Hi Mira:

below I did a cd for a part of the new language.
It was part of the final exam for fall 97.

Does this look right?

-- Karl
==============

From:
/proj/adaptive/www/course/exams/f-3360-f97
Preparation in:
/proj/asl/lieber/java/new-java-envs/fall97/


Question 2:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
7 UNKNOWNs, 10 points each


You are given the following artifacs:

program.cd 
  defines a new visitor notation
program.input
  gives an example of the new visitor notation
DisplayVisitor.beh 
  generated from program.cd by gendisplayvis.beh
gendisplayvis.beh
  DisplayVisitor generator
A summary of demjava.cd
  only what is important for display visitor generation
out
  the output produced by DisplayVisitor.beh for the
  object in program.input

program.cd
====================================

Visitors = Visitor_List.

Visitor = VisitorName [Modification] VisitorBody.
Modification = "modifies" VisitorName.
VisitorBody = VisitorEntry_CList.
VisitorEntry : ModifyStructure | ModifyBehavior | During | Boundary.
ModifyStructure : DataMember | Init | Return.
Boundary : Start | Finish *common* Strat JavaCode.
ModifyBehavior = <what> ClassExp <entries> BehaviorOrStructure_CList.
BehaviorEntry :  WhenVisiting  *common* JavaCode.
BehaviorOrStructure : BehaviorEntry | ModifyStructure2.
ModifyStructure2 = ModifyStructure. // to prevent multiple inheritance
WhenVisiting = "when-visiting".
During = "during" Strat ModifyBehavior_CList.
DataMember = "local" Ident ";".
Init = "init" JavaCode.
Return = "return" JavaCode.
Start = "start". 
Finish = "finish".
ClassExp = Ident. 
JavaCode		= <code> Text.
Main = .
VisitorName = Ident.
Strat = "strategy".

Visitor_List ~ {Visitor}.
VisitorEntry_CList ~ "{" {VisitorEntry} "}".
BehaviorOrStructure_CList ~ "{" {BehaviorOrStructure} "}".
ModifyBehavior_CList ~ "{" {ModifyBehavior} "}".
  
program.input
=========================================

DFTVisitor
  // some strategy type
  // {-> Graph Adjacency
  //  -> Adjacency Vertex
  //  -> Vertex Adjacency}
   
{ // visitor entries
  Adjacency {
    local mark;
	init (@ mark = false; @)
    return (@ mark @)
	when-visiting (@ if (mark==false) {mark=true;}; @)
  }
}

ConnectivityVisitor modifies DFTVisitor
{ //visitor entries
  local count;
  init (@ count = 0;@)
  return (@ count @)
  during strategy // {-> Graph Adjacency stop}
  {
    Adjacency {
	  when-visiting (@
	    if (next.return()=false)
		  // check whether unmarked
		  {count+=1; next();};
	  @)
	}
  }
}

DisplayVisitor.beh
==============================================


     1	// This file is automatically generated by Demeter/Java.
       
     2	DisplayVisitor {
     3	  (@
     4	    private java.io.PrintWriter out = new java.io.PrintWriter(System.out, true);
     5	    java.io.PrintWriter get_out()             { return out; }
     6	    void set_out(java.io.PrintWriter new_out) { out = new_out; }
     7	    DisplayVisitor(java.io.PrintWriter out)     { set_out(out); }
     8	    DisplayVisitor(java.io.PrintStream out)
     9	      { set_out(new java.io.PrintWriter(out, true)); }
    10	  @)
       
       
    11	  before Visitors (@
    12	    out.print(": Visitors  (");
    13	    indent++;
    14	  @)
    15	  after Visitors (@
    16	    out.print(" )");
    17	    indent--;
    18	  @)
    19	  before -> Visitors, visitor_list, Visitor_List (@
    20	    out.println();    for (int i = 0; i < indent; i++) out.print("\t");
    21	    out.print("<visitor_list> ");
    22	  @)
    23	  before Visitor (@
    24	    out.print(": Visitor  (");
    25	    indent++;
    26	  @)
    27	  after Visitor (@
    28	    out.print(" )");
    29	    indent--;
    30	  @)
    31	  before -> Visitor, visitorname, VisitorName (@
    32	    out.println();    for (int i = 0; i < indent; i++) out.print("\t");
    33	    out.print("<visitorname> ");
    34	  @)
    35	  before -> Visitor, modification, Modification (@
    36	    out.println();    for (int i = 0; i < indent; i++) out.print("\t");
    37	    out.print("<modification> ");
    38	  @)

   OMITTED

   139	  before -> DataMember, ident, Ident (@
   140	    out.println();    for (int i = 0; i < indent; i++) out.print("\t");
   141	    out.print("<ident> ");
   142	    out.print(" : Ident");
   143	    out.print(" \"" + source.get_ident() + "\"");
   144	  @)
   145	  before Init (@
   146	    out.print(": Init  (");
   147	    indent++;
   148	  @)
   149	  after Init (@
   150	    out.print(" )");
   151	    indent--;
   152	  @)
   153	  before -> Init, javacode, JavaCode (@
   154	    out.println();    for (int i = 0; i < indent; i++) out.print("\t");
   155	    out.print("<javacode> ");
   156	  @)
   157	  before Return (@
   158	    out.print(": Return  (");
   159	    indent++;
   160	  @)

   CUT


gendisplayvis.beh:
(the first part is numbered; the second part contains
some utility functions which are not numbered. This code
is taken from the Demeter/Java source and was written by
Doug Orleans and Geoff Hulten.)
======================================


     1	// genuniversal.beh -- generate code for DisplayVisitor.
     2	// $Id: gendisplayvis.beh,v 1.8 1997/10/09 11:30:02 dougo Exp $
       
     3	Program {
     4	  /** Add a "DisplayVisitor" class to the set of class definitions.
     5	      Don't call this until after buildClassDefTable()! */
     6	  void addDisplayVisitor(String name) (@
     7	    addClassDef(ClassDef.parse("*notparsed* *visitor* " + name
     8					+ " = <indent> int."));
     9	  @)
    10	  /** Generate the behavior file for DisplayVisitor. */
    11	  void generateDisplayVisitor(String name, File file) = allParts {
    12	    before Program (@
    13	      host.openOutputFile(file);
    14	      Program.out.println(host.genericOutputVisitorPreamble(name));
    15	    @)
       
    16	    (@ ClassName classname; @)
    17	    before ClassDef (@
    18	      classname = host.get_classname();
       
    19	      // don't do anything for alternation classes
    20	      if (host.isAlternationClass()) return;
       
    21	      boolean rep = classname.isOrWasRepetitionClass();
    22	      String body =
    23	        "    out.print(\": " + classname + "  "
    24	      + (rep ? "{" : "(") + "\");\n"
    25	      + "    indent++;\n";
    26	      Program.out.println(classname.makeBefore(body));
       
    27	      body =
    28		"    out.print(\" "
    29	      + (rep ? "}" : ")") + "\");\n"
    30	      + "    indent--;\n";
    31	      Program.out.println(classname.makeAfter(body));
    32	    @)
       
    33	    before Part (@
    34	      ClassName dest = host.get_classname();
    35	      String deststr = dest.toString();
    36	      PartName partname = host.get_partname();
       
    37	      String body =
    38	        "    out.println();"
    39	      + "    for (int i = 0; i < indent; i++) out.print(\"\\t\");\n"
    40	      + "    out.print(\"<" + partname + "> \");\n";
       
    41	      if (dest.isBuiltinType()) {
    42		if (deststr.equals("char")) {
    43		  body += "    out.print(\" '\""
    44			  + " + source.get_" + partname + "() + \"' \");\n";
    45		} else {
    46		  body += "    out.print(\" : " 
    47			 + dest + " \\\"\" + dest + \"\\\"\");\n";
    48		}
    49	      } else if (dest.isTerminalClass()) {
    50		body += "    out.print(\" : " + dest + "\");\n";
    51		if (deststr.equals("String")) {
    52		  body += "    out.print(\" \\\"\""
    53			  + " + source.get_" + partname + "() + \"\\\" \");\n";
    54		} else if (deststr.equals("Text")) {
    55		  body += "    out.print(\" " + Text.begin + "\""
    56			  + " + source.get_" + partname + "() + "
    57			  + Text.quoted_end + " + \" \");\n";
    58		} else if (deststr.equals("Character")) {
    59		  body += "    out.print(\" '\""
    60			  + " + source.get_" + partname + "() + \"' \");\n";
    61		} else {
    62		  body += "    out.print(\" \\\"\" + source.get_" + partname + "() + \"\\\"\");\n";
    63		}
    64	      }
       
    65	      Program.out.println(host.makeBefore(classname, body));
    66	    @)
       
    67	    after Program (@
    68	      Program.out.println("}");
    69	      host.closeOutputFile();
    70	    @)
    71	  }
    72	}


ClassNameAccessor { before ClassSpec (@ @) before ClassName (@ @) }

ClassDef {
  traversal toClassName(ClassNameAccessor v) {
    bypassing { ClassParts, ClassMethods, -> *,parameters,* }
    to ClassName;
  }
}
{ Subclass, Superclass, Part, RepeatedPart } {
  traversal toClassName(ClassNameAccessor v) {
    bypassing { -> *,actual_parameters,* } to ClassName;
  }
}
{ ClassDef, Subclass, Superclass, Part, RepeatedPart } {
  ClassName get_classname() = toClassName {
    before ClassName (@ return_val = host; @)
  }
}
{ ClassDef, Part, RepeatedPart } {
  void set_classname(ClassName classname) = toClassName {
    before ClassSpec (@ host.set_classname(classname); @)
  }
}

Part {
  (@
    boolean isTerminal() {
      ClassDef def = Program.prog.findClassDef(get_classname());
      return def == null || def.isInterface();
    }
    String makeWrapper(ClassName source, String body) {
      return new PartGlob(source, get_partname(), get_classname())
	     + " " + Text.begin + body + Text.end;
    }
    String makeBefore(ClassName source, String body) {
      return "  before " + makeWrapper(source, "\n" + body + "  ");
    }
    String makeAfter(ClassName source, String body) {
      return "  after " + makeWrapper(source, "\n" + body + "  ");
    }
  @)
}

ClassName {
  (@
    String makeWrapper(String body) {
      return this + " " + Text.begin + body + Text.end;
    }
    String makeBefore(String body) {
      return "  before " + makeWrapper("\n" + body + "  ");
    }
    String makeAfter(String body) {
      return "  after " + makeWrapper("\n" + body + "  ");
    }
  @)
}

ClassName {
  (@
    private static String builtinTypes[] = {
      "boolean", "char", "byte", "short", "int", "long", "float", "double"
    };
    private static String terminalClasses[] = {
      // from java.lang.*:
      "Boolean", "Character", "Integer", "Long", "Float", "Double",
      "Number", "String", "StringBuffer",
      // from demeter.*:
      "Ident", "Text"
    };
    boolean isBuiltinType() {
      String s = toString();
      for (int i = 0; i < builtinTypes.length; i++) {
	if (builtinTypes[i].equals(s)) return true;
      }
      return false;
    }
    boolean isTerminalClass() {
      String s = toString();
      for (int i = 0; i < terminalClasses.length; i++) {
	if (terminalClasses[i].equals(s)) return true;
      }
      return false;
    }
    boolean isKnownTerminal() {
      return isBuiltinType() || isTerminalClass();
    }
  @)
}

PartGlob {
  public String toString() (@
	return "-> " + source + ", " + name + ", " + dest;
  @)
}

{ Program, ClassDef } {
  traversal allParts(PartVisitor v) { to { Part, RepeatedPart }; }
}

A summary of demjava.cd:
=========================================================
=========================================================

Instead of giving you the class dictionary for Demeter/Java
(which has several hundred lines) I summarize
the information it must contain for the purpose of
generating the DisplayVisitor:

generateDisplayVisitor:
{-> Program ClassDef
 -> ClassDef Part}

  get_classname:
  {-> {ClassDef,Part} ClassName}

  get_partname:
  {-> Part PartName}

This means that there must be classes 
    Program ClassDef Part ClassName PartName
which are connected as follows:
There must be a path from Program via ClassDef
to Part. From ClassDef and Part there must 
be a path to ClassName. From Part there
must be a path to PartName.


out:
=======================================================

     1	CLASSPATH=./gen:$CLASSPATH java Main < program.input
     2	 done  
     3	: Visitors  (
     4		<visitor_list> : Visitor_List  {
     5			<first> : Nonempty_Visitor_List  (
     6				<it> : Visitor  (
     7					<visitorname> : VisitorName  (
     8						<ident>  : Ident "DFTVisitor" )
     9					<visitorbody> : VisitorBody  (

     CUT

Here come the unknowns:

Example:

line 3 in out:  
  : Visitors  (
is printed by lines UNKNOWN100 in DisplayVisitor.beh
and those lines in DisplayVisitor.beh are
printed by lines UNKNOWN200 in gendisplayvis.beh

UNKNOWN100 = 12
UNKNOWN200 = 26

The following part of line 4 in out:
  <visitor_list> 
is printed by lines UNKNOWN1  in DisplayVisitor.beh.

Line 24 of DisplayVisitor.beh:
   out.print(": Visitor  (");
is printed by line UNKNOWN2  in gendisplayvis.beh.

Line 28 of DisplayVisitor.beh:
  out.print(" )");
is printed by line UNKNOWN3 in gendisplayvis.beh.

Line 31 of DisplayVisitor.beh:
  before -> Visitor, visitorname, VisitorName (@
is printed by line UNKNOWN4  in gendisplayvis.beh.

Line 142 of DisplayVisitor.beh:
  out.print(" : Ident");
is printed by line UNKNOWN5  in gendisplayvis.beh.


We want to modify the program as follows:
Instead of printing all the part names, as in:

: Visitors  (
<visitor_list> : Visitor_List  {
  <first> : Nonempty_Visitor_List  (
    <it> : Visitor  (
      <visitorname> : VisitorName  (
        <ident>  : Ident "DFTVisitor" )

we want a simplified form of display which looks like:

: Visitors  (
  : Visitor_List  {
    : Nonempty_Visitor_List  (
      : Visitor  (
        : VisitorName  (
          : Ident "DFTVisitor" )

Give in UNKNOWN6 the line number(s) of gendisplayvis.beh which
need to be changed, and indicate how to change them. Note
the the indentation should be kept as shown in the above
example.

===========

The following is a utility function in Demeter/Java:

// you can attach the same code to several classes
{ ClassDef, Subclass, Superclass, Part, RepeatedPart } {
  ClassName get_classname()  
    bypassing { ClassParts, ClassMethods, -> *,parameters,* }
    to ClassName 
    // the following is an inlined visitor
    { before ClassName (@ return_val = host; @)
    }
}

Explain the purpose of this code in UNKNOWN7.