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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
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]
@collector Credo.Check.Consistency.SpaceAroundOperators.Collector
@default_params [ignore: [:|]]
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 ...
# FIXME: this seems to be already implemented, but there don't seem to be
# any related test cases around.
@doc false
def run(source_files, exec, params \\ []) when is_list(source_files) do
@collector.find_and_append_issues(source_files, exec, params, &issues_for/3)
end
defp issues_for(expected, source_file, params) do
issue_meta = IssueMeta.for(source_file, params)
issue_locations =
expected
|> @collector.find_locations_not_matching(source_file)
|> Enum.reject(&ignored?(&1[:trigger], params))
|> Enum.filter(&create_issue?(&1, issue_meta))
Enum.map(issue_locations, fn(location) ->
format_issue issue_meta,
message: message_for(expected), line_no: location[:line_no],
column: location[:column], trigger: location[:trigger]
end)
end
defp message_for(:with_space = _expected) do
"There are spaces around operators most of the time, but not here."
end
defp message_for(:without_space = _expected) do
"There are no spaces around operators most of the time, but here there are."
end
defp ignored?(trigger, params) do
ignored_triggers = Params.get(params, :ignore, @default_params)
Enum.member?(ignored_triggers, trigger)
end
defp create_issue?(location, issue_meta) do
line =
issue_meta
|> IssueMeta.source_file()
|> SourceFile.line_at(location[:line_no])
create_issue?(line, location[:column], location[:trigger])
end
# Don't create issues for `c = -1`
# TODO: Consider moving these checks inside the Collector.
defp create_issue?(line, column, trigger) when trigger in [:+, :-] do
!number_with_sign?(line, column) &&
!number_in_range?(line, column) &&
!(trigger == :- && minus_in_binary_size?(line, column))
end
defp create_issue?(line, column, trigger) when trigger == :-> do
!arrow_in_typespec?(line, column)
end
defp create_issue?(_, _, _), do: true
defp arrow_in_typespec?(line, column) do
line
|> String.slice(0..column - 2) # -2 because we need to subtract the operator
|> String.match?(~r/\(\s*$/)
end
defp number_with_sign?(line, column) do
line
|> String.slice(0..column - 2) # -2 because we need to subtract the operator
|> String.match?(~r/(\A\s+|\@[a-zA-Z0-9\_]+|[\|\\\{\[\(\,\:\>\<\=\+\-\*\/])\s*$/)
end
defp number_in_range?(line, column) do
line
|> String.slice(column..-1)
|> String.match?(~r/^\d+\.\./)
end
# TODO: this implementation is a bit naive. improve it.
defp minus_in_binary_size?(line, column) do
binary_pattern_start_before? =
line
|> String.slice(0..column - 2) # -2 because we need to subtract the operator
|> String.match?(~r/\<\</)
double_colon_before? =
line
|> String.slice(0..column - 2) # -2 because we need to subtract the operator
|> String.match?(~r/\:\:/)
binary_pattern_end_after? =
line
|> String.slice(column..-1) # -1 because we need to subtract the operator
|> String.match?(~r/\>\>/)
typed_after? =
line
|> String.slice(column..-1) # -1 because we need to subtract the operator
|> String.match?(~r/^\s*(integer|native|signed|unsigned|binary|size|little|float)/)
typed_before? =
line
|> String.slice(0..column - 2) # -2 because we need to subtract the operator
|> String.match?(~r/(integer|native|signed|unsigned|binary|size|little|float)\s*$/)
heuristics_met_count =
[
binary_pattern_start_before?,
binary_pattern_end_after?,
double_colon_before?,
typed_after?,
typed_before?
]
|> Enum.filter(&(&1))
|> Enum.count
heuristics_met_count >= 2
end
end