World: r3wp

oh .. ok.

Actually, what I was wondering was how to break out of an action 
in a rule and still let it return true

In the new alphas you can do
>> catch [parse/all "   aa" [" " (throw true)]]
== true

ahh.. that's what I need.

In a paren, you can change a 'break-rule from an empty block to [to 
end], then include that break-rule in your main parse-rule somewhere.

(for a more backwards compatible solution)

parse/all "first second" [["first" break] to end]

Graham: break do not invalidate the rule by itself

Anton, can you give an example of what you mean?

Oh dear, looks like my memory was not so great. I was using 'break 
in the early-exit rule here:

extract-link-by-name: func ["Returns the first A link with the specified 
text in the source string."
	name [any-string!] "link text"
	str [any-string!] "html source string"
	/local start end terms non-terms link text early-exit
][
	early-exit: []
	if parse/all str [
		some [
			thru "<a " any " " 
			["name" | [
				"href" any " " "=" any " "

    [{"} (terms: {"}) | (terms: " >")] ; set terms depending on how url 
    starts, with double-quote?
				(non-terms: complement charset terms)
				start: some non-terms end: (link: copy/part start end)
				opt {"} any " "
				thru ">" copy text to "</a" ; <- was before just "<"
				(if text = name [early-exit: [to end break]])
			]]
			early-exit
		]
	][reduce ['link link 'name text]]
]

Ah, here is an example of what I was thinking:

>> rule: [] parse "aaabbbb" [any [rule ["a" (print 'a) | "b" (print 
'b rule: [to end " "])]] to end]
a
a
a
b
== true

When the first b is encountered, rule is set to a rule which cannot 
be succeed, thus breaking out of the outer any.

so, rule ends up by being redefined?

I'm using these rules in my server side implemention to the top command


one-line-rule: [copy line thru {^/} ( if line = ".^/" [ line: join 
"." line ] write-client line)]

header-rule: [copy header thru {^/^/} (write-client header write-client 
)]

msg is the email message including header and body
lines is the number of lines requested by the TOP command

parse msg compose [ header-rule (lines) one-line-rule ]


Now, I can't check the parse syntax as rebol.com is down, but I seem 
to always get the whole email with my header-rule and not just the 
header.

correction: header-rule: [copy header thru {^/^/} (write-client header)]

the rules work when tested at the console.  So, I'm thinking something 
else is wrong.

The email is obtained by reading from a port in binary mode, so could 
this be due to the lack of line ending conversion ?

From a unix system to windows32?

Hi Graham. Line ending in Internet protocols = Apples; Line/Paragraph 
representation in text files = Oranges. :-)

Best not to compare them for this task.  As far as I've seen, Internet 
protocols have an on-the-wire line ending of CRLF.  So yes this is 
very likely a problem with your parse rules.

With the port in binary mode - you must use CRLF to identify/transmit 
line endings.

Hi Brett.  Do you then see a problem with me parse rules?

seems link to get all possible raw line endings something  like  
copy line thru [ 1 2 ["^J" | "^M"]]   might work

my one-line-rule seems to work already ..

copy header thru [ 2 [ "^J" | "^M"] ] ... ?

unix would be a single "^J"

header is separated from body by one blank line.

So, I need to look for two consecutive line endings to find the end 
of the header

yes ,  my rule was for a single lin as in your first code  sample

is ^J the line feed ?

copy header ti ["^J^J" | "^M^M" | "^M^J^M^J"]

^J same as ^/

>> header-rule: [copy header thru ["^J^J" | "^M^M" | "^M^J^M^J"] 
 (write-client header)]
== [copy header thru ["^/^/" | "^M^M" | {^M
^M
}] (write-client header)]
>> parse m header-rule
** Script Error: Invalid argument:

 |


** Near: parse m header-rule

try {^M^/^M^/}

not that it shoulf matter

same problem

it is interperting the third newline ... odd  buggy odd

parse all?

os use |  2 CRLF

>> unix: [ copy header thru "^J^J" ]
== [copy header thru "^/^/"]
>> msdos: [ copy header thru "^/^/" ]
== [copy header thru "^/^/"]
>> parse m [ [ unix | msdos ] ( write-client header ) ]

ms dos  not correct

is that correct rule for unix ?

yes

what's msdos ?

mac ^M^M  dod ^M^J unix ^J

mac is a single ^M for a single line

[2 "^/" | 2 "^M" | 2 CLRF]

>> parse m [ [2 "^/" | 2 "^M" | 2 crlf ] ( write-client header ) 
]
== false

dos is : join crlf crlf .. isn't it ?

... copy haader theu ...

parse m [ copy header thru [2 "^/" | 2 "^M" | 2 crlf ] ( write-client 
header ) ]
** Script Error: Invalid argument: 2
 | 2 crlf