deliverable: comments and
desugaring
Note that this is one of two
deliverables due by the end of week 5!The following modifications should be made to the flex/bison C version of the
compiler. You
must document the lines that need to be changed; source code comments
are preferred.
C-style comments
The A- implementation only allows one-line comments such as:
// this is a comment
It would be nice to additionally allow multi-line comments, such as:
/* this is a
somewhat
longer comment */
This improvement can be implemented by only making changes to
the file joos.l.
Hint: if you get stuck,
it's a good idea to RTFM.
(Where F stands for Flex, naturally.) We do not demand that you implement
support for nested comments such as:
/* this is a comment /* this is a nested comment; comes in handy when commenting out large chunks of code*/ */
Increments and for-loops
It would be very nice to include standard increments and for-loops such as:
for (i=0; i<10; i++) k=k*i;
These constructs may be introduced as mere syntactic sugar,
since they
can readily be expressed in the JOOS language itself. This
improvement can be implemented by only making changes to the files joos.l
and joos.y.
You should not reject a for-loop in places where javac would accept it.
Also, note that you do not have to add the postincrement
instruction
in its full generality: you don't have to allow expressions of the form identifier++
- statements of the
form identifier++; are sufficient. Also, you don't have
to allow for on-the-fly declaration of variables within the for-loop,
i.e. it is sufficient to support for(i=0;... ; no need
to provide for for(int
i=0;...
Use Subversion to copy the A- JOOS source to your group directory:
$ svn cp public_html/joos/a- group-X/joos/scanparse
and commit that before beginning work. Then, make your
modifications,
include some tiny test programs that compile and run correctly with
your improved compiler---but also test your benchmark program for this
week if it uses these constructs---and add a README file (group-X/joos/scanparse/README)
describing
your work and the changes you needed to make. It is fine to leave
precise details to comments in the source code. Format your text in
80 column blocks for readability, and stick to the current JOOS
programming style.
Your TA will use Subversion to look at your changes and run your test
programs in order to evaluate you. Multiple small test
inputs are more useful than one big test input that attempts to cover
all features; a combination of both is even better.
There is no need to email us on completion. Unless you took a late day we will automatically take the version into account that was checked in last before the point of the deadline.