JShellParser.cc

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#include <iostream>
#include <iomanip>
#include <string>
#include <cstring>
#include <list>

#include "JLang/JNullType.hh"
#include "JLang/JEquation.hh"
#include "JLang/JEquationFacet.hh"
#include "JLang/JException.hh"
#include "JLang/JRedirectStream.hh"
#include "JLang/JLangToolkit.hh"
#include "JSystem/JSystemToolkit.hh"
#include "Jeep/JParser.hh"


/**
 * \author mdejong
 */

namespace {

  using namespace JPP;

  const char OPTIONS_SEPARATOR = ',';   //!< options separator
  

  /**
   * Auxiliary class for environment variable.
   */
  template<class T>
  struct JParameter {
    /**
     * Constructor.
     *
     * \param  variable             environment variable
     */
    JParameter(const std::string& variable) :
      name (variable),
      value()
    {}


    /**
     * Equals operator.
     *
     * \param  first                first  parameter
     * \param  second               second parameter
     * \return                      true if first parameter equals second parameter; else false
     */
    friend bool operator==(const JParameter& first, const JParameter& second)
    {
      return (first.name  == second.name &&
              first.value == second.value);
    }


    /**
     * Stream input.
     *
     * Note that only the value of the parameter is read.
     *
     * \param  in                   input stream
     * \return                      input stream
     */
    inline std::istream& read(std::istream& in)
    {
      return in >> this->value;
    }


    /**
     * Stream output.
     *
     * Note that only the value of the parameter is written.
     *
     * \param  out                  output stream
     * \return                      output stream
     */
    inline std::ostream& write(std::ostream& out) const
    {
      return out << this->value;
    }
      
    std::string   name;             //!< environment variable name
    T             value;            //!< environment variable value
  };


  /**
   * Template specialisation of JParameter<std::string>::read.
   *
   * Note that the complete text until the end-of-line is read, including possible white spaces.
   *
   * \param  in          input stream
   * \return             input stream
   */
  template<>
  inline std::istream& JParameter<std::string>::read(std::istream& in)
  {
    return std::getline(in, this->value);
  }


  /**
   * Template specialisation of JParameter<bool>::read.
   *
   * Note that no data are read; only the value is set to <tt>true</tt>
   *
   * \param  in          input stream
   * \return             input stream
   */
  template<>
  inline std::istream& JParameter<bool>::read(std::istream& in)
  {
    this->value = true;
    
    return in;
  }


  /**
   * Template specialisation of JParameter<bool>::write.
   *
   * \param  out         output stream
   * \return             output stream
   */
  template<>
  inline std::ostream& JParameter<bool>::write(std::ostream& out) const
  {
    return out << (this->value ? "1" : "0");
  }


  /**
   * Stream input of parameter.
   *
   * \param  in                   input stream
   * \param  parameter            parameter
   * \return                      input stream
   */
  template<class T>
  inline std::istream& operator>>(std::istream& in, JParameter<T>& parameter)
  {
    return parameter.read(in);
  }
  
  
  /**
   * Stream output of parameter.
   *
   * \param  out                  output stream
   * \param  parameter            parameter
   * \return                      output stream
   */
  template<class T>
  inline std::ostream& operator<<(std::ostream& out, const JParameter<T>& parameter)
  {
    return parameter.write(out);
  }


  /**
   * Base class for environment variables.
   */
  template<class T = JNullType>
  struct JShellParser;


  /**
   * Base class for environment variables.
   *
   * This class is used to redirect the standard output and error so that 
   *  - output is parsed via JSYSTEM::gprint; and
   *  - termination is handled via JSYSTEM::gexit.
   */
  template<>
  struct JShellParser<JNullType> :
    public JParser<>
  {
    typedef JParser<>::key_type                      key_type;


    /**
     * Default constructor.
     */
    JShellParser() :
      __terminate__(false),
      __exit_code__(0)
    {}


    /**
     * Terminate.
     *
     * \param  status      exit status
     */
    virtual void terminate(const int status) 
    {
      __terminate__ = true;
      __exit_code__ = status;
    }


    /**
     * Parse the program's command line options.
     *
     * \param  args        argument list
     * \return             argument list
     */
    JArgs operator()(const JArgs& args)
    {
      using namespace std;
      using namespace JPP;

      ostringstream os;

      {
        JRedirectStream rs_out(cout, os);
        JRedirectStream rs_err(cerr, os);

        if (rs_out &&
            rs_err) {
          static_cast<JParser<>&>(*this)(args);
        }
      }

      gprint(os.str());

      if (__terminate__) {
        gexit(__exit_code__);
      }

      return JArgs();
    }

  private:
    bool __terminate__;
    int  __exit_code__;
  };


  /**
   * Base class for environment variables.
   *
   * This class includes the data to be evaluated to shell variables in the end.
   */
  template<class T>
  struct JShellParser :
    public JShellParser<>
  {
    typedef JShellParser<>::key_type                   key_type;
    typedef JParameter<T>                              parameter_type;
    typedef std::list<parameter_type>                  data_type;


    /**
     * Evaluate environment to shell commands.
     */
    void evaluate() const
    {
      for (typename data_type::const_iterator i = this->data.begin(); i != this->data.end(); ++i) {

        std::ostringstream os;

        os << *i;

        set_variable(i->name, os.str());
      }
    }


  protected:
    data_type data;     //!< internal memory
  };


  /**
   * Parser for environment variables.
   */
  template<class T>
  struct JEnvironment;

  
  /**
   * Template specialisation of JEnvironment for regular environment variables.
   */
  template<>
  struct JEnvironment<std::string> :
    public JShellParser<std::string>
  {
    typedef JShellParser<std::string>::key_type          key_type;
    typedef JShellParser<std::string>::parameter_type    parameter_type;


    /**
     * Default constructor.
     */
    JEnvironment() 
    {}


    /**
     * Stream input.
     *
     * \param  in                   input stream
     * \param  environment          environment
     * \return                      input stream
     */
    friend inline std::istream& operator>>(std::istream& in, JEnvironment& environment)
    {
      using namespace std;
      using namespace JPP;

      static const JEquationFacet facet(JEquationParameters("=", ";\n", "./", "#"));

      char       c;
      key_type   key;
      JEquation  equation;

      if (!has_facet<JEquationFacet>(in.getloc())) {
        in.imbue(locale(in.getloc(), facet.clone()));
      }

      if (in >> c >> key >> equation) {

        if (c == '-' && !equation.getKey().empty()) {

          environment.data.push_back(parameter_type(equation.getKey()));

          parameter_type& parameter = environment.data.back();

          if (facet.isSeparator(equation.getSeparator())) {

            // read possible values
            
            istringstream is(equation.getValue());

            vector<parameter_type> possible_values;
            
            for (parameter_type buffer(parameter.name); getline(is, buffer.value, OPTIONS_SEPARATOR); ) {

              buffer.value = trim(buffer.value);

              possible_values.push_back(buffer);
            }
            
            environment[key] = JPARSER::getOption(parameter, equation.getKey(), possible_values.begin(), possible_values.end());

          } else {

            environment[key] = JPARSER::getOption(parameter, equation.getKey());
          }

        } else {

          THROW(JParseError, "JEnvironment: error parsing " << c << " <" << equation.getKey() << ">");
        }
      }

      return in;
    }
  };


  /**
   * Template specialisation of JEnvironment for boolean environment variables.
   */
  template<>
  struct JEnvironment<bool> :
    public JShellParser<bool>
  {
    typedef JShellParser<bool>::key_type                 key_type;
    typedef JShellParser<bool>::parameter_type           parameter_type;


    /**
     * Default constructor.
     */
    JEnvironment() 
    {}


    /**
     * Stream input.
     *
     * \param  in                   input stream
     * \param  environment          environment
     * \return                      input stream
     */
    friend inline std::istream& operator>>(std::istream& in, JEnvironment& environment)
    {
      using namespace std;
      using namespace JPP;

      static const JEquationFacet facet(JEquationParameters("=", ";\n", "./", "#"));

      char       c;
      key_type   key;
      JEquation  equation;

      if (!has_facet<JEquationFacet>(in.getloc())) {
        in.imbue(locale(in.getloc(), facet.clone()));
      }

      if (in >> c >> key >> equation) {

        if (c == '-' && !equation.getKey().empty()) {

          environment.data.push_back(parameter_type(equation.getKey()));

          parameter_type& parameter = environment.data.back();
          
          if (facet.isSeparator(equation.getSeparator()) || equation.getValue() != "") {

            THROW(JParseError, "JEnvironment: invalid operation " << c << " <" << equation.getKey() << ">");
          
          } else {

            environment[key] = JPARSER::getOption(parameter.value, equation.getKey());
          }

        } else {

          THROW(JParseError, "JEnvironment: error parsing " << c << " <" << equation.getKey() << ">");
        }
      }

      return in;
    }
  };
}


/**
 * \file
 *
 * Auxiliary program to interface JPARSER::JParser to command line of shell scripts.
 * Syntax:
 * <pre>
 *   eval `JShellParser -o "-a <environment variable> [= <default value>[, <possible value>]]" -- $*`
 * </pre>
 */
int main(int argc, char **argv)
{
  using namespace std;
  using namespace JPP;
  
  try {

    JEnvironment<bool>   boolean;
    JEnvironment<string> regular;

    JParser<> zap;

    zap['b'] = make_field(boolean) = JPARSER::initialised();
    zap['o'] = make_field(regular) = JPARSER::initialised();

    const JArgs options = zap(argc, argv);

    JShellParser<> buffer;

    buffer.join(boolean);
    buffer.join(regular);

    buffer(options);

    boolean.evaluate();
    regular.evaluate();
  }
  catch(const exception& error) {
    return gexit(2, error.what());
  }
}