# SurfaceFormatter
[](https://github.com/surface-ui/surface_formatter/actions?query=workflow%3A%22CI%22)
[](https://hex.pm/packages/surface_formatter)
[](https://hex.pm/packages/surface_formatter)
A code formatter for [https://hex.pm/packages/surface](https://hex.pm/packages/surface).
The complete documentation for SurfaceFormatter is located [here](https://hexdocs.pm/surface_formatter/).
## Installation
Add `:surface_formatter` as a dependency in `mix.exs`:
```elixir
defp deps do
[
{:surface_formatter, "~> 0.7.3"}
]
end
```
## Formatter Plugin Usage (Elixir 1.13 and later)
### Configuration
Modify the following in `.formatter.exs`:
- `inputs` - add patterns for all Surface files
- `plugins` - add `Surface.Formatter.Plugin`
```elixir
# .formatter.exs
[
...,
# match all .sface files and all .ex files with ~F sigils
inputs: ["lib/**/*.{ex,sface}", ...],
plugins: [Surface.Formatter.Plugin]
]
```
For documentation of other `.formatter.exs` options, see `Surface.Formatter.Plugin`.
### Usage
```bash
$ mix format
```
(Formats both Elixir and Surface code.)
## Mix Task Usage (Elixir 1.12 and earlier)
### Configuration
Add `surface_inputs` to `.formatter.exs` with patterns for all Surface files:
```elixir
# .formatter.exs
[
...,
# match all .sface files and all .ex files with ~F sigils
surface_inputs: ["lib/**/*.{ex,sface}", ...]
]
```
If your project does not use `sface` files, you can omit `:surface_inputs` and
specify file patterns in the standard `:inputs` field instead. (`mix
surface.format` will fall back to `:inputs`.) But be warned that including
`.sface` files in `:inputs` causes `mix format` to crash in Elixir 1.12 and
earlier.
For documentation of other `.formatter.exs` options, see `mix surface.format`.
### Usage
```bash
$ mix surface.format
```
## Formatting rules
The formatter mostly follows these rules:
- Only formats code inside of `~F"""` blocks and `.sface` files.
- Child nodes are typically indented 2 spaces in from their parent.
- Interpolated Elixir code (inside `{ }` brackets) is formatted by the
[official Elixir formatter](https://hexdocs.pm/elixir/Code.html#format_string!/2).
- HTML attributes are put on separate lines if the line is too long.
- Retains "lack of whitespace" such as `<p>No whitespace between text and tags</p>`.
- Collapses extra newlines down to at most one blank line.
See `Surface.Formatter.format_string!/2` for further documentation.
## Example at a glance
Out of the box, Surface code that looks like this:
```html
<RootComponent with_many_attributes={ true } causing_this_line_to_wrap={ true} because_it_is_too_long={ "yes, this line is long enough to wrap" }>
<!-- HTML public comment (hits the browser) -->
{!-- Surface private comment (does not hit the browser) --}
<div :if={ @show_div }
class="container">
<p> Text inside paragraph </p>
<span>Text touching parent tags</span>
</div>
<Child items={[%{name: "Option 1", key: 1}, %{name: "Option 2", key: 2}, %{name: "Option 3", key: 3}, %{name: "Option 4", key: 4}]}>
Default slot contents
</Child>
</RootComponent>
```
will be formatted like this:
```html
<RootComponent
with_many_attributes
causing_this_line_to_wrap
because_it_is_too_long="yes, this line is long enough to wrap"
>
<!-- HTML public comment (hits the browser) -->
{!-- Surface private comment (does not hit the browser) --}
<div :if={@show_div} class="container">
<p>
Text inside paragraph
</p>
<span>Text touching parent tags</span>
</div>
<Child items={[
%{name: "Option 1", key: 1},
%{name: "Option 2", key: 2},
%{name: "Option 3", key: 3},
%{name: "Option 4", key: 4}
]}>
Default slot contents
</Child>
</RootComponent>
```
