Re: [Gcl-devel] Re: possible lisp reader enhancement/modification

[Camm Maguire]

Greetings!  OK, here is take three -- this should ensure that the
stack is popped on input error somewhere in the list:

=============================================================================
diff -u -r1.14 read.d
--- read.d      26 Feb 2003 22:21:37 -0000      1.14
+++ read.d      9 Jul 2003 15:45:45 -0000
@@ -392,6 +392,11 @@
        Read_object(in) reads an object from stream in.
        This routine corresponds to COMMON Lisp function READ.
 */
+
+/* FIXME What should this be? Apparently no reliable way to use value stack */ 
+#define MAX_PACKAGE_STACK 100 
+static object P0[MAX_PACKAGE_STACK],*PP0=P0;
+
 object
 read_object(in)
 object in;
@@ -428,6 +433,7 @@
        });
                a = cat(c);
        } while (a == cat_whitespace);
+       if (c->ch.ch_code==')' && PP0>P0) PP0--;
        delimiting_char = vs_head;
        if (delimiting_char != OBJNULL && c == delimiting_char) {
                delimiting_char = OBJNULL;
@@ -587,6 +593,17 @@
                token->st.st_fillp = length - (colon + 2);
        } else
                p = current_package();
+       /* FIXME Perhaps one of these is redundant */
+       if (c->ch.ch_code=='(' && !token->st.st_fillp && colon_type) {
+         if (PP0-P0>=MAX_PACKAGE_STACK)
+           FEerror("Too many nested package specifiers",0);
+         *PP0++=p;
+         x=read_object(in);
+         vs_reset;
+         return (x);
+       }
+       if (PP0>P0 && !colon_type)
+         p=PP0[-1];
        vs_push(p);
        x = intern(token, p);
        vs_push(x);
=============================================================================
(sid)address@hidden:/fix/t1/camm/gcl/unixport$ ./saved_gcl
GCL (GNU Common Lisp)  (2.5.3) Tue Jul  8 17:07:32 UTC 2003
Licensed under GNU Library General Public License
Dedicated to the memory of W. Schelter

Use (help) to get some basic information on how to use GCL.

>(read)
(quote (q lisp::(a b si::c d) e))

'(Q (LISP::A LISP::B SYSTEM::C LISP::D) E)

>(read)
(quote (q lisp::(a b si::c . . d) e))

Error: Two dots appeared consecutively.
Fast links are on: do (si::use-fast-links nil) for debugging
Error signalled by READ.
Broken at READ.  Type :H for Help.
>>
Error: The variable LISP::D is unbound.
Fast links are on: do (si::use-fast-links nil) for debugging
Error signalled by EVALHOOK.
Backtrace: system:universal-error-handler > EVALHOOK

Broken at READ.
>>
Error: The variable E is unbound.
Fast links are on: do (si::use-fast-links nil) for debugging
Error signalled by EVALHOOK.
Backtrace: system:universal-error-handler > EVALHOOK

Broken at READ.
>>(quote (q lisp::(a b si::c d) e))

(Q (LISP::A LISP::B SYSTEM::C LISP::D) E)
>>:q

Top level.
>(quote (q lisp::(a b si::c d) e))

(Q (LISP::A LISP::B SYSTEM::C LISP::D) E)

>(by)
=============================================================================

Take care,

Matt Kaufmann <address@hidden> writes:

> Thanks, Camm!  Rob Sumners put your mods in and built GCL with them.  He 
> looked
> at your code and described your approach, so I tried an example with nested
> package prefixes.  Unfortunately, it didn't do what I expected, which is to 
> use
> the closest package prefix:
> 
> GCL:
> 
> >'lisp::(a b user::c)
> 
> (LISP::A LISP::B LISP::C)
> 
> >
> 
> Allegro CL:
> 
> CL-USER(1): 'lisp::(a b user::c)
> (COMMON-LISP::A COMMON-LISP::B C)
> CL-USER(2): 
> 
> Maybe an easy fix for you?
> 
> Thanks --
> -- Matt
>    cc: address@hidden
>    From: Camm Maguire <address@hidden>
>    Date: 08 Jul 2003 12:52:30 -0400
>    User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2
>    Content-Type: text/plain; charset=us-ascii
> 
>    Greetings!  Given Paul's analysis, let's put in this feature.  You
>    might want to try this patch:
> 
>    diff -u -r1.14 read.d
>    --- read.d 26 Feb 2003 22:21:37 -0000      1.14
>    +++ read.d 8 Jul 2003 16:47:32 -0000
>    @@ -392,6 +392,9 @@
>          Read_object(in) reads an object from stream in.
>          This routine corresponds to COMMON Lisp function READ.
>     */
>    +
>    +static object p0=Cnil;
>    +
>     object
>     read_object(in)
>     object in;
>    @@ -587,6 +590,15 @@
>                  token->st.st_fillp = length - (colon + 2);
>          } else
>                  p = current_package();
>    +  if (c->ch.ch_code=='(' && !token->st.st_fillp && colon_type) {
>    +    p0=p;
>    +    x=read_object(in);
>    +    p0=Cnil;
>    +    vs_reset;
>    +    return (x);
>    +  }
>    +  if (p0!=Cnil)
>    +    p=p0;
>          vs_push(p);
>          x = intern(token, p);
>          vs_push(x);
> 
> 
>    
> =============================================================================
>    (sid)address@hidden:/fix/t1/camm/gcl/unixport$ ./saved_gcl
>    GCL (GNU Common Lisp)  (2.5.3) Tue Jul  8 15:22:09 UTC 2003
>    Licensed under GNU Library General Public License
>    Dedicated to the memory of W. Schelter
> 
>    Use (help) to get some basic information on how to use GCL.
> 
>    >(quote lisp::(a b c))
> 
>    (LISP::A LISP::B LISP::C)
> 
>    >(quote (a b c))
> 
>    (A B C)
> 
>    >(by)
>    
> =============================================================================
> 
>    I'll test this and commit to the unstable branch if all is well.
>    Comments welcome, as always.
> 
>    Take care,
> 
>    Matt Kaufmann <address@hidden> writes:
> 
>    > Thanks for the quick reply!
>    > 
>    > -- Matt
>    >    cc: address@hidden, "Paul F. Dietz" <address@hidden>
>    >    From: Camm Maguire <address@hidden>
>    >    Date: 02 Jul 2003 15:42:16 -0400
>    >    User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2
>    >    Content-Type: text/plain; charset=us-ascii
>    > 
>    >    Greetings, and thanks for your suggestion!
>    > 
>    >    I'm forwarding this to the list to solicit opinions from our ANSI
>    >    standard experts on whether such a change would be permissible in ANSI
>    >    common lisp.  Comments?
>    > 
>    >    Take care,
>    > 
>    >    Matt Kaufmann <address@hidden> writes:
>    > 
>    >    > Hi --
>    >    > 
>    >    > I wonder if it would be possible to modify the GCL reader so that 
> package
>    >    > prefixes can apply to lists, not just symbols.  Here's an example 
> of what I
>    >    > mean.
>    >    > 
>    >    >   >'lisp::(a b)
>    >    > 
>    >    >   LISP::||
>    >    > 
>    >    >   >
>    >    >   Error: The function A is undefined.
>    >    >   Fast links are on: do (si::use-fast-links nil) for debugging
>    >    >   Error signalled by EVAL.
>    >    >   Broken at EVAL.  Type :H for Help.
>    >    >   >>
>    >    > 
>    >    > Here is the corresponding log for Allegro Common Lisp.
>    >    > 
>    >    >   CL-USER(2): 'lisp::(a b)
>    >    >   (COMMON-LISP::A COMMON-LISP::B)
>    >    >   CL-USER(3): 
>    >    > 
>    >    > I'm pretty sure that there's no CLtL requirement to make such a 
> change.  It's
>    >    > even possible that GCL does this right and Allegro CL does it 
> wrong.  But
>    >    > anyhow, I thought I'd ask, because it would be very handy to have 
> such a
>    >    > capability in GCL (it could affect which Lisp is used under ACL2 at 
> AMD).
>    >    > 
>    >    > Thanks --
>    >    > -- Matt
>    >    > 
>    >    > 
>    >    > 
>    > 
>    >    -- 
>    >    Camm Maguire                                          address@hidden
>    >    
> ==========================================================================
>    >    "The earth is but one country, and mankind its citizens."  --  
> Baha'u'llah
>    > 
>    > 
>    > 
> 
>    -- 
>    Camm Maguire                                               address@hidden
>    ==========================================================================
>    "The earth is but one country, and mankind its citizens."  --  Baha'u'llah
> 
> 
> _______________________________________________
> Gcl-devel mailing list
> address@hidden
> http://mail.gnu.org/mailman/listinfo/gcl-devel
> 
> 
> 

-- 
Camm Maguire                                            address@hidden
==========================================================================
"The earth is but one country, and mankind its citizens."  --  Baha'u'llah