Support for .html.heex

[NatoBoram]

Description

Phoenix is a web framework in Elixir which uses some special server-side HTML tags.

Right now, the result is pretty good. I think the only missing thing is adding an indent level when there's a do %> and removing one when there's an <% end %>. These special tags can be opened by either <%= or <%.

There's a large demand for this feature spanning many projects :

• heex templates are not supported adamzapasnik/prettier-plugin-eex#71
• Support for .html.heex #1964
• HTML indention does not work correctly in eex and leex files elixir-lsp/vscode-elixir-ls#162
• ~H sigil support elixir-lsp/vscode-elixir-ls#201
• Feature: Good support for eex/leex files elixir-lsp/vscode-elixir-ls#98
• Add ~H support elixir-lsp/vscode-elixir-ls#193
• Code formatting support phoenixframework/vscode-phoenix#6
• Support for .html.heex prettier/prettier#12269

Input

With this new feature, when I give like this input:

<%= submit class: "btn btn-outline-primary" do %>
<%= gettext("Create") %>
<% end %>

<%= if @component do %>
<%= for dep <- @component.dependencies() do %>
<.live_component module={dep} id={dep.id()} />
<% end %>
<% end %>

Expected Output

I'd like to see this output:

<%= submit class: "btn btn-outline-primary" do %>
  <%= gettext("Create") %>
<% end %>

<%= if @component do %>
  <%= for dep <- @component.dependencies() do %>
    <.live_component module={dep} id={dep.id()} />
  <% end %>
<% end %>

Environment

OS: Pop!_OS 21.04 x86_64