monic part 5: writing C programs on the calculator

[Jonathan Busby]

(02-12-2021 11:01 PM)Jonathan Busby Wrote:  Well, I found more absent-minded stupid associativity errors in the EBNF grammar for C- . Here is the corrected grammar :

Code:

program = declaration-list ;
declaration-list = declaration , { declaration } ;
declaration = var-declaration , fun-declaration ;
var-declaration = type-specifier , ID , [ "[" NUM "]" ] , ";" ;
type-specifier = "int" | "void" ;
fun-declaration = type-specifier , ID , "(" , params , ")" , compound-stmt ;
params = ( param , { "," , param } ) | void ;
param = type-specifier , ID [ "[" , "]" ] ;
compound-stmt = "{" , local-declarations , statement-list , "}" ;
local-declarations = { var-declaration } ;
statement-list = [ statement , { statement } ] ;
statement = expression-stmt | compound-stmt | selection-stmt | iteration-stmt | return-stmt ;
expression-stmt = [ expression ] , ";" ;
selection-stmt = if , "(" , expression , ")" , statement , [ "else" , statement ] ;
iteration-stmt =  while , "(" , expression , ")" , statement ;
return-stmt = "return" , [ expression ] , ";" ;
expression =  { var , "=" } , simple-expression ;
var = ID , [ "[" , expression , "]" ] ;
simple-expression = additive-expression , { relop , additive-expression } ;
relop = "<=" | "<" | ">" | ">=" | "==" | "!=" ;
additive-expression = term , { addop , term } ;
addop = "+" | "-" ;
term = factor , { mulop , factor } ;
mulop = "*" | "/" ;
factor = "(" , expression , ")" | var | call | NUM ;
call = ID , "(" , args , ")" ;
args = [ expression , { "," , expression } ] ;

Sorry for any inconvenience.

Regards,

Jonathan

NOTE #1 : I had also accidentally left out some non-superfluous non-terminals. Also, the "C-" assignment operator ( "=" ) is *right associative*, just like in full blown C. So, if that part of the grammar looks like it needs correcting, then just know that it doesn't because I intentionally made the EBNF version right associative to be fully compatible with the "C-" BNF grammar.

The following can be simplified :

Code:

statement-list = statement , { statement } | empty ;

The simplified version is :

Code:

statement-list = [ statement , { statement } ] ;

Regards,

Jonathan

EDIT #1 : Incorporated above changes into EBNF grammar