cs345 project presentation

CS345 Project Presentation

TanmayaGodbole, Melissa Olson,

Sriratana Sutasirisap

Language: Hmm++

Project Overview: Hmm++

• Revise and correct existing BNF• Implement First Class Function • Add an object oriented feature: Classes

- Modified BNF to recognize syntax for classes and object instantiation- Interpreter

BNF: What exists in Hmm• Program : {[ Declaration ]|retType Identifier Function | MyClass | MyObject}• Function : ( ) Block• MyClass: Class Idenitifier { {retType Identifier Function}Constructor {retType

Identifier Function } }• MyObject: Identifier Identifier = create Identifier callArgs• Constructor: Identifier ([{ Parameter } ]) block • Declaration : Type Identifier [ [Literal] ]{ , Identifier [ [ Literal ] ] }• Type : int|bool| float | list |tuple| object | string | void• Statements : { Statement }• Statement : ; | Declaration| Block |ForEach| Assignment |IfStatement|

WhileStatement|CallStatement|ReturnStatement• Block : { Statements }• ForEach: for( Expression <- Expression ) Block• Assignment : Identifier [ [ Expression ] ]= Expression ;• Parameter : Type Identifier• IfStatement: if ( Expression ) Block [elseifStatement| Block ]• WhileStatement: while ( Expression ) Block

BNF: What exists in Hmm

• Expression : Conjunction {|| Conjunction }• Conjunction : Equality {&&Equality }• Equality : Relation [EquOp Relation ]• EquOp: == | != • Relation : Addition [RelOp Addition ]• RelOp: <|<= |>|>= • Addition : Term {AddOp Term }• AddOp: + | -• Term : Factor {MulOp Factor }• MulOp: * | / | %• Factor : [UnaryOp]Primary• UnaryOp: - | !

BNF: What exists in Hmm• Primary : callOrLambda|IdentifierOrArrayRef| Literal |

subExpressionOrTuple|ListOrListComprehension| ObjFunction• callOrLambda : Identifier callArgs|LambdaDef• callArgs : ([Expression |passFunc { ,Expression |passFunc}] )• passFunc : Identifier (Type Identifier { Type Identifier } )• LambdaDef : (\\ Identifier { ,Identifier } -> Expression)• IdentifierOrArrayRef : Identifier [ [Expression] ]• subExpressionOrTuple : ([ Expression [,[ Expression { , Expression } ]

] ] )• ListOrListComprehension: [ Expression {, Expression } ] | |

Expression[<- Expression ] {, Expression[<- Expression ] } ]• ObjFunction: Identifier . Identifier . Identifier callArgs

BNF: What actually exists in Hmm

• Identifier : (a |b|…|z| A | B |…| Z){ (a |b|…|z| A | B |…| Z )|(0 | 1 |…| 9)}

• Literal : Integer | True | False | ClFloat | ClString• Integer : Digit { Digit }• ClFloat: 0 | 1 |…| 9 {0 | 1 |…| 9}.{0 | 1 |…| 9} • ClString: ” {~[“] }”

BNF: Revised and Corrected

• Update the concrete syntax, it matches the existing code.• Change ClFloat , after the dot, should be a ()+ not a ()*old: ClFloat: (0 | 1 |…| 9) {0 | 1 |…| 9}.{0 | 1 |…| 9} new: ClFloat: (0 | 1 |…| 9) {0 | 1 |…| 9}. (0 | 1 |…| 9) {0 | 1 |…| 9})• In ifStatement : (in the else for ifStatement)old: IfStatement: if ( Expression ) Block [elseifStatement| Block ]new: IfStatement: if ( Expression ) Block [ Block ]

First Class Function: Changes in BNF

Old• Primary : callOrLambda|IdentifierOrArrayRef| Literal |

subExpressionOrTuple|ListOrListComprehensionNew• Primary : callOrLambda|IdentifierOrArrayRef|FuncArg| Literal |

subExpressionOrTuple|ListOrListComprehension• FuncArg : Identifier ({Parameter})

int main() { list emp = createEmp();int x = 6000;println( selectDept20(emp, getSelector()) );}

(object, bool) getSelector(){int x = 1000;return (\ y -> y < x);}

list selectDept20(list emp,(object, bool) selector) {int x = 20; return [ (name, sal) | (_, name, _, _, _, sal, dept) <- emp, selector(sal), dept == x];}

list createEmp(){ return [ (7839, "KING", "PRESIDENT", 0, "17-NOV-81", 5000, 10), (7369, "SMITH", "CLERK", 7902, "17-DEC-80", 800, 20)];}

First Class Function: OldImplementation

Program (abstract syntax): Function = main; Return type = intparams = Block: list emp = Call: createEmp, stackOffset=2args =int x =IntValue: 6000 Call: println, stackOffset=0args = Call: selectDept20, stackOffset=3args = Variable: emp, LOCAL addr=1 Call: getSelector, stackOffset=3args = Function = getSelector; Return type = (object, bool)params = Block:int x =IntValue: 1000 Return: Variable: return#getSelector, LOCAL addr=0 Lambda: [y] Binary: Operator: < Variable: y, LAMBDA addr=0 Variable: x, LAMBDA addr=1 Function = selectDept20; Return type = listparams = list emp (object, bool) selector

Block:int x =IntValue: 20 Return: Variable: return#selectDept20, LOCAL addr=0ListComprehension:ListTupleExpression: Tuple of: Variable: name, LOCAL addr=4 Variable: sal, LOCAL addr=5TupleGenerator: (null, name, null, null, null, sal, dept) Variable: emp, LOCAL addr=1 Call: selector, stackOffset=0args = Variable: sal, LOCAL addr=5 Binary: Operator: == Variable: dept, LOCAL addr=6 Variable: x, LOCAL addr=3 Function = createEmp; Return type = listparams = Block: Return: Variable: return#createEmp, LOCAL addr=0ListTupleExpression: List of:ListTupleExpression: Tuple of:IntValue: 7839StringValue: KINGStringValue: PRESIDENTIntValue: 0StringValue: 17-NOV-81IntValue: 5000IntValue: 10

ListTupleExpression: Tuple of:IntValue: 7369StringValue: SMITHStringValue: CLERKIntValue: 7902StringValue: 17-DEC-80IntValue: 800IntValue: 20

[ (SMITH, 800)]

int main() { list emp = createEmp();int x = 6000;println( selectDept20(emp, getSelector(int y)) );}

bool getSelector(int y) {int x = 1000; return y < x;}

list selectDept20(list emp, (int ->bool) selector) {int x = 20; return [ (name, sal) | (_, name, _, _, _, sal, dept) <- emp, selector(sal), dept == x];}


First Class Function: New Implementation

Program (abstract syntax): Function = main; Return type = intparams = Block: list emp = Call: createEmp, stackOffset=2args =int x =IntValue: 6000 Call: println, stackOffset=0args = Call: selectDept20, stackOffset=3args = Variable: emp, LOCAL addr=1FuncArg: getSelectorargs =int y Function = getSelector; Return type = boolparams =int y Block:int x =IntValue: 1000 Return: Variable: return#getSelector, LOCAL addr=0 Binary: Operator: INT< Variable: y, LOCAL addr=1 Variable: x, LOCAL addr=2 Function = selectDept20; Return type = listparams = list emp (int ->bool) selector

Block:int x =IntValue: 20 Return: Variable: return#selectDept20, LOCAL addr=0ListComprehension:ListTupleExpression: Tuple of: Variable: name, LOCAL addr=4 Variable: sal, LOCAL addr=5TupleGenerator: (null, name, null, null, null, sal, dept) Variable: emp, LOCAL addr=1 Call: selector, stackOffset=0args = Variable: sal, LOCAL addr=5 Binary: Operator: == Variable: dept, LOCAL addr=6 Variable: x, LOCAL addr=3 Function = createEmp; Return type = listparams = Block: Return: Variable: return#createEmp, LOCAL addr=0ListTupleExpression: List of:ListTupleExpression: Tuple of:IntValue: 7839StringValue: KINGStringValue: PRESIDENTIntValue: 0StringValue: 17-NOV-81IntValue: 5000IntValue: 10

ListTupleExpression: Tuple of:IntValue: 7369StringValue: SMITHStringValue: CLERKIntValue: 7902StringValue: 17-DEC-80IntValue: 800IntValue: 20

First Class Function: Changes to the Code

Changes to Parser.jj• Changed Primary to also include funcArg• funcArg method

- identifies the arguments of the first class function that is passed as a parameter.

- It creates a FuncArg object which is added to the ASTChanges to AbstractSyntax.java• FuncArg class

- stores information about parameters

public static class FuncArg extends Expression implements LValue{ private String name; private List<Declaration>args; private intlineNum;

public FuncArg(Token t, List<Declaration> a) { name = t.image;lineNum = t.beginLine;args = a; }

public void display(int level){super.display(level); Indenter indent = new Indenter(level);System.out.print(name);indent.display(" args = ");

for( Declaration d: args){d.display(level + 1); } }

public String getName(){ return name; }

@Override public intgetLineNum(){ return lineNum; } }

First Class Function: Parser.jj

Expression primary() :{ Expression e; Token t;}{ LOOKAHEAD(3) e = callOrLambda() { return e; } | LOOKAHEAD(3) e = funcArg() { return e; } //added later | LOOKAHEAD(2) e = identifierOrArrayRef() { return e; } | e = literal() { return e; } | LOOKAHEAD(2) t = <LBRACE><RBRACE> { return ListTupleExpression.emptyList(t.beginLine); } | e = subExpressionOrTuple() { return e; } | e = listOrListComprehension() { return e; }/* TODO: Figure out the cast: | type() <LPAREN> e = expression() <RPAREN> { return e; } */}

//function added laterExpression funcArg() :{Token id; Declaration dec = null; List<Declaration>args= new ArrayList<Declaration>(); }{ id = <IDENTIFIER><LPAREN> (dec = parameter() {args.add(dec);})* <RPAREN> {return new FuncArg(id, args);}}

First Class Function: AbstractSyntax.java

Interpreter: Overview• main files are Interpreter.java, StaticTypeCheck.java, and SymbolTable.java• StaticTypeCheck.java is where compile time error checking occurs. This includes:

processing occurs by traveling down the parse tree simulating the program, even parts that are never called making sure arguments and parameters match type checking variables and associated declarations are stored on symbol table

• SymbolTable.java controls scoping (static) – maintains a system of global and local scopes contains 2 hash maps – one for global variables and one for local variables

• Interpreter.java – where runtime errors occur processing occurs by actual running of the program (call history) – starts in main and travels to any function calls, etc. retrieves variable values according to their address, retrieved from symbol table and corresponds to location on runtime stack

int main() { list emp = createEmp(); int x = 6000; println( selectDept20(emp, getSelector(int y)) );}

bool getSelector(int y) { int x = 1000; return y < x;}

list selectDept20(list emp, (int -> bool) selector) { int x = 20; return [ (name, sal) | (_, name, _, _, _, sal, dept) <- emp, selector(sal), dept == x];}


First Class Function: New Implementation

First Class Function: Interpreter

• a function call evaluates its arguments and passes the resulting values to the corresponding parameters

println( selectDept20(emp, getSelector(int c)) );

• When the program execution sees a FuncArg, then a FuncArgValue is returned which is equivalent to the FuncArg • expressions must return values because they are used in assignments, if statements, etc.• FuncArgValue allows a function to be stored in a variable and returned

if(exp instanceof FuncArg){ FuncArg funcArg = (FuncArg) exp; FuncArgValue val = new FuncArgValue(funcArg.getName(), funcArg.getArgs()); return val; }

First Class Function: Interpreter• The parameters of a method call are stored on the symbol table so that they can be used in the method body

for (int i = 0, size = args.size(); i < size; i++) { setVarValue(params.get(i).getVariable(), args.get(i)); }

• Sees call to selector – function to call has not been set in StaticTypeCheck, we must set it now

if(exp instanceof Call) { Value val = getVarValue(call.getVar());

if(val instanceof FuncArgValue){ FuncArgValue newVal = (FuncArgValue)val; Function methodToCall = Util.findFunction(prog.getFunctions(),

newVal.getMethodName()); call.setFunctWithoutOffset(methodToCall); return callRealFunction(call, args); }}

First Class Function: Demo Databaselist createEmp(){ return [ (7839, "KING", "PRESIDENT", 0, "17-NOV-81", 5000, 10), (7698, "BLAKE", "MANAGER", 7839, "01-MAY-81", 2850, 30), (7782, "CLARK", "MANAGER", 7839, "09-JUN-81", 2450, 10), (7566, "JONES", "MANAGER", 7839, "02-APR-81", 2975, 20), (7788, "SCOTT", "ANALYST", 7566, "09-DEC-82", 3000, 20), (7902, "FORD", "ANALYST", 7566, "03-DEC-81", 3000, 20), (7369, "SMITH", "CLERK", 7902, "17-DEC-80", 800, 20), (7499, "ALLEN", "SALESMAN", 7698, "20-FEB-81", 1600, 30), (7521, "WARD", "SALESMAN", 7698, "22-FEB-81", 1250, 30), (7654, "MARTIN", "SALESMAN", 7698, "28-SEP-81", 1250, 30), (7844, "TURNER", "SALESMAN", 7698, "08-SEP-81", 1500, 30), (7876, "ADAMS", "CLERK", 7788, "12-JAN-83", 1100, 20), (7900, "JAMES", "CLERK", 7698, "03-DEC-81", 950, 30), (7934, "MILLER", "CLERK", 7782, "23-JAN-82", 1300, 10) ];}

int main() { list emp = createEmp(); int x = 6000; println( selectDept20(emp, getSelector(int c)) ); //don't need to use variable y}


list selectDept20(list emp, (object -> bool) selector) { //type of selector must be (object -> bool) because we do not know that sal is an int int x = 20; return [ (name, sal) | (_, name, _, _, _, sal, dept) <- emp, selector(sal), dept == x];}

list createEmp(){…}

First Class Function: Demo fcf_test1.c

int main() { list emp = createEmp(); int x = 6000; (object -> bool) selector = getSelector(int y); //storing in a variable println( selectDept20(emp, selector ));}


list selectDept20(list emp, (object -> bool) selector) { //type of selector must be (object -> bool) because we do not know that sal is an int int x = 20; return [ (name, sal) | (_, name, _, _, _, sal, dept) <- emp, selector(sal), dept == x];}

list createEmp(){…}

First Class Function: Demo fcf_test2.c

First Class Function: Demo fcf_test3.cint main() { list emp = createEmp(); int x = 6000; (object -> bool) selector = returnFunct(); println( selectDept20(emp, selector ));}


(object -> bool) returnFunct(){ return getSelector(int y);}

list selectDept20(list emp, (object -> bool) selector) { //type of selector must be (object -> bool) because we do not know that sal is an int int x = 30; return [ (name, sal) | (_, name, _, _, _, sal, dept) <- emp, selector(sal), dept == x];} …

Classes: Modifications to BNF• Program: {[ Declaration ]|retType Identifier Function | MyClass | MyObject}• Primary: callOrLambda|IdentifierOrArrayRef| Literal |subExpressionOrTuple|

ListOrListComprehension| ObjFunction• BNF for creating a new classMyClass: Class Idenitifier { {retType Identifier Function}Constructor {retTypeIdentifier

Function } }Constructor: Identifier ([{ Parameter } ]) block • BNF for creating an instance of a classMyObject: Identifier Identifier = create Identifier callArgs• BNF for calling the class’s functionObjFunction: Identifier . Identifier . Identifier callArgs

Classes: ExampleClass Test{intmyX;intmyY; Test(intx, inty){myX= x;myY = y; }intfun (intmatch){ println(myX +myY + match); return myX + myY + match; }}

temp = Test.oneObj.fun(4);

• Creating a new class

• Creating an instance of a class Test oneObj = create Test(9, 78);

• Calling the class’s function

Classes:Changes to Parser.jj• Modified Program() to recognize class and object | c= myClass() {classList.add(c);} | o= obj() {objList.add(o);}

• Added ObjFunction to be a part of Primary()| LOOKAHEAD(3) e = objFunc() { return e; }

• Added MyClassmyClass(), Constructor constructor(), MyObjectobj(), ObjFunctionobjFunc()

MyClassmyClass() :{ Constructor cons; List<Declaration> globals= new ArrayList<Declaration>(); List<Declaration>decList List<Function>funcList = new ArrayList<Function>(); Token className; Function f;}{ <MYCLASS>className = <IDENTIFIER><LCURLY> (curTopLevelType = retType() curTopLevelToken = <IDENTIFIER> ( decList = restOfGlobalDec() {globals.addAll(decList); } | f = restOfFunction() { funcList.add(f); } ))* cons = constructor() (curTopLevelType = retType() curTopLevelToken = <IDENTIFIER> ( decList = restOfGlobalDec() {globals.addAll(decList); } | f = restOfFunction() { funcList.add(f); } ))*<RCURLY> {return new MyClass(className, globals, funcList, cons); }

Classes:Changes to AbstractSyntax.java• Modified the class Program{…} public Program(List<Declaration>globals, List<Function> functions, List<MyClass> classes, List<MyObject>

objects) { this.globals = globals; this.functions = functions; this.classes = classes; this.objects= objects; }

• Added these classes: - MyClass{…} - Constructor{…} - MyObject extends Statement{…} - ObjFunction extends Expression {…}

Classes:ASTProgram (abstract syntax): Function = main; Return type = int params = Block: int x = Call: foo, stackOffset=2 args = Call: println, stackOffset=0 args = StringValue: It worked! Function = foo; Return type = int params = Block: int temp = IntValue: 10 Object = oneObj; Object type = Test args = IntValue: 20 IntValue: 4 Assignment: Variable: temp, LOCAL addr=1 Object Function = oneObj; Function Name = fun args = Variable: temp, LOCAL addr=1 Return: Variable: return#foo, LOCAL addr=0 Variable: temp, LOCAL addr=1 Class: Test int myX int myY Function = fun; Return type = int params = int match

Block: Call: println, stackOffset=0 args = StringValue: The result from method fun is: Call: println, stackOffset=0 args = Binary: Operator: INT+ Binary: Operator: INT+ Variable: myX, INSTANCE addr=2 Variable: myY, INSTANCE addr=3 Variable: match, LOCAL addr=5 Return: Variable: return#fun, LOCAL addr=4 Binary: Operator: INT+ Binary: Operator: INT+ Variable: myX, INSTANCE addr=2 Variable: myY, INSTANCE addr=3 Variable: match, LOCAL addr=5 Constructor = Test params = int x int y Block: Assignment: Variable: myX, INSTANCE addr=2 Variable: x, LOCAL addr=4 Assignment: Variable: myY, INSTANCE addr=3 Variable: y, LOCAL addr=5

Classes: Demo

Class Test{ int myX; int myY; Test(int x, int y){ myX = x; myY = y; } int fun (int match){ println (myX +myY + match); return myX + myY + match; }}

int main() { int x = foo(); println( "It worked!" ); }

int foo(){ int temp = 10; Test oneObj = create Test(20, 4); temp = Test.oneObj.fun(temp); println(temp); return temp;}

Classes: Checking the class syntax

• The class goes through Static Type Check and is then added to the Symbol Table (stored in an ArrayList)

• The object and a list of its instance variables are stored in the symbol table in a HashMap the object as the key, and a list of the Instance Variables as the values

• Each object of a class is given its own copies of the global variables of a class.

Classes: Objects An outline of the steps required to actually create the object, assign the instance

variables an address in the symbol table, and call the constructor• An object can be created in main, or any other function• checkStatement in StaticTypeCheck, checks if the statement in the body of the

function is if(s instanceof MyObject) { MyObject obj = (MyObject) s; if( !symbolTable.classExistence(obj.getType())){ logger.error(obj.getLineNum(), UNDEFINED_CLASS, obj.getType()); } symbolTable.createObj(obj); checkClass(obj, obj.getType()); return; }

Classes: Symbol Tablepublic void createObj(MyObject obj) { Scope lastScope = scopes.get(scopes.size() - 1); int curCount = lastScope.getCurCount(); MyClass c = globalClasses.get(obj.getType()); List<Declaration> objVars = c.getGlobals(); for(Declaration decl: objVars){ Variable current = decl.getVariable(); current.setExecutionData(VarType.INSTANCE, instanceCount +

curCount, null); instanceCount++; } instanceVariables.put(obj, objVars); }

Classes: Static Type Checkvoid checkClass(MyObject obj, String className) { //added later MyClass c = symbolTable.getClass(className); Constructor cons = c.getConstructor(); checkConstructor(obj, cons); for(Function funct : c.getFunctions()) { checkOOFunction(obj, funct); } }

void checkConstructor(MyObject obj, Constructor cons) { symbolTable.startConstructor(cons);checkOOStatement(obj, cons.getBody());symbolTable.endConstructor(cons);

}

Classes: Static Type Checkpublic void startConstructor(Constructor cons){ curConstructor = cons; scopes.add(new Scope(getCurCount(), cons.getNumScopeVariables())); addLocalDeclarations(cons.getParams()); }

public void endConstructor(Constructor cons {scopes.get(scopes.size() - 1).closeScope(curConstructor.getNumScopeVariables());scopes.remove(scopes.size() - 1);

curConstructor = null; }

Classes: Static Type Check• startConstructor opens a new scope within the scope of the object• endConstructor closes the scope of the constructor

void checkOOFunction(MyObject obj, Function f) { symbolTable.startFunction(f); checkOOStatement(obj, f.getBody()); symbolTable.endFunction();}

Classes: Static Type Checkif (s instanceof Return) { Return ret = (Return) s; Type funType = symbolTable.getCurFunctionType(); // Make sure the 'void' type is actually consistent with a return expression. if (funType == BaseType.VOID && ret.getResult() != null) { logger.error(ret.getLineNum(), VOID_CAN_NOT_RETURN); return; } if (funType != BaseType.VOID && ret.getResult() == null) { logger.error(ret.getLineNum(), NON_VOID_MUST_RETURN); return; } // We also need to process the "variable" that serves as a return value: checkOOExpression(ret.getTarget()); if (ret.getResult() != null) { Type expType = checkOOExpression(ret.getResult()); testAssignment(expType, funType, ret.getLineNum(), -1) } return; }}

Classes: Static Type Check

Checks binary, and then each term in the binary. Since myX, myY are variables, it processes the Variables – which finds the instance

variables, and assigns them an address on the stack which is recorded by the symbol table.

private Type processOOVariableUse(MyObject obj, Variable var) { Type type = symbolTable.assignOOAddress(obj, var); if (type == null) { logger.error(var.getLineNum(), VAR_UNDEFINED, var.getName()); return null; } return type; }

Classes: Symbol Tablepublic Type assignOOAddress(MyObject obj, Variable var){ if (lambdaContexts.size() == 0) { Declaration decl = findNormalOODeclaration(obj, var); //myX, myY go into this if (decl == null) { decl = findNormalDeclaration(var); // x goes into this } if (decl == null) { return null; } // We have established the declaration: copy the variable type and address: var.setExecutionData(decl.getVariable()); // Make sure the type is defined: myAssert(decl.getType() != null, "The type in the declaration is null"); return decl.getType(); }

Classes: Symbol TableThe FindNormalOODeclaration method finds the instance variable in the symbol table

private Declaration findNormalOODeclaration(MyObject obj, Variable var) { List<Declaration> decList = instanceVariables.get(obj); Declaration result = null; for(Declaration decl : decList){ String curName = decl.getVariable().getName(); if(curName.equals(var.getName())) result = decl; } return result; }

Classes: Object Function

The steps involved in calling a function of an object –• temp = Test.oneObj.fun(temp); goes to checkStatement.• Since it is an instance of Expression, it goes into checkExpression

if (exp instanceof ObjFunction){ ObjFunction of = (ObjFunction) exp; return processOOFunction(of);}

Classes: Symbol Tableprivate Type processOOFunction (ObjFunction of) { List<Expression> args = of.getArgs(); String funcName = of.getFuncName(); MyObject obj = symbolTable.getObject(of.getObjName()); MyClass c = symbolTable.getClass(obj.getType()); Function funct = null; List<Function> fList = c.getFunctions(); for(Function func : fList){ if(func.getName().equals(of.getFuncName())) funct = func; } // Just in case the call has been already processed, don't try to do it again! FunctionType protoType; String name = funct.getName();

Classes: ProcessOOFunction

if (funct == null) { logger.error(of.getLineNum(), UNDEF_FUNCTION, name); return null; } // Update the 'function' reference in the call: of.setOOFunction(funct, symbolTable.getCurCount()); int lineNum = of.getLineNum(); List<Type> paramTypes = protoType.getParamTypes(); // Checking the Prototype: if (of.getArgs().size() != paramTypes.size()) { logger.error(lineNum, INV_NUM_ARGS, name, paramTypes.size(),

of.getArgs().size()); }

Classes: ProcessOOFunctionelse { for (int i = 0, size = args.size(); i < size; i++) { Type argType = checkExpression(args.get(i)); if (argType == null) { continue; } // check if arg type matches param type testAssignment(argType, paramTypes.get(i), lineNum, i); } } return protoType.getResultType(); }

Classes: InterpreterRun Statement –

if (s instanceof MyObject) { MyObject obj = (MyObject)s; MyClass c = Util.findClass(prog.getClasses(), obj.getType()); Constructor cons = c.getConstructor(); List<Value> args = evaluateExpList(obj.getArgs()); callConstructor(cons, args); return false; }

Classes: Interpreter

private List<Value> evaluateExpList(List<Expression> members) throws InterpreterRuntimeError { List<Value> result = new ArrayList<Value>(members.size());

for (Expression exp : members) { result.add(runExpression(exp)); } return result; }

Classes: Constructor

public void callConstructor(Constructor c, List<Value> args) throws InterpreterRuntimeError

{List<Declaration> params = c.getParams();if (args.size() != params.size()) { throw new InterpreterRuntimeError(c.getLineNum(), INV_NUM_ARGS, "constructor" , params.size(), args.size());}for (int i = 0, size = args.size(); i < size; i++) { setVarValue(params.get(i).getVariable(), args.get(i)); //need to worry about this! } runStatement(c.getBody()); }

Classes: Object Function

if (exp instanceof ObjFunction) { ObjFunction of = (ObjFunction)exp; List<Expression> unevaluated = of.getArgs(); List<Value> args = evaluateExpList(unevaluated); return callOOFunction(of, args); }

callOOFunction returns the result of the function which is defined in the body of the class

Classes: Interpreter

public Value callOOFunction(ObjFunction objFunc, List<Value> args) throws InterpreterRuntimeError

{ MyClass c = Util.findClass(prog.getClasses(), objFunc.getClassName()); Function f = null; List<Function> fList = c.getFunctions(); for(Function func : fList){ if(func.getName().equals(objFunc.getFuncName())) f = func; } Value result = null; basePtr += objFunc.getStackOffset(); if(f == null) throw new InterpreterRuntimeError(objFunc.getLineNum(), UNDEF_FUNCTION, "object

function");

Classes: callOOFunction

List<Declaration> params = f.getParams(); if (args.size() != params.size()) { throw new InterpreterRuntimeError(objFunc.getLineNum(), INV_NUM_ARGS, f.getName(), params.size(), args.size()); } for (int i = 0, size = args.size(); i < size; i++) { setVarValue(params.get(i).getVariable(), args.get(i)); //need to worry about this! } // Now, execute the actual Function body: runStatement(f.getBody());

Classes: callOOFunction

// NOTE: By convention, the return value shall be assigned the FIRST address: if (f.isVoid() == false) { Declaration returnDec = f.getReturnDecl(); Variable v = returnDec.getVariable(); int address = v.getAddress(); result = stack[basePtr + address]; if (result == null) { throw new InterpreterRuntimeError(objFunc.getLineNum(), FUNCTION_DID_NOT_RETURN_VALUE, f.getName()); } } basePtr -= objFunc.getStackOffset(); return result; //this result corresponds to the result of the actualy function you're calling }

Classes: Demo classTest.c

Class Test{ int myX; int myY; Test(int x, int y){ myX = x; myY = y; } int fun (int match){ println(myX +myY + match); return myX + myY + match; }}

int main() { int x = foo(); println( "It worked!" ); }

int foo(){ int temp = 10; Test oneObj = create Test(20, 4); temp = Test.oneObj.fun(temp); println(temp); return temp;}

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