Julia version of C++ next_perm -- GPL Licensed since it's a direct translation :/

next_perm.jl

function next_perm!(itr)                      
    isempty(itr) && return false              
    length(itr) == 1 && return false          
    i = lastindex(itr)                        
                                              
    while true                                
        old_i = i                             
        i -= 1                                
        if itr[i] < itr[old_i] # find an element that's less than our last checked element
          j = lastindex(itr)                  
          while itr[i] >= itr[j]; j -= 1 end  # find the last element smaller than our current one
          itr[i], itr[j] = itr[j], itr[i]     # swap them
          reverse!(itr, old_i, lastindex(itr)) # reverse all elements from our last element to the end for the next permutation
          return true                         
        end                                   
        if i == firstindex(itr)               
            reverse!(itr)                     
            return false                      
        end                                   
    end                                       
end