Multisplit
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.
You are encouraged to solve this task according to the task description, using any language you may know.
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: ()
Arturo
<lang rebol>print split.by:["==" "!=" "="] "a!===b=!=c"</lang>
- Output:
a b c
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/Wolfram Language
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
with javascript_semantics procedure multisplit(string text, sequence delims) integer k = 1, kdx while true 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], delim = iff(kmin=0?"":sprintf(", delimiter (%s) at %d",{delims[kdx],kmin})) printf(1,"Token: [%s] at %d%s\n",{token,k,delim}) if kmin=0 then exit end if k = kmin+length(delims[kdx]) end while end procedure multisplit("a!===b=!=c",{"==","!=","="})
- 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"]
Swift
Swift strings are purposefully not index by integers to avoid confusion and performance traps when dealing with unicode. As such the indexes returned by this method are not very helpful to a human reader, but can be used to manipulate the original string.
<lang swift>extension String {
func multiSplit(on seps: [String]) -> ([Substring], [(String, (start: String.Index, end: String.Index))]) {
var matches = [Substring]()
var matched = [(String, (String.Index, String.Index))]()
var i = startIndex
var lastMatch = startIndex
main: while i != endIndex {
for sep in seps where self[i...].hasPrefix(sep) {
if i > lastMatch {
matches.append(self[lastMatch..<i])
} else {
matches.append("")
}
lastMatch = index(i, offsetBy: sep.count)
matched.append((sep, (i, lastMatch)))
i = lastMatch
continue main
}
i = index(i, offsetBy: 1) }
if i > lastMatch {
matches.append(self[lastMatch..<i])
}
return (matches, matched) }
}
let (matches, matchedSeps) = "a!===b=!=c".multiSplit(on: ["==", "!=", "="])
print(matches, matchedSeps.map({ $0.0 }))</lang>
- Output:
["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
Vlang
Without using additional libraries or regular expressions: <lang vlang>fn main() {
str := "a!===b=!=c" sep := ["==","!=","="] println(ms(str, sep))
}
fn ms(txt string, sep []string) (map[int]string,[]string, []string) {
mut ans, mut extra := []string{}, []string{}
mut place := map[int]string{}
mut temp :=
mut vlen := 0
for slen in sep {if slen.len > vlen {vlen = slen.len}}
for cidx, cval in txt {
temp += cval.ascii_str()
for value in sep {
if temp.contains(value) && temp.len >= vlen {
place[cidx] = value
temp =
}
}
}
for tidx, tval in txt {
for pkey, pval in place {
if tidx == pkey {
ans <<
extra << '(' + pval + ')'
} } if sep.any(it.contains(tval.ascii_str())) == false { ans << tval.ascii_str() extra << tval.ascii_str()
}
}
println('Ending indices: $place')
println('Answer: $ans')
println('Extra: $extra')
return place, ans, extra
}</lang>
- Output:
Ending indices: {2: '!=', 4: '==', 6: '=', 8: '!='}
Answer: ['a', '', '', 'b', '', '', 'c']
Extra: ['a', '(!=)', '(==)', 'b', '(=)', '(!=)', 'c']
({2: '!=', 4: '==', 6: '=', 8: '!='}, ['a', '', '', 'b', '', '', 'c'], ['a', '(!=)', '(==)', 'b', '(=)', '(!=)', 'c'])
Wren
<lang ecmascript>import "/pattern" for Pattern import "/fmt" for Fmt
var input = "a!===b=!=c" var p = Pattern.new("[/=/=|!/=|/=]") var separators = p.findAll(input) System.print("The separators matched and their starting/ending indices are:") for (sep in separators) {
System.print(" %(Fmt.s(-4, Fmt.q(sep.text))) between %(sep.span)")
} var parts = p.splitAll(input) System.print("\nThe substrings between the separators are:") System.print(parts.map { |p| (p != "") ? Fmt.q(p) : "empty string" }.toList)</lang>
- Output:
The separators matched and their starting/ending indices are: "!=" between [1, 2] "==" between [3, 4] "=" between [6, 6] "!=" between [7, 8] The substrings between the separators are: ["a", empty string, "b", empty string, "c"]
Yabasic
<lang Yabasic>t$ = "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")