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credo lib credo check refactor apply.ex
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lib/credo/check/refactor/apply.ex

defmodule Credo.Check.Refactor.Apply do
use Credo.Check,
id: "EX4003",
base_priority: :low,
explanations: [
check: """
Prefer calling functions directly if the number of arguments is known
at compile time instead of using `apply/2` and `apply/3`.
Example:
# preferred
fun.(arg_1, arg_2, ..., arg_n)
module.function(arg_1, arg_2, ..., arg_n)
# NOT preferred
apply(fun, [arg_1, arg_2, ..., arg_n])
apply(module, :function, [arg_1, arg_2, ..., arg_n])
"""
]
@doc false
@impl true
def run(%SourceFile{} = source_file, params) do
ctx = Context.build(source_file, params, __MODULE__)
result = Credo.Code.prewalk(source_file, &walk/2, ctx)
result.issues
end
defp walk({:@, _, [{:spec, _, _}]}, ctx) do
{nil, ctx}
end
defp walk({:apply, _meta, [{:__MODULE__, _, _}, _fun, _args]} = ast, ctx) do
{ast, ctx}
end
defp walk(ast, ctx) do
case issue(ast, ctx) do
:stop ->
{nil, ctx}
nil ->
{ast, ctx}
issue ->
{ast, put_issue(ctx, issue)}
end
end
defp issue({:|>, meta, [{_, _, _} = arg0, {:apply, _, apply_args}]}, ctx) do
issue({:apply, meta, [arg0 | apply_args]}, ctx) || :stop
end
defp issue({:apply, meta, [fun, args]}, ctx) do
issue(:apply2, fun, args, meta, ctx)
end
defp issue({:apply, meta, [_module, fun, args]}, ctx) do
issue(:apply3, fun, args, meta, ctx)
end
defp issue(_ast, _ctx), do: nil
defp issue(tag, fun, args, meta, ctx) do
args = if(is_list(args), do: Enum.reverse(args), else: args)
do_issue(tag, fun, args, meta, ctx)
end
defp do_issue(_apply, _fun, [{:|, _, _} | _], _meta, _ctx), do: nil
defp do_issue(:apply2, {name, _meta, nil}, args, meta, ctx)
when is_atom(name) and is_list(args) do
issue_for(meta, ctx)
end
defp do_issue(:apply3, fun, args, meta, ctx) when is_atom(fun) and is_list(args) do
issue_for(meta, ctx)
end
defp do_issue(_apply, _fun, _args, _meta, _ctx), do: nil
defp issue_for(meta, ctx) do
format_issue(
ctx,
message: "Avoid `apply/2` and `apply/3` when the number of arguments is known.",
trigger: "apply",
line_no: meta[:line]
)
end
end