CS252-Shell-Lab-3/shell.y at main · code-help-tutor/CS252-Shell-Lab-3 · GitHub

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/*
 * CS-252
 * shell.y: parser for shell
 *
 * This parser compiles the following grammar:
 *
 *	cmd [arg]* [> filename]
 *
 * you must extend it to understand the complete shell grammar
 *
 */

%code requires
{
#include <string>

#if __cplusplus > 199711L
#define register      // Deprecated in C++11 so remove the keyword
#endif
}

%union
{
  char        *string_val;
  // Example of using a c++ type in yacc
  std::string *cpp_string;
}

%token <cpp_string> WORD
%token NOTOKEN GREAT NEWLINE TWOGREAT AMPERSAND GREATGREATAMP GREATAMP GREATGREAT LESS PIPE

%{
//#define yylex yylex
#include <cstdio>
#include "shell.hh"

void yyerror(const char * s);
int yylex();

%}

%%

goal:
  commands
  ;

commands:
  command
  | commands command
  ;

command: simple_command
       ;

io_list:
  io_list iomodifier_opt
  | /* */
  ;

simple_command:
 pipe_list io_list background_opt NEWLINE { /*removed the ">" */
  /*command_and_args iomodifier_opt NEWLINE {*/

    printf("   Yacc: Execute command\n");
    Shell::_currentCommand.exe();
  }
  | NEWLINE
  | error NEWLINE { yyerrok; }
  ;

pipe_list:
  pipe_list PIPE command_and_args
  | command_and_args
  ;

background_opt:
AMPERSAND
| /* */
;
command_and_args:
  command_word argument_list {
    Shell::_currentCommand.
    insertSimpleCommand( Command::_currentSimpleCommand );
  }
  ;

argument_list:
  argument_list argument
  | /* can be empty  */
  ;

argument:
  WORD {
    printf("   Yacc: insert argument \"%s\"\n", $1->c_str());
    Command::_currentSimpleCommand->insertArgument( $1 );
  }
  ;

command_word:
  WORD {
    printf("   Yacc: insert command \"%s\"\n", $1->c_str());
    Command::_currentSimpleCommand = new SimpleCommand();
    Command::_currentSimpleCommand->insertArgument( $1 );
  }
  ;

iomodifier_opt:
  GREAT WORD {
    printf(" Yacc: insert output \"%s\"\n", $2->c_str());
    Shell::_currentCommand._outFile = $2;
  }
  | GREATGREAT WORD {
  printf("  Yacc: append output \"%s\"\n", $2->c_str());
  Shell::_currentCommand._append = 1;
  Shell::_currentCommand._outFile = $2;
  /* append*/
  }
  | GREATAMP WORD {
 printf(" Yacc: insert outerr \"%s\"\n", $2->c_str());
  Shell::_currentCommand._outFile = $2;
  Shell::_currentCommand._errFile = $2;
  }
  | GREATGREATAMP WORD {
  printf(" Yacc: append output error \"%s\"\n",$2->c_str());
  Shell::_currentCommand._append = 1;
  Shell::_currentCommand._outFile = $2;
  Shell::_currentCommand._errFile = $2;
  }
  | TWOGREAT WORD {
  printf(" Yacc: insert err \"%s\"\n",$2->c_str());
  Shell::_currentCommand._errFile = $2;}
  | LESS WORD {
  printf(" Yacc: insert input \"%s\"\n",$2->c_str());
  Shell::_currentCommand._inFile = $2;}
  ;
   /* cannot  be empty  empty case done in list*/

%%

void
yyerror(const char * s)
{
  fprintf(stderr,"%s", s);
}

#if 0
main()
{
  yyparse();
}
#endif