[antlr-interest] simple function exercise

[Sohail Somani]

On Mon, 2005-17-10 at 04:13 -0700, Eric Nelson wrote:
> I haven't posted for awhile since my research responsibilities shifted
> over the summer, but my goal is still to learn ANTLR ... Its actually
> been driving me crazy, although mabye that's why it holds my
> interest? ;)
>  
> Well here is a simple exercise that would give me some insight:
>  
> Using a Java grammar, write a source to source translator that simply
> recognizes functions and replaces the names as such:
>  
> 1) replace "main" (or "int main" or whatever) with "func_0"
> 2) append to all other functions "func_1" ... "func_n"
>  
> I'd like the new source code to be written to a file ... although
> honestly I'll take anything you can throw my way.  You might ask me
> for what purpose I'd like to do this ... I'd probably just answer its
> because I have no idea what I'm doing ;)  Thanks for any tips!

I'd suggest something slightly less ambitious (than modifying a java
grammar!).

Make up your own language that has only two sentences (you'll have to
figure out how to get the below to actually work, define a lexer and a
parser atleast):

funcDefn: "Function" IDENTIFIER LCURLY EOL
	(singleStatement EOL)+
	RCURLY EOL
	;
singleStatement: "MOV" IDENTIFIER (COMMA IDENTIFIER);

Transform the source text by changing MOV A,B to "A = B" and change the
function name to be the concatenation of identifiers of the last
statement.

My guess is you will need atleast a tree grammar, though I might be
mistaken.

Also, make sure you work with streams, not files.

Best of luck.

Sohail