Re: ipairs_remove - remove items from array while iterating it

[Philipp Janda <siffiejoe@...>]

Am 03.11.2013 05:50 schröbte Dirk Laurie:
> Microlight has 'ifilter'.
>
> --- filter a array using a predicate.
> -- If `pred` is absent, then we provide a default which
> -- filters out any `false` values.
> -- @param t a table
> -- @param pred the predicate function
> -- @param ... any extra arguments to the predicate
> -- @return a array such that `pred(t[i])` is true
>
> This is O(n) and does not destroy the original table.
> You can do that yourself by assigning the result of
> ifilter to it.

If creating an updated copy instead of removing elements in-place is 
acceptable, I'd suggest the slightly more general `imodify` function 
which can replace/remove/insert before/insert after the current element:


    do
      local function helper( t, n, ... )
        local n_v = select( '#', ... )
        for i = 1, n_v do
          t[ n+i ] = select( i, ... )
        end
        return n + n_v
      end

      function imodify( t, cb )
        local new_t, n = {}, 0
        for i = 1, #t do
          n = helper( new_t, n, cb( i, t[ i ] ) )
        end
        return new_t, n
      end
    end


Philipp