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08-03-2008, 04:01 PM #1
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- Aug 2008
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Data Structures Assignment 1
Due: Aug 10, 5pm
(Submit at moodle.)
Write an interpreter for the following language. Define and use a Procedure class that stores information about one procedure, i.e., the list of its instructions. The instructions are stored parsed: i.e., as < OPERATION-CODE, OPERANDS > tuple. You may choose any representation for op codes (but make sure that you use no literal constant in any of your methods). You need classes Program Instruction, OpCode and Operand. Classed Program and Procedure should each have the execute method that sequentially executes its Instructions. You will also need a VirtualMachine class (that will have your main program) as well as a Parser class. Make sure you handle exceptions (wrong input programs). The execute method for the PRINT instruction may directly call the JAVA print function.
DEFINEPROC procedurename parametername
SET variablename anothervariablename/value
CALLIF variablename/value procedurename variablename/value
All procedures take one input parameter and return no values
The input parameter can only be an integer (of arbitrary size)
All calls are by value
Recursion is allowed
No global variables
Only integer constants -- but of arbitrary width
Each program must have an entry procedure named "start".
CALLIF calls the function if the first operand is non-zero; the last operand provides the parameter value.
COMMENT This is a comment
DEFINEPROC recur level
CALLIF level recur level-1
SET call 1
CALLIF call recur 3
COULD ANYONE EXPLAIN ME THE PROBLEM FIRST? I HAVE NO CLUE AT ALL.
08-04-2008, 07:02 AM #2
Congratulations on coming up with the worst thread title I've ever seen here, and with some very stiff competition too.
If you don't understand this question you should probably just drop the class. You are expected to produce a Java program that compiles this limited grammar to some arbitrary instruction set, and write a (presumably also Java) virtual machine that interprets and executes the instruction set.
08-07-2008, 08:55 AM #3
hahaha ralph, best reply to a post i have ever seen.