Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.0.rc.1)
// Compass (v1.0.0.alpha.20)
// ----

$themes: (
  "theme-1": (
    "color": red
  ), 
  "theme-2": (
    "color": orange
  ), 
  "theme-3": (
    "color": yellow
  ), 
  "theme-4": (
    "color": green
  ), 
  "theme-5": (
    "color": blue
  )
);

@function map-fetch($map, $keys) {
	$key: nth($keys, 1);
	$length: length($keys);
	$value: map-get($map, $key);

	@if $value != null {
		@if $length > 1 {
			$rest: ();

			@for $i from 2 through $length {
				$rest: append($rest, nth($keys, $i))
			}

			@return map-fetch($value, $rest);

		} @else {
			@return $value;
		}
	} @else {
		@return false;
	}
}

@mixin themify ($themes: $themes) {
  @each $theme, $map in $themes {
    .#{$theme} &  {
      // Define theme color
      $theme-color: map-fetch($themes, $theme "color") !global;
      // ... other vars to use
      
      @content;
      
      // Reset theme color to null
      $theme-color: null !global;
    }
  }
}

.test {
  @include themify() {
    color: $theme-color;
  }
}

SassMeister-output.css

.theme-1 .test {
  color: red;
}
.theme-2 .test {
  color: orange;
}
.theme-3 .test {
  color: yellow;
}
.theme-4 .test {
  color: green;
}
.theme-5 .test {
  color: blue;
}