popenをfstreamっぽく使うためのラッパー

pipestream.h

#pragma once

#include <cstdio>
#include <iostream>
#include <memory>
#include <stdexcept>

class invalid_command : std::runtime_error {
  public:
    invalid_command(const std::string &cause)
      : std::runtime_error(cause) {}
};

class pipestream : public std::iostream {
  public:
    pipestream(const char *path, const char *type);
    pipestream(const pipestream &p);
    ~pipestream();
  private:
    pipestream();
  public:
    int get();
    pipestream &put(char c);
  private:
    std::shared_ptr<FILE> _file_ptr;
};

pipestream::pipestream(const char *path, const char *type) {
  _file_ptr = std::shared_ptr<FILE>(popen(path, type));
  if(&*_file_ptr == nullptr) {
    throw invalid_command("popen");
  }
}

pipestream::pipestream(const pipestream &p) {
  _file_ptr = p._file_ptr;
}

pipestream::~pipestream() {
  if(_file_ptr.unique()) pclose(&*_file_ptr);
}

int pipestream::get() {
  return std::fgetc(&*_file_ptr);
}

pipestream &pipestream::put(char c) {
  std::fputc(c, &*_file_ptr);
  return *this;
}