Deep nested values in Sass maps

SassMeister-input.scss

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

// Deep nested values in Sass maps.


// Fetch a deep value in a multi-level map.
// https://gist.github.com/KittyGiraudel/9933331
@function map-fetch($map, $keys) {
  @each $key in $keys {
    $map: map-get($map, $key);
  }
  @return $map;
}


// Set or update a deep nested value in map.
@function map-set($map, $keys, $new) {
  $orig: $map;
  $cache: ();
  $length: length($keys);
  $last: nth($keys, $length);
  
  @each $key in $keys {
    $map: map-get($map, $key);
    @if $key == $last {
      $map: map-merge($map, $new);
    }
    $cache: append($cache, $map);
  }
  
  $i: $length;
  @while $i > 1 {
    $prev: $i - 1;
    $cache: set-nth($cache, $prev, map-merge(
      nth($cache, $prev), 
      (nth($keys, $i): nth($cache, $i))
    ));
    $i: $prev;
  }
  
  @return map-merge($orig, (nth($keys, 1): nth($cache, 1)));
}


// Test
Sass {
  $map: (
    one: (
      val: 1,
      two: (
        val: 2,
        three: (
          val: 3,
          four: (
            val: 4
          )
        )
      )
    ),
    foo: "foo",
    bar: "bar"
  );
  $flag: "flag!";
  
  /* It should append a new value */
  $test: map-set($map, one two three four, (test: $flag));
  test: inspect($test);
  test: map-fetch($test, one two three four test) == $flag;
  
  /* It should update a defined value */
  $test: map-set($map, one two three four, (val: $flag));
  test: inspect($test);
  test: map-fetch($test, one two three four val) == $flag;
}

SassMeister-output.css

Sass {
  /* It should append a new value */
  test: (one: ((val: 1, two: ((val: 2, three: ((val: 3, four: ((val: 4, test: "flag!")))))))), foo: "foo", bar: "bar");
  test: true;
  /* It should update a defined value */
  test: (one: ((val: 1, two: ((val: 2, three: ((val: 3, four: ((val: "flag!")))))))), foo: "foo", bar: "bar");
  test: true;
}

Thank you - what a great little snippet 😄