World: r3wp
[Parse] Discussion of PARSE dialect
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[unknown: 5] 30-Jun-2008 [2630x3] | It might work for you if you not in need of multi-user (simultaenous access) |
The next version of TRETBASE which is in work is multi-user and supports indexing. | |
But not finished. | |
amacleod 30-Jun-2008 [2633] | I'm using mysql for the online component but I need a local storage method too for offline use |
[unknown: 5] 30-Jun-2008 [2634] | It might work for that. Can also do the images conversion for you in REBOL format which is nice. |
amacleod 30-Jun-2008 [2635x2] | That was one of the things that had me thinking of using it. |
What I would need is a simple method to sync them | |
[unknown: 5] 30-Jun-2008 [2637] | Best thing to do is try it out as it really takes very little time to setup and try and you will know probably if it is suitable for you in about 10 minutes. |
amacleod 18-Jul-2008 [2638] | Is there a difference between a "space" and a "tab"? Can you parse for tab and not sapce? |
Graham 18-Jul-2008 [2639x2] | I would think you would have to parse/all .. and a space is #" " and a tab is #"^-" |
or you can use charsets | |
amacleod 18-Jul-2008 [2641] | Parse/all...works thanks |
Henrik 18-Jul-2008 [2642x2] | amacleod, small tip: |
help char! | |
amacleod 18-Jul-2008 [2644] | thanks |
btiffin 21-Aug-2008 [2645] | A long time ago, I offered to try a lecture. Don't feel worthy. So I thought I'd throw out a few (mis)understandings and have them corrected to build up a level of comfort that I wouldn't be leading a group of high potential rebols down a garden path. So; one of the critical mistakes in PARSE can be remembered as "so many", or a butchery of some [ any [ , so many. some asks for a truth among alternatives and any say's "yep, got zero of the thing I was looking for", but doesn't consume anything. SOME says, great and then asks for a truth. ANY say "yep, got zero of the thing I was looking for", and still doesn't move, ready to answer yes to every question SOME can ask. An infinite PARSE loop. Aside: to protect against infinite loops always start a fresh PARSE block with [() the "immediate block" of the paren! will allow for a keyboard escape, and not the more drastic Ctrl-C. So, I'd like to ask the audience; what other PARSE command sequences can cause infinite loops? end? and is it only "end", "to end" but "thru end" will alleviate that one? end end end end being true? >> parse "" [some [() end end end]] (escape) >> parse "" [some [() thru end end end]] == false >> parse "" [some [() to end end end]] (escape) >> Ok, but thru end is false. Is there an idiom to avoid looping on end, but still being true on the first hit? Other trip ups? |
Oldes 21-Aug-2008 [2646x3] | >> parse "" [any [()]] (escape) |
it's one of the most simple ways how to halt rebol if you don't include the parens. | |
These condition are already fixed in R3 | |
Louis 20-Sep-2008 [2649] | x: "12---dflksdf+++fhkw---sd+++sad" How can I remove everything to "---" thru "+++" to end up with "12fhkwsad" |
Anton 20-Sep-2008 [2650x2] | parse x [any [to "---" here: thru "+++" there: (remove/part here there) :here]] |
Notice, after the remove that I have reset the parse index to the beginning of the removed part, ready to continue parsing the rest of the data. | |
Louis 20-Sep-2008 [2652] | Anton, thanks. I'll try that now. Sorry to take so long to respond---I've been eating. |
Anton 20-Sep-2008 [2653] | No problem, Louis. You're welcome. |
Louis 20-Sep-2008 [2654] | Works great! Many, many thanks. |
Henrik 28-Sep-2008 [2655x3] | parse [a] ['a] ;== true parse ['a] reduce [to-lit-word 'a] ; == false (why?) |
forget it. I was confused for a second, but is there a way to parse that 'a correctly? The same goes for get-word! and set-word!. | |
I should clarify: I would like to parse a specific get-word!, lit-word! or set-word! as opposed to parsing on the type and then checking the value in some kind of action afterwards: parse ['a 'b 'c] ['a 'b 'c] ;== true (I know this is the wrong parser block, but it's something to that effect I would like to see) | |
Anton 28-Sep-2008 [2658x2] | If I remember correctly, this was a problem of parse (and may still be)... |
You may have to use a workaround. | |
Henrik 28-Sep-2008 [2660] | thought so :-) |
Geomol 28-Sep-2008 [2661] | If you can go with a reduced block, this can work: parse reduce ['a 'b 'c] ['a 'b 'c] |
Henrik 28-Sep-2008 [2662] | what if there are set-words in it? I wanted to parse the content of an object, which can be a mixture of word types. |
Chris 28-Sep-2008 [2663x2] | Is there any objection to matching type -> checking value other than the inconvience? |
You could also preprocess the block using an alternative to 'reduce -- parse blk [any [mk: lit-word! (mk: change mk switch mk/1 [...]) :mk | skip]] | |
BrianH 28-Sep-2008 [2665x4] | In general that restriction of parse is part of an overall pattern in REBOL of encouraging you to use lit-words as lit-words rather than some other kind of datatype. Lit-words in REBOL are generally used to express literal expressions of words, rather than being used as a distinct datatype. In general you convert them to words before use. |
It's usually a bad idea to use lit-words as keywords - they make better values. If you are comparing to a particular lit-word value, that is using it as a keyword. If any lit-word value would do and their meaning is semantic rather than syntactic, that works. In general, PARSE is better for determining syntactic stuff - use the DO dialect code in the parens for semantic stuff. | |
Not that I don't want a LIT or LITERAL directive in PARSE that would turn off the PARSE-dialect treatment of the next value in the spec. | |
It would only be for block parsing though. | |
Anton 10-Oct-2008 [2669x5] | term: [word! | into term] parse [a b [c]] [some term] ;== true parse [a b [c d]] [some term] ;== false |
I'm a bit confused by that. I need to parse recursively. | |
duh... never mind. | |
Solution: | |
terms: [some [word! | into terms]] parse [a b [c d]] terms ;== true | |
Terry 12-Oct-2008 [2674x2] | blk: [aa "test" bb "two" cc "#block"] rules: [some [cc set cc string! ]] parse blk rules no go? I have a more complicated rule set that chokes on the "#block" string.. does it think it's an issue! ? |
... rules looks like this rather.. rules: [some ['cc set cc string! ]] | |
Henrik 12-Oct-2008 [2676] | Your parser would stop at 'aa, since you never specify it in the rule block. Perhaps something like: rules: [some [['cc set cc string!] | [word! string!]] |
sqlab 12-Oct-2008 [2677] | rules: [some [set ww word! set ss string! (do reduce [to-set-word ww ss]) ]] |
Henrik 30-Oct-2008 [2678] | >> parse/all {2008-10-30|"This is" NOK|http://www.example.com}"|" == ["2008-10-30" "This is" " NOK" "http://www.example.com"] I caught this on the mailing list. Bug? |
sqlab 30-Oct-2008 [2679] | Yes, this is an old bug. It does not work, if " is next to your delimiter. Insert a blank, and it works again. |
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