World: r3wp

Your example with alternates (and bug fixes, still ignoring leap 
years):


 m31: ["Jan" | "Mar" | "May" | "Jul" | "Aug" | "Oct" | "Dec"]  ; joins 
 were in wrong direction
	m30: join m31 [| "Apr" | "Jun" | "Sep" | "Nov"]
	m28: join m30 [| "Feb"]

 b28: next repeat x 28 [repend [] ['| form x]]  ; next to skip leading 
 |, numbers don't work in string parsing
	b30: ["29" | "30"]  ; optimization based on above reversed joins
	b31: ["31"]
	parse date-str [
		b28 "-" m28
		| b30 "-" m30
		| b31 "-" m31
	]

The above with CHECK instead:

	m31: ["Jan" "Mar" "May" "Jul" "Aug" "Oct" "Dec"]
	m30: join m31 ["Apr" "Jun" "Sep" "Nov"]
	m28: join m30 ["Feb"]
	b28: repeat x 28 [append [] form x]  ; not assuming 
	b30: ["29" "30"]  ; optimization based on above reversed joins
	b31: ["31"]
	parse date-str [
		copy d some digit "-" copy m some alpha
		check (	any [
			all [find b31 d  find m31 m]
			all [find b30 d  find m30 m]
			all [find b28 d  find m28 m]
		])
	]

Which would be faster would depend on the data and scenario.

(the comments on the second example can be ignored)

Your proposal seems like a slightly faster but more limited version 
of alternates, and not as flexible or optimizable as check. Does 
this situation come up so often that you need direct support for 
it?

Here's a simpler date checker with CHECK:


parse date-str [copy d [1 2 digit "-" 3 alpha "-" 4 digit] check 
(attempt [to-date d])]

That requires years too, but at least it gets leap year 29-Feb.

Brian, JOIN does a REDUCE on the second block.

Right you are, whoops. It's been a while since I used it with blocks.

'append would do it...

numbers don't work in string parsing

 - I thought about this when I developed the example, thought it might 
 be possible as the numbers appear outside the dialect.  But 'check 
 seems like the better option.  

joins were in the wrong direction
 - d'oh!

simpler date checker

 - that's only useful if to-date recognizes the date format : )  (and 
 using dates was illustrative - there are other situations with similar 
 needs).  Though on dates, what would be the most succinct way with 
 the proposals on the table to do the following?

	ameridate: "2/15/2008"
	parse ameridate ...rule...
	newdate = 15-Feb-2008

One attempt:

	parse ameridate [
		use [d m][
			change [copy m 1 2 digit "/" copy d 1 2 digit]
			(rejoin [d "/" m])
		]
		"/" 4 digit end check (newdate: to-date ameridate)
	]

(making the assumption it is a valid date)

(and that it's ok tomodify the original string)

If I am parsing something like javascript that has { and } in it 
like C, how can I put that into a string to parse without using {}

my test cases for testing a dialect, I usually use this form:

print parse/all {test case that 
can't have {} inside } parse-rule

There must be some dead-simple guru trick for this...

I think I raised the same question on the ML years ago, and got  
a disappointing answer. Maybe things have changed since. Or, if not, 
it may not be too late to add to the R3 parse wishlist:
    http://www.rebol.org/ml-display-thread.r?m=rmlSQHQ

My first inclination is to "go binary" on it...;-) but that is inelegant, 
and the MSB of binary gets wonky sometimes.

(MSB bit is a sign bit oftentimes)

I was thinking of taking away the special meaning of { but not yet 
sure how to unset it...it initially seems hardcoded in there....not 
like I would expect.

I don't understand what do you mean.

In the console if you type a {  and then hit Enter, it continues 
on the next line.

:{   and }:   don't seem to work, either.

The problem is if you have a string of Javascript which uses {} inside, 
then it is hard to get REBOL to make a string of Javascript that 
has {} inside.

Replace "{" with to-char 0 then put it back afterwards? (Assuming 
to-char 0 does not occur in your string)?

I've done that sort of thing before to get around parse limitations 
(whether the limitation is in 'parse or my understanding of it)

what about escaping?

so ^{ is what you mean by escaping?

yes

that's the old XON/XOFF sw handshaking trick.


So you mean to add ^ in the Javascript, and then wrapping it with 
{} won't cause a script error?

You want to write JS in Rebol console?

>> s: {a^/{b}c^{d^}"e"}
== {a
{b}c{d}"e"}

no, I am parsing it automatically...the console I was just testing, 
but that makes the problem worse, methinks

I think you meant this (or at least I would have wanted you to mean 
this):
>> s: {a^{b^}c^{d^}"e"}
== {a{b}c{d}"e"}

that still doesn't cut the mustard for me...but can be useful for 
part of it.


to-string 4838f{gmgmg{    ;this doesn't work because REBOL doesn't 
know what datatype 4838f{gmgmg{ is, but I don't want REBOL to know 
that.  I want REBOL to make it into a string.

to-string/raw or to-string/force could be a useful refinement so 
that I could write parse like this:


print parse/all to-string/force ;alksjdf;alsjdflk;{""""}}}}}    parse-rules 
  ;I think this would be a VERY useful thing.

I don't understand how it could work like

it would need a terminator pattern to know when to stop it


print parse/all to-string/force ;alksjdf;alsjdflk;{""""}}}}}terminate 
parse-rules   ;I think this would be a VERY useful thing.

you mean something like that http://en.wikipedia.org/wiki/HEREDOC
? That could be useful.

but that's not parse related, the Rebol lexer should be improved 
to do that.

we can try to ask Carl

It is strongly related...for sure.  One of my requirements in a good 
OS which is not done yet is to NEVER lose anything I type, EVER.

That page of Wiki is very good to beg my case, thanks!

I remember another cool console that someone did in a web page that 
was very slick...sorry, my mind associates things that it shouldn't...my 
parser is too massively parallel...;-)

It's like closing the loop on Chris's make-doc-anywhere...but REBOL 
can be the most elegant here for that Heredoc.

eFishAnt, the {} nesting rules only apply to strings entered in {}, 
not "". They are also only a REBOL syntax trick. Strings that you 
construct or read from somewhere don't have any special escaping 
rules or syntax.

REBOL doesn't lose what you type, but if what you are typing is treated 
as REBOL syntax, then it is interpreted as such, not lost.

I have a problem with sub-rule parsing I have:

myrules: [
	any [
		set src path! set des path! (?? src ?? des)
		| 'keyword into [
			...
		]
	]
]

If the input is

a/1 a/2
mykeyword
a/1 a/2


Only the first paths are printed. Why this? I thought the ANY rule 
keeps going on unti the end.

I think it has something to do with INTO not return true.

The INTO is still just a proposal http://www.rebol.net/wiki/Parse_Project#INTO

Robert, your rule steps INTO the second a/1, and then, I suppose, 
fails to reach the end of it.

Show us the INTO rule, and we will tell you what is wrong with it. 
PARSE will treat the path a/1 like the block [a 1] eg:
	>> parse [a/1][into [here: (print mold here) 'a 1 1 1]]
	[a 1]
	== true

(You also wrote 'keyword in your rules, but 'mykeyword in your input. 
I'm hoping that was just a typo.)

INTO is not a proposal, the proposal is to extend INTO to string 
types, possibly with a type check.

Thanks for all the helps on parse...I have my new platform working 
100% as of this morning.  The labor of over a year of technology...and 
the code keeps getting smaller and faster.  100% REBOL.  It's all 
dialects.

eFish - what is your new platform about? Still an IOS, or anything 
new? Once new rebol.com site is done, we need your success stories 
:-)