World: r3wp

yes

Here's an idea to toss into the mix:

I am thinking of a new notation for strings using underscore (eg. 
 _"hello"_  ) in a parse block, which allows to specify whether they 
are delimited by whitespace or not. This would allow you to enable/disable 
the necessity for delimiters per-string. eg:

parse input [

 _"house"_   ; a complete word surrounded both sides by whitespace

 _"hous"   ;  this would match "house", "housing", "housed" or even 
 "housopoly" etc.. but left side must be whitespace

 "ad"_ ; this would match "ad", "fad", "glad" and right side must 
 be whitespace
]

But this would need string datatype to change.

On the other hand, I could just set underscore _ to a charset of 
whitespace, then use that with parse/all eg:

	_: charset " ^-^/"

parse/all input [
	[ _ "house" _ ]
]


though that wouldn't be as comfortable. Maybe I can create parse 
rules from a simpler dialect which understands the underscore _.
Just an idea...

Anton, Andrew had defined white space patterns in his patterns.r 
script which seems usable then you can use [ ws* "house" ws*] or 
other combinations as needed without underscore.  Andrew's solution 
for this and a lot of other things have given me some good mileage 
over the past few years.   WS*: [some WS]   and WS?: [any WS].   
 It makes for clean parse scripts clear once you adopt it.

I think either approach above can work well. I like the "look" of 
the underscore, and have done similar things with standard function 
names. For SOME, ANY, and OPT, the tag chars I prefer are +, *, and 
? resepctively; which are EBNF standard.

Oh yes, I've seen Andrew's patterns.r. I was just musing how to make 
it more concise without even using a short word like WS.  Actually 
the use case which sparked this idea was more of a "regex-level" 
pattern matcher, just a simple pattern matcher where the user writes 
the pattern to match filenames and to match strings appearing in 
file contents.

Gregg, + * ? could be a good idea. I'll throw that into my mix-bowl.

I also have a naming convention I've been playing with for a while, 
where parse rule words have an "=" at the end (e.g. date=) and parse 
variables--values set during the parse process--have it at the beginning 
(e.g. =date). The idea is that it's sort of a cross between BNF syntax 
for production rules and set-word/get-word syntax; the goal being 
to easily distinguish parse-related words. By using the same word 
for a rule and an associated variable, with the equal sign at the 
head or tail, respectively, it also makes it easier to keep track 
of what gets set where, when you have a lot of rules.

simple and clean, good idea!

I'm just starting to be able to actually USE parse for dialecting. 
 So far I've been almost solely using it to replace regexp functionality.

so many years of reboling (since core 1.2) , and still parse remains 
largely untaimed by myself.

This was I thought a simple task .. to parse a csv file....

COHEN

,"WILLIAM   ",""," 305782","123 "C" AVENUE","CORONADO ","CA","92118","560456788","(619)555-2730","( 
  )   -   0","08/22/1927","M","SHARP CORONADO/MISSI","","","","","POLLICK","JAMES 
    ","","MOUNTAIN","RODERICK  ","",

this seems to be a difficult line as there is an embedded quote viz 
"123 "c" Avenue"

this is Gabriele's published parser 


CSV-parser: make object! [ line-rule: [field any [separator field]] 
field: [[quoted-string | string] (insert tail fields any [f-val copy 
""])] string: [copy f-val any str-char] quoted-string: [{"} copy 
f-val any qstr-char {"} (replace/all f-val {""} {"})] str-char: none 
qstr-char: [{""} | separator | str-char] fields: [] f-val: none separator: 
#";" set 'parse-csv-line func [ "Parses a CSV line (returns a block 
of strings)" line [string!] /with sep [char!] "The separator between 
fields" ] [ clear fields separator: any [sep #";"] str-char: complement 
charset join {"} separator parse/all line line-rule copy fields ] 
]

which was written to cope with embedded quotes, but fails where there 
is an empty field eg , "" ,

This is Joel Neely's from the same day ...

readcsv: make object! [

	all-records: copy []
	one-record:  copy []
	one-segment: copy ""
	one-field:   copy ""

	noncomma:    complement charset ","
	nonquote:    complement charset {"}

	segment: [
		copy one-segment any nonquote
		(if found? one-segment [append one-field one-segment])
	]

	quoted: [
		{"} (one-field: copy "")
		segment
		any [{""} (append one-field {"}) segment]
		{"}
	]

	unquoted: [copy one-field any noncomma]
	field:    [[quoted | unquoted] (append one-record one-field)]
	record:   [field any ["," field]]

	run: func [f [file!] /local line] [
		all-records: copy []
		foreach line read/lines f [
			one-record: copy []
			either parse/all line record [
				append/only all-records one-record
			][
				print ["parse failed:" line]
			]
		]
		all-records
	]
]

which reports an error with this line.

this might fix Gabriele's parser ..

CSV-parser: make object! [
	line-rule: [field any [separator field]]

 field: [[quoted-string | string] (insert tail fields any [f-val copy 
 ""])]
	string: [copy f-val any str-char] 

 quoted-string: [{"} copy f-val any qstr-char {"} (if found? f-val 
 [ replace/all f-val {""} {"}])]
	str-char: none qstr-char: [{""} | separator | str-char]
	fields: []
	f-val: none
	separator: #";" set 'parse-csv-line func [
		"Parses a CSV line (returns a block of strings)"
		line [string!]
		/with sep [char!] "The separator between fields"
	] [
		clear fields
		separator: any [sep #";"]

  str-char: complement charset join {"} separator parse/all line line-rule 
  copy fields
	]
]

perhaps not.

Why you do not use split?

graham, iirc my version is meant to handle embedded quotes when properly 
escaped, i.e. you should have "123 ""C"" AVENUE" there for it to 
work.

i actually wonder why are quotes used in that line. they are only 
needed if the field contains the separator.

split will work if there are no embedded commas I guess

What's the parse rule to go backwards ?
	-1 skip  ?

maybe this will help:

x: [1 2 3 4 5] parse x [any [x: set d number! (probe x probe d x: 
next x) :x]]

you can set the x to another position if you need

Ah yes - very good :)

my god, I think I finally  -get-  Parse... call me the village idiot. 
 I used to use parse, now I also understand subconciously it  ;-)

that should read "... I also understand  it subconciously"

(parse rule inversion ;-)

That's a ~very~ good example, Oldes... it should be put in the docs 
somewhere (if it isn't already.)  I didn't understand how get-words 
and set-words worked in parse, either, before..

Nice demo of parse-position main features :)

I've got following PARSE problem:


I've got string - "<good tag><bad tag><other tag><good tag>" and 
I want to keep "good tag" and "<>" in other tags change to let's 
say "X" (I need to change it to HTML entities but that doesn't matter 
now). So result will look like: "<good tag>Xbad tagXXother tagX<good 
tag>"


I'm working on it for last few hours but still not found sollution. 
Is there any?

string: "<good tag><bad tag><other tag><good tag>"
entity: "<ENTITY>"
parse/all string [
	any [
		to "<" start: skip
		to ">" end: skip 
		(if not find copy/part start end "good tag" [
			change/part start entity 1

   ; fix up END (for when your entity is other than a 1-character long 
   string)
			end: skip end (length? entity) - 1
			change/part end entity 1
			; fix up END again
			end: skip end (length? entity) - 1
		])
		:end skip
	]
	to end
]
string

;== {<good tag><ENTITY>bad tag<ENTITY><ENTITY>other tag<ENTITY><good 
tag>}

Anton nice thanks. But I also need it to work on this: string: "<good 
tag><bad tag> 3 > 5 <other tag><good tag with something inside>". 
I almost got it, but that non-symmetric "3 > 5" is still problem 
for me.

I'll probable replace everything and then just revert the "good tag" 
back. It's not very elegant, but...

(hm, 3 > 5. my examples are not very 'real-life' :-))

Such unmatched tags cause a headache for any parser.

YES

What are the HTML entities by the way ?

<, and >  ?

Yes.

Anton: yes. I have to check lot of XML files full of errors (actually 
it's Vista documentation, so it's understandable...)

Ok, give this a burl.

string: "<good tag><bad tag> 3 > 5 <other tag><good tag with something 
inside>"

string: " > >> < <<good tag><bad tag> 3 > 5 <other tag><good tag 
etc> >> > "

; (1) search for end tags >, they are erroneous so replace them

; (2) search for start tags <, if there is more than one, replace 
all except the last one

; (3) search for end tag >, check tag body and replace if necessary

entity: "&entity;"
ntag: complement charset "<>" ; non tag
parse/all result: copy string [
	any [
		; (1)
		any [
			any ntag start: ">" end: (

    change/part start entity 1 end: skip start length? entity  ;print 
    [1 index? start]
			) 
			:end
		]
	
		; (2)
		(start: none stop?: none)
		any [
			any ntag start: "<" end:   ;(print [2 mold start])
			any ntag "<" (  ;print "found a second start tag"

    change/part start entity 1 end: skip start length? entity  ;(print 
    [2.1 mold copy/part start end]) 
				start: none
			) :end
		]
		(if none? start [stop?: 'break]) stop?
		
		; ok, we found at least one start tag
		;(print ["OK we found at least one start tag" mold start])
		:start skip
		
		; (3)
		any ntag end: ">"   ;(print [3 mold copy/part start end])
		(if not find copy/part start end "good tag" [
			;print ["found a bad tag" mold copy/part start end]
			change/part start entity 1

   ; fix up END (for when your entity is other than a 1-character long 
   string)
			end: skip end (length? entity) - 1
			change/part end entity 1
			; fix up END again
			end: skip end (length? entity) - 1
		])
		:end skip
	]
	to end
]
result

All you need to do now is define two separate entity strings for 
< and >  and then use the right one when replacing.

great, I'll test it, thanks

Holy ---- ! where did two and a half hours go ?

oh no.. maybe I only spent one and a half hours on it, but still...!

Erhm sorry ;)