program         -> body
body            -> '(' BodyDef line '(' {declarations} ')'  statement ')'
declarations    -> '(' VarDecs '(' {var-dec} ')' ')'
                -> '(' TypeDecs '(' {type-dec} ')' ')'
                -> '(' ProcDecs '(' {proc-dec} ')' ')'
var-dec         -> '(' VarDec line ID type expression ')'
type-dec        -> '(' TypeDec line ID type ')' 
proc-dec        -> '(' ProcDec line ID '(' { formal-param } ')' type body ')' 
type            -> '(' NamedTyp line ID ')'
                -> '(' ArrayTyp line type ')'
                -> '(' RecordTyp line '(' { component } ')' ')'
                -> '(' NoTyp ')'
component       -> '(' Comp line ID type ')'
formal-param    -> '(' Param line ID type ')'
statement       -> '(' AssignSt line lvalue expression ')'
                -> '(' CallSt line ID '(' { expression } ')' ')'
                -> '(' ReadSt line '(' { lvalue } ')' ')'
                -> '(' WriteSt line '(' { expression } ')' ')'
                -> '(' IfSt line expression statement statement ')'
                -> '(' WhileSt line expression statement ')'
                -> '(' LoopSt line statement ')'
                -> '(' ForSt line ID expression expression expression statement ')'
                -> '(' ExitSt line ')'
                -> '(' RetSt line [ expression ] ')'
                -> '(' SeqSt '(' { statement } ')' ')'
expression      -> '(' BinOpExp line binop expression expression ')'
                -> '(' UnOpExp line unop expression ')'
                -> '(' LvalExp lvalue ')'
                -> '(' CallExp line ID '(' { expression } ')' ')'
                -> '(' RecordExp line ID '(' { record-init } ')' ')'
                -> '(' ArrayExp line ID '(' { array-init } ')' ')'
                -> '(' IntConst line INTEGER ')'
                -> '(' RealConst line STRING ')'
                -> '(' StringConst line STRING ')'
record-init     -> '(' RecordInit ID expression ')'
array-init      -> '(' ArrayInit expression expression ')'      
lvalue          -> '(' Var line ID ')'
                -> '(' ArrayDeref line lvalue expression ')'
                -> '(' RecordDeref line lvalue ID ')'
binop           -> GT | LT | EQ | GE | LE | NE | PLUS | MINUS | TIMES | SLASH
                -> DIV | MOD | AND | OR 
unop            -> UPLUS | UMINUS | NOT
line            -> INTEGER