I have to convert SQL function to postgress formate

SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER OFF
GO


CREATE FUNCTION [dbo].[Lk_Split](@String varchar(MAX), @Delimiter char(1))       
returns @temptable TABLE (items varchar(MAX), rn int)       
as       
begin      
    declare @idx int       
    declare @slice varchar(8000)   
    declare @rn int = 1 -- row number that increments with each value in the delimited string

    select @idx = 1       
        if len(@String)<1 or @String is null  return       

    while @idx!= 0       
    begin       
        set @idx = charindex(@Delimiter,@String)       
        if @idx!=0       
            set @slice = left(@String,@idx - 1)   
        else       
            set @slice = @String       

        if(len(@slice)>0)  
            insert into @temptable(Items, rn) values(@slice, @rn)       

        set @String = right(@String,len(@String) - @idx)       
        set @rn = @rn +1

        if len(@String) = 0 break       
    end   
return 
end
GO

CREATE FUNCTION LK_Split(String varchar(5000), Delimiter char(1))       
returns table       
language plpgsql
as
$$    
declare
idx integer;      
slice varchar(8000); 
table1 table; 

select idx = 1       
if length(String)<1 or String is null  return       

while idx!= 0       
begin       
set idx = charindex(Delimiter,String);      
if idx!=0       
set slice = left(String,idx - 1;   
else       
set slice = String  ;     

if(length(slice)>0)  
select values(slice) into temptable(Items) from table1
return table1;

set String = right(String,length(String) - idx)       
if length(String) = 0 break ;      
end;
end;
$$;