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|
defmodule Mix.Tasks.Format do
use Mix.Task
@shortdoc "Formats the given files/patterns"
@moduledoc """
Formats the given files and patterns.
mix format mix.exs "lib/**/*.{ex,exs}" "test/**/*.{ex,exs}"
If any of the files is `-`, then the output is read from stdin
and written to stdout.
## Formatting options
The formatter will read a `.formatter.exs` file in the current directory for
formatter configuration. Evaluating this file should return a keyword list.
Here is an example of a `.formatter.exs` file that works as a starting point:
[
inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
]
Besides the options listed in `Code.format_string!/2`, the `.formatter.exs`
file supports the following options:
* `:inputs` (a list of paths and patterns) - specifies the default inputs
to be used by this task. For example, `["mix.exs", "{config,lib,test}/**/*.{ex,exs}"]`.
Patterns are expanded with `Path.wildcard/2`.
* `:plugins` (a list of modules) (since v1.13.0) - specifies a list of
modules to customize how the formatter works. See the "Plugins" section
below for more information.
* `:subdirectories` (a list of paths and patterns) - specifies subdirectories
that have their own formatting rules. Each subdirectory should have a
`.formatter.exs` that configures how entries in that subdirectory should be
formatted as. Configuration between `.formatter.exs` are not shared nor
inherited. If a `.formatter.exs` lists "lib/app" as a subdirectory, the rules
in `.formatter.exs` won't be available in `lib/app/.formatter.exs`.
Note that the parent `.formatter.exs` must not specify files inside the "lib/app"
subdirectory in its `:inputs` configuration. If this happens, the behaviour of
which formatter configuration will be picked is unspecified.
* `:import_deps` (a list of dependencies as atoms) - specifies a list
of dependencies whose formatter configuration will be imported.
See the "Importing dependencies configuration" section below for more
information.
* `:export` (a keyword list) - specifies formatter configuration to be exported.
See the "Importing dependencies configuration" section below.
## Task-specific options
* `--check-formatted` - checks that the file is already formatted.
This is useful in pre-commit hooks and CI scripts if you want to
reject contributions with unformatted code. If the check fails,
the formatted contents are not written to disk. Keep in mind
that the formatted output may differ between Elixir versions as
improvements and fixes are applied to the formatter.
* `--dry-run` - does not save files after formatting.
* `--dot-formatter` - path to the file with formatter configuration.
Defaults to `.formatter.exs` if one is available. See the
"Formatting options" section above for more information.
## When to format code
We recommend developers to format code directly in their editors, either
automatically when saving a file or via an explicit command or key binding. If
such option is not available in your editor of choice, adding the required
integration is usually a matter of invoking:
cd $project && mix format $file
where `$file` refers to the current file and `$project` is the root of your
project.
It is also possible to format code across the whole project by passing a list
of patterns and files to `mix format`, as shown at the top of this task
documentation. This list can also be set in the `.formatter.exs` file under the
`:inputs` key.
## Plugins
It is possible to customize how the formatter behaves. Plugins must implement
the `Mix.Tasks.Format` behaviour. For example, imagine that your project uses
Markdown in two distinct ways: via a custom `~M` sigil and via files with the
`.md` and `.markdown` extensions. A custom plugin would look like this:
defmodule MixMarkdownFormatter do
@behaviour Mix.Tasks.Format
def features(_opts) do
[sigils: [:M], extensions: [".md", ".markdown"]]
end
def format(contents, opts) do
# logic that formats markdown
end
end
The `opts` passed to `format/2` contains all the formatting options and either:
* `:sigil` (atom) - the sigil being formatted, e.g. `:M`.
* `:modifiers` (charlist) - list of sigil modifiers.
* `:extension` (string) - the extension of the file being formatted, e.g. `".md"`.
Now any application can use your formatter as follows:
# .formatters.exs
[
# Define the desired plugins
plugins: [MixMarkdownFormatter],
# Remember to update the inputs list to include the new extensions
inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}", "posts/*.{md,markdown}"]
]
Remember that, when running the formatter with plugins, you must make
sure that your dependencies and your application have been compiled,
so the relevant plugin code can be loaded. Otherwise a warning is logged.
## Importing dependencies configuration
This task supports importing formatter configuration from dependencies.
A dependency that wants to export formatter configuration needs to have a
`.formatter.exs` file at the root of the project. In this file, the dependency
can list an `:export` option with configuration to export. For now, only one
option is supported under `:export`: `:locals_without_parens` (whose value has
the same shape as the value of the `:locals_without_parens` in `Code.format_string!/2`).
The functions listed under `:locals_without_parens` in the `:export` option of
a dependency can be imported in a project by listing that dependency in the
`:import_deps` option of the formatter configuration file of the project.
For example, consider you have a project called `my_app` that depends on another one called `my_dep`.
`my_dep` wants to export some configuration, so `my_dep/.formatter.exs`
would look like this:
# my_dep/.formatter.exs
[
# Regular formatter configuration for my_dep
# ...
export: [
locals_without_parens: [some_dsl_call: 2, some_dsl_call: 3]
]
]
In order to import configuration, `my_app`'s `.formatter.exs` would look like
this:
# my_app/.formatter.exs
[
import_deps: [:my_dep]
]
"""
@switches [
check_equivalent: :boolean,
check_formatted: :boolean,
dot_formatter: :string,
dry_run: :boolean
]
@manifest "cached_dot_formatter"
@manifest_vsn 1
@doc """
Returns which features this plugin should plug into.
"""
@callback features(Keyword.t()) :: [sigils: [atom()], extensions: [binary()]]
@doc """
Receives a string to be formatted with options and returns said string.
"""
@callback format(String.t(), Keyword.t()) :: String.t()
@impl true
def run(args) do
{opts, args} = OptionParser.parse!(args, strict: @switches)
{dot_formatter, formatter_opts} = eval_dot_formatter(opts)
if opts[:check_equivalent] do
IO.warn("--check-equivalent has been deprecated and has no effect")
end
{formatter_opts_and_subs, _sources} =
eval_deps_and_subdirectories(dot_formatter, [], formatter_opts, [dot_formatter])
# In case plugins are given, we need to reenable those tasks
Mix.Task.reenable("loadpaths")
Mix.Task.reenable("deps.loadpaths")
args
|> expand_args(dot_formatter, formatter_opts_and_subs)
|> Task.async_stream(&format_file(&1, opts), ordered: false, timeout: 30000)
|> Enum.reduce({[], []}, &collect_status/2)
|> check!()
end
@doc """
Returns a formatter function and the formatter options to
be used for the given file.
The function must be called with the contents of the file
to be formatted. The options are returned for reflection
purposes.
"""
@doc since: "1.13.0"
def formatter_for_file(file, opts \\ []) do
{dot_formatter, formatter_opts} = eval_dot_formatter(opts)
{formatter_opts_and_subs, _sources} =
eval_deps_and_subdirectories(dot_formatter, [], formatter_opts, [dot_formatter])
find_formatter_and_opts_for_file(file, formatter_opts_and_subs)
end
@doc """
Returns formatter options to be used for the given file.
"""
# TODO: Deprecate on Elixir v1.17
@doc deprecated: "Use formatter_for_file/2 instead"
def formatter_opts_for_file(file, opts \\ []) do
{_, formatter_opts} = formatter_for_file(file, opts)
formatter_opts
end
defp eval_dot_formatter(opts) do
cond do
dot_formatter = opts[:dot_formatter] ->
{dot_formatter, eval_file_with_keyword_list(dot_formatter)}
File.regular?(".formatter.exs") ->
{".formatter.exs", eval_file_with_keyword_list(".formatter.exs")}
true ->
{".formatter.exs", []}
end
end
# This function reads exported configuration from the imported
# dependencies and subdirectories and deals with caching the result
# of reading such configuration in a manifest file.
defp eval_deps_and_subdirectories(dot_formatter, prefix, formatter_opts, sources) do
deps = Keyword.get(formatter_opts, :import_deps, [])
subs = Keyword.get(formatter_opts, :subdirectories, [])
plugins = Keyword.get(formatter_opts, :plugins, [])
if not is_list(deps) do
Mix.raise("Expected :import_deps to return a list of dependencies, got: #{inspect(deps)}")
end
if not is_list(subs) do
Mix.raise("Expected :subdirectories to return a list of directories, got: #{inspect(subs)}")
end
if not is_list(plugins) do
Mix.raise("Expected :plugins to return a list of modules, got: #{inspect(plugins)}")
end
if plugins != [] do
args = ["--no-elixir-version-check", "--no-deps-check", "--no-archives-check"]
Mix.Task.run("loadpaths", args)
end
for plugin <- plugins do
cond do
not Code.ensure_loaded?(plugin) ->
Mix.shell().error(
"Skipping formatter plugin #{inspect(plugin)} because module cannot be found"
)
not function_exported?(plugin, :features, 1) ->
Mix.shell().error(
"Skipping formatter plugin #{inspect(plugin)} because it does not define features/1"
)
true ->
:ok
end
end
sigils =
for plugin <- plugins,
sigil <- find_sigils_from_plugins(plugin, formatter_opts),
do: {sigil, &plugin.format(&1, &2 ++ formatter_opts)}
formatter_opts =
formatter_opts
|> Keyword.put(:plugins, plugins)
|> Keyword.put(:sigils, sigils)
if deps == [] and subs == [] do
{{formatter_opts, []}, sources}
else
manifest = Path.join(Mix.Project.manifest_path(), @manifest)
maybe_cache_in_manifest(dot_formatter, manifest, fn ->
{subdirectories, sources} = eval_subs_opts(subs, prefix, sources)
{{eval_deps_opts(formatter_opts, deps), subdirectories}, sources}
end)
end
end
defp maybe_cache_in_manifest(dot_formatter, manifest, fun) do
cond do
is_nil(Mix.Project.get()) or dot_formatter != ".formatter.exs" -> fun.()
entry = read_manifest(manifest) -> entry
true -> write_manifest!(manifest, fun.())
end
end
defp read_manifest(manifest) do
with {:ok, binary} <- File.read(manifest),
{:ok, {@manifest_vsn, entry, sources}} <- safe_binary_to_term(binary),
expanded_sources = Enum.flat_map(sources, &Path.wildcard(&1, match_dot: true)),
false <- Mix.Utils.stale?([Mix.Project.config_mtime() | expanded_sources], [manifest]) do
{entry, sources}
else
_ -> nil
end
end
defp safe_binary_to_term(binary) do
{:ok, :erlang.binary_to_term(binary)}
rescue
_ -> :error
end
defp write_manifest!(manifest, {entry, sources}) do
File.mkdir_p!(Path.dirname(manifest))
File.write!(manifest, :erlang.term_to_binary({@manifest_vsn, entry, sources}))
{entry, sources}
end
defp eval_deps_opts(formatter_opts, []) do
formatter_opts
end
defp eval_deps_opts(formatter_opts, deps) do
deps_paths = Mix.Project.deps_paths()
parenless_calls =
for dep <- deps,
dep_path = assert_valid_dep_and_fetch_path(dep, deps_paths),
dep_dot_formatter = Path.join(dep_path, ".formatter.exs"),
File.regular?(dep_dot_formatter),
dep_opts = eval_file_with_keyword_list(dep_dot_formatter),
parenless_call <- dep_opts[:export][:locals_without_parens] || [],
uniq: true,
do: parenless_call
Keyword.update(
formatter_opts,
:locals_without_parens,
parenless_calls,
&(&1 ++ parenless_calls)
)
end
defp eval_subs_opts(subs, prefix, sources) do
{subs, sources} =
Enum.flat_map_reduce(subs, sources, fn sub, sources ->
prefix = Path.join(prefix ++ [sub])
{Path.wildcard(prefix), [Path.join(prefix, ".formatter.exs") | sources]}
end)
Enum.flat_map_reduce(subs, sources, fn sub, sources ->
sub_formatter = Path.join(sub, ".formatter.exs")
if File.exists?(sub_formatter) do
formatter_opts = eval_file_with_keyword_list(sub_formatter)
{formatter_opts_and_subs, sources} =
eval_deps_and_subdirectories(:in_memory, [sub], formatter_opts, sources)
{[{sub, formatter_opts_and_subs}], sources}
else
{[], sources}
end
end)
end
defp assert_valid_dep_and_fetch_path(dep, deps_paths) when is_atom(dep) do
case Map.fetch(deps_paths, dep) do
{:ok, path} ->
if File.dir?(path) do
path
else
Mix.raise(
"Unavailable dependency #{inspect(dep)} given to :import_deps in the formatter configuration. " <>
"The dependency cannot be found in the file system, please run \"mix deps.get\" and try again"
)
end
:error ->
Mix.raise(
"Unknown dependency #{inspect(dep)} given to :import_deps in the formatter configuration. " <>
"The dependency is not listed in your mix.exs for environment #{inspect(Mix.env())}"
)
end
end
defp assert_valid_dep_and_fetch_path(dep, _deps_paths) do
Mix.raise("Dependencies in :import_deps should be atoms, got: #{inspect(dep)}")
end
defp eval_file_with_keyword_list(path) do
{opts, _} = Code.eval_file(path)
unless Keyword.keyword?(opts) do
Mix.raise("Expected #{inspect(path)} to return a keyword list, got: #{inspect(opts)}")
end
opts
end
defp expand_args([], dot_formatter, formatter_opts_and_subs) do
if no_entries_in_formatter_opts?(formatter_opts_and_subs) do
Mix.raise(
"Expected one or more files/patterns to be given to mix format " <>
"or for a .formatter.exs file to exist with an :inputs or :subdirectories key"
)
end
dot_formatter
|> expand_dot_inputs([], formatter_opts_and_subs, %{})
|> Enum.map(fn {file, {_dot_formatter, formatter_opts}} ->
{file, find_formatter_for_file(file, formatter_opts)}
end)
end
defp expand_args(files_and_patterns, _dot_formatter, {formatter_opts, subs}) do
files =
for file_or_pattern <- files_and_patterns,
file <- stdin_or_wildcard(file_or_pattern),
uniq: true,
do: file
if files == [] do
Mix.raise(
"Could not find a file to format. The files/patterns given to command line " <>
"did not point to any existing file. Got: #{inspect(files_and_patterns)}"
)
end
for file <- files do
if file == :stdin do
{file, &elixir_format(&1, [file: "stdin"] ++ formatter_opts)}
else
{formatter, _opts} = find_formatter_and_opts_for_file(file, {formatter_opts, subs})
{file, formatter}
end
end
end
defp expand_dot_inputs(dot_formatter, prefix, {formatter_opts, subs}, acc) do
if no_entries_in_formatter_opts?({formatter_opts, subs}) do
Mix.raise("Expected :inputs or :subdirectories key in #{dot_formatter}")
end
map =
for input <- List.wrap(formatter_opts[:inputs]),
file <- Path.wildcard(Path.join(prefix ++ [input]), match_dot: true),
do: {expand_relative_to_cwd(file), {dot_formatter, formatter_opts}},
into: %{}
acc =
Map.merge(acc, map, fn file, {dot_formatter1, _}, {dot_formatter2, formatter_opts} ->
Mix.shell().error(
"Both #{dot_formatter1} and #{dot_formatter2} specify the file " <>
"#{Path.relative_to_cwd(file)} in their :inputs option. To resolve the " <>
"conflict, the configuration in #{dot_formatter1} will be ignored. " <>
"Please change the list of :inputs in one of the formatter files so only " <>
"one of them matches #{Path.relative_to_cwd(file)}"
)
{dot_formatter2, formatter_opts}
end)
Enum.reduce(subs, acc, fn {sub, formatter_opts_and_subs}, acc ->
sub_formatter = Path.join(sub, ".formatter.exs")
expand_dot_inputs(sub_formatter, [sub], formatter_opts_and_subs, acc)
end)
end
defp expand_relative_to_cwd(path) do
case File.cwd() do
{:ok, cwd} -> Path.expand(path, cwd)
_ -> path
end
end
defp find_formatter_for_file(file, formatter_opts) do
ext = Path.extname(file)
cond do
plugin = find_plugin_for_extension(formatter_opts, ext) ->
&plugin.format(&1, [extension: ext] ++ formatter_opts)
ext in ~w(.ex .exs) ->
&elixir_format(&1, [file: file] ++ formatter_opts)
true ->
& &1
end
end
defp find_plugin_for_extension(formatter_opts, ext) do
plugins = Keyword.get(formatter_opts, :plugins, [])
Enum.find(plugins, fn plugin ->
Code.ensure_loaded?(plugin) and function_exported?(plugin, :features, 1) and
ext in List.wrap(plugin.features(formatter_opts)[:extensions])
end)
end
defp find_formatter_and_opts_for_file(file, formatter_opts_and_subs) do
split = file |> Path.relative_to_cwd() |> Path.split()
formatter_opts = recur_formatter_opts_for_file(split, formatter_opts_and_subs)
{find_formatter_for_file(file, formatter_opts), formatter_opts}
end
defp recur_formatter_opts_for_file(split, {formatter_opts, subs}) do
Enum.find_value(subs, formatter_opts, fn {sub, formatter_opts_and_subs} ->
if List.starts_with?(split, Path.split(sub)) do
recur_formatter_opts_for_file(split, formatter_opts_and_subs)
end
end)
end
defp no_entries_in_formatter_opts?({formatter_opts, subs}) do
is_nil(formatter_opts[:inputs]) and subs == []
end
defp stdin_or_wildcard("-"), do: [:stdin]
defp stdin_or_wildcard(path), do: path |> Path.expand() |> Path.wildcard(match_dot: true)
defp elixir_format(content, formatter_opts) do
IO.iodata_to_binary([Code.format_string!(content, formatter_opts), ?\n])
end
defp find_sigils_from_plugins(plugin, formatter_opts) do
if Code.ensure_loaded?(plugin) and function_exported?(plugin, :features, 1) do
List.wrap(plugin.features(formatter_opts)[:sigils])
else
[]
end
end
defp read_file(:stdin), do: IO.stream() |> Enum.to_list() |> IO.iodata_to_binary()
defp read_file(file), do: File.read!(file)
defp format_file({file, formatter}, task_opts) do
input = read_file(file)
output = formatter.(input)
check_formatted? = Keyword.get(task_opts, :check_formatted, false)
dry_run? = Keyword.get(task_opts, :dry_run, false)
cond do
check_formatted? ->
if input == output, do: :ok, else: {:not_formatted, file}
dry_run? ->
:ok
true ->
write_or_print(file, input, output)
end
rescue
exception ->
{:exit, file, exception, __STACKTRACE__}
end
defp write_or_print(file, input, output) do
cond do
file == :stdin -> IO.write(output)
input == output -> :ok
true -> File.write!(file, output)
end
:ok
end
defp collect_status({:ok, :ok}, acc), do: acc
defp collect_status({:ok, {:exit, _, _, _} = exit}, {exits, not_formatted}) do
{[exit | exits], not_formatted}
end
defp collect_status({:ok, {:not_formatted, file}}, {exits, not_formatted}) do
{exits, [file | not_formatted]}
end
defp check!({[], []}) do
:ok
end
defp check!({[{:exit, :stdin, exception, stacktrace} | _], _not_formatted}) do
Mix.shell().error("mix format failed for stdin")
reraise exception, stacktrace
end
defp check!({[{:exit, file, exception, stacktrace} | _], _not_formatted}) do
Mix.shell().error("mix format failed for file: #{Path.relative_to_cwd(file)}")
reraise exception, stacktrace
end
defp check!({_exits, [_ | _] = not_formatted}) do
Mix.raise("""
mix format failed due to --check-formatted.
The following files are not formatted:
#{to_bullet_list(not_formatted)}
""")
end
defp to_bullet_list(files) do
Enum.map_join(files, "\n", &" * #{&1 |> to_string() |> Path.relative_to_cwd()}")
end
end
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