Re: [Bug-apl] Not a bug, need help coding search&replace on a vector

[Xiao-Yong Jin]

Here is the dyalog ⎕R (replace), you can find ⎕S too.  It’s a nice interface, 
but not easy to remember everything.
http://help.dyalog.com/14.1/Content/Language/System%20Functions/r.htm

> On Jun 21, 2016, at 10:10 PM, Christian Robert <address@hidden> wrote:
> 
> Oh yes, would be nice. (pcre would be as nice as regex, may be more)
> 
> make it a ⎕regex or ⎕pcre so, no need to load a specific .so file or )lib to 
> use it ;-)
> 
> Ideal would be to be able to not only scan but be able to compile a pcre, 
> find patterns, search & replace ...
> 
> I am dreaming, but still awake ...
> 
> Xtian.
> 
> 
> On 2016-06-21 22:39, Elias Mårtenson wrote:
>> Would anyone be interested if I actually implemented support regex by 
>> calling into the C library?
>> 
>> I'm envisioning something like this:
>> 
>> *      "^([a-z]+):([0-9]+)$" regex∆scan "foo:123"*
>> ┏→━━━━━━━━━━┓
>> ┃"foo" "123"┃
>> ┗∊━━━━━━━━━━┛
>> 
>> Regards,
>> Elias
>> 
>> On 22 June 2016 at 10:35, Xiao-Yong Jin <address@hidden 
>> <mailto:address@hidden>> wrote:
>> 
>>    At some point I really wanted to implement the simplest editor, namely ed 
>> (it would be much better than any APL system has offered), in APL, but I 
>> never finished the regex part.  Perhaps it would be a nice exercise for 
>> someone who’s interested in learning APL to actually implement some of the 
>> most used Unix command line utilities.
>> 
>>    > On Jun 21, 2016, at 8:53 PM, Christian Robert 
>> <address@hidden<mailto:address@hidden>> wrote:
>>    >
>>    > Hi,
>>    >
>>    > A more general purpose search&replace (some bug fixed), take (2), was 
>> "snr".
>>    >
>>    >
>>    >
>>    >      )sic
>>    >      )erase replace
>>    >      ∇z←s replace p;fr;to;P;i;⎕io
>>    > ⍝ -------------
>>    > →(2≤≡s)/ForEach
>>    > →(2≤⍴⍴s)/Matrix
>>    > →Vector
>>    > ⍝ -------------
>>    > ForEach: z←{⍵ replace p}¨s ◊ →0
>>    > Matrix: z←⊃ {⍵ replace p}¨ ⊂[2]s ◊ →0
>>    > ⍝ -------------
>>    > Vector: p←,¨p ◊ z←s←,s ⋄ ⎕io←1
>>    > Loop:→((⍴p)<2)/0
>>    > (fr to)←2↑p ◊ p←2↓p
>>    > P←¯1↓∧/[1](¯1+⍳⍴fr)⌽fr∘.=z,⎕ucs 1
>>    > i←0
>>    > Sanitize: i←i+1
>>    > →(i>(⍴P)-⍴fr)/Substitute
>>    > →(0=P[i])/Sanitize
>>    > ((⊂ i+¯1+⍳⍴fr)⌷P)←(⍴fr)↑1
>>    > →Sanitize
>>    > Substitute: P←⌽(P/⍳⍴P)
>>    > ⊣ {z←((¯1+⍵)↑z),to,(¯1+⍵+⍴fr)↓z}¨P
>>    > →Loop
>>    > ∇
>>    >
>>    > It should be vector, matrix and embedded objects "aware" (as long as it 
>> is all text)
>>    >
>>    > Syntax:
>>    >
>>    >  source replace "this" "by_that" "this" "by_that" [...]  (eg: pairs of 
>> "from" and "to")
>>    >
>>    > Examples:
>>    >
>>    >      (⎕cr 'replace') replace 'replace' 'snr' 'ForEach' "Each" 
>> "Substitute" "Subst" "Sanitize" "Sane"
>>    > z←s snr p;fr;to;P;i;⎕io
>>    > ⍝ -------------
>>    > →(2≤≡s)/Each
>>    > →(2≤⍴⍴s)/Matrix
>>    > →Vector
>>    > ⍝ -------------
>>    > Each: z←{⍵ snr p}¨s ◊ →0
>>    > Matrix: z←⊃ {⍵ snr p}¨ ⊂[2]s ◊ →0
>>    > ⍝ -------------
>>    > Vector: p←,¨p ◊ z←s←,s ⋄ ⎕io←1
>>    > Loop:→((⍴p)<2)/0
>>    > (fr to)←2↑p ◊ p←2↓p
>>    > P←¯1↓∧/[1](¯1+⍳⍴fr)⌽fr∘.=z,⎕ucs 1
>>    > i←0
>>    > Sane: i←i+1
>>    > →(i>(⍴P)-⍴fr)/Subst
>>    > →(0=P[i])/Sane
>>    > ((⊂ i+¯1+⍳⍴fr)⌷P)←(⍴fr)↑1
>>    > →Sane
>>    > Subst: P←⌽(P/⍳⍴P)
>>    > ⊣ {z←((¯1+⍵)↑z),to,(¯1+⍵+⍴fr)↓z}¨P
>>    > →Loop
>>    >
>>    >
>>    > You can even try "⎕fx" the result if it looks like Ok. (ps: always 
>> check the result before committing)
>>    >
>>    > Substitutions are done in pair sequence for each 
>> /vector/matrix/embedded obj.
>>    >
>>    > So replace order is *very* important.
>>    >
>>    > It must still have some bugs, report them to me, with examples if so. 
>> Will do my best but no promises.
>>    >
>>    > Purpose: well, not sure, it was an exercise. I used it on itself to 
>> finally rename the function and change some variables/labels names.
>>    >
>>    >
>>    > Features: would be fun to pass parameters to each of the /from/to/ like 
>> maximum number of substitutions to do per line ...
>>    >          whole words only (taking apl characters as blanks) ... so 
>> variable "s" won't match last character of variable "pairs"
>>    >          ... no limits
>>    >
>>    >
>>    > Xtian.
>>    >
>>    >
>>    > On 2016-06-21 12:27, Juergen Sauermann wrote:
>>    >> Hi Xtian,
>>    >>
>>    >> how about this:
>>    >>
>>    >> *      
>> **s←"444This4is4a4444test44with44444lot4of4blanks4444at4beginning4and444end444444"**
>>    >>      from←"444"**
>>    >> **      to←"5"**
>>    >> **
>>    >> **      ↑⍎')HOST echo "',s,'" | sed s/',from,'/',to,'/g'**
>>    >> **5This4is4a54test44with544lot4of4blanks54at4beginning4and5end55**
>>    >> **  **
>>    >> *I have replaced the *^* in your example because it (and some other 
>> characters) have a special meaning in
>>    >> regular expressions. But the special characters can be easily quoted 
>> in APL if needed, for example:
>>    >>
>>    >> *      
>> s←"^^^This^is^a^^^^test^^with^^^^^lot^of^blanks^^^^at^beginning^and^^^end^^^^^^"
>>  **
>>    >> **      ((s='^')/s)←⊂'\^'**
>>    >> **      ⊃,/s**
>>    >> 
>> **\^\^\^This\^is\^a\^\^\^\^test\^\^with\^\^\^\^\^lot\^of\^blanks\^\^\^\^at\^beginning\^and\^\^\^end\^\^\^\^\^\^**
>>    >> *
>>    >> /// Jürgen
>>    >>
>>    >>
>>    >> On 06/21/2016 05:12 AM, Christian Robert wrote:
>>    >>> Hi, it's not a bug but a request for help,
>>    >>>
>>    >>>
>>    >>> suppose 
>> s="^^^This^is^a^^^^test^^with^^^^^lot^of^blanks^^^^at^beginning^and^^^end^^^^^^"
>>    >>> suppose from="^^^"
>>    >>> suppose to="^"
>>    >>>
>>    >>> I need a function who can replace ("^^^" to "^"), or ("^" to 
>> "^^^^^^^^") or ("" to "blabla" with limits of source size)  ie: without 
>> being lost in infinite loop.
>>    >>>
>>    >>>
>>    >>>
>>    >>> "s" is a character vector, "from" is a character vector, and "to" is 
>> a character vector,
>>    >>> both "s", "from" and "to" can be "".
>>    >>>
>>    >>>
>>    >>>
>>    >>> I'm pretty sure this idiom already exist.
>>    >>>
>>    >>> if you can help me, please do.
>>    >>>
>>    >>> Xtian.
>>    >>>
>>    >>>
>>    >>>
>>    >>>
>>    >>>
>>    >>>
>>    >>