Multisplit: Difference between revisions
Updated to work with Nim 1.4: added missing parameter type, replaced ".. <" with "..< ". |
MaiconSoft (talk | contribs) Added Delphi example |
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{{out}} (separator locations indicated by braces): |
{{out}} (separator locations indicated by braces): |
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<pre>a {} {} b {} {} c</pre> |
<pre>a {} {} b {} {} c</pre> |
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=={{header|Delphi}}== |
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{{libheader| System.SysUtils}} |
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<lang Delphi> |
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program Multisplit; |
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{$APPTYPE CONSOLE} |
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uses |
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System.SysUtils; |
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begin |
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write('['); |
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for var s in 'a!===b=!=c'.Split(['==', '!=', '=']) do |
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write(s.QuotedString('"'), ' '); |
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write(']'); |
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readln; |
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end.</lang> |
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{{out}} |
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<pre>["a" "" "b" "" "c" ]</pre> |
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=={{header|Elixir}}== |
=={{header|Elixir}}== |
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{{trans|Erlang}} |
{{trans|Erlang}} |
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Line 531: | Line 549: | ||
["a",[],"b",[],"c"] |
["a",[],"b",[],"c"] |
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</pre> |
</pre> |
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=={{header|F_Sharp|F#}}== |
=={{header|F_Sharp|F#}}== |
Revision as of 14:56, 17 March 2021
![Task](http://static.miraheze.org/rosettacodewiki/thumb/b/ba/Rcode-button-task-crushed.png/64px-Rcode-button-task-crushed.png)
You are encouraged to solve this task according to the task description, using any language you may know.
It is often necessary to split a string into pieces based on several different (potentially multi-character) separator strings, while still retaining the information about which separators were present in the input.
This is particularly useful when doing small parsing tasks.
The task is to write code to demonstrate this.
The function (or procedure or method, as appropriate) should take an input string and an ordered collection of separators.
The order of the separators is significant:
The delimiter order represents priority in matching, with the first defined delimiter having the highest priority.
In cases where there would be an ambiguity as to
which separator to use at a particular point
(e.g., because one separator is a prefix of another)
the separator with the highest priority should be used.
Delimiters can be reused and the output from the function should be an ordered sequence of substrings.
Test your code using the input string “a!===b=!=c
” and the separators “==
”, “!=
” and “=
”.
For these inputs the string should be parsed as "a" (!=) "" (==) "b" (=) "" (!=) "c"
, where matched delimiters are shown in parentheses, and separated strings are quoted, so our resulting output is "a", empty string, "b", empty string, "c"
.
Note that the quotation marks are shown for clarity and do not form part of the output.
Extra Credit: provide information that indicates which separator was matched at each separation point and where in the input string that separator was matched.
11l
<lang 11l>F multisplit(text, sep)
V lastmatch = 0 V i = 0 V matches = ‘’ L i < text.len L(s) sep V j = L.index I text[i..].starts_with(s) I i > lastmatch matches ‘’= text[lastmatch .< i] matches ‘’= ‘{’s‘}’ lastmatch = i + s.len i += s.len L.break L.was_no_break i++ I i > lastmatch matches ‘’= text[lastmatch .< i] R matches
print(multisplit(‘a!===b=!=c’, [‘==’, ‘!=’, ‘=’]))</lang>
- Output:
a{!=}{==}b{=}{!=}c
Ada
multisplit.adb: <lang Ada>with Ada.Containers.Indefinite_Doubly_Linked_Lists; with Ada.Text_IO;
procedure Multisplit is
package String_Lists is new Ada.Containers.Indefinite_Doubly_Linked_Lists (Element_Type => String); use type String_Lists.Cursor;
function Split (Source : String; Separators : String_Lists.List) return String_Lists.List is Result : String_Lists.List; Next_Position : Natural := Source'First; Prev_Position : Natural := Source'First; Separator_Position : String_Lists.Cursor; Separator_Length : Natural; Changed : Boolean; begin loop Changed := False; Separator_Position := Separators.First; while Separator_Position /= String_Lists.No_Element loop Separator_Length := String_Lists.Element (Separator_Position)'Length; if Next_Position + Separator_Length - 1 <= Source'Last and then Source (Next_Position .. Next_Position + Separator_Length - 1) = String_Lists.Element (Separator_Position) then if Next_Position > Prev_Position then Result.Append (Source (Prev_Position .. Next_Position - 1)); end if; Result.Append (String_Lists.Element (Separator_Position)); Next_Position := Next_Position + Separator_Length; Prev_Position := Next_Position; Changed := True; exit; end if; Separator_Position := String_Lists.Next (Separator_Position); end loop; if not Changed then Next_Position := Next_Position + 1; end if; if Next_Position > Source'Last then Result.Append (Source (Prev_Position .. Source'Last)); exit; end if; end loop; return Result; end Split;
Test_Input : constant String := "a!===b=!=c"; Test_Separators : String_Lists.List; Test_Result : String_Lists.List; Pos : String_Lists.Cursor;
begin
Test_Separators.Append ("=="); Test_Separators.Append ("!="); Test_Separators.Append ("="); Test_Result := Split (Test_Input, Test_Separators); Pos := Test_Result.First; while Pos /= String_Lists.No_Element loop Ada.Text_IO.Put (" " & String_Lists.Element (Pos)); Pos := String_Lists.Next (Pos); end loop; Ada.Text_IO.New_Line; -- other order of separators Test_Separators.Clear; Test_Separators.Append ("="); Test_Separators.Append ("!="); Test_Separators.Append ("=="); Test_Result := Split (Test_Input, Test_Separators); Pos := Test_Result.First; while Pos /= String_Lists.No_Element loop Ada.Text_IO.Put (" " & String_Lists.Element (Pos)); Pos := String_Lists.Next (Pos); end loop;
end Multisplit;</lang>
- Output:
a != == b = != c a != = = b = != c
ALGOL 68
<lang algol68># split a string based on a number of separators #
- MODE to hold the split results #
MODE SPLITINFO = STRUCT( STRING text # delimited string, may be empty #
, INT position # starting position of the token # , STRING delimiter # the delimiter that terminated the token # );
- calculates the length of string s #
OP LENGTH = ( STRING s )INT: ( UPB s + 1 ) - LWB s;
- returns TRUE if s starts with p, FALSE otherwise #
PRIO STARTSWITH = 5; OP STARTSWITH = ( STRING s, p )BOOL: IF LENGTH p > LENGTH s THEN FALSE ELSE s[ LWB s : ( LWB s + LENGTH p ) - 1 ] = p FI;
- returns an array of SPLITINFO describing the tokens in str based on the delimiters #
- zero-length delimiters are ignored #
PRIO SPLIT = 5; OP SPLIT = ( STRING str, []STRING delimiters )[]SPLITINFO:
BEGIN # count the number of tokens # # allow there to be as many tokens as characters in the string + 2 # # that would cater for a string composed of delimiters only # [ 1 : ( UPB str + 3 ) - LWB str ]SPLITINFO tokens; INT token count := 0; INT str pos := LWB str; INT str max = UPB str; BOOL token pending := FALSE; # construct the tokens # str pos := LWB str; INT prev pos := LWB str; token count := 0; token pending := FALSE; WHILE str pos <= str max DO BOOL found delimiter := FALSE; FOR d FROM LWB delimiters TO UPB delimiters WHILE NOT found delimiter DO IF LENGTH delimiters[ d ] > 0 THEN IF found delimiter := str[ str pos : ] STARTSWITH delimiters[ d ] THEN token count +:= 1; tokens[ token count ] := ( str[ prev pos : str pos - 1 ], prev pos, delimiters[ d ] ); str pos +:= LENGTH delimiters[ d ]; prev pos := str pos; token pending := FALSE FI FI OD; IF NOT found delimiter THEN # the current character is part of s token # token pending := TRUE; str pos +:= 1 FI OD; IF token pending THEN # there is an additional token after the final delimiter # token count +:= 1; tokens[ token count ] := ( str[ prev pos : ], prev pos, "" ) FI; # return an array of the actual tokens # tokens[ 1 : token count ] END # SPLIT # ;
- test the SPLIT operator #
[]SPLITINFO test tokens = "a!===b=!=c" SPLIT []STRING( "==", "!=", "=" ); FOR t FROM LWB test tokens TO UPB test tokens DO
SPLITINFO token = test tokens[ t ]; print( ( "token: [", text OF token, "] at: ", whole( position OF token, 0 ), " delimiter: (", delimiter OF token, ")", newline ) )
OD</lang>
- Output:
token: [a] at: 1 delimiter: (!=) token: [] at: 4 delimiter: (==) token: [b] at: 6 delimiter: (=) token: [] at: 8 delimiter: (!=) token: [c] at: 10 delimiter: ()
AutoHotkey
<lang AutoHotkey>Str := "a!===b=!=c" Sep := ["==","!=", "="] Res := StrSplit(Str, Sep) for k, v in Res Out .= (Out?",":"") v MsgBox % Out for k, v in Sep N .= (N?"|":"") "\Q" v "\E" MsgBox % RegExReplace(str, "(.*?)(" N ")", "$1 {$2}")</lang>
- Output:
a,,b,,c a {!=} {==}b {=} {!=}c
AWK
<lang AWK>
- syntax: GAWK -f MULTISPLIT.AWK
BEGIN {
str = "a!===b=!=c" sep = "(==|!=|=)" printf("str: %s\n",str) printf("sep: %s\n\n",sep) n = split(str,str_arr,sep,sep_arr) printf("parsed: ") for (i=1; i<=n; i++) { printf("'%s'",str_arr[i]) if (i<n) { printf(" '%s' ",sep_arr[i]) } } printf("\n\nstrings: ") for (i=1; i<=n; i++) { printf("'%s' ",str_arr[i]) } printf("\n\nseparators: ") for (i=1; i<n; i++) { printf("'%s' ",sep_arr[i]) } printf("\n") exit(0)
} </lang>
- Output:
str: a!===b=!=c sep: (==|!=|=) parsed: 'a' '!=' '' '==' 'b' '=' '' '!=' 'c' strings: 'a' '' 'b' '' 'c' separators: '!=' '==' '=' '!='
BBC BASIC
<lang bbcbasic> DIM sep$(2)
sep$() = "==", "!=", "=" PRINT "String splits into:" PRINT FNmultisplit("a!===b=!=c", sep$(), FALSE) PRINT "For extra credit:" PRINT FNmultisplit("a!===b=!=c", sep$(), TRUE) END DEF FNmultisplit(s$, d$(), info%) LOCAL d%, i%, j%, m%, p%, o$ p% = 1 REPEAT m% = LEN(s$) FOR i% = 0 TO DIM(d$(),1) d% = INSTR(s$, d$(i%), p%) IF d% IF d% < m% m% = d% : j% = i% NEXT IF m% < LEN(s$) THEN o$ += """" + MID$(s$, p%, m%-p%) + """" IF info% o$ += " (" + d$(j%) + ") " ELSE o$ += ", " p% = m% + LEN(d$(j%)) ENDIF UNTIL m% = LEN(s$) = o$ + """" + MID$(s$, p%) + """"</lang>
- Output:
String splits into: "a", "", "b", "", "c" For extra credit: "a" (!=) "" (==) "b" (=) "" (!=) "c"
Bracmat
This is a surprisingly difficult task to solve in Bracmat, because in a naive solution using a alternating pattern ("=="|"!="|"=") the shorter pattern "="
would have precedence over "=="
. In the solution below the function oneOf
iterates (by recursion) over the operators, trying to match the start of the current subject string sjt
with one operator at a time, until success or reaching the end of the list with operators, whichever comes first. If no operator is found at the start of the current subject string, the variable nonOp
is extended with one byte, thereby shifting the start of the current subject string one byte to the right. Then a new attempt is made to find an operator. This is repeated until either an operator is found, in which case the unparsed string is restricted to the part of the input after the found operator, or no operator is found, in which case the whl
loop terminates.
<lang bracmat>( ( oneOf
= operator . !arg:%?operator ?arg & ( @(!sjt:!operator ?arg)&(!operator.!arg) | oneOf$!arg ) )
& "a!===b=!=c":?unparsed & "==" "!=" "=":?operators & whl
' ( @( !unparsed : ?nonOp [%(oneOf$!operators:(?operator.?unparsed)) ) & put$(!nonOp str$("{" !operator "} ")) )
& put$!unparsed & put$\n );</lang>
- Output:
a {!=} {==} b {=} {!=} c
C
What kind of silly parsing is this? <lang C>#include <stdio.h>
- include <string.h>
void parse_sep(const char *str, const char *const *pat, int len) { int i, slen; while (*str != '\0') { for (i = 0; i < len || !putchar(*(str++)); i++) { slen = strlen(pat[i]); if (strncmp(str, pat[i], slen)) continue; printf("{%.*s}", slen, str); str += slen; break; } } }
int main() { const char *seps[] = { "==", "!=", "=" }; parse_sep("a!===b=!=c", seps, 3);
return 0; }</lang>
- Output:
<lang>a{!=}{==}b{=}{!=}c</lang>
C#
Extra Credit Solution
<lang csharp>using System; using System.Collections.Generic; using System.Linq; using System.Text;
namespace Multisplit {
internal static class Program { private static void Main(string[] args) { foreach (var s in "a!===b=!=c".Multisplit(true, "==", "!=", "=")) // Split the string and return the separators. { Console.Write(s); // Write the returned substrings and separators to the console. } Console.WriteLine(); }
private static IEnumerable<string> Multisplit(this string s, bool returnSeparators = false, params string[] delimiters) { var currentString = new StringBuilder(); /* Initiate the StringBuilder. This will hold the current string to return * once we find a separator. */
int index = 0; // Initiate the index counter at 0. This tells us our current position in the string to read.
while (index < s.Length) // Loop through the string. { // This will get the highest priority separator found at the current index, or null if there are none. string foundDelimiter = (from delimiter in delimiters where s.Length >= index + delimiter.Length && s.Substring(index, delimiter.Length) == delimiter select delimiter).FirstOrDefault();
if (foundDelimiter != null) { yield return currentString.ToString(); // Return the current string. if (returnSeparators) // Return the separator, if the user specified to do so. yield return string.Format("{{\"{0}\", ({1}, {2})}}", foundDelimiter, index, index + foundDelimiter.Length); currentString.Clear(); // Clear the current string. index += foundDelimiter.Length; // Move the index past the current separator. } else { currentString.Append(s[index++]); // Add the character at this index to the current string. } }
if (currentString.Length > 0) yield return currentString.ToString(); // If we have anything left over, return it. } }
}</lang>
- Output:
a{"!=", (1, 3)}{"==", (3, 5)}b{"=", (6, 7)}{"!=", (7, 9)}c
C++
using the Boost library tokenizer! <lang cpp>#include <iostream>
- include <boost/tokenizer.hpp>
- include <string>
int main( ) {
std::string str( "a!===b=!=c" ) , output ; typedef boost::tokenizer<boost::char_separator<char> > tokenizer ; boost::char_separator<char> separator ( "==" , "!=" ) , sep ( "!" ) ; tokenizer mytok( str , separator ) ; tokenizer::iterator tok_iter = mytok.begin( ) ; for ( ; tok_iter != mytok.end( ) ; ++tok_iter ) output.append( *tok_iter ) ; tokenizer nexttok ( output , sep ) ; for ( tok_iter = nexttok.begin( ) ; tok_iter != nexttok.end( ) ;
++tok_iter )
std::cout << *tok_iter << " " ; std::cout << '\n' ; return 0 ;
}</lang>
- Output:
a b c
CoffeeScript
<lang coffeescript> multi_split = (text, separators) ->
# Split text up, using separators to break up text and discarding # separators. # # Returns an array of strings, which can include empty strings when # separators are found either adjacent to each other or at the # beginning/end of the text. # # Separators have precedence, according to their order in the array, # and each separator should be at least one character long. result = [] i = 0 s = while i < text.length found = false for separator in separators if text.substring(i, i + separator.length) == separator found = true i += separator.length result.push s s = break if !found s += text[i] i += 1 result.push s result
console.log multi_split 'a!===b=!=c', ['==', '!=', '='] # [ 'a', , 'b', , 'c' ] console.log multi_split , ['whatever'] # [ ] </lang>
D
<lang d>import std.stdio, std.array, std.algorithm;
string[] multiSplit(in string s, in string[] divisors) pure nothrow {
string[] result; auto rest = s.idup;
while (true) {
bool done = true;
string delim; { string best; foreach (const div; divisors) { const maybe = rest.find(div); if (maybe.length > best.length) { best = maybe; delim = div; done = false; } } }
result.length++; if (done) {
result.back = rest.idup;
return result; } else {
const t = rest.findSplit(delim);
result.back = t[0].idup; rest = t[2]; }
}
}
void main() {
"a!===b=!=c" .multiSplit(["==", "!=", "="]) .join(" {} ") .writeln;
}</lang>
- Output:
(separator locations indicated by braces)
a {} {} b {} {} c
Delphi
<lang Delphi> program Multisplit;
{$APPTYPE CONSOLE}
uses
System.SysUtils;
begin
write('['); for var s in 'a!===b=!=c'.Split(['==', '!=', '=']) do write(s.QuotedString('"'), ' '); write(']'); readln;
end.</lang>
- Output:
["a" "" "b" "" "c" ]
Elixir
<lang elixir>iex(1)> Regex.split(~r/==|!=|=/, "a!====b=!=c") ["a", "", "", "b", "", "c"]</lang>
Erlang
20> re:split("a!===b=!=c", "==|!=|=",[{return, list}]). ["a",[],"b",[],"c"]
F#
If we ignore the "Extra Credit" requirements and skip 'ordered separators' condition (i.e. solving absolute different task), this is exactly what one of the overloads of .NET's String.Split
method does. Using F# Interactive:
<lang fsharp>> "a!===b=!=c".Split([|"=="; "!="; "="|], System.StringSplitOptions.None);;
val it : string [] = [|"a"; ""; "b"; ""; "c"|]
> "a!===b=!=c".Split([|"="; "!="; "=="|], System.StringSplitOptions.None);; val it : string [] = [|"a"; ""; ""; "b"; ""; "c"|]</lang>
System.StringSplitOptions.None
specifies that empty strings should be included in the result.
Factor
<lang factor>USING: arrays fry kernel make sequences ;
IN: rosetta-code.multisplit
- ?pair ( ? x -- {?,x}/f )
over [ 2array ] [ 2drop f ] if ;
- best-separator ( seq -- pos index )
dup [ first ] map infimum '[ first _ = ] find nip first2 ;
- first-subseq ( separators seq -- n separator )
dupd [ swap [ subseq-start ] dip ?pair ] curry map-index sift [ drop f f ] [ best-separator rot nth ] if-empty ;
- multisplit ( string separators -- seq )
'[ [ _ over first-subseq dup ] [ length -rot cut-slice swap , swap tail-slice ] while 2drop , ] { } make ;</lang>
- Output:
> "a!===b=!=c" { "==" "!=" "=" } multisplit [ >string ] map . { "a" "" "b" "" "c" }
FreeBASIC
FreeBASIC does not have a built in 'split' function so we need to write one: <lang freebasic>' FB 1.05.0 Win64
Sub Split(s As String, sepList() As String, result() As String, removeEmpty As Boolean = False, showSepInfo As Boolean = False)
If s = "" OrElse UBound(sepList) = -1 Then Redim result(0) result(0) = s Return End If Dim As Integer i = 0, j, count = 0, empty = 0, length Dim As Integer position(len(s) + 1) Dim As Integer sepIndex(1 To len(s)) Dim As Integer sepLength(len(s)) position(0) = 0 : sepLength(0) = 1 While i < Len(s) For j = lbound(sepList) To ubound(sepList) length = len(sepList(j)) If length = 0 Then Continue For ignore blank separators If mid(s, i + 1, length) = sepList(j) Then count += 1 position(count) = i + 1 sepIndex(count) = j sepLength(count) = length i += length - 1 Exit For End If Next j i += 1 Wend
Redim result(count) If count = 0 Then If showSepInfo Then Print "No delimiters were found" : Print End If result(0) = s Return End If position(count + 1) = len(s) + 1 For i = 1 To count + 1 length = position(i) - position(i - 1) - sepLength(i - 1) result(i - 1 - empty) = Mid(s, position(i - 1) + sepLength(i - 1), length) If removeEmpty AndAlso cbool(length = 0) Then empty += 1 Next
If empty > 0 Then Redim Preserve result(count - empty)
If showSepInfo Then Print "The 1-based indices of the delimiters found are : " Print For x As Integer = 1 To count Print "At index"; position(x), sepList(sepIndex(x)) Next Print End If
End Sub
Dim s As String = "a!===b=!=c"
Print "The string to be split is : "; s
Print
Dim a() As String to hold results
Dim b(1 To 3) As String = {"==", "!=", "="} separators to be used in order of priority (highest first)
split s, b(), a(), False, True show separator info
Print "The sub-strings are : "
Print
For i As integer = 0 To ubound(a)
Print Using "##"; i + 1; Print " : "; a(i)
Next Print Print "Press any key to quit" Sleep</lang>
- Output:
The 1-based indices of the delimiters found are : At index 2 != At index 4 == At index 7 = At index 8 != The sub-strings are : 1 : a 2 : 3 : b 4 : 5 : c
Go
<lang go>package main
import (
"fmt" "strings"
)
func ms(txt string, sep []string) (ans []string) {
for txt > "" { sepMatch := "" posMatch := len(txt) for _, s := range sep { if p := strings.Index(txt, s); p >= 0 && p < posMatch { sepMatch = s posMatch = p } } ans = append(ans, txt[:posMatch]) txt = txt[posMatch+len(sepMatch):] } return
}
func main() {
fmt.Printf("%q\n", ms("a!===b=!=c", []string{"==", "!=", "="}))
}</lang>
- Output:
["a" "" "b" "" "c"]
Haskell
<lang Haskell>import Data.List
(isPrefixOf, stripPrefix, genericLength, intercalate)
trysplit :: String -> [String] -> Maybe (String, String) trysplit s delims =
case filter (`isPrefixOf` s) delims of [] -> Nothing (d:_) -> Just (d, (\(Just x) -> x) $ stripPrefix d s)
multisplit :: String -> [String] -> [(String, String, Int)] multisplit list delims =
let ms [] acc pos = [(acc, [], pos)] ms l@(s:sx) acc pos = case trysplit l delims of Nothing -> ms sx (s : acc) (pos + 1) Just (d, sxx) -> (acc, d, pos) : ms sxx [] (pos + genericLength d) in ms list [] 0
main :: IO () main = do
let parsed = multisplit "a!===b=!=c" ["==", "!=", "="] mapM_ putStrLn [ "split string:" , intercalate "," $ map (\(a, _, _) -> a) parsed , "with [(string, delimiter, offset)]:" , show parsed ]</lang>
- Output:
split string: a,,b,,c with [(string, delimiter, offset)]: [("a","!=",1),("","==",3),("b","=",6),("","!=",7),("c","",10)]
Or as a fold:
<lang haskell>import Data.List (find, isPrefixOf, foldl') --' import Data.Bool (bool)
multiSplit :: [String] -> String -> [(String, String, Int)] multiSplit ds s =
let (ts, ps, o) = foldl' --' (\(tokens, parts, offset) (c, i) -> let inDelim = offset > i in maybe (bool (c : tokens) tokens inDelim, parts, offset) (\x -> ([], (tokens, x, i) : parts, i + length x)) (bool (find (`isPrefixOf` drop i s) ds) Nothing inDelim)) ([], [], 0) (zip s [0 ..]) in reverse $ (ts, [], length s) : ps
main :: IO () main = print $ multiSplit ["==", "!=", "="] "a!===b=!=c"</lang>
- Output:
[("a","!=",1),("","==",3),("b","=",6),("","!=",7),("c","",10)]
Icon and Unicon
<lang Icon>procedure main()
s := "a!===b=!=c" # just list the tokens every writes(multisplit(s,["==", "!=", "="])," ") | write() # list tokens and indices every ((p := "") ||:= t := multisplit(s,sep := ["==", "!=", "="])) | break write() do if t == !sep then writes(t," (",*p+1-*t,") ") else writes(t," ")
end
procedure multisplit(s,L) s ? while not pos(0) do {
t := =!L | 1( arb(), match(!L)|pos(0) ) suspend t }
end
procedure arb() suspend .&subject[.&pos:&pos <- &pos to *&subject + 1] end</lang>
- Output:
a != == b = != c a != (2) == (4) b = (7) != (8) c
J
<lang j>multisplit=: 4 :0
'sep begin'=. |: t=. y /:~&.:(|."1)@;@(i.@#@[ ,.L:0"0 I.@E.L:0) x end=. begin + sep { #@>y last=. next=. 0 r=. 2 0$0 while. next<#begin do. r=. r,.(last}.x{.~next{begin);next{t last=. next{end next=. 1 i.~(begin>next{begin)*.begin>:last end. r=. r,.;~last}.x
)</lang>
Explanation:
First find all potentially relevant separator instances, and sort them in increasing order, by starting location and separator index. sep
is separator index, and begin
is starting location. end
is ending location.
Then, loop through the possibilities, skipping over those separators which would overlap with previously used separators.
The result consists of two rows: The first row is the extracted substrings, the second row is the "extra credit" part -- for each extracted substring, the numbers in the second row are the separator index for the following separator (0 for the first separator, 1 for the second, ...), and the location in the original string where the beginning of the separator appeared (which is the same as where the end of the extracted substring appeared). Note that the very last substring does not have a separator following it, so the extra credit part is blank for that substring.
Example use:
<lang j> S=: 'a!===b=!=c'
S multisplit '==';'!=';'='
┌───┬───┬───┬───┬─┐ │a │ │b │ │c│ ├───┼───┼───┼───┼─┤ │1 1│0 3│2 6│1 7│ │ └───┴───┴───┴───┴─┘
S multisplit '=';'!=';'=='
┌───┬───┬───┬───┬───┬─┐ │a │ │ │b │ │c│ ├───┼───┼───┼───┼───┼─┤ │1 1│0 3│0 4│0 6│1 7│ │ └───┴───┴───┴───┴───┴─┘
'X123Y' multisplit '1';'12';'123';'23';'3'
┌───┬───┬─┐ │X │ │Y│ ├───┼───┼─┤ │0 1│3 2│ │ └───┴───┴─┘</lang>
Java
<lang java>import java.util.*;
public class MultiSplit {
public static void main(String[] args) { System.out.println("Regex split:"); System.out.println(Arrays.toString("a!===b=!=c".split("==|!=|=")));
System.out.println("\nManual split:"); for (String s : multiSplit("a!===b=!=c", new String[]{"==", "!=", "="})) System.out.printf("\"%s\" ", s); }
static List<String> multiSplit(String txt, String[] separators) { List<String> result = new ArrayList<>(); int txtLen = txt.length(), from = 0;
for (int to = 0; to < txtLen; to++) { for (String sep : separators) { int sepLen = sep.length(); if (txt.regionMatches(to, sep, 0, sepLen)) { result.add(txt.substring(from, to)); from = to + sepLen; to = from - 1; // compensate for the increment break; } } } if (from < txtLen) result.add(txt.substring(from)); return result; }
}</lang>
Regex split: [a, , b, , c] Manual split: "a" "" "b" "" "c"
JavaScript
ES5
Based on Ruby example.
<lang JavaScript>RegExp.escape = function(text) {
return text.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&");
}
multisplit = function(string, seps) {
var sep_regex = RegExp(_.map(seps, function(sep) { return RegExp.escape(sep); }).join('|')); return string.split(sep_regex);
}</lang>
ES6
Without importing an external library, and generalizing to allow for any set of delimiters (avoiding the need for a hand-crafted regex):
(Multisplit by fold example)
<lang javascript>(() => {
/// Delimiter list -> String -> list of parts, delimiters, offsets
// multiSplit :: [String] -> String -> // [{part::String, delim::String, offset::Int}] const multiSplit = (ds, s) => { const dcs = map(chars, ds), xs = chars(s), dct = foldl( (a, c, i, s) => { const inDelim = a.offset > i, mb = inDelim ? ( nothing() ) : find(d => isPrefixOf(d, drop(i, xs)), dcs); return mb.nothing ? { tokens: a.tokens.concat(inDelim ? ( [] ) : [c]), parts: a.parts, offset: a.offset } : { tokens: [], parts: append(a.parts, [{ part: intercalate(, a.tokens), delim: intercalate(, mb.just), offset: i }]), offset: i + length(mb.just) }; }, { tokens: [], parts: [], offset: 0 }, xs ); return append(dct.parts, [{ part: intercalate(, dct.tokens), delim: "", offset: length(s) }]); };
// GENERIC FUNCTIONS -----------------------------------------------------
// append (++) :: [a] -> [a] -> [a] const append = (xs, ys) => xs.concat(ys);
// chars :: String -> [Char] const chars = s => s.split();
// drop :: Int -> [a] -> [a] // drop :: Int -> String -> String const drop = (n, xs) => xs.slice(n);
// find :: (a -> Bool) -> [a] -> Maybe a const find = (p, xs) => { for (var i = 0, lng = xs.length; i < lng; i++) { var x = xs[i]; if (p(x)) return just(x); } return nothing('Not found'); };
// foldl :: (a -> b -> a) -> a -> [b] -> a const foldl = (f, a, xs) => xs.reduce(f, a);
// intercalate :: String -> [String] -> String const intercalate = (s, xs) => xs.join(s);
// isPrefixOf takes two lists or strings and returns // true iff the first is a prefix of the second. // isPrefixOf :: [a] -> [a] -> Bool // isPrefixOf :: String -> String -> Bool const isPrefixOf = (xs, ys) => { const pfx = (xs, ys) => xs.length ? ( ys.length ? xs[0] === ys[0] && pfx( xs.slice(1), ys.slice(1) ) : false ) : true; return typeof xs !== 'string' ? pfx(xs, ys) : ys.startsWith(xs); };
// just :: a -> Just a const just = x => ({ nothing: false, just: x });
// length :: [a] -> Int const length = xs => xs.length;
// map :: (a -> b) -> [a] -> [b] const map = (f, xs) => xs.map(f);
// nothing :: () -> Nothing const nothing = (optionalMsg) => ({ nothing: true, msg: optionalMsg });
// show :: Int -> a -> Indented String // show :: a -> String const show = (...x) => JSON.stringify.apply( null, x.length > 1 ? [x[1], null, x[0]] : x );
// TEST ------------------------------------------------------------------ const strTest = 'a!===b=!=c', delims = ['==', '!=', '='];
return show(2, multiSplit(delims, strTest) );
})();</lang>
- Output:
[ { "part": "a", "delim": "!=", "offset": 1 }, { "part": "", "delim": "==", "offset": 3 }, { "part": "b", "delim": "=", "offset": 6 }, { "part": "", "delim": "!=", "offset": 7 }, { "part": "c", "delim": "", "offset": 10 } ]
jq
This version does not use regular expressions, which are only supported in later versions of jq.
multisplit(delims) produces the desired parse using an intermediate parse produced by multisplit_parse(delims).
Both helper functions could be made inner functions of the main function, but are kept separate here for clarity.
<lang jq># peeloff(delims) either peels off a delimiter or
- a single character from the input string.
- The input should be a nonempty string, and delims should be
- a non-empty array of delimiters;
- return [peeledoff, remainder]
- where "peeledoff" is either [delim] or the peeled off character:
def peeloff(delims):
delims[0] as $delim | if startswith($delim) then [ [$delim], .[ ($delim|length):]] elif (delims|length)>1 then peeloff(delims[1:]) else [ .[0:1], .[1:]] end ;
- multisplit_parse(delims) produces an intermediate parse.
- Input must be of the parse form: [ string, [ delim ], ... ]
- Output is of the same form.
def multisplit_parse(delims):
if (delims|length) == 0 or length == 0 then . else .[length-1] as $last | .[0:length-1] as $butlast | if ($last|type) == "array" then . # all done elif $last == "" then . else ($last | peeloff(delims)) as $p # [ peeledoff, next ] | $p[0] as $peeledoff | $p[1] as $next | if ($next|length) > 0 then $butlast + [$peeledoff] + ([$next]|multisplit_parse(delims)) else $butlast + $p end end end ;
def multisplit(delims):
[.] | multisplit_parse(delims) # insert "" between delimiters, compress strings, remove trailing "" if any | reduce .[] as $x ([]; if length == 0 then [ $x ] elif ($x|type) == "array" then if (.[length-1]|type) == "array" then . + ["", $x] else . + [$x] end elif .[length-1]|type == "string" then .[0:length-1] + [ .[length-1] + $x ] else . + [$x] end ) ;</lang>
Examples
("a!===b=!=c", "aaa!===bbb=!=ccc") | multisplit( ["==", "!=", "="] )
- Output:
$ jq -n -M -c -f multisplit.jq ["a",["!="],"",["=="],"b",["="],"",["!="],"c"] ["aaa",["!="],"",["=="],"bbb",["="],"",["!="],"ccc"]
Julia
From REPL: <lang julia> julia> split(s, r"==|!=|=")
5-element Array{SubString{String},1}: "a" "" "b" "" "c"
</lang>
Kotlin
<lang scala>// version 1.0.6
fun main(args: Array<String>) {
val input = "a!===b=!=c" val delimiters = arrayOf("==", "!=", "=") val output = input.split(*delimiters).toMutableList() for (i in 0 until output.size) { if (output[i].isEmpty()) output[i] = "empty string" else output[i] = "\"" + output[i] + "\"" } println("The splits are:") println(output)
// now find positions of matched delimiters val matches = mutableListOf<Pair<String, Int>>() var index = 0 while (index < input.length) { var matched = false for (d in delimiters) { if (input.drop(index).take(d.length) == d) { matches.add(d to index) index += d.length matched = true break } } if (!matched) index++ } println("\nThe delimiters matched and the indices at which they occur are:") println(matches)
}</lang>
- Output:
The splits are: ["a", empty string, "b", empty string, "c"] The delimiters matched and the indices at which they occur are: [(!=, 1), (==, 3), (=, 6), (!=, 7)]
Lua
The function I've written here is really excessive for this task but it has historically been hard to find example code for a good Lua split function on the Internet. This one behaves the same way as Julia's Base.split and I've included a comment describing its precise operation. <lang Lua>--[[ Returns a table of substrings by splitting the given string on occurrences of the given character delimiters, which may be specified as a single- or multi-character string or a table of such strings. If chars is omitted, it defaults to the set of all space characters, and keep is taken to be false. The limit and keep arguments are optional: they are a maximum size for the result and a flag determining whether empty fields should be kept in the result. ]] function split (str, chars, limit, keep)
local limit, splitTable, entry, pos, match = limit or 0, {}, "", 1 if keep == nil then keep = true end if not chars then for e in string.gmatch(str, "%S+") do table.insert(splitTable, e) end return splitTable end while pos <= str:len() do match = nil if type(chars) == "table" then for _, delim in pairs(chars) do if str:sub(pos, pos + delim:len() - 1) == delim then match = string.len(delim) - 1 break end end elseif str:sub(pos, pos + chars:len() - 1) == chars then match = string.len(chars) - 1 end if match then if not (keep == false and entry == "") then table.insert(splitTable, entry) if #splitTable == limit then return splitTable end entry = "" end else entry = entry .. str:sub(pos, pos) end pos = pos + 1 + (match or 0) end if entry ~= "" then table.insert(splitTable, entry) end return splitTable
end
local multisplit = split("a!===b=!=c", {"==", "!=", "="})
-- Returned result is a table (key/value pairs) - display all entries print("Key\tValue") print("---\t-----") for k, v in pairs(multisplit) do
print(k, v)
end</lang>
- Output:
Key Value --- ----- 1 a 2 3 b 4 5 c
M2000 Interpreter
Code from BBC BASIC with little changes to fit in M2000.
<lang M2000 Interpreter> Module CheckIt {
DIM sep$() sep$() = ("==", "!=", "=") PRINT "String splits into:" FNmultisplit("a!===b=!=c", sep$(), FALSE) PRINT "For extra credit:" FNmultisplit("a!===b=!=c", sep$(), TRUE) END SUB FNmultisplit(s$, d$(), info%) LOCAL d%, i%, j%, m%, p%, o$ p% = 1 REPEAT { m% = LEN(s$) FOR i% = 0 TO DIMENSION(d$(),1)-1 d% = INSTR(s$, d$(i%), p%) IF d% THEN IF d% < m% THEN m% = d% : j% = i% NEXT I% IF m% < LEN(s$) THEN { o$ += """" + MID$(s$, p%, m%-p%) + """" IF info% THEN {o$ += " (" + d$(j%) + ") "} ELSE o$ += ", " p% = m% + LEN(d$(j%)) } } UNTIL m% = LEN(s$) PRINT o$ + """" + MID$(s$, p%) + """" END SUB
} CheckIt </lang>
Mathematica
Just use the built-in function "StringSplit": <lang mathematica>StringSplit["a!===b=!=c", {"==", "!=", "="}]</lang>
- Output:
{a,,b,,c}
MiniScript
<lang MiniScript>parseSep = function(s, pats)
result = [] startPos = 0 pos = 0 while pos < s.len for pat in pats if s[pos : pos+pat.len] != pat then continue result.push s[startPos : pos] result.push "{" + pat + "}" startPos = pos + pat.len pos = startPos - 1 break end for pos = pos + 1 end while return result
end function
print parseSep("a!===b=!=c", ["==", "!=", "="])</lang>
- Output:
["a", "{!=}", "", "{==}", "b", "{=}", "", "{!=}"]
Nim
<lang nim>import strutils
iterator tokenize(text: string; sep: openArray[string]): tuple[token: string, isSep: bool] =
var i, lastMatch = 0 while i < text.len: for j, s in sep: if text[i..text.high].startsWith s: if i > lastMatch: yield (text[lastMatch ..< i], false) yield (s, true) lastMatch = i + s.len i += s.high break inc i if i > lastMatch: yield (text[lastMatch ..< i], false)
for token, isSep in "a!===b=!=c".tokenize(["==", "!=", "="]):
if isSep: stdout.write '{',token,'}' else: stdout.write token
echo ""</lang>
- Output:
a{!=}{==}b{=}{!=}c
Perl
<lang Perl>sub multisplit {
my ($sep, $string, %opt) = @_ ; $sep = join '|', map quotemeta($_), @$sep; $sep = "($sep)" if $opt{keep_separators}; split /$sep/, $string, -1;
}
print "'$_' " for multisplit ['==','!=','='], "a!===b=!=c"; print "\n"; print "'$_' " for multisplit ['==','!=','='], "a!===b=!=c", keep_separators => 1; print "\n";</lang>
- Output:
'a' '' 'b' '' 'c' 'a' '!=' '' '==' 'b' '=' '' '!=' 'c'
Phix
<lang Phix>procedure multisplit(string text, sequence delims) integer k = 1, kdx
while 1 do integer kmin = 0 for i=1 to length(delims) do integer ki = match(delims[i],text,k) if ki!=0 then if kmin=0 or ki<kmin then kmin = ki kdx = i end if end if end for string token = text[k..kmin-1] if kmin=0 then printf(1,"Token: [%s] at %d\n",{token,k}) exit end if printf(1,"Token: [%s] at %d, delimiter (%s) at %d\n",{token,k,delims[kdx],kmin}) k = kmin+length(delims[kdx]) end while
end procedure
multisplit("a!===b=!=c",{"==","!=","="})</lang>
- Output:
Token: [a] at 1, delimiter (!=) at 2 Token: [] at 4, delimiter (==) at 4 Token: [b] at 6, delimiter (=) at 7 Token: [] at 8, delimiter (!=) at 8 Token: [c] at 10
PicoLisp
<lang PicoLisp>(de multisplit (Str Sep)
(setq Sep (mapcar chop Sep)) (make (for (S (chop Str) S) (let L (make (loop (T (find head Sep (circ S)) (link (list (- (length Str) (length S)) (pack (cut (length @) 'S)) ) ) ) (link (pop 'S)) (NIL S (link NIL)) ) ) (link (pack (cdr (rot L)))) (and (car L) (link @)) ) ) ) )
(println (multisplit "a!===b=!=c" '("==" "!=" "="))) (println (multisplit "a!===b=!=c" '("=" "!=" "==")))</lang>
- Output:
("a" (1 "!=") NIL (3 "==") "b" (6 "=") NIL (7 "!=") "c") ("a" (1 "!=") NIL (3 "=") NIL (4 "=") "b" (6 "=") NIL (7 "!=") "c")
Pike
<lang Pike>string input = "a!===b=!=c"; array sep = ({"==", "!=", "=" });
array result = replace(input, sep, `+("\0", sep[*], "\0"))/"\0"; result; Result: ({ "a", "!=", "", "==", "b", "=", "", "!=", "c" })
int pos = 0; foreach(result; int index; string data) {
if ((<"==", "!=", "=">)[data]) result[index] = ({ data, pos }); pos+=sizeof(data);
}
result; Result: ({"a", ({"!=", 1}), "", ({"==", 3}), "b", ({"=", 6}), "", ({"!=", 7}), "c"})</lang>
PowerShell
<lang PowerShell> $string = "a!===b=!=c" $separators = [regex]"(==|!=|=)"
$matchInfo = $separators.Matches($string) |
Select-Object -Property Index, Value | Group-Object -Property Value | Select-Object -Property @{Name="Separator"; Expression={$_.Name}}, Count, @{Name="Position" ; Expression={$_.Group.Index}}
$matchInfo </lang>
- Output:
Separator Count Position --------- ----- -------- != 2 {1, 7} == 1 3 = 1 6
Prolog
Works with SWI-Prolog. <lang Prolog>multisplit(_LSep, ) --> {!}, [].
multisplit(LSep, T) --> {next_sep(LSep, T, [], Token, Sep, T1)}, ( {Token \= },[Token], {!}; []), ( {Sep \= },[Sep], {!}; []), multisplit(LSep, T1).
next_sep([], T, Lst, Token, Sep, T1) :- % if we can't find any separator, the game is over ( Lst = [] -> Token = T, Sep = , T1 = ;
% we sort the list to get nearest longest separator predsort(my_sort, Lst, [(_,_, Sep)|_]), atomic_list_concat([Token|_], Sep, T), atom_concat(Token, Sep, Tmp), atom_concat(Tmp, T1, T)).
next_sep([HSep|TSep], T, Lst, Token, Sep, T1) :- sub_atom(T, Before, Len, _, HSep), next_sep(TSep, T, [(Before, Len,HSep) | Lst], Token, Sep, T1).
next_sep([_HSep|TSep], T, Lst, Token, Sep, T1) :- next_sep(TSep, T, Lst, Token, Sep, T1).
my_sort(<, (N1, _, _), (N2, _, _)) :-
N1 < N2.
my_sort(>, (N1, _, _), (N2, _, _)) :- N1 > N2.
my_sort(>, (N, N1, _), (N, N2, _)) :- N1 < N2.
my_sort(<, (N, N1, _), (N, N2, _)) :- N1 > N2. </lang>
- Output:
?- multisplit(['==', '!=', '='], 'ax!===b=!=c', Lst, []). Lst = [ax,'!=',==,b,=,'!=',c] .
Python
Procedural
Using regular expressions: <lang python>>>> import re >>> def ms2(txt="a!===b=!=c", sep=["==", "!=", "="]): if not txt or not sep: return [] ans = m = [] for m in re.finditer('(.*?)(?:' + '|'.join('('+re.escape(s)+')' for s in sep) + ')', txt): ans += [m.group(1), (m.lastindex-2, m.start(m.lastindex))] if m and txt[m.end(m.lastindex):]: ans += [txt[m.end(m.lastindex):]] return ans
>>> ms2() ['a', (1, 1), , (0, 3), 'b', (2, 6), , (1, 7), 'c'] >>> ms2(txt="a!===b=!=c", sep=["=", "!=", "=="]) ['a', (1, 1), , (0, 3), , (0, 4), 'b', (0, 6), , (1, 7), 'c']</lang>
Not using regular expressions: Inspired by C-version <lang python>def multisplit(text, sep):
lastmatch = i = 0 matches = [] while i < len(text): for j, s in enumerate(sep): if text[i:].startswith(s): if i > lastmatch: matches.append(text[lastmatch:i]) matches.append((j, i)) # Replace the string containing the matched separator with a tuple of which separator and where in the string the match occured lastmatch = i + len(s) i += len(s) break else: i += 1 if i > lastmatch: matches.append(text[lastmatch:i]) return matches
>>> multisplit('a!===b=!=c', ['==', '!=', '=']) ['a', (1, 1), (0, 3), 'b', (2, 6), (1, 7), 'c'] >>> multisplit('a!===b=!=c', ['!=', '==', '=']) ['a', (0, 1), (1, 3), 'b', (2, 6), (0, 7), 'c'] </lang>
Alternative version <lang python>def min_pos(List): return List.index(min(List))
def find_all(S, Sub, Start = 0, End = -1, IsOverlapped = 0): Res = [] if End == -1: End = len(S) if IsOverlapped: DeltaPos = 1 else: DeltaPos = len(Sub) Pos = Start while True: Pos = S.find(Sub, Pos, End) if Pos == -1: break Res.append(Pos) Pos += DeltaPos return Res
def multisplit(S, SepList): SepPosListList = [] SLen = len(S) SepNumList = [] ListCount = 0 for i, Sep in enumerate(SepList): SepPosList = find_all(S, Sep, 0, SLen, IsOverlapped = 1) if SepPosList != []: SepNumList.append(i) SepPosListList.append(SepPosList) ListCount += 1 if ListCount == 0: return [S] MinPosList = [] for i in range(ListCount): MinPosList.append(SepPosListList[i][0]) SepEnd = 0 MinPosPos = min_pos(MinPosList) Res = [] while True: Res.append( S[SepEnd : MinPosList[MinPosPos]] ) Res.append([SepNumList[MinPosPos], MinPosList[MinPosPos]]) SepEnd = MinPosList[MinPosPos] + len(SepList[SepNumList[MinPosPos]]) while True: MinPosPos = min_pos(MinPosList) if MinPosList[MinPosPos] < SepEnd: del SepPosListList[MinPosPos][0] if len(SepPosListList[MinPosPos]) == 0: del SepPosListList[MinPosPos] del MinPosList[MinPosPos] del SepNumList[MinPosPos] ListCount -= 1 if ListCount == 0: break else: MinPosList[MinPosPos] = SepPosListList[MinPosPos][0] else: break if ListCount == 0: break Res.append(S[SepEnd:]) return Res
S = "a!===b=!=c"
multisplit(S, ["==", "!=", "="]) # output: ['a', [1, 1], , [0, 3], 'b', [2, 6], , [1, 7], 'c']
multisplit(S, ["=", "!=", "=="]) # output: ['a', [1, 1], , [0, 3], , [0, 4], 'b', [0, 6], , [1, 7], 'c']</lang>
Functional
In terms of a fold (reduce), without use of regular expressions:
<lang python>Multisplit
from functools import reduce
- multiSplit :: [String] -> String -> [(String, String, Int)]
def multiSplit(separators):
List of triples: [(token, separator, start index of separator in string)]. def go(s): def f(tokensPartsOffset, ic): tokens, parts, offset = tokensPartsOffset i, c = ic inDelim = offset > i return maybe( (tokens if inDelim else c + tokens, parts, offset) )( lambda x: (, [(tokens, x, i)] + parts, i + len(x)) )( Nothing() if inDelim else find( s[i:].startswith )(separators) ) ts, ps, _ = reduce(f, enumerate(s), (, [], 0)) return list(reversed(ps)) + [(ts, , len(s))] return go
- --------------------------TEST---------------------------
- main :: IO ()
def main():
String split on three successive separators. print( multiSplit(['==', '!=', '='])( 'a!===b=!=c' ) )
- --------------------GENERIC FUNCTIONS--------------------
- Just :: a -> Maybe a
def Just(x):
Constructor for an inhabited Maybe (option type) value. Wrapper containing the result of a computation. return {'type': 'Maybe', 'Nothing': False, 'Just': x}
- Nothing :: Maybe a
def Nothing():
Constructor for an empty Maybe (option type) value. Empty wrapper returned where a computation is not possible. return {'type': 'Maybe', 'Nothing': True}
- find :: (a -> Bool) -> [a] -> Maybe a
def find(p):
Just the first element in the list that matches p, or Nothing if no elements match. def go(xs): for x in xs: if p(x): return Just(x) return Nothing() return lambda xs: go(xs)
- maybe :: b -> (a -> b) -> Maybe a -> b
def maybe(v):
Either the default value v, if m is Nothing, or the application of f to x, where m is Just(x). return lambda f: lambda m: v if ( None is m or m.get('Nothing') ) else f(m.get('Just'))
- MAIN ---
if __name__ == '__main__':
main()</lang>
- Output:
[('a', '!=', 1), ('', '==', 3), ('b', '=', 6), ('', '!=', 7), ('c', '', 10)]
Racket
<lang racket>
- lang racket
(regexp-match* #rx"==|!=|=" "a!===b=!=c" #:gap-select? #t #:match-select values)
- => '("a" ("!=") "" ("==") "b" ("=") "" ("!=") "c")
</lang>
Raku
(formerly Perl 6)
<lang perl6>sub multisplit($str, @seps) { $str.split(/ ||@seps /, :v) }
my @chunks = multisplit( 'a!===b=!=c==d', < == != = > );
- Print the strings.
say @chunks».Str.raku;
- Print the positions of the separators.
for grep Match, @chunks -> $s {
say " $s from $s.from() to $s.to()";
}</lang>
- Output:
("a", "!=", "", "==", "b", "=", "", "!=", "c", "==", "d") != from 1 to 3 == from 3 to 5 = from 6 to 7 != from 7 to 9 == from 10 to 12
Using the array @seps in a pattern automatically does alternation. By default this would do longest-term matching (that is, | semantics), but we can force it to do left-to-right matching by embedding the array in a short-circuit alternation (that is, || semantics). As it happens, with the task's specified list of separators, it doesn't make any difference.
Raku automatically returns Match objects that will stringify to the matched pattern, but can also be interrogated for their match positions, as illustrated above by post-processing the results two different ways.
REXX
<lang rexx>/*REXX program splits a (character) string based on different separator delimiters.*/ parse arg $ /*obtain optional string from the C.L. */ if $= then $= "a!===b=!=c" /*None specified? Then use the default*/ say 'old string:' $ /*display the old string to the screen.*/ null= '0'x /*null char. It can be most anything.*/ seps= '== != =' /*list of separator strings to be used.*/
/* [↓] process the tokens in SEPS. */ do j=1 for words(seps) /*parse the string with all the seps. */ sep=word(seps,j) /*pick a separator to use in below code*/ /* [↓] process characters in the sep.*/ do k=1 for length(sep) /*parse for various separator versions.*/ sep=strip(insert(null, sep, k), , null) /*allow imbedded "nulls" in separator, */ $=changestr(sep, $, null) /* ··· but not trailing "nulls". */ /* [↓] process strings in the input. */ do until $==old; old=$ /*keep changing until no more changes. */ $=changestr(null || null, $, null) /*reduce replicated "nulls" in string. */ end /*until*/ /* [↓] use BIF or external program.*/ sep=changestr(null, sep, ) /*remove true nulls from the separator.*/ end /*k*/ end /*j*/
showNull= ' {} ' /*just one more thing, display the ··· */ $=changestr(null, $, showNull) /* ··· showing of "null" chars. */ say 'new string:' $ /*now, display the new string to term. */
/*stick a fork in it, we're all done. */</lang>
Some older REXXes don't have a changestr BIF, so one is included here ──► CHANGESTR.REX.
output when using the default input:
old string=a!===b=!=c new string=a {} b {} c
Ring
<lang ring>
- Project : Multisplit
str = "a!===b=!=c" sep = "=== != =! b =!=" sep = str2list(substr(sep, " ", nl)) for n = 1 to len(sep)
pos = substr(str, sep[n]) see "" + n + ": " + substr(str, 1, pos-1) + " Sep By: " + sep[n] + nl
next </lang> Output:
1: a! Sep By: === 2: a Sep By: != 3: a!===b Sep By: =! 4: a!=== Sep By: b 5: a!===b Sep By: =!=
Ruby
The simple method, using a regular expression to split the text.
<lang ruby>text = 'a!===b=!=c' separators = ['==', '!=', '=']
def multisplit_simple(text, separators)
text.split(Regexp.union(separators))
end
p multisplit_simple(text, separators) # => ["a", "", "b", "", "c"] </lang>
The version that also returns the information about the separations.
<lang ruby>def multisplit(text, separators)
sep_regex = Regexp.union(separators) separator_info = [] pieces = [] i = prev = 0 while i = text.index(sep_regex, i) separator = Regexp.last_match(0) pieces << text[prev .. i-1] separator_info << [separator, i] i = i + separator.length prev = i end pieces << text[prev .. -1] [pieces, separator_info]
end
p multisplit(text, separators)
- => [["a", "", "b", "", "c"], [["!=", 1], ["==", 3], ["=", 6], ["!=", 7]]]</lang>
Also demonstrating a method to rejoin the string given the separator information.
<lang ruby>def multisplit_rejoin(info)
str = info[0].zip(info[1])[0..-2].inject("") {|str, (piece, (sep, idx))| str << piece << sep} str << info[0].last
end
p multisplit_rejoin(multisplit(text, separators)) == text
- => true</lang>
Run BASIC
<lang runbasic>str$ = "a!===b=!=c" sep$ = "=== != =! b =!="
while word$(sep$,i+1," ") <> ""
i = i + 1 theSep$ = word$(sep$,i," ") split$ = word$(str$,1,theSep$) print i;" ";split$;" Sep By: ";theSep$
wend</lang>
- Output:
1 a! Sep By: === 2 a Sep By: != 3 a!===b Sep By: =! 4 a!=== Sep By: b 5 a!===b Sep By: =!=
Scala
<lang scala>import scala.annotation.tailrec def multiSplit(str:String, sep:Seq[String])={
def findSep(index:Int)=sep find (str startsWith (_, index)) @tailrec def nextSep(index:Int):(Int,Int)= if(index>str.size) (index, 0) else findSep(index) match { case Some(sep) => (index, sep.size) case _ => nextSep(index + 1) } def getParts(start:Int, pos:(Int,Int)):List[String]={ val part=str slice (start, pos._1) if(pos._2==0) List(part) else part :: getParts(pos._1+pos._2, nextSep(pos._1+pos._2)) } getParts(0, nextSep(0))
}
println(multiSplit("a!===b=!=c", Seq("!=", "==", "=")))</lang>
- Output:
List(a, , b, , c)
Scheme
<lang Scheme>(use srfi-13) (use srfi-42)
(define (shatter separators the-string)
(let loop ((str the-string) (tmp "")) (if (string=? "" str) (list tmp) (if-let1 sep (find (^s (string-prefix? s str)) separators) (cons* tmp sep (loop (string-drop str (string-length sep)) "")) (loop (string-drop str 1) (string-append tmp (string-take str 1)))))))
(define (glean shards)
(list-ec (: x (index i) shards) (if (even? i)) x))</lang>
Testing:
(glean (shatter '("==" "!=" "=") "a!===b=!=c")) ("a" "" "b" "" "c") (shatter '("==" "!=" "=") "a!===b=!=c") ("a" "!=" "" "==" "b" "=" "" "!=" "c")
SenseTalk
First approach, using line delimiters. Lines are delimited by an array of separator strings, normally [CRLF, LF, CR, lineSeparator(0x2028), paragraphSeparator(0x2029)]. Supplying an alternate set of delimiters lets us split a string by a different (ordered) set of strings:
<lang sensetalk>set source to "a!===b=!=c" set separators to ["==", "!=", "="]
put each line delimited by separators of source</lang> Output: <lang sensetalk>(a,,b,,c)</lang>
Second approach, using a pattern. SenseTalk's pattern language lets us define a pattern (a regex) which can then be used to split the string and also to display the actual separators that were found. <lang sensetalk>set source to "a!===b=!=c" set separatorPattern to <"==" or "!=" or "=">
put source split by separatorPattern
put each occurrence of separatorPattern in source </lang> Output: <lang sensetalk>(a,,b,,c) (!=,==,=,!=)</lang>
Sidef
<lang ruby>func multisplit(sep, str, keep_sep=false) {
sep = sep.map{.escape}.join('|'); var re = Regex.new(keep_sep ? "(#{sep})" : sep); str.split(re, -1);
}
[false, true].each { |bool|
say multisplit(%w(== != =), 'a!===b=!=c', keep_sep: bool);
}</lang>
- Output:
["a", "", "b", "", "c"] ["a", "!=", "", "==", "b", "=", "", "!=", "c"]
Tcl
This simple version does not retain information about what the separators were: <lang tcl>proc simplemultisplit {text sep} {
set map {}; foreach s $sep {lappend map $s "\uffff"} return [split [string map $map $text] "\uffff"]
} puts [simplemultisplit "a!===b=!=c" {"==" "!=" "="}]</lang>
- Output:
a {} b {} c
However, to keep the match information a more sophisticated technique is best. Note that the most natural model of result here is to return the split substrings as a separate list to the match information (because the two collections of information are of different lengths). <lang tcl>proc multisplit {text sep} {
foreach s $sep {lappend sr [regsub -all {\W} $s {\\&}]} set sepRE [join $sr "|"] set pieces {} set match {} set start 0 while {[regexp -indices -start $start -- $sepRE $text found]} {
lassign $found x y lappend pieces [string range $text $start [expr {$x-1}]] lappend match [lsearch -exact $sep [string range $text {*}$found]] $x set start [expr {$y + 1}]
} return [list [lappend pieces [string range $text $start end]] $match]
}</lang> Demonstration code: <lang tcl>set input "a!===b=!=c" set matchers {"==" "!=" "="} lassign [multisplit $input $matchers] substrings matchinfo puts $substrings puts $matchinfo</lang>
- Output:
a {} b {} c 1 1 0 3 2 6 1 7
TXR
Using text-extraction pattern language
Here, the separators are embedded into the syntax rather than appearing as a datum. Nevertheless, this illustrates how to do that small tokenizing task with various separators.
The clauses of choose
are applied in parallel, and all potentially match at the current position in the text.
However :shortest tok
means that only that clause survives (gets to propagate its bindings and position advancement) which minimizes the length of the string which is bound to the tok
variable.
The :gap 0
makes the horizontal collect repetitions strictly adjacent. This means that coll
will quit when faced with a nonmatching suffix portion of the data rather than scan forward (no gap allowed!). This creates an opportunity for the tail
variable to grab the suffix which remains, which may be an empty string.
<lang txr>@(next :args) @(coll :gap 0)@(choose :shortest tok)@\
@tok@{sep /==/}@\ @(or)@\ @tok@{sep /!=/}@\ @(or)@\ @tok@{sep /=/}@\ @(end)@(end)@tail
@(output) @(rep)"@tok" {@sep} @(end)"@tail" @(end)</lang>
Runs:
$ ./txr multisplit.txr 'a!===b=!=c' "a" {!=} "" {==} "b" {=} "" {!=} "c" $ ./txr multisplit.txr 'a!===!==!=!==b' "a" {!=} "" {==} "" {!=} "" {=} "" {!=} "" {!=} "" {=} "b" $ ./txr multisplit.txr '' "" $ ./txr multisplit.txr 'a' "a" $ ./txr multisplit.txr 'a=' "a" {=} "" $ ./txr multisplit.txr '=' "" {=} "" $ ./txr multisplit.txr '==' "" {==} "" $ ./txr multisplit.txr '===' "" {==} "" {=} ""
Using the tok-str
function
<lang sh>$ txr -p '(tok-str "a!===b=!=c" #/==|!=|=/ t)' ("a" "!=" "" "==" "b" "=" "" "!=" "c")</lang>
Here the third boolean argument means "keep the material between the tokens", which in the Racket version seems to be requested by the argument #:gap-select? #:t
.
UNIX Shell
<lang bash>multisplit() {
local str=$1 shift local regex=$( IFS='|'; echo "$*" ) local sep while $str =~ $regex ; do sep=${BASH_REMATCH[0]} words+=( "${str%%${sep}*}" ) seps+=( "$sep" ) str=${str#*$sep} done words+=( "$str" )
}
words=() seps=()
original="a!===b=!=c" recreated=""
multisplit "$original" "==" "!=" "="
for ((i=0; i<${#words[@]}; i++)); do
printf 'w:"%s"\ts:"%s"\n' "${words[i]}" "${seps[i]}" recreated+="${words[i]}${seps[i]}"
done
if $original == $recreated ; then
echo "successfully able to recreate original string"
fi</lang>
- Output:
w:"a" s:"!=" w:"" s:"==" w:"b" s:"=" w:"" s:"!=" w:"c" s:"" successfully able to recreate original string
VBScript
<lang vb> Function multisplit(s,sep) arr_sep = Split(sep,"|") For i = 0 To UBound(arr_sep) arr_s = Split(s,arr_sep(i)) s = Join(arr_s,",") Next multisplit = s End Function
Function multisplit_extra(s,sep) Set dict_sep = CreateObject("Scripting.Dictionary") arr_sep = Split(sep,"|") For i = 0 To UBound(arr_sep) dict_sep.Add i,"(" & arr_sep(i) & ")" arr_s = Split(s,arr_sep(i)) s = Join(arr_s,i) Next For Each key In dict_sep.Keys s = Replace(s,key,dict_sep.Item(key)) Next multisplit_extra = s End Function
WScript.StdOut.Write "Standard: " & multisplit("a!===b=!=c","!=|==|=") WScript.StdOut.WriteLine WScript.StdOut.Write "Extra Credit: " & multisplit_extra("a!===b=!=c","!=|==|=") WScript.StdOut.WriteLine</lang>
- Output:
Standard: a,,b,,c Extra Credit: a(!=)(==)b(=)(!=)c
Wren
<lang ecmascript>import "/pattern" for Pattern import "/fmt" for Fmt
var input = "a!===b=!=c" var p = Pattern.new("[/=/=|!/=|/=]") var separators = p.findAll(input) System.print("The separators matched and their starting/ending indices are:") for (sep in separators) {
System.print(" %(Fmt.s(-4, Fmt.q(sep.text))) between %(sep.span)")
} var parts = p.splitAll(input) System.print("\nThe substrings between the separators are:") System.print(parts.map { |p| (p != "") ? Fmt.q(p) : "empty string" }.toList)</lang>
- Output:
The separators matched and their starting/ending indices are: "!=" between [1, 2] "==" between [3, 4] "=" between [6, 6] "!=" between [7, 8] The substrings between the separators are: ["a", empty string, "b", empty string, "c"]
Yabasic
<lang Yabasic>t$ = "a!===b=!=c" s$ = "==,!=,="
dim n$(1)
n = token(s$, n$(), ",") dim p(n)
do
l = len(t$) j = 0 for i = 1 to n p(i) = instr(t$, n$(i)) if p(i) and p(i) < l then l = p(i) : j = i end if next if not j print t$ : break print left$(t$, l - 1), " with separator ", n$(j) t$ = right$(t$, len(t$) - (l + len(n$(j))) + 1)
loop</lang>
zkl
<lang zkl>fcn multisplit(text, sep){
lastmatch := i := 0; matches := List(); while(i < text.len()){ foreach j,s in ([0..].zip(sep)){ if(i == text.find(s,i)){
if(i > lastmatch) matches.append(text[lastmatch,i-lastmatch]); matches.append(T(j,i)); # Replace the string containing the matched separator with a tuple of which separator and where in the string the match occured lastmatch = i + s.len(); i += s.len()-1; break; }
} i += 1; } if(i > lastmatch) matches.append(text[lastmatch,i-lastmatch]); return(matches);
}</lang> <lang zkl>multisplit("a!===b=!=c", T("==", "!=", "=")).println(); multisplit("a!===b=!=c", T("!=", "==", "=")).println();</lang>
- Output:
L("a",L(1,1),L(0,3),"b",L(2,6),L(1,7),"c") L("a",L(0,1),L(1,3),"b",L(2,6),L(0,7),"c")
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