[REBOL] Re: "a REBOL dialect is usually limited...
From: rebol-list2:seznam:cz at: 12-Nov-2002 16:26
Hello Gabriele,
Friday, November 8, 2002, 9:25:42 PM, you wrote:
GS> Hi RebOldes,
GS> On Wednesday, November 6, 2002, 12:41:47 AM, you wrote:
R>> myFunc(arg, someObject.someOtherFunction(random(100)))
GS> Couldn't you write it as:
GS> myFunc (arg someObject/someOtherFunction (random (100)))
No, because the interpreter has no hint that someOtherFunction is function so this
would be parsed only as property of someObject and the (random (100))
as third parameter of myFunc :-(
The commas are usefull helpers for interpreter that tells that the myFunc
has only 2 arguments and so it know that the someOtherFunction is the
function in the someObject with argument random(100)
I'm still not sutisfied with my Actions interpreter in my
Rebol/Flash dialect, but it's quite complicated thing and I don't want
to spend so much time on it, although sometimes I think I will make it
again (to make it better). But I'm not so good in the recursive
parsing (and to tell the true, without your help, I'm not sure if the
actions-parser would be here at all)
GS> or, even being more aggressive on the syntax.
GS> If you need to keep the original syntax, a string parser is the
GS> best way IMHO; you can't expect REBOL to be able to parse into
GS> REBOL values any syntax if you aren't willing to provide the
GS> parser yourself.
For string x block parsing I did this test:
;--cut--
test: {aaa "bbb" 111 ddd}
;string based parsing:
t: now/time/precise
digit: charset [#"0" - #"9"]
alpha: charset [#"A" - #"Z" #"a" - #"z"]
alphanum: union alpha digit
spa: charset [#" " #"^-" #"^/"]
string: [#"^"" any alphanum #"^""]
word: [some alphanum]
probe parse/all test [any [word | some digit | string | some spa]]
loop 100000 [
parse/all test [any [word | some digit | string | some spa]]
]
print now/time/precise - t
;block based parsing:
t: now/time/precise
probe parse/all load test [any [word! | integer! | string!]]
loop 100000 [
parse/all load test [any [word! | integer! | string!]]
]
print now/time/precise - t
;--cut--
with these result:
true
0:00:00.991
true
0:00:00.821
As you can see, the string parsing is not faster and that's only
simple example. Try to make string based parser with corect handler of
blocks and strings and all these things.
String parsing is good for example for parsing web-pages where you
need only small part of large page (so you don't want to load/markup
the page) but for large dialect projects is the block parsing much
more better.
The possible solutions:
1. to have access to rules which are used in loading (so we can
make our own datatypes!
2. to have load/safe or load/all which will not throw error as
invalid tag etc. but will convert these words into something which
we can parse using for example string parsing (maybe something like
unknown! datatype?)
I think that the second way is more simple to implement.
Cheers, Oldes
