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Add String.{cut,rcut}.#13

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Add String.{cut,rcut}.#13
dbuenzli wants to merge 1 commit intoocaml:trunkfrom
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@dbuenzli dbuenzli commented Feb 16, 2014

As a follow up to pull request #10. This pull request adds String.{cut,rcut} which cuts a string in two at a given non empty separator sep starting either from the beginning of the string or from the end. The signature for StringLabels is :

val cut : ~sep:string -> string -> (string * string) option
val rcut : ~sep:string -> string -> (string * string) option

These functions have the following invariants. First for any non empty sep and s such that sep is in s we have:

assert (String.{cut,rcut} sep s = Some (l,r))
assert (l ^ sep ^ r = s)

Then for any s such that sep doesn't occur in s:

assert (String.{rcut,cut} sep s = None)

Here is the result of String.{cut,rcut} on a few edge cases.

  (* String.cut *) 
  assert (try ignore (String.cut "" ""); false with Invalid_argument _ -> true);
  assert (try ignore (String.cut "" "123"); false with Invalid_argument _ -> true);
  assert (String.cut "," "" = None);
  assert (String.cut "," "," = Some ("", ""));
  assert (String.cut "," ",," = Some ("", ","));
  assert (String.cut "," ",,," = Some ("", ",,"));
  assert (String.cut "," "123" = None); 
  assert (String.cut "," ",123" = Some ("", "123"));
  assert (String.cut "," "123," = Some ("123", "")); 
  assert (String.cut "," "1,2,3" = Some ("1", "2,3")); 
  assert (String.cut "," " 1,2,3" = Some (" 1", "2,3")); 
  assert (String.cut "<>" "" = None); 
  assert (String.cut "<>" "<>" = Some ("", ""));
  assert (String.cut "<>" "<><>" = Some ("", "<>"));
  assert (String.cut "<>" "<><><>" = Some ("", "<><>"));
  assert (String.rcut "<>" "1" = None);
  assert (String.cut "<>" "123" = None);
  assert (String.cut "<>" "<>123" = Some ("", "123"));
  assert (String.cut "<>" "123<>" = Some ("123", ""));
  assert (String.cut "<>" "1<>2<>3" = Some ("1", "2<>3"));
  assert (String.cut "<>" " 1<>2<>3" = Some (" 1", "2<>3"));
  assert (String.cut "<>" ">>><>>>><>>>><>>>>" = 
          Some (">>>", ">>><>>>><>>>>"));
  assert (String.cut "<->" "<->>->" = Some ("", ">->"));
  assert (String.rcut "<->" "<-" = None);
  assert (String.cut "aa" "aa" = Some ("", "")); 
  assert (String.cut "aa" "aaa" = Some ("", "a"));
  assert (String.cut "aa" "aaaa" = Some ("", "aa"));
  assert (String.cut "aa" "aaaaa" = Some ("", "aaa";));
  assert (String.cut "aa" "aaaaaa" = Some ("", "aaaa"));
  (* String.rcut *) 
  assert (try ignore (String.rcut "" ""); false with Invalid_argument _ -> true);
  assert (try ignore (String.rcut "" "123"); false with Invalid_argument _ -> true);
  assert (String.rcut "," "" = None);
  assert (String.rcut "," "," = Some ("", ""));
  assert (String.rcut "," ",," = Some (",", ""));
  assert (String.rcut "," ",,," = Some (",,", ""));
  assert (String.rcut "," "123" = None); 
  assert (String.rcut "," ",123" = Some ("", "123"));
  assert (String.rcut "," "123," = Some ("123", "")); 
  assert (String.rcut "," "1,2,3" = Some ("1,2", "3")); 
  assert (String.rcut "," "1,2,3 " = Some ("1,2", "3 ")); 
  assert (String.rcut "<>" "" = None); 
  assert (String.rcut "<>" "<>" = Some ("", ""));
  assert (String.rcut "<>" "<><>" = Some ("<>", ""));
  assert (String.rcut "<>" "<><><>" = Some ("<><>", ""));
  assert (String.rcut "<>" "1" = None);
  assert (String.rcut "<>" "123" = None);
  assert (String.rcut "<>" "<>123" = Some ("", "123"));
  assert (String.rcut "<>" "123<>" = Some ("123", ""));
  assert (String.rcut "<>" "1<>2<>3" = Some ("1<>2", "3"));
  assert (String.rcut "<>" "1<>2<>3 " = Some ("1<>2", "3 "));
  assert (String.rcut "<>" ">>><>>>><>>>><>>>>" = 
          Some (">>><>>>><>>>>", ">>>"));
  assert (String.rcut "<->" "<->>->" = Some ("", ">->"));
  assert (String.rcut "<->" "<-" = None);
  assert (String.rcut "aa" "aa" = Some ("", "")); 
  assert (String.rcut "aa" "aaa" = Some ("a", ""));
  assert (String.rcut "aa" "aaaa" = Some ("aa", ""));
  assert (String.rcut "aa" "aaaaa" = Some ("aaa", "";));
  assert (String.rcut "aa" "aaaaaa" = Some ("aaaa", ""));

@dbuenzli dbuenzli mentioned this pull request Feb 16, 2014
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dbuenzli commented Feb 16, 2014

One disputable aspect of the proposal is that it doesn't respect String's design conventions to raise Not_found rather than return options. I'm on the side that new additions should not perpetuate the (wrong in my eyes) idea of using exceptions for non-exceptional cases. But I'm willing to turn that option into a raise Not_found if that is a pre-condition for including the patch.

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dbuenzli commented Apr 14, 2015

Let's not even consider this.

@dbuenzli dbuenzli closed this Apr 14, 2015
@dbuenzli dbuenzli deleted the cut branch January 6, 2016 15:43
@dbuenzli dbuenzli mentioned this pull request Jul 9, 2016
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@vicuna vicuna mentioned this pull request Mar 14, 2019
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dra27 referenced this pull request in dra27/ocaml Mar 20, 2019
@emillon
Use dune.configurator
48dc57c 
This uses `extract_blank_separated_words` instead of splitting by hand.

Closes #13
ulrikstrid pushed a commit to ulrikstrid/ocaml that referenced this pull request Sep 25, 2019
@bobzhang
Merge pull request ocaml#13 from chenglou/4.06
fd9e4cb 
Patch printtyp
poechsel pushed a commit to poechsel/ocaml that referenced this pull request Jul 2, 2021
@gretay-js @poechsel
Add HACKING.md (ocaml#13)
527c573
@TheLortex TheLortex mentioned this pull request Aug 3, 2022
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@andreas-schwab andreas-schwab mentioned this pull request Nov 28, 2022
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DMaroo pushed a commit to DMaroo/ocaml that referenced this pull request Jan 6, 2024
@kayceesrk
Merge pull request ocaml#13 from dipeshkaphle/verified-gc
2208a22 
Add caml_trigger_verified_gc primitive
gasche pushed a commit that referenced this pull request Sep 27, 2024
@yallop @nojb
Add support for top-level floatarray printing. (#13)
54bf62f
turly221 pushed a commit to scantist-ossops-m2/ocaml that referenced this pull request Nov 30, 2024
@lpw25
Merge pull request ocaml#13 from janestreet/patch/fix-6972
1174311 
Fix 6972
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