shell.y

/*
 * 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>
#include <cstring>

#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 GREATGREAT TWOGREAT GREATAMPERSAND GREATGREATAMPERSAND 
%token AMPERSAND PIPE LESS NEWLINE IF FI THEN LBRACKET RBRACKET SEMI
%token DO DONE WHILE FOR IN

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

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

%}

%%

goal: command_list;

arg_list:
        arg_list WORD { 
          Shell::TheShell->_simpleCommand->insertArgument( $2 ); 
        }
        | /*empty string*/
	;

cmd_and_args:
	WORD { 
          char * w = (char *) $1->c_str();
	        //printf("%s\n", w);		
          if (strcmp(w, "exit") == 0) {
            printf("Good bye!!\n");
            exit(1);
          }
          Shell::TheShell->_simpleCommand = new SimpleCommand(); 
          Shell::TheShell->_simpleCommand->insertArgument( $1 );
        } 
        arg_list
	;

pipe_list:
        cmd_and_args 
	    { 
		    Shell::TheShell->_pipeCommand->insertSimpleCommand( 
		    Shell::TheShell->_simpleCommand ); 
		    Shell::TheShell->_simpleCommand = new SimpleCommand();
	    }
	| pipe_list PIPE cmd_and_args
      {
        Shell::TheShell->_pipeCommand->insertSimpleCommand(
        Shell::TheShell->_simpleCommand );
        Shell::TheShell->_simpleCommand = new SimpleCommand();
      }
	;

io_modifier:
	   GREATGREAT WORD // append std out
	    {
      if (Shell::TheShell->_pipeCommand->_outFile != NULL) {
        printf("Ambiguous output redirect.\n");
        exit(1);
      } else {
        Shell::TheShell->_pipeCommand->_outFile = $2;
        Shell::TheShell->_pipeCommand->_append = true;
      } 
	    }	
	 | GREAT WORD //redirect std out 
	    {
      if (Shell::TheShell->_pipeCommand->_outFile != NULL) {
        printf("Ambiguous output redirect.\n");
        exit(0);
      } else {
        Shell::TheShell->_pipeCommand->_outFile = $2;
      }
      }
	 |   TWOGREAT WORD // redirect std err 2
      {
        Shell::TheShell->_pipeCommand->_errFile = new std::string($2->c_str());
      }
	 | GREATGREATAMPERSAND WORD // redirect append to err and out
	    {
      if (Shell::TheShell->_pipeCommand->_outFile != NULL) {
        printf("Ambiguous output redirect.\n");
        exit(1);
      } else {
        Shell::TheShell->_pipeCommand->_outFile = $2;
        Shell::TheShell->_pipeCommand->_errFile = new std::string($2->c_str());
        Shell::TheShell->_pipeCommand->_append = true;
      }
      }
	 | GREATAMPERSAND WORD //redirect to err and out
	    {
      if (Shell::TheShell->_pipeCommand->_outFile != NULL) {
        printf("Ambiguous output redirect.\n");
        exit(1);
      } else {
        Shell::TheShell->_pipeCommand->_outFile = $2;
        Shell::TheShell->_pipeCommand->_errFile = new std::string($2->c_str());
        Shell::TheShell->_pipeCommand->_append = false;
      }
	    }
	 | LESS WORD //redirect std in
	    { 
      if (Shell::TheShell->_pipeCommand->_inFile != NULL) {
        printf("Ambiguous output redirect.\n");
        exit(1);
      } else {
		    Shell::TheShell->_pipeCommand->_inFile = $2;
      }
      }
	;

io_modifier_list:
	io_modifier_list io_modifier
	| /*empty*/
	;

background_optional: 
	AMPERSAND 
      {
        Shell::TheShell->_pipeCommand->_background = true;
      }
	| /*empty*/
	;

SEPARATOR:
	NEWLINE
	| SEMI
	;

command_line:
	 pipe_list io_modifier_list background_optional SEPARATOR 
         { 
	    Shell::TheShell->_listCommands->
		insertCommand(Shell::TheShell->_pipeCommand);
	    Shell::TheShell->_pipeCommand = new PipeCommand(); 
         }
        | if_command SEPARATOR 
         {
	    Shell::TheShell->_listCommands->
		insertCommand(Shell::TheShell->_ifCommand);
         }
        | while_command SEPARATOR 
        {
      Shell::TheShell->_listCommands->
    insertCommand(Shell::TheShell->_whileCommand);
        }
        | for_command SEPARATOR
        {
          printf("for\n");
        }
        | SEPARATOR /*accept empty cmd line*/
        | error SEPARATOR {yyerrok; Shell::TheShell->clear(); }
	;          /*error recovery*/

command_list :
     command_line 
	{ 
	   Shell::TheShell->execute();
	}
     | 
     command_list command_line 
	{
	    Shell::TheShell->execute();
	}
     ;  /* command loop*/

if_command:
    IF LBRACKET 
	{ 
	    Shell::TheShell->_level++; 
	    Shell::TheShell->_ifCommand = new IfCommand();
	} 
    arg_list RBRACKET SEMI THEN 
	{
	    Shell::TheShell->_ifCommand->insertCondition( 
		    Shell::TheShell->_simpleCommand);
	    Shell::TheShell->_simpleCommand = new SimpleCommand();
	}
    command_list FI 
	{ 
	    Shell::TheShell->_level--; 
	    Shell::TheShell->_ifCommand->insertListCommands( 
		    Shell::TheShell->_listCommands);
	    Shell::TheShell->_listCommands = new ListCommands();
	}
    ;

while_command:
    IF LBRACKET 
	{ 
	    Shell::TheShell->_level++; 
	    Shell::TheShell->_ifCommand = new IfCommand();
	} 
    arg_list RBRACKET SEMI THEN 
	{
	    Shell::TheShell->_ifCommand->insertCondition( 
		    Shell::TheShell->_simpleCommand);
	    Shell::TheShell->_simpleCommand = new SimpleCommand();
	}
    command_list FI 
	{ 
	    Shell::TheShell->_level--; 
	    Shell::TheShell->_ifCommand->insertListCommands( 
		    Shell::TheShell->_listCommands);
	    Shell::TheShell->_listCommands = new ListCommands();
	}
  ;

for_command:
        IF LBRACKET 
	{ 
	    Shell::TheShell->_level++; 
	    Shell::TheShell->_ifCommand = new IfCommand();
	} 
    arg_list RBRACKET SEMI THEN 
	{
	    Shell::TheShell->_ifCommand->insertCondition( 
		    Shell::TheShell->_simpleCommand);
	    Shell::TheShell->_simpleCommand = new SimpleCommand();
	}
    command_list FI 
	{ 
	    Shell::TheShell->_level--; 
	    Shell::TheShell->_ifCommand->insertListCommands( 
		    Shell::TheShell->_listCommands);
	    Shell::TheShell->_listCommands = new ListCommands();
	}
    ;

%%

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

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