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shell.y
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shell.y
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/*
* CS-413 Spring 98
* shell.y: parser for shell
*
* This parser compiles the following grammar:
*
* cmd [arg]* [> filename]
*
* you must extend it to understand the complete shell grammar
*
*/
%token <string_val> WORD
%token NOTOKEN GREAT NEWLINE PIPE ADDLINE LESS BACKGROUND
%union {
char *string_val;
}
%{
extern "C"
{
int yylex();
void yyerror (char const *s);
}
#define yylex yylex
#include <stdio.h>
#include "command.h"
%}
%%
goal:
commands
;
commands:
command
| commands command
;
command: simple_command
;
// simple command | command
simple_command:
command_and_args iomodifier_opt iomodifier_opt2 NEWLINE {
printf(" Yacc: Execute command\n");
Command::_currentCommand.execute();
}
|
command_and_args iomodifier_opt iomodifier_opt2 PIPE commands{
printf(" Yacc: Execute command\n");
Command::_currentCommand.execute();
}
| NEWLINE
| error NEWLINE { yyerrok; }
;
command_and_args:
command_word arg_list {
Command::_currentCommand.
insertSimpleCommand( Command::_currentSimpleCommand );
}
;
arg_list:
arg_list argument
| /* can be empty */
;
argument:
WORD {
printf(" Yacc: insert argument \"%s\"\n", $1);
Command::_currentSimpleCommand->insertArgument( $1 );\
}
|
BACKGROUND {
printf(" Yacc: working on background \n");
Command::_currentCommand._background = 1;
}
;
command_word:
WORD {
printf(" Yacc: insert command \"%s\"\n", $1);
Command::_currentSimpleCommand = new SimpleCommand();
Command::_currentSimpleCommand->insertArgument( $1 );
}
;
iomodifier_opt:
GREAT WORD {
printf(" Yacc: insert output \"%s\"\n", $2);
Command::_currentCommand._outFile = $2;
}
|
LESS WORD {
printf(" Yacc: insert input \"%s\"\n", $2);
Command::_currentCommand._inputFile = $2;
}
|
ADDLINE WORD {
printf(" Yacc: insert output \"%s\"\n", $2);
Command::_currentCommand._appendFile = $2;
}
| /* can be empty */
;
iomodifier_opt2:
GREAT WORD {
printf(" Yacc: insert output \"%s\"\n", $2);
Command::_currentCommand._outFile = $2;
}
|
LESS WORD {
printf(" Yacc: insert input \"%s\"\n", $2);
Command::_currentCommand._inputFile = $2;
}
|
ADDLINE WORD {
printf(" Yacc: insert output \"%s\"\n", $2);
Command::_currentCommand._appendFile = $2;
}
|/* can be empty */
;
%%
void
yyerror(const char * s)
{
fprintf(stderr,"%s", s);
}
#if 0
main()
{
yyparse();
}
#endif