Re: Parsing Questions

"Stefan Ewing" <sewing@uvic.ca> writes:


>How can the postfix increment/decrement operators in C, C++, and Java
>be represented in a parse tree? For example, if we have the
>epxression


>a = b++ + c;


>b will be incremented after b + c has been calculated. But the only
>place to put the operator (it seems to me) is between "b" and "+".
>But doesn't this imply we should increment b *before* adding it to c?


Simply treat prefix and postfix versions as different unary operators
-- the parser can certainly be written to tell which it's got, and
generate an appropriate parse tree, e.g.:


                =
              / \
            a +
                  / \
              p++ c
                |
                b


Here, I mean for "p++" to mean "the postfix increment operator". How
you represent these in your compiler is, of course, up to you. :)


>Also, how should one represent the Java field access operator (.) in
>a parse tree? At first glance, it seems like a binary operator to me
>(given the object name and the field name, a memory address is
>returned), but one operator precedence chart I saw online shows . as
>a unary operator.


Where were you looking?


-M


--
Michael J. Fromberger Software Engineer, Thayer School of Engineering
    sting <at> linguist.dartmouth.edu http://www.dartmouth.edu/~sting/


"If people do not believe that mathematics is simple, it is only because
they do not realize how complicated life is." -- John von Neumann

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