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Text File | 1985-04-17 | 16.0 KB | 429 lines

PASCAL S Syntax Diagrams (All words in caps are required key words) program ---> PROGRAM ---> identifier ---> ( ---> identifier list ---> ) ---> ; ---+ | +-------------------------------------------------------------<-+ | +--> block ------> . block --+---> CONST -------> identifier --------> = ---> constant ---> ; ---+ | | +-<---------------------------------------------------------------<-+ | +---> TYPE --------> identifier --------> = ---> type -------> ; ---+ | | +-<---------------------------------------------------------------<-+ | +---> VAR ---------> identifier list ---> : ---> type -------> ; ---+ | | +-<---------------------------------------------------------------<-+ | v | +-+-> PROCEDURE ---> identifier --------> formal parameter list ---+ | ^ | v | | +-+-<----------- ; <------- block <---------- ; <-------------------+ | | +---> FUNCTION ----> identifier ----> formal parameter list ---+ | | | | | +-<----------------------------------------------------+ | | | | | +---> : ----------> type identifier ---------------------->-+ | +---> BEGIN -------> statement sequence -----> END -----> type --+-----------------------> type identifier --------------------------------+-> | | +--> ARRAY --> [ -+> constant --> .. --> constant -+> ] --> OF --> type --+ | | | | | +-------------- + <-------------+ | | | | +->-------------------------------------->-+ | | | | | +--> RECORD ---+-+-> identifier list ---> : ---> type -+--+-> END ------>-+ | | +----------------------- ; <----------+ formal parameter list +->--------------------------------------------------------------------->-+ | | --+-> ( -+-+->-------+--> identifier list --> : --> type identifier -+-> ) -+-> | | | | | +-> VAR --+ | | | +-<--------------------------------- ; <--------------------+ identifier list -----------------+---> identifier ----+---------------------------->-------> | | +--------- , <---------+ identifier -----------------> letter -----+--->-----------+--------------------->-------> | | +--- letter <---+ | | +--- digit <---+ statement sequence -----------------+---> statement ----+---------------------------->-------> | | +--------- , <---------+ statement --+--+-> variable -------------+--> := ----------------------------------->-+-> | | | | | +-> function identifier --+ | | | +----> procedure identifier ----+---> actual parameter list ---+-------->-+ | | | | | +--->--------------------------+ | | | +----> BEGIN ------> statement sequence ------> END -------------------->-+ | | | +->------------------->-+ | | | | | +--> IF --> expression --> THEN --> statement -+-> ELSE --> statement -+--+ | | | +--->-------------------------------+ | | | | | +-> CASE -> expression -> OF +-+-> constant +-> : -> statement +-+-> END -+ | | | | | | +----- , <---+ | | | | | | | +--------------- ; <------------+ | | | +----> WHILE ----> expression ------> DO ------> statement ------------->-+ | | +----> REPEAT ---> statement sequence ---> UNTIL ---> statement -------->-+ | | +----> FOR ------> variable identifier ---> := ---> expression --+ | | | | | +----<----------------------------------------------------<-+ | | | | | +--+-> TO -------+--> expression ---> DO ---> statement ----------->-+ | | | | | +-> DOWN TO --+ | | | +---->------------------------------------------------------------------>-+ expression ---> simple expression --+---+---+---+---+---+------------------------->-+--> | | | | | | | v v v v v v | = <> < > >= <= | | | | | | | | +---+---+---+---+---+--> simple expression --->-+ simple expression ---+-->-----+--> term ----+--->-----------------+----+----+---------->------> | | | | | | +--> + --+ | v v v | | | + - OR +--> - --+ | | | | +---- term <----------+----+----+ term ------> factor -----------+--->------------+----+----+----+----+----->------> | | | | | | | v v v v v | * / DIV MOD AND | | | | | | +--- factor <----+----+----+----+----+ factor ---+--> unsigned constant --------------------------------------------->-+--> | | +--> variable ------------------------------------------------------>-+ | | +--> function identifier ------> actual parameter list ------------->-+ | | +--> ( -------> expression ----> ) --------------------------------->-+ | | +--> NOT -----> factor --------------------------------------------->-+ actual parameter list ------> ( ------+---> expression ---+------> ) ---------------------->------> | | +-------- , <-------+ variable ----> variable identifier ---+----+--->------------------------------>-------> | | | +---> [ --+--> expression --+--> ] --+ | | | | | | | +------- , <------+ | | | | | +---> . -----> field identifier -->--+ | | +---<----------------------------------<--+ constant ---+---+-->-----+-----+---> unsigned number ---------------->-+------>------> | | | | | | +--> + --+ | | | | | +---> constant identifier ------------>-+ | +--> - --+ | | | +----------------------> ' ----> character ----> ' ------>-+ unsigned constant ---+------> constant identifier ---------------------------->-+------>------> | | +------> unsigned number -------------------------------->-+ | | +------> ' ----> character ----> ' ---------------------->-+ unsigned number ---> unsigned integer ---+--->----------------------------------+->-+-------> | | | +---> . ----> unsigned integer --+--->-+ | | | | v | | +---<-------------------------<--+ | | | +---> E --+-->-----+-> unsigned integer ->-+ | | +--> + --+ | | +--> - --+ unsigned number ------------------------+-----> digit -----+------------------------->------> | | +-----<------------+ The first 10 characters are significant in identifiers (variables) Types supported by PASCAL-S integer real boolean char Records and arrays are supported All standard builtin functions are supported abs atan chr cos eof eoln exp ln odd ord pred round sin sqr sqrt succ trunc Builtin procedures supported read readln write writeln Compiler/Interpreter options A comment that has the character '$' as its first character is used to specify compiler options. These take the form of a letter followed by a plus sign (option on) or a minus sign (option off). All options default to off. The following options are available: T : Symbol table to be printed (to list file) S : Run time stack printed (to list file) on entry to procedure Pascal-S Error Summary 0 undefined identifier 1 attempt at multiple definition 2 identifier expected (but not found) 3 'program' expected (but not found) 4 ')` expected (but not found) 5 ':' expected (but not found) 6 illegal symbol 7 error in formal parameters list 8 'of' expected 9 '(' expected 10 type error 11 '[' expected 12 ']' expected 13 '..' expected 14 ';' expected 15 error in function result type 16 '=' expected 17 expression must have boolean result 18 control variable must be of type variable 19 type conflict between control variable and expression 20 error in program parameter list 21 number too large 22 '.' expected 23 invalid expression type following case 24 illegal character 25 identifier of type constant expected 26 array index type conflict 27 type conflict in declaration of array index bounds 28 no such array 29 error on type of identifier 30 undefined type 31 no such record 32 boolean type expected 33 arithmetic type expected 34 integer type expected 35 invalid operator 36 actual/formal parameter type conflict 37 item must be of type variable 38 string expected 39 not enough actual parameters 40 no digits after decimal point 41 incorrect type 42 type real expected 43 integer expected 44 variable of constant expected 45 variable of procedure identifier expected 46 type conflict in operands 47 label type incompatable with selecting expression 48 incorrect type of expression for standard function 49 store overflow 50 constant expected 51 ';=' expected 52 'then' expected 53 'until' expected 54 'do' expected 55 'to' or 'down to' expected 56 'begin' expected 57 'end' expected 58 factor expected Pascal-S operation codes (These are shown in the list file when the T option is selected) Code x y Action 0 x y Load address 1 x y Load value 2 x y Load indirect 3 x y Update DISPLAY 4 not used 5 not used 6 not used 7 not used 8 y Standard functions (selected by 0 .. 18) 9 y Add y to the element on top of the stack 10 y Jump to y (unconditional) 11 y Jump to y if stack top false 12 y Jump to y (case table) and select entry 13 y Entry in case table ... NOT EXECUTABLE 14 y For loop entry test - UP 15 y For loop retry test - UP 16 y For loop entry test - DOWN 17 y For loop retry test - DOWN 18 y Mark stack 19 y Call user procedure 20 y Indexed fetch (element size <> 1) 21 y Indexed fetch 22 y Load block 23 y Copy block 24 y Load literal 25 y Load real 26 y Float 27 y Read (y denotes type .. 1 integer, 2 real, 4 char) 28 y Write string 29 y Write .. default field widths 30 y Write .. given field widths 31 HALT 32 Exit procedure 33 Exit function 34 Fetch 35 Not 36 Negate 37 Write real .. given field widths 38 Store 39 Real = 40 Real <> 41 Real < 42 Real <= 43 Real > 44 Real >= 45 Integer = 46 Integer <> 47 Integer < 48 Integer <= 49 Integer > 50 Integer >= 51 Or 52 + integer 53 - integer 54 + real 55 - real 56 And 57 * integer 58 Div 59 Mod 60 * real 61 / 62 Readln 63 Writeln A special thanks to Anthony Marcy and Phil Windley for their help on this project. If you should have and comments or improvements to the Pascal-S compiler/interpreter, please contact: John Naleszkiewicz (301)468-1439 (data) 6:30pm to 8:30am weekdays 24Hrs weekends. John Naleszkiewicz (301)468-1439 (dat