[parenscript-devel] [PATCH] Define bit-shifting special forms >> and <<, and ASH as a macro.

[sblist at me.com]

Thanks Vladimir,

I don't have any need to use << and >> directly, so exporting only ASH
is just fine.

	Scott

On 2010-12-05, at 11:01 PM, Vladimir Sedach wrote:

> Hi Scott,
> 
> Thanks for the patch. I've applied it against the current changes and pushed.
> 
> One thing I didn't do is export << and >> special forms, just ash.
> What do you think about that?
> 
> Vladimir
> 
> 2010/10/29  <sblist at me.com>:
>> I'm not sure how you feel about adding >> and << as special forms, but
>> this seems to allow for a simpler implementation of ASH since it needs
>> to do some higher-level transformations such as optimizing forms with a
>> a constant COUNT argument along with avoiding multiple evaluation.
>> 
>>        Scott
>> 
>> ---
>>  src/macros.lisp        |   14 ++++++++++++++
>>  src/package.lisp       |    4 ++++
>>  src/printer.lisp       |    2 +-
>>  src/special-forms.lisp |    4 +++-
>>  4 files changed, 22 insertions(+), 2 deletions(-)
>> 
>> diff --git a/src/macros.lisp b/src/macros.lisp
>> index 2014330..2c0c295 100644
>> --- a/src/macros.lisp
>> +++ b/src/macros.lisp
>> @@ -59,6 +59,20 @@
>> 
>>  (define-ps-symbol-macro pi (getprop *math '*pi*))
>> 
>> +(defpsmacro ash (integer count)
>> +  (let ((count (ps-macroexpand count)))
>> +    (cond ((and (numberp count) (> count 0)) `(<< ,integer ,count))
>> +          ((numberp count) `(>> ,integer ,(- count)))
>> +          ((complex-js-expr? count)
>> +           (let ((count-var (ps-gensym)))
>> +             `(let ((,count-var ,count))
>> +                (if (> ,count-var 0)
>> +                    (<< ,integer ,count-var)
>> +                    (>> ,integer (- ,count-var))))))
>> +          (t `(if (> ,count 0)
>> +                  (<< ,integer ,count)
>> +                  (>> ,integer (- ,count)))))))
>> +
>>  ;;; Types
>> 
>>  (defpsmacro stringp (x)
>> diff --git a/src/package.lisp b/src/package.lisp
>> index 7921a37..92922e7 100644
>> --- a/src/package.lisp
>> +++ b/src/package.lisp
>> @@ -99,6 +99,10 @@
>>    #:logxor
>>    #:lognot
>> 
>> +   #:ash
>> +   #:>>
>> +   #:<<
>> +
>>    #:*
>>    #:/
>>    #:rem
>> diff --git a/src/printer.lisp b/src/printer.lisp
>> index 73df146..5f119b7 100644
>> --- a/src/printer.lisp
>> +++ b/src/printer.lisp
>> @@ -169,7 +169,7 @@ vice-versa.")
>>  (defprinter js:post-- (x)
>>   (ps-print x)"--")
>> 
>> -(defprinter (js:+ js:- js:* js:/ js:% js:&& js:\|\| js:& js:\| js:-= js:+= js:*= js:/= js:%= js:^ js:&= js:^= js:\|= js:= js:== js:=== js:!== js:in js:!= js:> js:>= js:< js:<=)
>> +(defprinter (js:+ js:- js:* js:/ js:% js:&& js:\|\| js:& js:\| js:-= js:+= js:*= js:/= js:%= js:^ js:&= js:^= js:\|= js:= js:== js:=== js:!== js:in js:!= js:> js:>= js:< js:<= js:<< js:>>)
>>     (&rest args)
>>   (loop for (arg . remaining) on args do
>>        (print-op-argument op arg)
>> diff --git a/src/special-forms.lisp b/src/special-forms.lisp
>> index 6633b2f..5ca7a52 100644
>> --- a/src/special-forms.lisp
>> +++ b/src/special-forms.lisp
>> @@ -25,7 +25,9 @@
>>     logior     js:\|
>>     logxor     js:^
>>     lognot     js:~
>> -    ;; todo: ash for shifts
>> +
>> +    >>         js:>>
>> +    <<         js:<<
>> 
>>     throw      js:throw
>>     array      js:array
>> --
>> 1.7.2.1
>> 
>> 
>> 
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>> parenscript-devel at common-lisp.net
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>> 
> 
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