_jacket.scss

///////////////////////////////////////////////////////////
// Jacket
// Conditional Styles with Sass. Dress you CSS appropriately.
///////////////////////////////////////////////////////////

// Jacket is a Compass component that prints and hides styles based on
// context variables you set in your stylesheet. Write and maintain a master
// stylesheet, then output custom tailored stylesheets for modern and legacy
// browsers, site and app builds, or any other context you can think of.

///////////////////////////////////////////////////////////
// Settings variables
///////////////////////////////////////////////////////////

// Default list of jacket contexts.
$jacket: null !default;

// Private variable used by jacket-context().
$jckt-context: null;

///////////////////////////////////////////////////////////
// Jacket mixin
// Takes a list of jacket contexts.
// Outputs a block of styles if a context is set.
///////////////////////////////////////////////////////////
@mixin jacket($contexts...) {

  $naked: false;
  $selectors: ();
  $filtered: ();
  $selector-string: '';

  // Set the global context variable.
  $jckt-context: $contexts !global;

  // If jacket is a single context and selector list, encapsulate.
  @if list-separator($jacket) == 'space' {
    $jacket: $jacket, null !global;
  }

  // Test if a jacket context and jacket value match.
  @each $item in $jacket {
    @each $context in $contexts {
      @if index($context, nth($item, 1)) {

        // Gather wrapping selectors.
        @if length($item) == 1 {
          $naked: true;
        }
        @if length($item) == 2 {
          $selectors: append($selectors, nth($item, 2) + ' &');
        }
      }
    }
  }

  // Filter out duplicate selectors.
  // If reject() is added to Sass we can remove the $filtered holder variable.
  @each $selector in $selectors {
    @if index($filtered, $selector) == false {
      $filtered: append($filtered, $selector);
    }
  }

  // Build the selector string.
  @each $selector in $filtered {
    @if $selector-string != '' {
      $selector-string: $selector-string + ", ";
    }
    $selector-string: $selector-string + $selector;
  }

  // If the weather is right, output that jacketed code!
  @if $naked {
    @content;
  }
  @if $selector-string != '' {
    #{$selector-string} {
      @content;
    }
  }
}

///////////////////////////////////////////////////////////
// Jacket function
// Takes a list of jacket contexts.
// Outputs a value if a context is set.
///////////////////////////////////////////////////////////
@function jacket($value, $contexts...) {

  @each $item in $jacket {
    @each $context in $contexts {
      @if index($context, nth($item, 1)) {
        // If the weather is right, return the value!
        @return $value;
      }
    }
  }

  // Else return null. If null is the only value for a selector, the selector
  // will not be printed.
  @return null;
}

///////////////////////////////////////////////////////////
// Jacket Context function
// Takes a jacket context value. Use when code inside a jacket
// needs to know if a specific jacket context is set.
///////////////////////////////////////////////////////////
@function jacket-context($context) {
  @return if(index($jckt-context, $context), true, false);
}