Packages
credo
0.7.0
1.7.19
1.7.18
1.7.17
1.7.16
1.7.15
1.7.14
1.7.13
1.7.12
1.7.11
1.7.10
1.7.9
1.7.8
1.7.7
1.7.7-rc.0
1.7.6
1.7.5
1.7.4
1.7.3
1.7.2
1.7.2-rc.4
1.7.2-rc.3
1.7.2-rc.2
1.7.2-rc.1
1.7.2-rc.0
1.7.1
1.7.0
1.7.0-rc.2
1.7.0-rc.1
1.6.7
1.6.6
1.6.5
1.6.4
1.6.3
1.6.2
1.6.1
1.6.0
1.6.0-rc.1
1.6.0-rc.0
1.5.6
1.5.5
1.5.4
1.5.3
1.5.2
1.5.1
1.5.0
1.5.0-rc.5
1.5.0-rc.4
1.5.0-rc.3
1.5.0-rc.2
1.5.0-rc.1
1.4.1
1.4.0
1.4.0-rc.2
1.4.0-rc.1
1.3.2
1.3.1
1.3.0
1.3.0-rc3
1.3.0-rc2
1.3.0-rc1
1.2.3
1.2.2
1.2.1
1.2.0
1.2.0-rc4
1.2.0-rc3
1.2.0-rc2
1.2.0-rc1
1.1.5
1.1.4
1.1.3
1.1.2
1.1.1
1.1.0
1.1.0-rc3
1.1.0-rc2
1.1.0-rc1
1.0.5
1.0.4
1.0.3
1.0.2
1.0.1
1.0.1-rc1
1.0.0
1.0.0-rc1
0.10.2
0.10.1
0.10.0
0.9.3
0.9.2
0.9.1
0.9.0
0.9.0-rc8
0.9.0-rc7
0.9.0-rc6
0.9.0-rc5
0.9.0-rc4
0.9.0-rc3
0.9.0-rc2
0.9.0-rc1
0.8.10
0.8.9
0.8.8
0.8.7
0.8.6
0.8.5
0.8.4
0.8.3
0.8.2
0.8.1
0.8.0
0.8.0-rc7
0.8.0-rc6
0.8.0-rc5
0.8.0-rc4
0.8.0-rc3
0.8.0-rc2
0.8.0-rc1
0.7.4
0.7.3
0.7.2
0.7.1
0.7.0
0.6.1
0.6.0
0.6.0-rc2
0.6.0-rc1
0.5.3
0.5.2
0.5.1
0.5.0
0.4.14
0.4.13
0.4.12
0.4.11
0.4.10
0.4.10-dev
0.4.9
0.4.8
0.4.7
0.4.6
0.4.5
0.4.4
0.4.3
0.4.2
0.4.1
0.4.0
0.4.0-beta5
0.4.0-beta4
0.4.0-beta3
0.4.0-beta2
0.4.0-beta1
0.3.13
0.3.12
0.3.11
0.3.10
0.3.9
0.3.8
0.3.7
0.3.6
0.3.5
0.3.4
0.3.3
0.3.2
0.3.1
0.3.0
0.3.0-dev2
0.3.0-dev
0.2.6
0.2.5
0.2.4
0.2.3
0.2.2
0.2.1
0.2.0
0.1.10
0.1.9
0.1.8
0.1.7
0.1.6
0.1.5
0.1.4
0.1.3
0.1.2
0.1.1
0.1.0
0.0.1-dev
A static code analysis tool with a focus on code consistency and teaching.
Current section
Files
Jump to
Current section
Files
lib/credo/check/warning/map_get_unsafe_pass.ex
defmodule Credo.Check.Warning.MapGetUnsafePass do
@moduledoc """
`Map.get/2` can lead into runtime errors if the result is passed into a pipe
without a proper default value. This happens when the next function in the
pipe cannot handle `nil` values correctly.
Example:
%{foo: [1, 2 ,3], bar: [4, 5, 6]}
|> Map.get(:missing_key)
|> Enum.each(&IO.puts/1)
This will cause a `Protocol.UndefinedError`, since `nil` isn't `Enumerable`.
Often times while iterating over enumerables zero iterations is preferrable
to being forced to deal with an exception. Had there been a `[]` default
parameter this could have been averted.
If you are sure the value exists and can't be nil, please use `Map.fetch!/2`.
If you are not sure, `Map.get/3` can help you provide a safe default value.
"""
@explanation [check: @moduledoc]
@call_string "Map.get"
@unsafe_modules [:Enum]
use Credo.Check, base_priority: :normal
@doc false
def run(%SourceFile{} = source_file, params \\ []) do
issue_meta = IssueMeta.for(source_file, params)
Credo.Code.prewalk(source_file, &traverse(&1, &2, issue_meta))
end
defp traverse({:|>, _meta , _args} = ast, issues, issue_meta) do
pipe_issues =
ast
|> Macro.unpipe
|> Enum.with_index
|> find_pipe_issues(issue_meta)
{ast, issues ++ pipe_issues}
end
defp traverse(ast, issues, _issue_meta) do
{ast, issues}
end
defp find_pipe_issues(pipe, issue_meta) do
pipe
|> Enum.reduce([], fn ({expr, idx}, acc) ->
required_length = required_argument_length(idx)
{next_expr, _} = Enum.at(pipe, idx + 1, {nil, nil})
case {expr, nil_safe?(next_expr)} do
{{{{:., meta, [{_, _, [:Map]}, :get]}, _, args}, _}, false} when length(args) != required_length ->
acc ++ [issue_for(issue_meta, meta[:line], @call_string)]
_ ->
acc
end
end)
end
defp required_argument_length(idx) when idx == 0, do: 3
defp required_argument_length(_), do: 2
defp nil_safe?(expr) do
case expr do
{{{:., _, [{_, _, [module]}, _]}, _, _}, _} ->
!(module in @unsafe_modules)
_ ->
true
end
end
defp issue_for(issue_meta, line_no, trigger) do
format_issue issue_meta,
message: "Map.get with no default return value is potentially unsafe
in pipes, use Map.get/3 instead",
trigger: trigger,
line_no: line_no
end
end