import edu.neu.ccs.demeter.dj.*;
import java.util.*;

FileSystem = <root> CompoundFile EOF.
File : SimpleFile | CompoundFile common <f> FileName.
SimpleFile = "simple".
CompoundFile = "compound" <contents> PList(File)[ <parents> CompoundFile ]. 

Commands = "("List(Command) ")".
Command : Simple.
Simple : MakeDirectory | ChangeDirectoryUp | ChangeDirectoryDown |
RecursiveCopy | DiskUsage | Find | Echo |
SymbolicLink | RemoveDirectory | CreateEmptyFile | RemoveFile.
MakeDirectory = "mkdir" DirectoryName.
ChangeDirectoryUp = "cd ..".
ChangeDirectoryDown = "cd" DirectoryName.
RecursiveCopy = "cp -r ../* ." .
DiskUsage = "du .".
SymbolicLink = "ln -s" <from> FileName <to> FileName.
RemoveDirectory = "rmdir" DirectoryName.

// "touch f" creates an empty file called f.
CreateEmptyFile = "touch" FileName.
RemoveFile = "rm" FileName.

Find = "find . -name" DirectoryName "-print".

Echo = "echo" Message.

FileName = Ident.
DirectoryName = Ident.
Message = String.

PList(S) ~ "(" {S} ")".
List(S) ~ {S}.

CommandsVisitor = extends Visitor.

FindVisitor =  <findName> Ident
			   <dV> MyDisplayVisitor
			   <result> boolean
                extends Visitor.
                  
MyDisplayVisitor = <displayResult> String
				  <start> CompoundFile
                 <stack> Stack extends Visitor.
                 
DiskUsageVisitor = <dV> MyDisplayVisitor extends Visitor.                 
Main = .