@mixin form-validation-state-selector($state) {
    $selector: nth(&, 1);
    $number-of-elements: length($selector);
    $first-element: nth($selector, 1);
    @if (contains-was-validated($selector)) {
        @if ($state == 'valid' or $state == 'invalid') {
            #{if(&, "&", "")}:#{$state},
            #{if(&, '&', '')}.is-#{$state} {
                @content;
            }
        } @else {
            #{if(&, '&', '')}.is-#{$state} {
                @content;
            }
        }
    } @else if $number-of-elements == 1 and is-bs-selector($first-element) {
        & .is-#{$state} {
            @content;
        }
    } @else {
        #{if(&, '&', '')}.is-#{$state} {
            @content;
        }
    }
}

@function contains-was-validated($context) {
    @if type-of($context) != list {
        @debug 'Not a list';
        @return -1;
    }
    @return index($context, '.was-validated');
}

@function is-bs-selector($context) {
    $bs-body-classes: '.bootstrap-dark', '.bootstrap';
    @if type-of($context) != string {
        @debug 'Not a string';
        @return -1;
    }

    @each $class in $bs-body-classes {
        @if $context == $class {
            @return 1;
        }
    }
    @return 0;
}