[antlr-interest] Tree transformation
Arnar Birgisson
arnarb at oddi.is
Thu Oct 9 04:43:32 PDT 2003
Hello..
Thanks, but what I need is a bit more. I need a more general method of
converting a list like structure like
PARENT
|
C1 - C2 - C3 - ... - CN
to a right-balanced tree like this:
FUNC
|
C1 - FUNC
|
C2 - FUNC
|
C3 - FUNC
|
...
C(N-1) - FUNC
|
CN - EMPTY_LIST
What I am implementing is basically the conversion from
"[expr1,expr2,...,exprN]" to a lisp-like list, which is equivalent to
"expr1 : (expr2 : (expr3 : ... (exprN : []) ... ))", where ":" is like
the "cons" operator in lisp, and "[]" is a lexical constant representing
the nil list.
I thought of writing a function that takes three ASTs, one like this
#(FUNC), one #(EMPTY_LIST) and the third one like #(LIST node1 node2 ...
nodeN), and returns an AST like this: #(FUNC node1 #(FUNC node2 #(...
#(FUNC nodeN EMPTY_LIST) ...) ) ). I will try this and let you know.
Hope that explains it..
Arnar
> -----Original Message-----
> From: mzukowski at yci.com [mailto:mzukowski at yci.com]
> Sent: 8. október 2003 22:19
> To: antlr-interest at yahoogroups.com
> Subject: RE: [antlr-interest] Tree transformation
>
>
> Ack, the formatting got blarked. Should be this:
>
> list_expr! : #(l:LIST s:stmt_list) {##=#(#[LPAREN,")"],
> #[NAME,"func"], s);}
>
> stmt_list : #(STATEMENT_LIST (stmt)*)
>
> -----Original Message-----
> From: mzukowski at yci.com [mailto:mzukowski at yci.com]
> Sent: Wednesday, October 08, 2003 3:11 PM
> To: antlr-interest at yahoogroups.com
> Subject: RE: [antlr-interest] Tree transformation
>
> Your description is a bit unclear, but to get this:
>
> LPAREN
> |
> NAME("func") - STATEMENT_LIST
> |
> ID(a) - ID(b) - ID(c)
>
> Do this:
>
> list_expr! : #(l:LIST s:stmt_list) {##=#(#[LPAREN,")"],
> #[NAME,"func"], s);}
> stmt_list : #(STATEMENT_LIST (stmt)*)
>
> Monty
>
> -----Original Message-----
> From: Arnar Birgisson [mailto:arnarb at oddi.is]
> Sent: Wednesday, October 08, 2003 12:03 PM
> To: antlr-interest at yahoogroups.com
> Subject: [antlr-interest] Tree transformation
>
> Hello..
>
> I have a programming construct "[a,b,c]" which defines a list (in the
> lisp sense) of the results of expressions a, b and c. The
> parser returns
> this tree: #([LIST,"["], #(STATEMENT_LIST, #a, #b, #c)). I.e.
>
> LIST
> |
> STATEMENT_LIST
> |
> ID - ID - ID
>
> My languages sematnics define "[a,b,c]" to be eqivalent
> "func(;a,func(;b,c))", and moreover, the user program might define
> "func" to be whatever function the user wants it to be.
>
> (As a side note: the function call syntax in the language is
> func(x1,..,xN;y1,..,yM) where x1,..,xN are copy-in copy-out
> parameters,
> and y1,...,yM are pass-by-value. Also, there is no distinction between
> statements and expressions.)
>
> I have one tree parser that takes the parser output and simplifies the
> tree, before that is passed to another tree-parser, the code
> generator.
>
> The simplifying treeparser (the transformer) does things like convert
> "expr1 + expr1" to "+(;expr1,expr2)", and I furthermore want it to
> convert the tree for "[a,b,c]" to the tree "func(;a,func(;b,c))" would
> have generated.
>
> In a nutshell, I need to convert trees of the form depicted above, to
> this:
>
> LPAREN
> |
> NAME("func") - STATEMENT_LIST - STATEMENT_list
> |
> ID(a) - ID(b) - ID(c)
>
> How would you do in a tree-parser rule? The rules I have to match the
> input tree are:
>
> list_expr : #(LIST stmt_list)
> stmt_list : #(STATEMENT_LIST (stmt)*)
>
> Arnar
>
> ps. for the sake of completeness, the actual language doesn't
> use "func"
> as the function name, but rather ":". Operatrs in the language are
> simply functions as the equivalence "a+b"="+(;a,b)" implied.
>
>
>
>
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