-- Gustave
--
-- Formal grammar for a small subset of Eiffel.
--
-- written by mike slattery - jan 2004
-- updated to include AbSyn notations - feb 2004
--
-- Require and Ensure restricted to one boolean
--  expression - feb 2004
--
-- Before each set of production rules, I list
-- which abstract syntax tree will be used as the
-- attribute of the left-hand-side non-terminal.
-- In the case of Type, Stmt and Expr, I also
-- indicate which trees get used for the various
-- individual productions (in cases where it might
-- not be obvious).  All of the "List" cases use
-- "Pair..." or "Last..." as appropriate.
--
-- Tokens are written in upper-case, non-terminals
-- in lower-case.  This means that when I write
-- CLASS, for instance, I'm referring to the token
-- whose lexeme is "class" (in other words, the
-- upper-case means it's a token, it doesn't tell
-- you whether that token is upper or lower-case in
-- the source code).
--
-- NUMBER is the token returned by the scanner for
-- an integer (with an attribute of type Integer).
-- ID is the token returned by the scanner for a
-- identifier (name).  It has an attribute of type
-- String.
--

-- Program
program -> rootclass classdecs

-- RootClass
rootclass -> CLASS ID CREATION MAKE
		optvardecs
		METHOD MAKE IS optlocals DO stmts END
		methoddecs
		END

-- ClassDecList
classdecs -> classdec classdecs
          ->

-- ClassDec
classdec -> CLASS ID optvardecs optmethoddecs END
	
-- VarDecList
optvardecs -> ATTRIBUTE vardecs
           ->

-- VarDecList    
vardecs -> vardec vardecs
        ->

-- VarDec       
vardec -> ID : type

-- VarDecList
optlocals -> LOCAL vardecs
             ->
  
-- MethodDecList
optmethoddecs -> METHOD methoddecs
              ->

-- MethodDecList
methoddecs -> methoddec methoddecs
           -> 

-- MethodDec     
methoddec -> ID optformals opttype IS
		optrequire optlocals DO stmts optensure END

-- VarDecList
optformals -> ( formals )
           ->

-- VarDecList           
formals -> vardec ; formals
        -> vardec

-- Type
opttype -> : type
        ->

-- Expr
optrequire -> REQUIRE expr
           ->

-- Expr
optensure -> ENSURE expr
          ->
 
type -> INTEGER			-- IntegerType
     -> BOOLEAN			-- BooleanType
     -> ARRAY [ INTEGER ]	-- IntArrayType
     -> ID			-- ClassType (used for object declarations)
   
-- StmtList
stmts -> stmt stmts
      ->
      
stmt -> ID := expr
     -> IF expr THEN stmts END
     -> IF expr THEN stmts ELSE stmts END
     -> FROM stmts UNTIL expr LOOP stmts END
     -> ID optparams			-- method call (AccessStmt)
     -> ID . ID optparams		-- method call (AccessStmt)
     -> IO.PUT_INTEGER ( expr )	  -- treat "io.put_integer" as a
     -> IO.PUT_STRING ( STRING )  --  single token (similar for string)
     -> ID . PUT ( expr, expr )		-- array assignment
     -> !! ID . MAKE ( expr , expr )	-- array creation
     -> !! ID				-- Create (object creation)
     

expr -> expr + expr
     -> expr - expr
     -> expr * expr
     -> expr // expr		-- integer divide
     -> - expr   		-- use Minus(0,expr) to represent
     -> ( expr )
     -> ID
     -> NUMBER
     -> expr = expr
     -> expr /= expr		-- not equal
     -> expr < expr
     -> expr > expr
     -> expr <= expr
     -> expr >= expr
     -> NOT expr
     -> expr AND expr
     -> expr OR expr
     -> TRUE
     -> FALSE
     -> ID . ITEM ( expr )
     -> ID @ expr		-- same as ITEM
     -> ID . LOWER
     -> ID . UPPER
     -> ID ( exprs )            -- Access (method call within class)
     -> ID . ID optparams	-- Access (method call or attrib access)

-- ExprList
optparams -> ( exprs )
          ->

-- ExprList         
exprs -> expr , exprs
      -> expr