splittext() not correctly splitting on delimiter

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ID:2026759
 
Jan 29 2016, 3:25 pm (Edited on Jan 29 2016, 4:44 pm)
Resolved
By popular demand, splittext() has been changed so that the delimiter is an exact match, rather than a set of characters to match. The delimiter is always case-sensitive.
Applies to:DM Language
BYOND Version:510.1321
Operating System:Windows 7 Home Premium 64-bit
Web Browser:Chrome 47.0.2526.111
Status: Resolved (510.1322)
This issue has been resolved.
Descriptive Problem Summary:
splittext() appears to be incorrectly ignoring the second character of a two character delimiter, instead assuming the first character is the only condition, resulting in a bad list.

Edit: This is entirely a guess I dunno what the fuck is really going on.
Edit 2: Actually it appears to occur any time a character in the delimiter is used further on, regardless of if it only matches the delimiter partially. This is thus only applicable when using multi-character delimiters.
Edit 3: Heck the docs actually make it sound like this might be INTENDED behavior (referring to the delimiter parameter as "delimiters" and such). If this is the case: ahaha no this is not how this proc should work, 100% absolutely and truly not.

Code Snippet (if applicable) to Reproduce Problem:
/client/verb/test()
    var/text = "foo@=bar@baz"
    var/list/thing = splittext(text, "@=")
    src << list2params(thing)


Expected Results:
foo&bar%40baz

Actual Results:
foo&bar&baz
Jan 29 2016, 6:07 pm
Both chars are delimiters, so the results you're seeing are correct.
Jan 29 2016, 6:07 pm
Lummox JR resolved issue (Not a bug)
Jan 29 2016, 6:14 pm
But the final @ is not being seen as a delimiter, it's being returned as a literal @ ...that doesn't seem correct?
Jan 29 2016, 6:32 pm
No its not Saiyan.
And the intended behavior should be to use the entire string as the delimeter, otherwise its just a separator, not a delimeter.
If people want to use it like the current behavior they can use regex, but no language implements splitting of strings by having a string of single character separators. This should not be the intended behavior IMO
Jan 29 2016, 6:33 pm
Yeah this is very objectively not sane behavior for this proc. In other languages this is not how this sort of thing works.
Jan 29 2016, 6:38 pm
Oh, I misread actual results vs expected results.
Jan 29 2016, 9:48 pm
I feel the need to chip in that this is incredibly dumb. I'd understand if C couldn't make the distinction between char[] and char*, but since we have built-in byond constructs that represent this differently, why not use them? If someone handed me a splittext proc, I'd expect it to split:
- On an exact, full match if I use a string as a delimiter
- Same for regexes
- And only exhibit this behaviour if a list of strings is passed instead.
Jan 29 2016, 9:57 pm
There are basically two ways to look at splitting text: One is with a delimiter that could be a multi-char string, and the other is with a set of possible delimiters. Lots of tokenizers use the second way, and it's also the easiest to implement.

There's no reason I couldn't change the implementation at this stage if the general consensus calls for it, I suppose, but how many people truly want to split by a multi-char string?

And of course whichever way the implementation goes, regular expressions can always handle the other way.
Jan 29 2016, 10:50 pm
Make a vote? I dunno.
Jan 29 2016, 11:39 pm (Edited on Jan 29 2016, 11:54 pm)
In response to Lummox JR
Lummox JR wrote:
There's no reason I couldn't change the implementation at this stage if the general consensus calls for it, I suppose, but how many people truly want to split by a multi-char string?

I do... If I wanted to split 2 different characters I would just call the proc again. It's also the exact behavior I would expect. I don't see the first approach used very much.

Consider this:
var/message = "One Two|@|Three Four|@|Five Six|@|Seven Eight"

var/list/L = splittext(message, "|@|") // expected: list("One Two", "Three Four", "Five Six", "Seven Eight")
var/list/L2

world << "And..."

for (var/word in L)
    L2 = splittext(word, " ") // expected: list("One", "Two")

    world << L2[1]
    sleep(5)
    world << L2[2]

    sleep(15)


Not the best example I'm sure, but just by reading this code I would expect that the message is split by the full "|@|" and not by every character in the string "|@|".

The latter sounds weird (to me) and I'd only expect that behavior if I were specifying a list of strings, like so:

var/message = "One@Two=Three&Four,Five:Six;Seven!Eight"

var/list/L = splittext(message, list("@", "&", ";", ":", "!", ",")) // expected: list("One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight")


This has the reader's expectation that the text will be split by each character provided. I'm sure it's not economical given the creation of a list and several strings, but as you said regular expressions would be a viable alternative.

EDIT: Originally I used "<br/>" instead of "|@|" as the delimiter. Unfortunately the forum replaces "<br/>" with an empty string if you use it in a "<DM>" tag and there's no alternative as "&lt;br/&gt;" isn't transformed.
Jan 29 2016, 11:51 pm (Edited on Jan 30 2016, 12:00 am)
In response to Lummox JR
JavaScript uses the 2nd approach, taking the whole string. I think this is particularly relevant as it's the secondary language used for the webclient.

The only language I've found so far that doesn't use the 2nd method is C++. So I understand now where you're coming from. But someone probably came up with the strok function somewhere in the 80's/90's, so I don't think it's the right benchmark for this time and age.
Jan 30 2016, 12:31 am (Edited on Jan 30 2016, 12:40 am)
I would definitely prefer having a set of possible delimiters. The current behavior isn't really what I would expect. Why should delimiters be limited to a single character? Multi-character delimiters are just too useful.

This is the kind of behavior that I would expect:
var/text = "foo@=bar@baz"

splittext(text, "@=") // returns list("foo", "bar@baz")

// Use any number of delimiter arguments:
splittext(text, "@=", "@") // returns list("foo", "bar", "baz")

// or just pass a list as an alternative:
splittext(text, list("@=", "@")) // also returns list("foo", "bar", "baz")


This would make splittext() both strict and flexible.
Jan 30 2016, 2:21 am
I haven't toyed with it but how would you accomplish splitting strings with multi-char strings at the moment?
Jan 30 2016, 3:12 am
In response to Somepotato
Somepotato wrote:
no language implements splitting of strings by having a string of single character separators.

False. Erlang does.
Jan 30 2016, 8:55 am
In response to Rotem12
Rotem12 wrote:
I haven't toyed with it but how would you accomplish splitting strings with multi-char strings at the moment?

Regular expressions.
Jan 30 2016, 11:44 am
lummox: how about splitting by each string if the delimiter is a list, and the whole string otherwise.

Then devs have the ability to do both.
Jan 30 2016, 11:47 am
In response to MrStonedOne
MrStonedOne wrote:
lummox: how about splitting by each string if the delimiter is a list, and the whole string otherwise.

Then devs have the ability to do both.

^ This, very much.
Jan 30 2016, 11:56 am
That is a good solution. Agreed.
Jan 30 2016, 12:06 pm
its either that, or an arg
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