//下一个断点
@function breakpoint-next(
  $name,
  $breakpoints: breakpoints,
  $breakpoint-names: map-keys($breakpoints)
) {
  $n: index($breakpoint-names, $name);
  @return if(
    $n < length($breakpoint-names),
    nth($breakpoint-names, $n + 1),
    null
  );
}

//断点最小值
@function breakpoint-min($name, $breakpoints: $breakpoints) {
  $min: map-get($breakpoints, $name); // @return if($min != 0, $min, null);
  @return $min;
}

//断点最大值
@function breakpoint-max($name, $breakpoints: $breakpoints) {
  $next: breakpoint-next($name, $breakpoints);
  @return if($next, breakpoint-min($next, $breakpoints) - 1px, null);
}

//生成类名“-sm、-md、-lg、-cl” -xs?
@function breakpoint-infix($name, $breakpoints: $breakpoints) {
  @return if(breakpoint-min($name, $breakpoints) ==null, '', '-#{$name}');
}

@function px2rem($pixels, $context: $remFactor) {
  @if (unitless($pixels)) {
    $pixels: $pixels * 1px;
  }

  @if (unitless($context)) {
    $context: $context * 1px;
  }

  @return $pixels / $context * 1rem;
}

@function tint($color, $intensity) {
  $r: red($color);
  $g: green($color);
  $b: blue($color);

  @return rgb(
    $r + (255 - $r) * $intensity,
    $g + (255 - $g) * $intensity,
    $b + (255 - $b) * $intensity
  );
}

@function shade($color, $intensity) {
  $r: red($color);
  $g: green($color);
  $b: blue($color);

  @return rgb($r * $intensity, $g * $intensity, $b * $intensity);
}

// 判断对象是否是 map
@function is-map($var) {
  @return type-of($var) == 'map';
}

@function str-replace($string, $search, $replace: '') {
  $str: #{'' + $string};
  $index: str-index($str, $search);

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

  @return $str;
}

@function selector-escape($str) {
  @return str-replace(
    str-replace(str-replace($str, '.', '\\.'), ':', '\\:'),
    '/',
    '\\/'
  );
}

@function suffixName($str) {
  @if $str == default {
    @return '';
  } @else {
    @return '-' + $str;
  }
}