65 lines
1.6 KiB
Ruby
65 lines
1.6 KiB
Ruby
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module RuboCop
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module Cop
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# This cop makes sure that custom error classes, when empty, are declared
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# with Class.new.
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#
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# @example
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# # bad
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# class FooError < StandardError
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# end
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#
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# # okish
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# class FooError < StandardError; end
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#
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# # good
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# FooError = Class.new(StandardError)
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class CustomErrorClass < RuboCop::Cop::Cop
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MSG = 'Use `Class.new(SuperClass)` to define an empty custom error class.'.freeze
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def on_class(node)
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_klass, parent, body = node.children
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return if body
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parent_klass = class_name_from_node(parent)
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return unless parent_klass && parent_klass.to_s.end_with?('Error')
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add_offense(node, :expression)
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end
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def autocorrect(node)
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klass, parent, _body = node.children
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replacement = "#{class_name_from_node(klass)} = Class.new(#{class_name_from_node(parent)})"
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lambda do |corrector|
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corrector.replace(node.source_range, replacement)
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end
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end
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private
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# The nested constant `Foo::Bar::Baz` looks like:
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#
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# s(:const,
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# s(:const,
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# s(:const, nil, :Foo), :Bar), :Baz)
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#
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# So recurse through that to get the name as written in the source.
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#
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def class_name_from_node(node, suffix = nil)
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return unless node&.type == :const
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name = node.children[1].to_s
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name = "#{name}::#{suffix}" if suffix
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if node.children[0]
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class_name_from_node(node.children[0], name)
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else
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name
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end
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end
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end
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end
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end
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