World: r3wp
[Parse] Discussion of PARSE dialect
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Henrik 9-Jul-2006 [1320x2] | I'm parsing: [image "String" image-word [action block]] |
where 'image is always first and the remaining items may come in random order | |
Oldes 9-Jul-2006 [1322] | there is no pair and no numbers - the pos must be none |
Henrik 9-Jul-2006 [1323] | oldes, my code is different from his. I used his as it's structurally similar to mine |
Oldes 9-Jul-2006 [1324] | and what exactly do you want? |
Henrik 9-Jul-2006 [1325] | I want to assign a variable to each element so I can process them later |
Oldes 9-Jul-2006 [1326] | so for the block above it would assing what? |
Henrik 9-Jul-2006 [1327x3] | the block is stored in 'attr. parse attr [ (txt: 123 print txt) 'image any [set txt string! (print txt) | set img word! | set action block!] (print txt) | 'face ] gives: 123 search none == true |
argh... forgot to show you attr | |
attr: [image test-image "Search" [print "test"]] | |
Oldes 9-Jul-2006 [1330] | Don't you want to use rather: parse/all attr [(txt: 123 print txt) 'image opt [set txt string! (print txt)] opt [ set img word!] opt [ set action block! (print txt)] (print txt) | 'face] |
Henrik 9-Jul-2006 [1331] | it seems the variable is stored in the last iteration, so it's definitely lost after one loop. |
Anton 9-Jul-2006 [1332] | Doesn't Henrik want to be able to process the attributes in any order ? |
Henrik 9-Jul-2006 [1333x3] | that's what I want. I'm catching fish :-) or rather information to store them safely for processing later. |
but let me try Oldes thing to see what it does | |
it works the exact opposite :-) Only the outer 'txt is set, and I can't reach the variable inside the block | |
Anton 9-Jul-2006 [1336x2] | Henrik, I parse your test attr block successfully: >> parse [image test-image "Search" [print "action"]] ['image any [set txt string! (?? txt) | set img word! | set action block!]] txt: "Search" == true |
Need more test data to parse. | |
Henrik 9-Jul-2006 [1338x2] | anton: yes, but what is txt after processing? |
I don't want to handle it inside the parse block but after it | |
Anton 9-Jul-2006 [1340] | it is none. |
Henrik 9-Jul-2006 [1341] | right. that's the problem |
Anton 9-Jul-2006 [1342x2] | add a block to control the evaluation. |
>> parse [image test-image "Search" [print "action"]] ['image any [[set txt string! (?? txt)] | set img word! | set action block!]] txt: "Search" == true >> txt == "Search" | |
Oldes 9-Jul-2006 [1344] | it always set the variables to none, if it fails to match |
Anton 9-Jul-2006 [1345] | You have to be careful in your interpretation of | |
Oldes 9-Jul-2006 [1346] | interesting, this is the solution: txt: 123 parse/all attr ['image any [[set txt string! (print txt)] | [set img word!] | [set action block! (print txt)]] (print txt) | 'face] |
Henrik 9-Jul-2006 [1347x2] | oldes solution seems to work |
the wonders of parse... :-) | |
Oldes 9-Jul-2006 [1349] | it's just improved anton's solution:-) |
Anton 9-Jul-2006 [1350] | I'm trying to figure out a simple example to show why. |
Henrik 9-Jul-2006 [1351] | I wonder what the difference is? If it's only for controlling how global a variable is, it seems a little backwards to me |
Oldes 9-Jul-2006 [1352] | without the extra brackets, the parse set the variables to none if it failes |
Henrik 9-Jul-2006 [1353] | the brackets would make it a "real" rule, wouldn't it? it would be possible to replace the rule with a variable and have the rule block placed elsewhere in your code |
Anton 9-Jul-2006 [1354] | You have to think of a rule like this: [ integer! | ] as equivalent to [ integer! | none ] or opt [ integer! ] |
Oldes 9-Jul-2006 [1355] | I don;t know how much complex will be the source to parse, but I would use the OPT settings as used above |
Anton 9-Jul-2006 [1356x2] | But Henrick wants it in any order, like LAYOUT code. (Thus, it's worth to look how LAYOUT works. :) |
>> parse ["hi"] [[set num integer! | ] string!] ?? num num: none | |
Oldes 9-Jul-2006 [1358x2] | I just think he can end with endless loop easily, as he will never be able to catch the second 'image |
>> parse ["hi"] [[set num [integer! | string!]] ] ?? num num: "hi" | |
Anton 9-Jul-2006 [1360] | Note the | . "set NUM to an integer or NONE, then... oh. it's the end of this block..." but in Henrick's rule above he continues to set other variables, which is of no concern to parse, it still has successfully set NUM to NONE. |
Henrik 9-Jul-2006 [1361] | there is only one 'image in the block fortunately |
Oldes 9-Jul-2006 [1362] | ok, so you will not catch the 'face word:-) as it end up in the img variable:-) |
Anton 9-Jul-2006 [1363] | I think he might be using 'test-image in place of a real image! for this example ? |
Henrik 9-Jul-2006 [1364x2] | oldes, nope, because I have many different blocks. they either start with 'face or with 'image |
never both | |
Anton 9-Jul-2006 [1366x2] | That's good. |
So you can use ANY in an unlimited fashion. | |
Henrik 9-Jul-2006 [1368x2] | and it makes the parse scalable, so I can add options later |
thanks for your help, everyone :-) | |
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