Splitting with empty string as separator causes high memory usage

[Esgorhannoth]

"test" "" split

causes high memory usage and heavy swapping, so that PC sometimes even freezes (Windows 10 x64, 8 GB RAM)

My intention was to get separate characters, but according to nim's split documentation, with empty separator nim's split returns unmodified string. Somehow split in mn does neither.

[h3rald]

This is really weird, because the split symbol can be used with an empty separator in min:

...but in mn it hangs. The annoying thing is that the implementation is essentially the same, but perhaps in min if the pcre library is included the behavior changes.

Perhaps the easiest thing would be to handle this as a special case in mn and if the separator is an empty string try to use something else in Nim to split the string, maybe create a sequence via an iterator or something.

[Esgorhannoth]

Seems like Nim problem. I have written a simple program to test my suggestion:

import
     strutils

proc main =
    var i = 0
    echo "hello".split("")    ## compiles, but assertion (sep.len > 0) error at runtime 
    #but
    for e in "hello".split(""):  ## infinite loop
        i.inc
        echo i       ## to confirm that something happens
        echo e

main()

Possible solution:

 def.symbol("split") do (i: In):
    let vals = i.expect("'sym", "'sym")
    let sep = vals[0].getString
    let s = vals[1].getString
    var q = newSeq[MnValue](0)
    if sep.len > 0:
      for e in s.split(sep):
        q.add e.newVal
    else:
      for e in s:
        q.add e.newVal
    i.push q.newVal

[h3rald]

Fixed on master 😊👍