Icon builder mixin

@icon-pos: before, right;
@icon-pos-override: after, left;
@icon-position: extract(@icon-pos, 1);
@icon-offset: extract(@icon-pos, 2);
@icon-position-override: extract(@icon-pos-override, 1);
@icon-offset-override: extract(@icon-pos-override, 2);

// Icons
@oneIcon: "\f110";
@twoIcon: "\f015";
@iconsList: ~"oneIcon" ~"twoIcon";

// ............................................................
// .for

.for(@i, @n) {.-each(@i)}
.for(@n)     when (isnumber(@n)) {.for(1, @n)}
.for(@i, @n) when not (@i = @n)  {
    .for((@i + (@n - @i) / abs(@n - @i)), @n);
}

// ............................................................
// .for-each

.for(@array)   when (default()) {.for-impl_(length(@array))}
.for-impl_(@i) when (@i > 1)    {.for-impl_((@i - 1))}
.for-impl_(@i) when (@i > 0)    {.-each(extract(@array, @i))}

/* Base icon styles to be extended */
.base-icon {
    font-size: inherit;
    text-rendering: auto;
    display: inline-block;
    -moz-osx-font-smoothing: grayscale;
    -webkit-font-smoothing: antialiased;
}

.create-icon-content(@content) {
	content: @content;
}

// Icon mixins
.create-icon-base (){
  &:extend(.base-icon);
}

.icon-mixin (@icon-pos: @icon-pos; @content: ""; @color: '#000'; @margin: 6px){
  &:@{icon-position} {
  	margin-@{icon-offset}:@margin;
    content: @content;
  }
}

.test-single-btn {
  .icon-mixin()
}

.test-single-alert {
  .icon-mixin(@icon-pos: @icon-pos-override)
}

.icon-builder(@list: @iconsList; @icon-pos: @icon-pos; @margin: 6px){
	&:@{icon-position} {
    .create-icon-base();
     margin-@{icon-offset}:@margin;
  }
 .for(@list); .-each(@name) {
    &-@{name}:@{icon-position} {
      .create-icon-content(@@name);
    }
  }
}

.btn {
  .icon-builder(@iconsList);
}

.alert {
  .icon-builder(@icon-pos: @icon-pos-override; @iconsList);
}