LCOV_EXCL_LINE */
    }
    if( !inFile_->is_open() )
      inErrExit( cmdline, "can not open file name '" + fn_ + "'" );
    return static_cast<bool>( std::getline( *inFile_, p_line ) );
  }
};