56 lines
1.3 KiB
Crystal
56 lines
1.3 KiB
Crystal
require "./base"
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module Ameba::Rule::Performance
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# This rule is used to identify usage of `size` calls that follow filter.
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#
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# For example, this is considered invalid:
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#
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# ```
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# [1, 2, 3].select { |e| e > 2 }.size
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# [1, 2, 3].reject { |e| e < 2 }.size
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# [1, 2, 3].select(&.< 2).size
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# [0, 1, 2].select(&.zero?).size
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# [0, 1, 2].reject(&.zero?).size
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# ```
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#
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# And it should be written as this:
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#
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# ```
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# [1, 2, 3].count { |e| e > 2 }
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# [1, 2, 3].count { |e| e >= 2 }
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# [1, 2, 3].count(&.< 2)
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# [0, 1, 2].count(&.zero?)
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# [0, 1, 2].count(&.!= 0)
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# ```
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#
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# YAML configuration example:
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#
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# ```
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# Performance/SizeAfterFilter:
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# Enabled: true
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# FilterNames:
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# - select
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# - reject
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# ```
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class SizeAfterFilter < Base
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properties do
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description "Identifies usage of `size` calls that follow filter"
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filter_names %w(select reject)
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end
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MSG = "Use `count {...}` instead of `%s {...}.size`."
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def test(source)
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AST::NodeVisitor.new self, source, skip: :macro
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end
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def test(source, node : Crystal::Call)
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return unless node.name == "size" && (obj = node.obj)
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return unless obj.is_a?(Crystal::Call) && obj.block
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return unless obj.name.in?(filter_names)
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issue_for obj.name_location, node.name_end_location, MSG % obj.name
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end
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end
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end
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