CSE505 Assignment 1-Object-Oriented Parsing Solved

Consider the following grammar (with EBNF notation) for a simple programming language, called TinyPL,  whose programs are a sequence of zero or more functions defined as follows:

 

 program  ->  { function } end 

 function -> int id '(' [ pars ] ')' '{' body '}'  

 pars ->  int id { ',' int id } 

        body    ->  [ decls ] stmts        decls   ->  int idlist ';'  idlist  ->  id { ',' id } 

 

 stmts   ->  stmt [ stmts ] 

 stmt    ->  assign ';' | loop | cond | cmpd |    return ‘;’ | print ‘;’ 

 

 assign  ->  id '=' expr   loop    ->  while '(' relexp ')' stmt  cond    ->  if '(' relexp ')' stmt [ else stmt ] 

 cmpd    ->  '{' stmts '}'  return  ->  ‘return’ expr    print   ->  ‘print’ expr 

  relexp ->  expr ('<' | '>' | '<=' | '>=' | '==' | '!= ') expr 

 

 expr    ->  term   [ ('+' | '-') expr ]  term    ->  factor [ ('*' | '/') term ] 

 factor  ->  int_lit | id | '(' expr ')' | funcall 

 

 funcall ->  id '(' [ exprlist ] ')' 

 exprlist -> expr [ ',' exprlist ] 

 

Write in Java an object-oriented parser that translates TinyPL programs into byte-codes as discussed in the lectures.

 

Starter code for this assignment is given in A1_Starter.zip.   The only file in which you need to supply missing code is Parser.java.  This file contains one Java class definition for each nonterminal of the above grammar.  The places where missing code is to be supplied are indicated by Java comments.

 

In generating byte-codes, follow the naming convention of Java byte-codes.  Note that TinyPL only has the int type.

 

a.       Generate iconst, bipush, or sipush according to the numeric value of the literal. 

b.       Generate iadd, isub, imult, and idiv for the arithmetic operators.  Note that TinyPL, unlike Java, has right-associative semantics for these operators. 

c.       For iload and istore, take the index of the variable into account when generating the bytecode. 

d.       Relational expressions (relexp) may be translated using the if_icmp* bytecodes.   Transfer of control is effected by the goto bytecode. 

 

Assumptions
 

1.      All input test cases will be syntactically correct; syntax error-checking is not necessary.    

 

2.      TinyPL does not permit syntactically nested calls such as x = f(g(10),h(20)).   When there is a need to write nested calls, the TinyPL programmer has to “flatten” them and write a sequence of assignments, like this:  t1 = g(10); t2 = h(20); x = f(t1,t2).

 

Testing your Program                        
 

Test cases and their output are given in the A1_Starter directory as files test_cases.txt and test_results.txt.     

 

Run your Java program and, when prompted for input, paste the contents of the file test_cases.txt into the Console panel.   Save the output printed on the Console by your program in a file A1_test_results.txt.   

 

Test that your byte-codes are correct by executing function calls using the byte-code interpreter supplied with the Starter code.

 

Perform another test of your program by running it under JIVE and obtain the object diagram for a test case consisting of just the gcd and friends functions.  Choose the “Stacked” option and save the object diagram as A1.png.

 

A demo of parsing and executing a TinyPL program will be posted.