Compiler Project (Bali#) Grammar Spring 2008 - Part 3

File			-> (ClassDefinition)*
ClassDefinition		-> class name { (classMember)* }

classMember		-> public (Method)
	Method		-> type name ([type name (, type name)*]) statementBlock

statement		-> (ifStatement | whileLoop | expressionStatement | statementBlock | returnStatement )
statementBlock		-> {(statement | localVariableDeclaration)*}
ifStatement		-> if(expression) statement [else statement]
whileLoop		-> while(expression) statement
returnStatement		-> return expression ;
expressionStatement	-> [expression] ;
localVariableDeclaration	-> my type name [= expression];

expression		-> e1
e1			-> e2 (= e2)*
e2			-> e3 ((||) e3)*
e3			-> e4 ((&&) e4)*
e4			-> e5 ((< | > | <= | =< | >= | => | == | !=) e5)*
e5			-> e6 ((+ | -) e6)*
e6			-> e7 ((* | / | %) e7)*
e7			-> e8 (functionCall)*
e8			-> (! | - | * | cast<type>)* e9
e9			-> literal | reference | (expression) | builtInFunction

builtInFunction		-> sizeof(Type) | ((malloc|print)(expression))
reference			-> name
functionCall		-> ([e1 (, e1)*] )
literal			-> number | string | character | true | false | null

type			-> name (*)*

Part 3 Notes:

• Only a single class exists in each file, it is called Entry
• The above implies that there is an implicit a no-args constructor (but can not be called in this part).
• There are only local variables, (except for the built in user-input variables). Also, there is no built-in Main variable. There are also no class member fields.
• User-input is available though the built-in user-input variables (see the full grammar's semantic section on User Input)
• Though a type may be any identifier, for this part of the assignment, the only types that are defined are: int, boolean, char (We will not be considering the void type this semester, neither in this assignment, nor in future parts).

Differences from Part 2

• Local variable declarations are no longer statements.  This makes it so that the following bali# program is no longer valid:

  # NOTE: This code is NOT valid (and should cause a syntax error)
  class Entry
  {
  	public int main()
  	{
  		while(true) my int x;
  	}
  }

  That being said, variables can still be declared in any block (as the syntax now allows for blocks to contain a 0 or more statements or local variable declarations.
• Local variable declarations can be declared anywhere within a block, and may be declared in nested blocks.
• There will again only be a single class (called Entry), but there can be multiple methods.
• We now insist that the type char be implemented, as well as int and boolean from last time.
• Pointers to primitive types must be implemented, as well as pointer operations, which include (but are not limited to)
  • the "value at" unary operator
  • pointer arithmetic (for plus and minus)
• There are new built in functions: malloc and sizeof. Also the print function must now work with characters and strings.
• The user input variable ReadString must be implemented (last time we had ReadInt and ReadChar. See the user input section in the full grammar for more information.
• Classes (or the single class Entry) and now have multiple methods/functions.
• Functions can now be called, there is an additional expression syntax to call methods. Methods can also be referenced.
• Strings are represented by a null terminated sequence of characters and can be printed.
• Any test cases that we released for part 2 should also compile and work in your part 3 compiler.