Snel/src/sequencer.h

/*
 * child.h
 *
 *  Created on: Feb 11, 2019
 *      Author: hoo2
 */

#ifndef __sequencer_h__
#define __sequencer_h__

#include <exception>
#include <string>
#include <iostream>
#include <sstream>
#include <fstream>
#include <vector>
#include <utility>
#include <algorithm>

#include <unistd.h>
#include <fcntl.h>
#include <sys/wait.h>


namespace snel {

   //! file descriptor type
   using fd_t = int;

   constexpr fd_t STDIN_  = STDIN_FILENO;
   constexpr fd_t STDOUT_ = STDOUT_FILENO;
   constexpr fd_t STDERR_ = STDERR_FILENO;

   /*!
    *
    */
   struct ArgList {
      using type        = char;     // Basic data type
      using vtype       = type*;    // Vector type
      using vtype_ptr   = vtype*;   // Pointer to vector type

      ~ArgList();
      ArgList() = default;
      ArgList(const ArgList&) = default;
      ArgList(ArgList&&) = default;

      ArgList& push_back(const std::basic_string<type>& item);
      vtype front () { return args_.front(); }
      size_t size () { return args_.size(); }

      vtype_ptr data() noexcept {
         return args_.data();
      }
      vtype_ptr operator*() noexcept {
         return data();
      }
   private:
      std::vector<vtype> args_ {nullptr};
   };


   struct Pipe {
      fd_t fd[2] {-1, -1};
      bool from  {false};
      bool to    {false};
   };

   class Child {
   public:
      enum class LogicOp { NONE=0, OR, AND };
      using command_t = std::vector<std::string>;
      using Error = std::runtime_error;

   public:
      ~Child ();
      Child () noexcept = default;
      Child (const command_t& c) : command{c} { }
      Child (command_t&& c) : command{std::move(c)} { }

      Child& make_arguments ();
      bool execute (const Child* previous);
      Pipe& pipe() { return pipe_; }
   private:
      void redirect_std_if(std::string fn, fd_t std_fd);
      void restore_std_if(fd_t std_fd);
   private:
      command_t command {};
      ArgList arguments {};

      fd_t  files[3] = {-1, -1, -1};
      fd_t  sstd [3] = {-1, -1, -1};
      std::string filenames[3] = {"", "", ""};
      LogicOp  logic  {LogicOp::NONE};
      Pipe pipe_;
   };

   class Sequencer {
   public:
      Sequencer& parse (const std::string& input);
      Sequencer& execute ();

   private:
      bool is_seperator (std::string& s) {
         return (s == "&&" || s == "||" || s == "|") ? true : false;
      }
      bool is_pipe (std::string& s) {
         return (s == "|") ? true : false;
      }

   private:
      std::vector <
         std::vector <Child>
      > seq_ {};
   };

}

#endif /* __sequencer_h__ */