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Sass::Script::Functions

Methods in this module are accessible from the SassScript context. For example, you can write

$color = hsl(120deg, 100%, 50%)

and it will call {Sass::Script::Functions#hsl}.

The following functions are provided:

*Note: These functions are described in more detail below.*

## RGB Functions

{#rgb rgb($red, $green, $blue)} : Converts an `rgb(red, green, blue)` triplet into a color.

{#rgba rgba($red, $green, $blue, $alpha)} : Converts an `rgba(red, green, blue, alpha)` quadruplet into a color.

{#rgba rgba($color, $alpha)} : Adds an alpha layer to any color value.

{#red red($color)} : Gets the red component of a color.

{#green green($color)} : Gets the green component of a color.

{#blue blue($color)} : Gets the blue component of a color.

{#mix mix($color-1, $color-2, [$weight])} : Mixes two colors together.

## HSL Functions

{#hsl hsl($hue, $saturation, $lightness)} : Converts an `hsl(hue, saturation, lightness)` triplet into a color.

{#hsla hsla($hue, $saturation, $lightness, $alpha)} : Converts an `hsla(hue, saturation, lightness, alpha)` quadruplet into a color.

{#hue hue($color)} : Gets the hue component of a color.

{#saturation saturation($color)} : Gets the saturation component of a color.

{#lightness lightness($color)} : Gets the lightness component of a color.

{#adjust_hue adjust-hue($color, $degrees)} : Changes the hue of a color.

{#lighten lighten($color, $amount)} : Makes a color lighter.

{#darken darken($color, $amount)} : Makes a color darker.

{#saturate saturate($color, $amount)} : Makes a color more saturated.

{#desaturate desaturate($color, $amount)} : Makes a color less saturated.

{#grayscale grayscale($color)} : Converts a color to grayscale.

{#complement complement($color)} : Returns the complement of a color.

{#invert invert($color)} : Returns the inverse of a color.

## Opacity Functions

{#alpha alpha($color)} / {#opacity opacity($color)} : Gets the alpha component (opacity) of a color.

{#rgba rgba($color, $alpha)} : Add or change an alpha layer for any color value.

{#opacify opacify($color, $amount)} / {#fade_in fade-in($color, $amount)} : Makes a color more opaque.

{#transparentize transparentize($color, $amount)} / {#fade_out fade-out($color, $amount)} : Makes a color more transparent.

## Other Color Functions

{#adjust_color adjust-color($color, [$red], [$green], [$blue], [$hue], [$saturation], [$lightness], [$alpha])} : Increase or decrease any of the components of a color.

{#scale_color scale-color($color, [$red], [$green], [$blue], [$saturation], [$lightness], [$alpha])} : Fluidly scale one or more components of a color.

{#change_color change-color($color, [$red], [$green], [$blue], [$hue], [$saturation], [$lightness], [$alpha])} : Changes one or more properties of a color.

{#ie_hex_str ie-hex-str($color)} : Converts a color into the format understood by IE filters.

## String Functions

{#unquote unquote($string)} : Removes the quotes from a string.

{#quote quote($string)} : Adds quotes to a string.

## Number Functions

{#percentage percentage($value)} : Converts a unitless number to a percentage.

{#round round($value)} : Rounds a number to the nearest whole number.

{#ceil ceil($value)} : Rounds a number up to the nearest whole number.

{#floor floor($value)} : Rounds a number down to the nearest whole number.

{#abs abs($value)} : Returns the absolute value of a number.

{#min min($x1, $x2, ...)} : Finds the minimum of several values.

{#max max($x1, $x2, ...)} : Finds the maximum of several values.

## List Functions {list-functions}

{#length length($list)} : Returns the length of a list.

{#nth nth($list, $n)} : Returns a specific item in a list.

{#join join($list1, $list2, [$separator])} : Joins together two lists into one.

{#append append($list1, $val, [$separator])} : Appends a single value onto the end of a list.

## Introspection Functions

{#type_of type-of($value)} : Returns the type of a value.

{#unit unit($number)} : Returns the units associated with a number.

{#unitless unitless($number)} : Returns whether a number has units or not.

{#comparable comparable($number-1, $number-2)} : Returns whether two numbers can be added or compared.

## Miscellaneous Functions

{#if if($condition, $if-true, $if-false)} : Returns one of two values, depending on whether or not a condition is true.

## Adding Custom Functions

New Sass functions can be added by adding Ruby methods to this module. For example:

module Sass::Script::Functions
  def reverse(string)
    assert_type string, :String
    Sass::Script::String.new(string.value.reverse)
  end
  declare :reverse, :args => [:string]
end

Calling {declare} tells Sass the argument names for your function. If omitted, the function will still work, but will not be able to accept keyword arguments. {declare} can also allow your function to take arbitrary keyword arguments.

There are a few things to keep in mind when modifying this module. First of all, the arguments passed are {Sass::Script::Literal} objects. Literal objects are also expected to be returned. This means that Ruby values must be unwrapped and wrapped.

Most Literal objects support the {Sass::Script::Literal#value value} accessor for getting their Ruby values. Color objects, though, must be accessed using {Sass::Script::Color#rgb rgb}, {Sass::Script::Color#red red}, {Sass::Script::Color#blue green}, or {Sass::Script::Color#blue blue}.

Second, making Ruby functions accessible from Sass introduces the temptation to do things like database access within stylesheets. This is generally a bad idea; since Sass files are by default only compiled once, dynamic code is not a great fit.

If you really, really need to compile Sass on each request, first make sure you have adequate caching set up. Then you can use {Sass::Engine} to render the code, using the {file:SASS_REFERENCE.md#custom-option `options` parameter} to pass in data that {EvaluationContext#options can be accessed} from your Sass functions.

Within one of the functions in this module, methods of {EvaluationContext} can be used.

### Caveats

When creating new {Literal} objects within functions, be aware that it's not safe to call {Literal#to_s to_s} (or other methods that use the string representation) on those objects without first setting {Node#options= the options attribute}.

Constants

Signature

A class representing a Sass function signature.

@attr args [Array<Symbol>] The names of the arguments to the function. @attr var_args [Boolean] Whether the function takes a variable number of arguments. @attr var_kwargs [Boolean] Whether the function takes an arbitrary set of keyword arguments.

Public Class Methods

declare(method_name, args, options = {}) click to toggle source

Declare a Sass signature for a Ruby-defined function. This includes the names of the arguments, whether the function takes a variable number of arguments, and whether the function takes an arbitrary set of keyword arguments.

It's not necessary to declare a signature for a function. However, without a signature it won't support keyword arguments.

A single function can have multiple signatures declared as long as each one takes a different number of arguments. It's also possible to declare multiple signatures that all take the same number of arguments, but none of them but the first will be used unless the user uses keyword arguments.

@param method_name [Symbol] The name of the method

whose signature is being declared.

@param args [Array<Symbol>] The names of the arguments for the function signature. @option options :var_args [Boolean] (false)

Whether the function accepts a variable number of (unnamed) arguments
in addition to the named arguments.

@option options :var_kwargs [Boolean] (false)

Whether the function accepts other keyword arguments
in addition to those in `:args`.
If this is true, the Ruby function will be passed a hash from strings
to {Sass::Script::Literal}s as the last argument.
In addition, if this is true and `:var_args` is not,
Sass will ensure that the last argument passed is a hash.

@example

declare :rgba, [:hex, :alpha]
declare :rgba, [:red, :green, :blue, :alpha]
declare :accepts_anything, [], :var_args => true, :var_kwargs => true
declare :some_func, [:foo, :bar, :baz], :var_kwargs => true
# File lib/sass/script/functions.rb, line 262
def self.declare(method_name, args, options = {})
  @signatures[method_name] ||= []
  @signatures[method_name] << Signature.new(
    args.map {|s| s.to_s},
    options[:var_args],
    options[:var_kwargs])
end
signature(method_name, arg_arity, kwarg_arity) click to toggle source

Determine the correct signature for the number of arguments passed in for a given function. If no signatures match, the first signature is returned for error messaging.

@param method_name [Symbol] The name of the Ruby function to be called. @param arg_arity [Number] The number of unnamed arguments the function was passed. @param kwarg_arity [Number] The number of keyword arguments the function was passed.

@return [{Symbol => Object}, nil]

The signature options for the matching signature,
or nil if no signatures are declared for this function. See {declare}.
# File lib/sass/script/functions.rb, line 281
def self.signature(method_name, arg_arity, kwarg_arity)
  return unless @signatures[method_name]
  @signatures[method_name].each do |signature|
    return signature if signature.args.size == arg_arity + kwarg_arity
    next unless signature.args.size < arg_arity + kwarg_arity

    # We have enough args.
    # Now we need to figure out which args are varargs
    # and if the signature allows them.
    t_arg_arity, t_kwarg_arity = arg_arity, kwarg_arity
    if signature.args.size > t_arg_arity
      # we transfer some kwargs arity to args arity
      # if it does not have enough args -- assuming the names will work out.
      t_kwarg_arity -= (signature.args.size - t_arg_arity)
      t_arg_arity = signature.args.size
    end

    if (  t_arg_arity == signature.args.size ||   t_arg_arity > signature.args.size && signature.var_args  ) &&
       (t_kwarg_arity == 0                   || t_kwarg_arity > 0                   && signature.var_kwargs)
      return signature
    end
  end
  @signatures[method_name].first
end

Public Instance Methods

abs(value) click to toggle source

Finds the absolute value of a number.

@example

abs(10px) => 10px
abs(-10px) => 10px

@param value [Number] The number @return [Number] The absolute value @raise [ArgumentError] if `value` isn't a number

# File lib/sass/script/functions.rb, line 1213
def abs(value)
  numeric_transformation(value) {|n| n.abs}
end
adjust_color(color, kwargs) click to toggle source

Adjusts one or more properties of a color. This can change the red, green, blue, hue, saturation, value, and alpha properties. The properties are specified as keyword arguments, and are added to or subtracted from the color's current value for that property.

`$red`, `$green`, and `$blue` properties should be between 0 and 255. `$saturation` and `$lightness` should be between 0% and 100%. `$alpha` should be between 0 and 1.

All properties are optional. You can't specify both RGB properties (`$red`, `$green`, `$blue`) and HSL properties (`$hue`, `$saturation`, `$value`) at the same time.

@example

adjust-color(#102030, $blue: 5) => #102035
adjust-color(#102030, $red: -5, $blue: 5) => #0b2035
adjust-color(hsl(25, 100%, 80%), $lightness: -30%, $alpha: -0.4) => hsla(25, 100%, 50%, 0.6)

@param color [Color] @param red [Number] @param green [Number] @param blue [Number] @param hue [Number] @param saturation [Number] @param lightness [Number] @param alpha [Number] @return [Color] @raise [ArgumentError] if `color` is not a color,

if any keyword argument is not a number,
if any keyword argument is not in the legal range,
if an unexpected keyword argument is given,
or if both HSL and RGB properties are given.
# File lib/sass/script/functions.rb, line 796
def adjust_color(color, kwargs)
  assert_type color, :Color
  with = Sass::Util.map_hash({
      "red" => [-255..255, ""],
      "green" => [-255..255, ""],
      "blue" => [-255..255, ""],
      "hue" => nil,
      "saturation" => [-100..100, "%"],
      "lightness" => [-100..100, "%"],
      "alpha" => [-1..1, ""]
    }) do |name, (range, units)|

    next unless val = kwargs.delete(name)
    assert_type val, :Number, name
    Sass::Util.check_range("$#{name}: Amount", range, val, units) if range
    adjusted = color.send(name) + val.value
    adjusted = [0, Sass::Util.restrict(adjusted, range)].max if range
    [name.to_sym, adjusted]
  end

  unless kwargs.empty?
    name, val = kwargs.to_a.first
    raise ArgumentError.new("Unknown argument $#{name} (#{val})")
  end

  color.with(with)
end
adjust_hue(color, degrees) click to toggle source

Changes the hue of a color while retaining the lightness and saturation. Takes a color and a number of degrees (usually between -360deg and 360deg), and returns a color with the hue rotated by that value.

@example

adjust-hue(hsl(120, 30%, 90%), 60deg) => hsl(180, 30%, 90%)
adjust-hue(hsl(120, 30%, 90%), 060deg) => hsl(60, 30%, 90%)
adjust-hue(#811, 45deg) => #886a11

@param color [Color] @param amount [Number] @return [Color] @raise [ArgumentError] If `color` isn't a color, or `number` isn't a number

# File lib/sass/script/functions.rb, line 741
def adjust_hue(color, degrees)
  assert_type color, :Color
  assert_type degrees, :Number
  color.with(:hue => color.hue + degrees.value)
end
alpha(*args) click to toggle source

Returns the alpha component (opacity) of a color. This is 1 unless otherwise specified.

This function also supports the proprietary Microsoft `alpha(opacity=20)` syntax.

@overload def alpha(color) @param color [Color] @return [Number] @see opacify @see transparentize @raise [ArgumentError] If `color` isn't a color

# File lib/sass/script/functions.rb, line 579
def alpha(*args)
  if args.all? do |a|
      a.is_a?(Sass::Script::String) && a.type == :identifier &&
        a.value =~ /^[a-zA-Z]+\s*=/
    end
    # Support the proprietary MS alpha() function
    return Sass::Script::String.new("alpha(#{args.map {|a| a.to_s}.join(", ")})")
  end

  raise ArgumentError.new("wrong number of arguments (#{args.size} for 1)") if args.size != 1

  assert_type args.first, :Color
  Sass::Script::Number.new(args.first.alpha)
end
append(list, val, separator = Sass::Script::String.new("auto")) click to toggle source

Appends a single value onto the end of a list.

Unless the `$separator` argument is passed, if the list has only one item, the resulting list will be space-separated.

@example

append(10px 20px, 30px) => 10px 20px 30px
append((blue, red), green) => blue, red, green
append(10px 20px, 30px 40px) => 10px 20px (30px 40px)
append(10px, 20px, comma) => 10px, 20px
append((blue, red), green, space) => blue red green

@overload append(list, val, separator: auto)

@param list [Literal] The list to add the value to
@param val [Literal] The value to add to the end of the list
@param separator [String] How the list separator (comma or space) should be determined.
  If this is `comma` or `space`, that is always the separator;
  if this is `auto` (the default), the separator is the same as that used by the list.
# File lib/sass/script/functions.rb, line 1344
def append(list, val, separator = Sass::Script::String.new("auto"))
  assert_type separator, :String
  unless ]auto space comma].include?(separator.value)
    raise ArgumentError.new("Separator name must be space, comma, or auto")
  end
  sep = list.separator if list.is_a?(Sass::Script::List)
  Sass::Script::List.new(
    list.to_a + [val],
    if separator.value == 'auto'
      sep || :space
    else
      separator.value.to_sym
    end)
end
blue(color) click to toggle source

Returns the blue component of a color.

@param color [Color] @return [Number] @raise [ArgumentError] If `color` isn't a color

# File lib/sass/script/functions.rb, line 511
def blue(color)
  assert_type color, :Color
  Sass::Script::Number.new(color.blue)
end
ceil(value) click to toggle source

Rounds a number up to the nearest whole number.

@example

ceil(10.4px) => 11px
ceil(10.6px) => 11px

@param value [Number] The number @return [Number] The rounded number @raise [ArgumentError] if `value` isn't a number

# File lib/sass/script/functions.rb, line 1187
def ceil(value)
  numeric_transformation(value) {|n| n.ceil}
end
change_color(color, kwargs) click to toggle source

Changes one or more properties of a color. This can change the red, green, blue, hue, saturation, value, and alpha properties. The properties are specified as keyword arguments, and replace the color's current value for that property.

`$red`, `$green`, and `$blue` properties should be between 0 and 255. `$saturation` and `$lightness` should be between 0% and 100%. `$alpha` should be between 0 and 1.

All properties are optional. You can't specify both RGB properties (`$red`, `$green`, `$blue`) and HSL properties (`$hue`, `$saturation`, `$value`) at the same time.

@example

change-color(#102030, $blue: 5) => #102005
change-color(#102030, $red: 120, $blue: 5) => #782005
change-color(hsl(25, 100%, 80%), $lightness: 40%, $alpha: 0.8) => hsla(25, 100%, 40%, 0.8)

@param color [Color] @param red [Number] @param green [Number] @param blue [Number] @param hue [Number] @param saturation [Number] @param lightness [Number] @param alpha [Number] @return [Color] @raise [ArgumentError] if `color` is not a color,

if any keyword argument is not a number,
if any keyword argument is not in the legal range,
if an unexpected keyword argument is given,
or if both HSL and RGB properties are given.
# File lib/sass/script/functions.rb, line 929
def change_color(color, kwargs)
  assert_type color, :Color
  with = Sass::Util.map_hash(]red green blue hue saturation lightness alpha]) do |name, max|
    next unless val = kwargs.delete(name)
    assert_type val, :Number, name
    [name.to_sym, val.value]
  end

  unless kwargs.empty?
    name, val = kwargs.to_a.first
    raise ArgumentError.new("Unknown argument $#{name} (#{val})")
  end

  color.with(with)
end
comparable(number_1, number_2) click to toggle source

Returns true if two numbers are similar enough to be added, subtracted, or compared.

@example

comparable(2px, 1px) => true
comparable(100px, 3em) => false
comparable(10cm, 3mm) => true

@param number_1 [Number] @param number_2 [Number] @return [Bool] indicating if the numbers can be compared. @raise [ArgumentError] if `number_1` or `number_2` aren't numbers

# File lib/sass/script/functions.rb, line 1144
def comparable(number_1, number_2)
  assert_type number_1, :Number
  assert_type number_2, :Number
  Sass::Script::Bool.new(number_1.comparable_to?(number_2))
end
complement(color) click to toggle source

Returns the complement of a color. This is identical to `adjust-hue(color, 180deg)`.

@param color [Color] @return [Color] @raise [ArgumentError] if `color` isn't a color @see adjust_hue adjust-hue

# File lib/sass/script/functions.rb, line 1029
def complement(color)
  adjust_hue color, Number.new(180)
end
darken(color, amount) click to toggle source

Makes a color darker. Takes a color and an amount between 0% and 100%, and returns a color with the lightness decreased by that value.

@example

darken(hsl(25, 100%, 80%), 30%) => hsl(25, 100%, 50%)
darken(#800, 20%) => #200

@param color [Color] @param amount [Number] @return [Color] @see lighten @raise [ArgumentError] If `color` isn't a color,

or `number` isn't a number between 0% and 100%
# File lib/sass/script/functions.rb, line 683
def darken(color, amount)
  _adjust(color, amount, :lightness, 0..100, :-, "%")
end
desaturate(color, amount) click to toggle source

Makes a color less saturated. Takes a color and an amount between 0% and 100%, and returns a color with the saturation decreased by that value.

@example

desaturate(hsl(120, 30%, 90%), 20%) => hsl(120, 10%, 90%)
desaturate(#855, 20%) => #726b6b

@param color [Color] @param amount [Number] @return [Color] @see saturate @raise [ArgumentError] If `color` isn't a color,

or `number` isn't a number between 0% and 100%
# File lib/sass/script/functions.rb, line 724
def desaturate(color, amount)
  _adjust(color, amount, :saturation, 0..100, :-, "%")
end
fade_in(color, amount) click to toggle source
Alias for: opacify
fade_out(color, amount) click to toggle source
Alias for: transparentize
floor(value) click to toggle source

Rounds down to the nearest whole number.

@example

floor(10.4px) => 10px
floor(10.6px) => 10px

@param value [Number] The number @return [Number] The rounded number @raise [ArgumentError] if `value` isn't a number

# File lib/sass/script/functions.rb, line 1200
def floor(value)
  numeric_transformation(value) {|n| n.floor}
end
grayscale(color) click to toggle source

Converts a color to grayscale. This is identical to `desaturate(color, 100%)`.

@param color [Color] @return [Color] @raise [ArgumentError] if `color` isn't a color @see desaturate

# File lib/sass/script/functions.rb, line 1016
def grayscale(color)
  return Sass::Script::String.new("grayscale(#{color})") if color.is_a?(Sass::Script::Number)
  desaturate color, Number.new(100)
end
green(color) click to toggle source

Returns the green component of a color.

@param color [Color] @return [Number] @raise [ArgumentError] If `color` isn't a color

# File lib/sass/script/functions.rb, line 500
def green(color)
  assert_type color, :Color
  Sass::Script::Number.new(color.green)
end
hsl(hue, saturation, lightness) click to toggle source

Creates a {Color} object from hue, saturation, and lightness. Uses the algorithm from the [CSS3 spec](www.w3.org/TR/css3-color/#hsl-color).

@param hue [Number] The hue of the color.

Should be between 0 and 360 degrees, inclusive

@param saturation [Number] The saturation of the color.

Must be between `0%` and `100%`, inclusive

@param lightness [Number] The lightness of the color.

Must be between `0%` and `100%`, inclusive

@return [Color] The resulting color @see hsla @raise [ArgumentError] if `saturation` or `lightness` are out of bounds

# File lib/sass/script/functions.rb, line 448
def hsl(hue, saturation, lightness)
  hsla(hue, saturation, lightness, Number.new(1))
end
hsla(hue, saturation, lightness, alpha) click to toggle source

Creates a {Color} object from hue, saturation, and lightness, as well as an alpha channel indicating opacity. Uses the algorithm from the [CSS3 spec](www.w3.org/TR/css3-color/#hsl-color).

@param hue [Number] The hue of the color.

Should be between 0 and 360 degrees, inclusive

@param saturation [Number] The saturation of the color.

Must be between `0%` and `100%`, inclusive

@param lightness [Number] The lightness of the color.

Must be between `0%` and `100%`, inclusive

@param alpha [Number] The opacity of the color.

Must be between 0 and 1, inclusive

@return [Color] The resulting color @see hsl @raise [ArgumentError] if `saturation`, `lightness`, or `alpha` are out of bounds

# File lib/sass/script/functions.rb, line 468
def hsla(hue, saturation, lightness, alpha)
  assert_type hue, :Number
  assert_type saturation, :Number
  assert_type lightness, :Number
  assert_type alpha, :Number

  Sass::Util.check_range('Alpha channel', 0..1, alpha)

  h = hue.value
  s = Sass::Util.check_range('Saturation', 0..100, saturation, '%')
  l = Sass::Util.check_range('Lightness', 0..100, lightness, '%')

  Color.new(:hue => h, :saturation => s, :lightness => l, :alpha => alpha.value)
end
hue(color) click to toggle source

Returns the hue component of a color.

See [the CSS3 HSL specification](en.wikipedia.org/wiki/HSL_and_HSV#Conversion_from_RGB_to_HSL_or_HSV).

Calculated from RGB where necessary via [this algorithm](en.wikipedia.org/wiki/HSL_and_HSV#Conversion_from_RGB_to_HSL_or_HSV).

@param color [Color] @return [Number] between 0deg and 360deg @see adjust_hue @raise [ArgumentError] if `color` isn't a color

# File lib/sass/script/functions.rb, line 527
def hue(color)
  assert_type color, :Color
  Sass::Script::Number.new(color.hue, ["deg"])
end
ie_hex_str(color) click to toggle source

Returns an IE hex string for a color with an alpha channel suitable for passing to IE filters.

@example

ie-hex-str(#abc) => #FFAABBCC
ie-hex-str(#3322BB) => #FF3322BB
ie-hex-str(rgba(0, 255, 0, 0.5)) => #8000FF00

@param color [Color] @return [String] @raise [ArgumentError] If `color` isn't a color

# File lib/sass/script/functions.rb, line 758
def ie_hex_str(color)
  assert_type color, :Color
  alpha = (color.alpha * 255).round.to_s(16).rjust(2, '0')
  Sass::Script::String.new("##{alpha}#{color.send(:hex_str)[1..-1]}".upcase)
end
if(condition, if_true, if_false) click to toggle source

Returns one of two values based on the truth value of the first argument.

@example

if(true, 1px, 2px) => 1px
if(false, 1px, 2px) => 2px

@param condition [Bool] Whether the first or second value will be returned. @param if_true [Literal] The value that will be returned if `$condition` is true. @param if_false [Literal] The value that will be returned if `$condition` is false.

# File lib/sass/script/functions.rb, line 1412
def if(condition, if_true, if_false)
  if condition.to_bool
    if_true
  else
    if_false
  end
end
index(list, value) click to toggle source

Returns the position of the given value within the given list. If not found, returns false.

@example

index(1px solid red, solid) => 2
index(1px solid red, dashed) => false
# File lib/sass/script/functions.rb, line 1393
def index(list, value)
  assert_type list, :List
  index = list.value.index {|e| e.eq(value).to_bool }
  if index
    Number.new(index + 1)
  else
    Bool.new(false)
  end
end
invert(color) click to toggle source

Returns the inverse (negative) of a color. The red, green, and blue values are inverted, while the opacity is left alone.

@param color [Color] @return [Color] @raise [ArgumentError] if `color` isn't a color

# File lib/sass/script/functions.rb, line 1040
def invert(color)
  return Sass::Script::String.new("invert(#{color})") if color.is_a?(Sass::Script::Number)

  assert_type color, :Color
  color.with(
    :red => (255 - color.red),
    :green => (255 - color.green),
    :blue => (255 - color.blue))
end
join(list1, list2, separator = Sass::Script::String.new("auto")) click to toggle source

Joins together two lists into a new list.

Unless the `$separator` argument is passed, if one list is comma-separated and one is space-separated, the first parameter's separator is used for the resulting list. If the lists have only one item each, spaces are used for the resulting list.

@example

join(10px 20px, 30px 40px) => 10px 20px 30px 40px
join((blue, red), (#abc, #def)) => blue, red, #abc, #def
join(10px, 20px) => 10px 20px
join(10px, 20px, comma) => 10px, 20px
join((blue, red), (#abc, #def), space) => blue red #abc #def

@overload join(list1, list2, separator: auto)

@param list1 [Literal] The first list to join
@param list2 [Literal] The second list to join
@param separator [String] How the list separator (comma or space) should be determined.
  If this is `comma` or `space`, that is always the separator;
  if this is `auto` (the default), the separator is determined as explained above.
# File lib/sass/script/functions.rb, line 1308
def join(list1, list2, separator = Sass::Script::String.new("auto"))
  assert_type separator, :String
  unless ]auto space comma].include?(separator.value)
    raise ArgumentError.new("Separator name must be space, comma, or auto")
  end
  sep1 = list1.separator if list1.is_a?(Sass::Script::List) && !list1.value.empty?
  sep2 = list2.separator if list2.is_a?(Sass::Script::List) && !list2.value.empty?
  Sass::Script::List.new(
    list1.to_a + list2.to_a,
    if separator.value == 'auto'
      sep1 || sep2 || :space
    else
      separator.value.to_sym
    end)
end
length(list) click to toggle source

Return the length of a list.

@example

length(10px) => 1
length(10px 20px 30px) => 3

@param list [Literal] The list @return [Number] The length

# File lib/sass/script/functions.rb, line 1256
def length(list)
  Sass::Script::Number.new(list.to_a.size)
end
lighten(color, amount) click to toggle source

Makes a color lighter. Takes a color and an amount between 0% and 100%, and returns a color with the lightness increased by that value.

@example

lighten(hsl(0, 0%, 0%), 30%) => hsl(0, 0, 30)
lighten(#800, 20%) => #e00

@param color [Color] @param amount [Number] @return [Color] @see darken @raise [ArgumentError] If `color` isn't a color,

or `number` isn't a number between 0% and 100%
# File lib/sass/script/functions.rb, line 665
def lighten(color, amount)
  _adjust(color, amount, :lightness, 0..100, :+, "%")
end
lightness(color) click to toggle source

Returns the hue component of a color.

See [the CSS3 HSL specification](en.wikipedia.org/wiki/HSL_and_HSV#Conversion_from_RGB_to_HSL_or_HSV).

Calculated from RGB where necessary via [this algorithm](en.wikipedia.org/wiki/HSL_and_HSV#Conversion_from_RGB_to_HSL_or_HSV).

@param color [Color] @return [Number] between 0% and 100% @see lighten @see darken @raise [ArgumentError] if `color` isn't a color

# File lib/sass/script/functions.rb, line 561
def lightness(color)
  assert_type color, :Color
  Sass::Script::Number.new(color.lightness, ["%"])
end
max(*values) click to toggle source

Finds the maximum of several values. This function takes any number of arguments.

@example

max(1px, 4px) => 4px
max(5em, 3em, 4em) => 5em

@return [Number] The maximum value @raise [ArgumentError] if any argument isn't a number, or if not all of

the arguments have comparable units
# File lib/sass/script/functions.rb, line 1243
def max(*values)
  values.each {|v| assert_type v, :Number}
  values.inject {|max, val| max.gt(val).to_bool ? max : val}
end
min(*values) click to toggle source

Finds the minimum of several values. This function takes any number of arguments.

@example

min(1px, 4px) => 1px
min(5em, 3em, 4em) => 3em

@param values [[Number]] The numbers @return [Number] The minimum value @raise [ArgumentError] if any argument isn't a number, or if not all of

the arguments have comparable units
# File lib/sass/script/functions.rb, line 1228
def min(*values)
  values.each {|v| assert_type v, :Number}
  values.inject {|min, val| min.lt(val).to_bool ? min : val}
end
mix(color1, color2, weight = Number.new(50)) click to toggle source

Mixes together two colors. Specifically, takes the average of each of the RGB components, optionally weighted by the given percentage. The opacity of the colors is also considered when weighting the components.

The weight specifies the amount of the first color that should be included in the returned color. The default, 50%, means that half the first color and half the second color should be used. 25% means that a quarter of the first color and three quarters of the second color should be used.

@example

mix(#f00, #00f) => #7f007f
mix(#f00, #00f, 25%) => #3f00bf
mix(rgba(255, 0, 0, 0.5), #00f) => rgba(63, 0, 191, 0.75)

@overload mix(color1, color2, weight: 50%)

@param color1 [Color]
@param color2 [Color]
@param weight [Number] between 0% and 100%
@return [Color]
@raise [ArgumentError] if `color1` or `color2` aren't colors,
  or `weight` isn't a number between 0% and 100%
# File lib/sass/script/functions.rb, line 969
def mix(color1, color2, weight = Number.new(50))
  assert_type color1, :Color
  assert_type color2, :Color
  assert_type weight, :Number

  Sass::Util.check_range("Weight", 0..100, weight, '%')

  # This algorithm factors in both the user-provided weight (w) and the
  # difference between the alpha values of the two colors (a) to decide how
  # to perform the weighted average of the two RGB values.
  #
  # It works by first normalizing both parameters to be within [-1, 1],
  # where 1 indicates "only use color1", -1 indicates "only use color2", and
  # all values in between indicated a proportionately weighted average.
  #
  # Once we have the normalized variables w and a, we apply the formula
  # (w + a)/(1 + w*a) to get the combined weight (in [-1, 1]) of color1.
  # This formula has two especially nice properties:
  #
  #   * When either w or a are -1 or 1, the combined weight is also that number
  #     (cases where w * a == -1 are undefined, and handled as a special case).
  #
  #   * When a is 0, the combined weight is w, and vice versa.
  #
  # Finally, the weight of color1 is renormalized to be within [0, 1]
  # and the weight of color2 is given by 1 minus the weight of color1.
  p = (weight.value/100.0).to_f
  w = p*2 - 1
  a = color1.alpha - color2.alpha

  w1 = (((w * a == -1) ? w : (w + a)/(1 + w*a)) + 1)/2.0
  w2 = 1 - w1

  rgb = color1.rgb.zip(color2.rgb).map {|v1, v2| v1*w1 + v2*w2}
  alpha = color1.alpha*p + color2.alpha*(1-p)
  Color.new(rgb + [alpha])
end
nth(list, n) click to toggle source

Gets the nth item in a list.

Note that unlike some languages, the first item in a Sass list is number 1, the second number 2, and so forth.

@example

nth(10px 20px 30px, 1) => 10px
nth((Helvetica, Arial, sans-serif), 3) => sans-serif

@param list [Literal] The list @param n [Number] The index into the list @return [Literal] The nth item in the list @raise [ArgumentError] If `n` isn't an integer between 1 and the list's length.

# File lib/sass/script/functions.rb, line 1273
def nth(list, n)
  assert_type n, :Number
  if !n.int?
    raise ArgumentError.new("List index #{n} must be an integer")
  elsif n.to_i < 1
    raise ArgumentError.new("List index #{n} must be greater than or equal to 1")
  elsif list.to_a.size == 0
    raise ArgumentError.new("List index is #{n} but list has no items")
  elsif n.to_i > (size = list.to_a.size)
    raise ArgumentError.new("List index is #{n} but list is only #{size} item#{'s' if size != 1} long")
  end

  list.to_a[n.to_i - 1]
end
opacify(color, amount) click to toggle source

Makes a color more opaque. Takes a color and an amount between 0 and 1, and returns a color with the opacity increased by that value.

@example

opacify(rgba(0, 0, 0, 0.5), 0.1) => rgba(0, 0, 0, 0.6)
opacify(rgba(0, 0, 17, 0.8), 0.2) => #001

@param color [Color] @param amount [Number] @return [Color] @see transparentize @raise [ArgumentError] If `color` isn't a color,

or `number` isn't a number between 0 and 1
# File lib/sass/script/functions.rb, line 623
def opacify(color, amount)
  _adjust(color, amount, :alpha, 0..1, :+)
end
Also aliased as: fade_in
opacity(color) click to toggle source

Returns the alpha component (opacity) of a color. This is 1 unless otherwise specified.

@param color [Color] @return [Number] @see opacify @see transparentize @raise [ArgumentError] If `color` isn't a color

# File lib/sass/script/functions.rb, line 603
def opacity(color)
  return Sass::Script::String.new("opacity(#{color})") if color.is_a?(Sass::Script::Number)
  assert_type color, :Color
  Sass::Script::Number.new(color.alpha)
end
percentage(value) click to toggle source

Converts a decimal number to a percentage.

@example

percentage(100px / 50px) => 200%

@param value [Number] The decimal number to convert to a percentage @return [Number] The percentage @raise [ArgumentError] If `value` isn't a unitless number

# File lib/sass/script/functions.rb, line 1158
def percentage(value)
  unless value.is_a?(Sass::Script::Number) && value.unitless?
    raise ArgumentError.new("#{value.inspect} is not a unitless number")
  end
  Sass::Script::Number.new(value.value * 100, ['%'])
end
quote(string) click to toggle source

Add quotes to a string if the string isn't quoted, or returns the same string if it is.

@param string [String] @return [String] @raise [ArgumentError] if `string` isn't a string @see unquote @example

quote("foo") => "foo"
quote(foo) => "foo"
# File lib/sass/script/functions.rb, line 1080
def quote(string)
  assert_type string, :String
  Sass::Script::String.new(string.value, :string)
end
red(color) click to toggle source

Returns the red component of a color.

@param color [Color] @return [Number] @raise [ArgumentError] If `color` isn't a color

# File lib/sass/script/functions.rb, line 489
def red(color)
  assert_type color, :Color
  Sass::Script::Number.new(color.red)
end
rgb(red, green, blue) click to toggle source

Creates a {Color} object from red, green, and blue values.

@param red [Number]

A number between 0 and 255 inclusive,
or between 0% and 100% inclusive

@param green [Number]

A number between 0 and 255 inclusive,
or between 0% and 100% inclusive

@param blue [Number]

A number between 0 and 255 inclusive,
or between 0% and 100% inclusive

@see rgba @return [Color]

# File lib/sass/script/functions.rb, line 373
def rgb(red, green, blue)
  assert_type red, :Number
  assert_type green, :Number
  assert_type blue, :Number

  Color.new([red, green, blue].map do |c|
      v = c.value
      if c.numerator_units == ["%"] && c.denominator_units.empty?
        v = Sass::Util.check_range("Color value", 0..100, c, '%')
        v * 255 / 100.0
      else
        Sass::Util.check_range("Color value", 0..255, c)
      end
    end)
end
rgba(*args) click to toggle source

@see rgb @overload rgba(red, green, blue, alpha)

Creates a {Color} object from red, green, and blue values,
as well as an alpha channel indicating opacity.

@param red [Number]
  A number between 0 and 255 inclusive
@param green [Number]
  A number between 0 and 255 inclusive
@param blue [Number]
  A number between 0 and 255 inclusive
@param alpha [Number]
  A number between 0 and 1
@return [Color]

@overload rgba(color, alpha)

Sets the opacity of a color.

@example
  rgba(#102030, 0.5) => rgba(16, 32, 48, 0.5)
  rgba(blue, 0.2)    => rgba(0, 0, 255, 0.2)

@param color [Color]
@param alpha [Number]
  A number between 0 and 1
@return [Color]
# File lib/sass/script/functions.rb, line 416
def rgba(*args)
  case args.size
  when 2
    color, alpha = args

    assert_type color, :Color
    assert_type alpha, :Number

    Sass::Util.check_range('Alpha channel', 0..1, alpha)
    color.with(:alpha => alpha.value)
  when 4
    red, green, blue, alpha = args
    rgba(rgb(red, green, blue), alpha)
  else
    raise ArgumentError.new("wrong number of arguments (#{args.size} for 4)")
  end
end
round(value) click to toggle source

Rounds a number to the nearest whole number.

@example

round(10.4px) => 10px
round(10.6px) => 11px

@param value [Number] The number @return [Number] The rounded number @raise [ArgumentError] if `value` isn't a number

# File lib/sass/script/functions.rb, line 1174
def round(value)
  numeric_transformation(value) {|n| n.round}
end
saturate(color, amount = nil) click to toggle source

Makes a color more saturated. Takes a color and an amount between 0% and 100%, and returns a color with the saturation increased by that value.

@example

saturate(hsl(120, 30%, 90%), 20%) => hsl(120, 50%, 90%)
saturate(#855, 20%) => #9e3f3f

@overload saturate(color, amount)

@param color [Color]
@param amount [Number]
@return [Color]
@see #desaturate
@raise [ArgumentError] If `color` isn't a color,
  or `number` isn't a number between 0% and 100%
# File lib/sass/script/functions.rb, line 702
def saturate(color, amount = nil)
  # Support the filter effects definition of saturate.
  # https://dvcs.w3.org/hg/FXTF/raw-file/tip/filters/index.html
  return Sass::Script::String.new("saturate(#{color})") if amount.nil?
  _adjust(color, amount, :saturation, 0..100, :+, "%")
end
saturation(color) click to toggle source

Returns the saturation component of a color.

See [the CSS3 HSL specification](en.wikipedia.org/wiki/HSL_and_HSV#Conversion_from_RGB_to_HSL_or_HSV).

Calculated from RGB where necessary via [this algorithm](en.wikipedia.org/wiki/HSL_and_HSV#Conversion_from_RGB_to_HSL_or_HSV).

@param color [Color] @return [Number] between 0% and 100% @see saturate @see desaturate @raise [ArgumentError] if `color` isn't a color

# File lib/sass/script/functions.rb, line 544
def saturation(color)
  assert_type color, :Color
  Sass::Script::Number.new(color.saturation, ["%"])
end
scale_color(color, kwargs) click to toggle source

Scales one or more properties of a color by a percentage value. Unlike {#adjust_color adjust-color}, which changes a color's properties by fixed amounts, {#scale_color scale-color} fluidly changes them based on how high or low they already are. That means that lightening an already-light color with {#scale_color scale-color} won't change the lightness much, but lightening a dark color by the same amount will change it more dramatically. This has the benefit of making `scale-color($color, ...)` have a similar effect regardless of what `$color` is.

For example, the lightness of a color can be anywhere between 0 and 100. If `scale-color($color, $lightness: 40%)` is called, the resulting color's lightness will be 40% of the way between its original lightness and 100. If `scale-color($color, $lightness: -40%)` is called instead, the lightness will be 40% of the way between the original and 0.

This can change the red, green, blue, saturation, value, and alpha properties. The properties are specified as keyword arguments. All arguments should be percentages between 0% and 100%.

All properties are optional. You can't specify both RGB properties (`$red`, `$green`, `$blue`) and HSL properties (`$saturation`, `$value`) at the same time.

@example

scale-color(hsl(120, 70, 80), $lightness: 50%) => hsl(120, 70, 90)
scale-color(rgb(200, 150, 170), $green: -40%, $blue: 70%) => rgb(200, 90, 229)
scale-color(hsl(200, 70, 80), $saturation: -90%, $alpha: -30%) => hsla(200, 7, 80, 0.7)

@param color [Color] @param red [Number] @param green [Number] @param blue [Number] @param saturation [Number] @param lightness [Number] @param alpha [Number] @return [Color] @raise [ArgumentError] if `color` is not a color,

if any keyword argument is not a percentage between 0% and 100%,
if an unexpected keyword argument is given,
or if both HSL and RGB properties are given.
# File lib/sass/script/functions.rb, line 864
def scale_color(color, kwargs)
  assert_type color, :Color
  with = Sass::Util.map_hash({
      "red" => 255,
      "green" => 255,
      "blue" => 255,
      "saturation" => 100,
      "lightness" => 100,
      "alpha" => 1
    }) do |name, max|

    next unless val = kwargs.delete(name)
    assert_type val, :Number, name
    if !(val.numerator_units == ['%'] && val.denominator_units.empty?)
      raise ArgumentError.new("$#{name}: Amount #{val} must be a % (e.g. #{val.value}%)")
    else
      Sass::Util.check_range("$#{name}: Amount", -100..100, val, '%')
    end

    current = color.send(name)
    scale = val.value/100.0
    diff = scale > 0 ? max - current : current
    [name.to_sym, current + diff*scale]
  end

  unless kwargs.empty?
    name, val = kwargs.to_a.first
    raise ArgumentError.new("Unknown argument $#{name} (#{val})")
  end

  color.with(with)
end
transparentize(color, amount) click to toggle source

Makes a color more transparent. Takes a color and an amount between 0 and 1, and returns a color with the opacity decreased by that value.

@example

transparentize(rgba(0, 0, 0, 0.5), 0.1) => rgba(0, 0, 0, 0.4)
transparentize(rgba(0, 0, 0, 0.8), 0.2) => rgba(0, 0, 0, 0.6)

@param color [Color] @param amount [Number] @return [Color] @see opacify @raise [ArgumentError] If `color` isn't a color,

or `number` isn't a number between 0 and 1
# File lib/sass/script/functions.rb, line 644
def transparentize(color, amount)
  _adjust(color, amount, :alpha, 0..1, :-)
end
Also aliased as: fade_out
type_of(value) click to toggle source

Inspects the type of the argument, returning it as an unquoted string.

@example

type-of(100px)  => number
type-of(asdf)   => string
type-of("asdf") => string
type-of(true)   => bool
type-of(#fff)   => color
type-of(blue)   => color

@param value [Literal] The object to inspect @return [String] The unquoted string name of the literal's type

# File lib/sass/script/functions.rb, line 1097
def type_of(value)
  Sass::Script::String.new(value.class.name.gsub(/Sass::Script::/,'').downcase)
end
unit(number) click to toggle source

Inspects the unit of the number, returning it as a quoted string. Complex units are sorted in alphabetical order by numerator and denominator.

@example

unit(100) => ""
unit(100px) => "px"
unit(3em) => "em"
unit(10px * 5em) => "em*px"
unit(10px * 5em / 30cm / 1rem) => "em*px/cm*rem"

@param number [Literal] The number to inspect @return [String] The unit(s) of the number @raise [ArgumentError] if `number` isn't a number

# File lib/sass/script/functions.rb, line 1114
def unit(number)
  assert_type number, :Number
  Sass::Script::String.new(number.unit_str, :string)
end
unitless(number) click to toggle source

Inspects the unit of the number, returning a boolean indicating if it is unitless.

@example

unitless(100) => true
unitless(100px) => false

@param number [Literal] The number to inspect @return [Bool] Whether or not the number is unitless @raise [ArgumentError] if `number` isn't a number

# File lib/sass/script/functions.rb, line 1128
def unitless(number)
  assert_type number, :Number
  Sass::Script::Bool.new(number.unitless?)
end
unquote(string) click to toggle source

Removes quotes from a string if the string is quoted, or returns the same string if it's not.

@param string [String] @return [String] @raise [ArgumentError] if `string` isn't a string @see quote @example

unquote("foo") => foo
unquote(foo) => foo
# File lib/sass/script/functions.rb, line 1061
def unquote(string)
  if string.is_a?(Sass::Script::String)
    Sass::Script::String.new(string.value, :identifier)
  else
    string
  end
end
zip(*lists) click to toggle source

Combines several lists into a single comma separated list space separated lists.

The length of the resulting list is the length of the shortest list.

@example

zip(1px 1px 3px, solid dashed solid, red green blue)
=> 1px solid red, 1px dashed green, 3px solid blue
# File lib/sass/script/functions.rb, line 1370
def zip(*lists)
  length = nil
  values = []
  lists.each do |list|
    assert_type list, :List
    values << list.value.dup
    length = length.nil? ? list.value.length : [length, list.value.length].min
  end
  values.each do |value|
    value.slice!(length)
  end
  new_list_value = values.first.zip(*values[1..-1])
  List.new(new_list_value.map{|list| List.new(list, :space)}, :comma)
end

[Validate]

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