Sass flexible prefixer mixin.

SassMeister-input.scss

// ----
// Sass (v3.3.7)
// Compass (v1.0.0.alpha.18)
// ----


// A Sass flexible prefixer mixin.


// Returns a list containing all the entries from `$list` 
// that are not present in any of the other `$lists`. 
// -----------------------------------------------------------------------------
// @param [list] $list
// @param [arglist] $lists
// -----------------------------------------------------------------------------
// @return [list]

@function diff(
  $list, 
  $lists...
) {
  $result: $list;

  @each $list in $lists {
    $temp: ();

    @each $item in $result {
      @if not index($list, $item) {
        $temp: append($temp, $item, list-separator($list));
      }
    }

    $result: $temp;
  }

  @return if(length($result) == 1, nth($result, 1), $result);
}


$prefixes: (
  webkit,
  khtml,
  moz,
  ms ,
  o,
  spec
) !default;


// Prefixer mixin.
// -----------------------------------------------------------------------------
// @param [map] $declaration
// @param [list] $include
// @param [list] $exclude
// -----------------------------------------------------------------------------
// @print [css]

@mixin prefixr(
  $declarations, 
  $include: $prefixes,
  $exclude: null
) {
  @if $exclude {
    $include: diff($include, $exclude);
  }

  @each $property, $value in $declarations {
    @each $prefix in $include {
      $prefix: if($prefix == spec, '', '-#{$prefix}-');
      #{$prefix + $property}: $value;
    }
  }
}


Sass {
  @include prefixr(
    (font-feature-settings: "onum=1"), moz
  );
  /**/
  @include prefixr(
    (font-feature-settings: "onum" 1), $exclude: khtml o
  );
}

SassMeister-output.css

Sass {
  -moz-font-feature-settings: "onum=1";
  /**/
  -webkit-font-feature-settings: "onum" 1;
  -moz-font-feature-settings: "onum" 1;
  -ms-font-feature-settings: "onum" 1;
  font-feature-settings: "onum" 1;
}