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credo lib credo check refactor cond_statements.ex
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lib/credo/check/refactor/cond_statements.ex

defmodule Credo.Check.Refactor.CondStatements do
@moduledoc false
@checkdoc """
Each cond statement should have 3 or more statements including the
"always true" statement. Otherwise an `if` and `else` construct might be more
appropriate.
Example:
cond do
x == y -> 0
true -> 1
end
# should be written as
if x == y do
0
else
1
end
"""
@explanation [check: @checkdoc]
use Credo.Check
@doc false
def run(source_file, params \\ []) do
issue_meta = IssueMeta.for(source_file, params)
Credo.Code.prewalk(source_file, &traverse(&1, &2, issue_meta))
end
defp traverse({:cond, meta, arguments} = ast, issues, issue_meta) do
count =
arguments
|> Credo.Code.Block.do_block_for!()
|> List.wrap()
|> Enum.count()
if count <= 2 do
{ast, issues ++ [issue_for(issue_meta, meta[:line], :cond)]}
else
{ast, issues}
end
end
defp traverse(ast, issues, _issue_meta) do
{ast, issues}
end
defp issue_for(issue_meta, line_no, trigger) do
format_issue(
issue_meta,
message:
"Cond statements should contain at least two conditions besides `true`, consider using `if` instead.",
trigger: trigger,
line_no: line_no
)
end
end