Assignment 4
Due: 20 March at 11:59pm
Implement a LeBlanc-Cook symbol table by completing the given class. You should create unit tests for the given methods.
Create a Visitor class called TypeCheckVisitor by completing the given class. Your visitor should traverse the AST generated by your parser from Assignment 3 and perform type checking according to the rules described below. Your Visitor class will both decorate the tree and check conditions along the way. If a condition is violated, throw a TypeCheckException.
Global rules: no variable may be declared more than once in the same scope.
The name of the program is not a variable name—it is used to name the class implemented by the program but does not preclude the same name begin declared as a variable.
SymbolTable symbab = new SymbolTable()
Program ∷= List<ParamDec> Block
ParamDec ∷= type ident symtab.insert(ident.getText(), ParamDec);
Block ∷= symtab.enterScope() List<Dec> List<Statement> symtab.leaveScope()
Dec ∷= type ident symtab.insert(ident.getText(), Dec);
Statement ∷= SleepStatement | WhileStatement | IfStatement | Chain
| AssignmentStatement
SleepStatement ∷= Expression condition: Expression.type==INTEGER
AssignmentStatement ∷= IdentLValue Expression
condition: IdentLValue.type== Expression.type
Chain ∷= ChainElem | BinaryChain
ChainElem ::= IdentChain | FilterOpChain | FrameOpChain | ImageOpChain
IdentChain ∷= ident
condition: ident has been declared and is visible in the current scope
IdentChain.type <- ident.type
ident.type <- symtab.lookup(ident.getText()).getType()
FilterOpChain ∷= filterOp Tuple
condition: Tuple.length == 0
FilterOpChain.type <- IMAGE
FrameOpChain ∷= frameOp Tuple
if (FrameOP.isKind(KW_SHOW, KW_HIDE) {
condition: Tuple.length == 0
FrameOpChain.type <- NONE
}
else if (FrameOp.isKind(KW_XLOC, KW_YLOC){
condition: Tuple.length == 0
FrameOpChain.type <- INTEGER
}
else if(FrameOp.isKind(KW_MOVE){
condition: Tuple.length == 2
FrameOpChain.type <- NONE
}
else there is a bug in your parser
ImageOpChain ∷= imageOp Tuple
if (imageOp.isKind(OP_WIDTH, OP_HEIGHT){
condition: Tuple.length == 0
ImageOpChain.type <- INTEGER
}
else if (imageOP.isKind(KW_SCALE)){
condition: Tuple.length==1
ImageOpChain.type <- IMAGE
}
BinaryChain ∷= Chain (arrow | bararrow) ChainElem
Legal combinations shown:
| BinaryChain | Chain | op | ChainElem | |
| type <-IMAGE | type =URL | arrow | type = IMAGE | |
| type <-IMAGE | type = FILE | arrow | type = IMAGE | |
| type <-INTEGER | type = FRAME | arrow | instanceof FrameOp &
firstToken ∈ { KW_XLOC, KW_YLOC} |
|
| type <-FRAME | type = FRAME | arrow | instanceof FrameOp &
firstToken ∈ { KW_SHOW, KW_HIDE, KW_MOVE} |
|
| type <-INTEGER | type = IMAGE | arrow | instanceof ImageOpChain) && firstToken ∈ { OP_WIDTH, OP_HEIGHT} | |
| type <-FRAME | type = IMAGE | arrow | type = FRAME | |
| type <-NONE | type = IMAGE | arrow | type = FILE | |
| type <-IMAGE | type = IMAGE | arrow | barrow | instanceof FilterOpChain &
firstToken ∈ {OP_GRAY, OP_BLUR, OP_CONVOLVE} |
|
| type <-IMAGE | type = IMAGE | arrow | instanceof ImageOpChain &
firstToken ∈ {KW_SCALE} |
|
| type <-IMAGE | type = IMAGE | arrow | instanceof IdentChain | |
WhileStatement ∷= Expression Block
condition: Expression.type = Boolean
IfStatement ∷= Expression Block
condition: Expression.type = Boolean
Expression ∷= IdentExpression | IntLitExpression | BooleanLitExpression| ConstantExpression | BinaryExpression
IdentExpression ∷= ident
condition: ident has been declared and is visible in the current scope
IdentExpression.type <- ident.type
IdentExpression.dec <- Dec of ident
IdentLValue ∷= ident
condition: ident has been declared and is visible in the current scope
IdentLValue.dec <- Dec of ident
IntLitExpression ∷= intLit
IntLitExpression.type <- INTEGER
BooleanLitExpression ∷= booleanLiteral
BooleanLitExpression.type <- BOOLEAN
ConstantExpression ∷= screenWidth | screenHeight
ConstantExpression.type <- INTEGER
BinaryExpression ∷= Expression op Expression
Legal combinations shown:
| BinaryExpression.type | Expression0.type | op | Expression1.type |
| INTEGER | INTEGER | PLUS, MINUS | INTEGER |
| IMAGE | IMAGE | PLUS, MINUS | IMAGE |
| INTEGER | INTEGER | TIMES,DIV | INTEGER |
| IMAGE | INTEGER | TIMES | IMAGE |
| IMAGE | IMAGE | TIMES | INTEGER |
| BOOLEAN | INTEGER | LT,GT,LE,GE | INTEGER |
| BOOLEAN | BOOLEAN | LT,GT,LE,GE | BOOLEAN |
| BOOLEAN | EQUAL, NOTEQUAL | condition: Expression0.type = Expression1.type |
Tuple ∷= List<Expression>
condition: for all expression in List<Expression>: Expression.type = INTEGER
op ∷= relOp | weakOp | strongOp
type ∷= integer | image | frame | file | boolean | url
You will need to add an attribute along with get and set methods to some of the AST classes to record the type. In particular, add a TypeName field to Expression, Dec, and Chain. TypeName is defined in class cop5556sp17.AST and provided for you. Note that it is inherited by all of the subclasses of the given classes. If your Parser and Scanner have been implemented correctly, you shouldn’t need to modify them.
A couple of junit tests have been provided in TypeCheckVisitorTest.java. You need to add more. As before you can work incrementally by calling the parser with a different method than parse.
Turn in a jar file containing your source code TypeCheckVisitor.java, SymbolTable.java, Parser.java, Scanner.java, all of the AST nodes, Type.java, and your TypeCheckVisitorTest.java.
Your TypeCheckVisitorTest.java will not be graded, but may be looked at in case of academic honesty issues. We will subject your classes to our set of junit tests and your grade will be determined solely by how many tests are passed. Name your jar file in the following format:
firstname_lastname_ufid_hw4.jar
Additional requirements:
- Your code must remain package cop5556sp17(case sensitive): do not create additional packages.
- The provided class Type is in package cop5556sp17.AST. As before, all of the classes in this package should be in a folder called AST inside the cop5556sp17 folder
- Names (of classes, method, variables, etc.) in the provided AST classes must not be changed.
- Unless otherwise specified, your code should not import any classes other than those from the standard Java distribution or those that are part of the project.
Submission Checklist
See the checklist from Assignment 1.
Comments and suggestions:
- Work incrementally, starting with small constructs and moving to bigger ones, and adding tests each time. As in previous assignments, you can call the routines corresponding to fragments of the grammar in Junit tests.
- You can use the firstToken field in the case of errors to provide
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