Pregenerate the icons with a mix task

lib/mix/heroicons/generator_helpers.ex

@@ -0,0 +1,19 @@
+defmodule Mix.Heroicons.GeneratorHelpers do
+  alias Mix.Heroicons.SvgProcessor
+
+  def icon_name(path) do
+    Path.basename(path, ".svg")
+    |> String.replace("-", "_")
+    |> String.to_atom()
+  end
+
+  def icon_body(path, svg_opts) do
+    icon =
+      File.read!(path)
+      |> SvgProcessor.process(svg_opts)
+
+    <<"<svg ", body::binary>> = icon
+
+    body
+  end
+end

lib/mix/heroicons/svg_processor.ex

@@ -0,0 +1,20 @@
+defmodule Mix.Heroicons.SvgProcessor do
+  alias Mix.Heroicons.SvgProcessor.Handler
+
+  @moduledoc """
+  An SVG parser loosly based on https://github.com/svg/svgo
+
+  ## Options
+
+  Currently supports the following options:
+  * `:remove_dimensions` - remove the `width` and `height` attributes. Defaults to false.
+  * `:sort_attributes` - sort the svg attributes by name. Default to false.
+  * `:remove_attributes` - list of attributes to remove
+  * `:add_attributes` - list of `{"name", "value"}` pairs of attributes to add
+  """
+
+  def process(svg, opts \\ []) do
+    {:ok, stack} = Saxy.parse_string(svg, Handler, {[], opts})
+    Saxy.encode!(stack)
+  end
+end

lib/mix/heroicons/svg_processor/handler.ex

@@ -0,0 +1,107 @@
+defmodule Mix.Heroicons.SvgProcessor.Handler do
+  @moduledoc false
+
+  @behaviour Saxy.Handler
+
+  @impl Saxy.Handler
+  def handle_event(:start_document, _prolog, {stack, opts}) do
+    {:ok, {stack, opts}}
+  end
+
+  @impl Saxy.Handler
+  def handle_event(:start_element, {"svg", attributes}, {stack, opts}) do
+    attributes =
+      remove_dimensions(attributes, Keyword.get(opts, :remove_dimensions))
+      |> remove_attributes(Keyword.get(opts, :remove_attributes))
+      |> add_attributes(Keyword.get(opts, :add_attributes))
+      |> sort_attributes(Keyword.get(opts, :sort_attributes))
+
+    tag = {"svg", attributes, []}
+    {:ok, {[tag | stack], opts}}
+  end
+
+  def handle_event(:start_element, {"path", attributes}, {stack, opts}) do
+    attributes = remove_attributes(attributes, Keyword.get(opts, :remove_path_attributes, []))
+    tag = {"path", attributes, []}
+    {:ok, {[tag | stack], opts}}
+  end
+
+  def handle_event(:start_element, {tag_name, attributes}, {stack, opts}) do
+    tag = {tag_name, attributes, []}
+    {:ok, {[tag | stack], opts}}
+  end
+
+  @impl Saxy.Handler
+  def handle_event(:characters, chars, {stack, opts}) do
+    [{tag_name, attributes, content} | stack] = stack
+
+    current = {tag_name, attributes, [chars | content]}
+
+    {:ok, {[current | stack], opts}}
+  end
+
+  @impl Saxy.Handler
+  def handle_event(:cdata, chars, {stack, opts}) do
+    [{tag_name, attributes, content} | stack] = stack
+
+    current = {tag_name, attributes, [{:cdata, chars} | content]}
+
+    {:ok, {[current | stack], opts}}
+  end
+
+  @impl Saxy.Handler
+  def handle_event(:end_element, tag_name, {[{tag_name, attributes, content} | stack], opts}) do
+    current = {tag_name, attributes, Enum.reverse(content)}
+
+    case stack do
+      [] ->
+        {:ok, {current, opts}}
+
+      [parent | rest] ->
+        {parent_tag_name, parent_attributes, parent_content} = parent
+        parent = {parent_tag_name, parent_attributes, [current | parent_content]}
+        {:ok, {[parent | rest], opts}}
+    end
+  end
+
+  @impl Saxy.Handler
+  def handle_event(:end_document, _, {stack, _opts}) do
+    {:ok, stack}
+  end
+
+  defp remove_dimensions(attributes, true) do
+    Enum.reject(attributes, fn {attr, _value} ->
+      attr == "width" || attr == "height"
+    end)
+  end
+
+  defp remove_dimensions(attributes, _) do
+    attributes
+  end
+
+  defp remove_attributes(attributes, nil) do
+    attributes
+  end
+
+  defp remove_attributes(attributes, remove_attrs) do
+    Enum.reject(attributes, fn {attr, _value} ->
+      attr in remove_attrs
+    end)
+  end
+
+  defp add_attributes(attributes, nil) do
+    attributes
+  end
+
+  defp add_attributes(attributes, add_attrs) do
+    attributes ++ add_attrs
+  end
+
+  defp sort_attributes(attributes, true) do
+    Enum.sort_by(attributes, fn {attr, _value} -> attr end)
+  end
+
+  defp sort_attributes(attributes, nil) do
+    attributes
+  end
+end