Syntax problem with sum operation in Java-Python translator

Question

I'm trying to realize a Java-Python translator. I'm using flex to recognize some java tokens. I managed integer number with this regular expression:

...
digit   [0-9]
number  (\+|\-)?{digit}+
...
%%
...
{number} {yylval.i= atoi (yytext);return(NUMBER);}
 "+"     {return (ADD);}

In the parser I define this production :

ArithmeticExpression
                : ExpressionStatement ADD ExpressionStatement
                | ExpressionStatement SUB ExpressionStatement
                | ExpressionStatement MULT ExpressionStatement
                | ExpressionStatement DIV ExpressionStatement
                | ExpressionStatement MOD ExpressionStatement
                ;

ExpressionStatement
                   : NUMBER
                   ;

if I give in input to translator expressions like this:

int a = 5 ++67;  (syntax error in java)

how can I manage this situation so that 5 ++67 is recognized like an error and not like 5 + +67 (therefor an ArithmeticExpression) by the translator ?

Answer 1

As has already been said in the comments, you need to introduce a ++ token.

You say that you don't need to handle unary operators. Even so, you still need the token. 5 ++67 is an error in Java exactly because ++ is its own token. If it weren't, 5 ++67 would be equivalent to 5 + +67. So if you want to get the same error as in Java in this case, you also need to have a ++ token - even if you never use it.