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defmodule Credo.Check.Readability.AliasOrder do | ||
@moduledoc """ | ||
Alphabetically ordered lists are more easily scannable by the read. | ||
# preferred | ||
alias Module1 | ||
alias Module2 | ||
alias Module3 | ||
# NOT preferred | ||
alias Module1 | ||
alias Module3 | ||
alias Module2 | ||
Alias should be alphabetically ordered among their group: | ||
# preferred | ||
alias Module3 | ||
alias Module4 | ||
alias Module1 | ||
alias Module2 | ||
# NOT preferred | ||
alias Module3 | ||
alias Module4 | ||
alias Module2 | ||
alias Module1 | ||
Like all `Readability` issues, this one is not a technical concern. | ||
But you can improve the odds of others reading and liking your code by making | ||
it easier to follow. | ||
""" | ||
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@explanation [check: @moduledoc] | ||
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alias Credo.Code | ||
alias Credo.Code.Name | ||
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use Credo.Check, base_priority: :high | ||
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@doc false | ||
def run(source_file, params \\ []) do | ||
issue_meta = IssueMeta.for(source_file, params) | ||
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Code.prewalk(source_file, &traverse(&1, &2, issue_meta)) | ||
end | ||
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defp traverse({:defmodule, _, _} = ast, issues, issue_meta) do | ||
new_issues = | ||
ast | ||
|> extract_alias_groups() | ||
|> Enum.reduce([], &traverse_groups(&1, &2, issue_meta)) | ||
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{ast, issues ++ new_issues} | ||
end | ||
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defp traverse(ast, issues, _), do: {ast, issues} | ||
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defp traverse_groups(group, acc, issue_meta) do | ||
group | ||
|> Credo.Backports.Enum.chunk_every(2, 1) | ||
|> Enum.reduce_while(nil, &process_group/2) | ||
|> case do | ||
nil -> | ||
acc | ||
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line -> | ||
acc ++ [issue_for(issue_meta, line)] | ||
end | ||
end | ||
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defp process_group([{_, first}, {line_no, second}], _) when first > second do | ||
line = [ | ||
line_no: line_no, | ||
trigger: Name.full(second -- first), | ||
module: second | ||
] | ||
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{:halt, line} | ||
end | ||
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defp process_group(_, _), do: {:cont, nil} | ||
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defp extract_alias_groups({:defmodule, _, _} = ast) do | ||
ast | ||
|> Code.postwalk(&find_alias_groups/2) | ||
|> Enum.reverse() | ||
|> Enum.reduce([[]], fn definition, acc -> | ||
case definition do | ||
nil -> | ||
[[]] ++ acc | ||
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definition -> | ||
[group | groups] = acc | ||
[group ++ [definition]] ++ groups | ||
end | ||
end) | ||
|> Enum.reverse() | ||
end | ||
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defp find_alias_groups( | ||
{:alias, _, [{:__aliases__, meta, mod_list}]} = ast, | ||
aliases | ||
) do | ||
modules = | ||
mod_list | ||
|> (&[{meta[:line], &1}]).() | ||
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accumulate_alias_into_group(ast, modules, meta[:line], aliases) | ||
end | ||
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defp find_alias_groups( | ||
{:alias, _, | ||
[ | ||
{{:., _, [{:__aliases__, meta, mod_list}, :{}]}, _, multi_mod_list} | ||
]} = ast, | ||
aliases | ||
) do | ||
modules = | ||
multi_mod_list | ||
|> Enum.map(fn {:__aliases__, meta2, mod} -> {meta2[:line], mod_list ++ mod} end) | ||
|> Enum.reverse() | ||
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accumulate_alias_into_group(ast, modules, meta[:line], aliases) | ||
end | ||
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defp find_alias_groups(ast, aliases), do: {ast, aliases} | ||
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defp accumulate_alias_into_group(ast, modules, line, [{line_no, _} | _] = aliases) | ||
when line_no != 0 and line_no != line - 1 do | ||
{ast, modules ++ [nil] ++ aliases} | ||
end | ||
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defp accumulate_alias_into_group(ast, modules, _, aliases) do | ||
{ast, modules ++ aliases} | ||
end | ||
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defp issue_for(issue_meta, line_no: line_no, trigger: trigger, module: module) do | ||
format_issue( | ||
issue_meta, | ||
message: "The alias `#{Name.full(module)}` is not alphabetically ordered among its group.", | ||
trigger: trigger, | ||
line_no: line_no | ||
) | ||
end | ||
end |
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