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lib/credo/check/consistency/space_around_operators.ex

defmodule Credo.Check.Consistency.SpaceAroundOperators do
@moduledoc """
Use spaces around operators like `+`, `-`, `*` and `/`. This is the
**preferred** way, although other styles are possible, as long as it is
applied consistently.
# preferred way
1 + 2 * 4
# also okay
1+2*4
While this is not necessarily a concern for the correctness of your code,
you should use a consistent style throughout your codebase.
"""
@explanation [check: @moduledoc]
@code_patterns [
Credo.Check.Consistency.SpaceAroundOperators.WithSpace,
Credo.Check.Consistency.SpaceAroundOperators.WithoutSpace
]
@default_params [ignore: [:|]]
alias Credo.Check.Consistency.Helper
alias Credo.Check.PropertyValue
use Credo.Check, run_on_all: true, base_priority: :high
# TODO: add *ignored* operators, so you can add "|" and still write
# [head|tail] while enforcing 2 + 3 / 1 ...
@doc false
def run(source_files, params \\ []) when is_list(source_files) do
source_files
|> Helper.run_code_patterns(@code_patterns, params)
|> Helper.append_issues_via_issue_service(&issue_for/5, params)
:ok
end
defp issue_for(_issue_meta, _actual_props, nil, _picked_count, _total_count), do: nil
defp issue_for(_issue_meta, [], _expected_prop, _picked_count, _total_count), do: nil
defp issue_for(issue_meta, actual_prop, expected_prop, _picked_count, _total_count) do
line_no = PropertyValue.meta(actual_prop, :line_no)
column = PropertyValue.meta(actual_prop, :column)
trigger = PropertyValue.meta(actual_prop, :trigger)
actual_prop = PropertyValue.get(actual_prop)
line = issue_meta |> IssueMeta.source_file() |> SourceFile.line_at(line_no)
params = issue_meta |> IssueMeta.params()
ignored_triggers = params |> Params.get(:ignore, @default_params)
if !Enum.member?(ignored_triggers, trigger) && create_issue?(line, column, trigger) do
format_issue issue_meta,
message: message_for(actual_prop, expected_prop),
line_no: line_no,
column: column,
trigger: trigger
end
end
defp message_for(:with_space, :without_space) do
"There are no spaces around operators most of the time, but here there are."
end
defp message_for(:without_space, :with_space) do
"There are spaces around operators most of the time, but not here."
end
# Don't create issues for `&Mod.fun/4`
defp create_issue?(line, column, :/) do
~r/\&[a-zA-Z0-9\.\_\?\!]+\/\d+/ # pattern to detect &Mod.fun/4
|> Regex.run(line, return: :index)
|> List.wrap
|> Enum.any?(fn({start_index, end_index}) ->
start_index < column && end_index > column
end)
end
# Don't create issues for `c = -1`
defp create_issue?(line, column, operator) when operator in [:+, :-] do
!number_with_sign?(line, column) &&
!number_in_range?(line, column) &&
!(operator == :- && minus_in_binary_size?(line, column))
end
defp create_issue?(_, _, _), do: true
defp number_with_sign?(line, column) do
line
|> String.slice(0..column - 2) # -2 because we need to substract the operator
|> String.match?(~r/(\s+|\@[a-zA-Z0-9\_]+|[\{\[\(\,\:\>\<\=\+\-\*\/])\s*$/)
end
defp number_in_range?(line, column) do
line
|> String.slice(column..-1)
|> String.match?(~r/^\d+\.\./)
end
# TODO: this implementation is a bit naive. improve it.
defp minus_in_binary_size?(line, column) do
binary_pattern_start_before? =
line
|> String.slice(0..column - 2) # -2 because we need to substract the operator
|> String.match?(~r/\<\</)
double_colon_before? =
line
|> String.slice(0..column - 2) # -2 because we need to substract the operator
|> String.match?(~r/\:\:/)
binary_pattern_end_after? =
line
|> String.slice(column..-1) # -1 because we need to substract the operator
|> String.match?(~r/\>\>/)
typed_after? =
line
|> String.slice(column..-1) # -1 because we need to substract the operator
|> String.match?(~r/^\s*(signed|unsigned|binary|size)/)
heuristics_met_count =
[
binary_pattern_start_before?,
binary_pattern_end_after?,
double_colon_before?,
typed_after?
]
|> Enum.filter(&(&1))
|> Enum.count
heuristics_met_count >= 2
end
end