Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.12)
// Compass (v1.0.3)
// ----

@function map-has-nested-keys($map, $keys...) {
  @each $key in $keys {
    @if not map-has-key($map, $key) {
      @return false;
    }
    $map: map-get($map, $key);
  }
  
  @return true;
}
@function map-deep-get($map, $keys...) {
  @each $key in $keys {
    $map: map-get($map, $key);
  }
 
  @return $map;
}
@function z($layers...) {
  @if not map-has-nested-keys($z-layers, $layers...) {
    @warn "No layer found for `#{inspect($layers...)}` in $z-layers map. Property omitted.";
  }
 
  @return map-deep-get($z-layers, $layers...);
}

$z-layers: (
  'bar':                   1000,
  'dropdown':              1000,
  'popover':               1060,
  'tooltip':               1070,
  'modal': (
    'base':                1100,
    'close':               1100,
    'header':              1050,
    'footer':              1010
  ),
  'default':               1,
  'below':                 -1,
) !default;

.modal {
  z-index: z(modal,base);
}
.tooltip{
  z-index: z(tooltip);
}

SassMeister-output.css

.modal {
  z-index: 1100;
}

.tooltip {
  z-index: 1070;
}