LiveViewNativeStylesheet

Stylesheet primitives for LiveView Native

The library is usually the dependency of another high level lib

Installation

If available in Hex, the package can be installed by adding live_view_native_stylesheet to your list of dependencies in mix.exs:

def deps do
  [
    {:live_view_native_stylesheet, "~> 0.3.0"}
  ]
end

Configuration

All LiveViewNative Stylesheet output can be configured. By default annotations and pretty printing is enabled. If you want smaller outputs for prod environments you’ll need these options off:

config :live_view_native_stylesheet,
  annotations: false,
  pretty: false

Building a stylesheet rules parser

defmodule MyCustomerRulesParser do
  use LiveViewNative.Stylesheet.RulesParser, :swiftui

  defmacro __using__(_) do
    quote do
      import MyCustomRulesParser, only: [sigil_RULES: 2]
      import MyCustomRulesHelpers
    end
  end

  def parse(rules) do
    # your custom parser defined here
  end
end

The format passed in during the use will define a new sigil_RULES/2 function within your customer parser. The format is carried through this function so make sure it matches the format used for the sheet itself.

You must implement the __using__/1 macro and at least importsigil_RULES/2 from your custom parser. sigil_RULES/2 is injected into your module from LiveViewNative.Stylesheet.RulesParser. This is also a good place to include other imports that are necessary to support the compilation of the final stylsheet. In the example above import MyCustomRulesHelpers may include additional helpers available to your parser’s rule set.

You must implement the parse/1 function as this is your primary hook for parsing the rules found within the body of each class from the sheet

Writing stylesheets

New stylesheets can be defined specific to each platform.

Note that variable interpolation is done with { } within the rules.

defmodule MySheet do
  use LiveViewNative.Stylesheet, :swiftui

  ~SHEET"""
  "color-" <> color_name do
    color(.{color_name})
  end
  """

  def class("color-" <> color_name) do
    ~RULES"""
    color(.{color_name})
    """
  end

  def class("star-red") do
    ~RULES"""
    background(alignment: .leading){:star-red}
    """
  end

  def class("star-blue") do
    ~RULES"""
    background(alignment: .trailing){:star-blue}
    """
  end
end

Compiling stylesheets

Stylesheets output only exactly what class names are matched in the templates. This is true of pattern matched class names as well. This keeps the output small lookups fast on the client.

To compile a stylesheet you simply provide a list of class names and a map of ASTs will be produced. Using MySheet from above:

MySheet.compile_ast(~w[color-blue star-red])

=> %{
  "color-blue" => [{:color, [], [{:., [], [nil, :blue]}]}]    [["color", [[".blue", :IME]], nil]]
  "star-red" => [{:background, [], [[alignment: {:., [], [nil, :trailing]}, content: :"star-red"]]}]
}

This map will be sent to the client for looking up the styles at runtime and applying with little to no parsing on the client side:

<Text class="color-blue star-red">
  ABCDEF
  <Star template="star-red" class="color-red"/>
</Text>

Some style/modifier values make more sense as attrs on the element itself. Custom parsers should support attr(value):

def class("searchable") do
  ~RULES"""
  searchable(placeholder: attr(placeholder))
  """
end

This will instruct the client to get the value from the element the class name matches on:

<Text class="searchable" placeholder={@placeholder}>Hello, world!</Text>

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/live_view_native_stylesheet.