ionic-framework/core/src/themes/ionic.functions.string.scss

// String Utility Functions
// --------------------------------------------------------------------------------

// String Replace Function
// --------------------------------------------------------------------------------

@function str-replace($string, $search, $replace: "") {
  $index: str-index($string, $search);

  @if $index {
    @return str-slice($string, 1, $index - 1) + $replace + str-replace(str-slice($string, $index + str-length($search)), $search, $replace);
  }

  @return $string;
}

// String Split Function
// --------------------------------------------------------------------------------


@function str-split($string, $separator) {
  // empty array/list
  $split-arr: ();
  // first index of separator in string
  $index: str-index($string, $separator);
  // loop through string
  @while $index != null {
    // get the substring from the first character to the separator
    $item: str-slice($string, 1, $index - 1);
    // push item to array
    $split-arr: append($split-arr, $item);
    // remove item and separator from string
    $string: str-slice($string, $index + 1);
    // find new index of separator
    $index: str-index($string, $separator);
  }
  // add the remaining string to list (the last item)
  $split-arr: append($split-arr, $string);

  @return $split-arr;
}


// String Extract Function
// --------------------------------------------------------------------------------

@function str-extract($string, $start, $end) {
  $start-index: str-index($string, $start);

  @if $start-index {
    $post: str-slice($string, $start-index + str-length($start));
    $end-index: str-index($post, $end);

    @if $end-index {
      @return str-slice($post, 1, $end-index - 1);
    }
  }

  @return null;
}


// String Contains Function
// --------------------------------------------------------------------------------

@function str-contains($string, $needle) {
  @if (type-of($string) == string) {
    @return str-index($string, $needle) != null;
  }

  @return false;
}


// URL Encode Function
// --------------------------------------------------------------------------------

@function url-encode($val) {
  $spaces: str-replace($val, " ", "%20");
  $encoded: str-replace($spaces, "#", "%23");
  @return $encoded;
}


// Add Root Selector
// --------------------------------------------------------------------------------
// Adds a root selector using host based on the selector passed
// --------------------------------------------------------------------------------

@function add-root-selector($root, $addHostSelector) {
  $selectors: str-split($root, ",");

  $list: ();

  @each $selector in $selectors {
    // If the selector contains :host( it means it is targeting a class on the host
    // element so we need to change how we target it:
    // @include add-root-selector(":host(.fixed)", "[dir=rtl]")
    // --> :host-context([dir=rtl]):host(.fixed)
    // --> :host-context([dir=rtl]).fixed
    @if str-contains($selector, ":host(") {
      // @include add-root-selector(":host(.fixed)", "[dir=rtl]")
      // --> :host-context([dir=rtl]):host(.fixed)
      $shadow-element: str-replace($selector, ":host(", ":host-context(#{$addHostSelector}):host(");
      $list: append($list, $shadow-element, comma);

      $new-element: ();
      $elements: str-split($selector, " ");

      @each $element in $elements {
        @if str-contains($element, ":host(") {
          $scoped-element: $element;

          // Replace the :host( and ) so all we have left is the class
          // inside of it:
          // :host(.fixed) -> .fixed
          $scoped-element: str-replace($scoped-element, ")", "");
          $scoped-element: str-replace($scoped-element, ":host(", "");

          // Add the class back inside of host with the rtl selector:
          // .fixed -> :host-context([dir=rtl]).fixed
          $scoped-element: str-replace($scoped-element, $scoped-element, ":host-context(#{$addHostSelector})#{$scoped-element}");

          // @include add-root-selector(":host(.fixed)", "[dir=rtl]")
          // --> :host-context([dir=rtl]).fixed
          $new-element: append($new-element, $scoped-element, space);
        } @else {
          // Add back any selectors that followed the host after transforming the
          // first selector:
          // :host(.fixed) ::slotted(ion-icon)
          // --> :host-context([dir=rtl]):host(.fixed) ::slotted(ion-icon)
          // --> :host-context([dir=rtl]).fixed ::slotted(ion-icon)
          $new-element: append($new-element, $element, space);
        }
      }

      $list: append($list, $new-element, comma);
    // If the selector contains :host without a parantheses
    // it means it is targeting just the host
    // element so we can change it to look for host-context
    // @include add-root-selector(":host", "[dir=rtl]")
    // --> :host-context([dir=rtl])
    // --> :host:dir(rtl)
    } @else if str-contains($selector, ":host") {
      $new-element: ();
      $elements: str-split($selector, " ");

      @each $element in $elements {
        @if str-contains($element, ":host") {
          // Replace the :host with the addHostSelector:
          // :host -> :host-context([dir=rtl])
          $updated-element: str-replace($element, ":host", ":host-context(#{$addHostSelector})");

          // Add the final selector after all transformations:
          // :host -> :host-context([dir=rtl])
          $new-element: append($new-element, $updated-element, space);
        } @else {
          // Add back any selectors that followed the host after transforming the
          // first selector:
          // :host ::slotted(ion-icon) -> :host-context([dir=rtl]) ::slotted(ion-icon)
          $new-element: append($new-element, $element, space);
        }
      }
      
      $list: append($list, $new-element, comma);
    // If the selector does not contain host at all it is either a shadow
    // or normal element so append both the addHostSelector and host-context
    // @include add-root-selector("ion-component", "[dir=rtl]")
    // --> :host-context([dir=rtl]) ion-component
    // --> [dir=rtl] ion-component
    } @else {
      $list: append($list, "#{$addHostSelector} #{$selector}", comma);
      $list: append($list, ":host-context(#{$addHostSelector}) #{$selector}", comma);
    }
  }

  @return $list;
}