class RuboCop::Cop::Style::IdenticalConditionalBranches
Checks for identical expressions at the beginning or end of each branch of a conditional expression. Such expressions should normally be placed outside the conditional expression - before or after it.
NOTE: The cop is poorly named and some people might think that it actually checks for duplicated conditional branches. The name will probably be changed in a future major RuboCop
release.
@safety
Autocorrection is unsafe because changing the order of method invocations may change the behavior of the code. For example: [source,ruby] ---- if method_that_modifies_global_state # 1 method_that_relies_on_global_state # 2 foo # 3 else method_that_relies_on_global_state # 2 bar # 3 end ---- In this example, `method_that_relies_on_global_state` will be moved before `method_that_modifies_global_state`, which changes the behavior of the program.
@example
# bad if condition do_x do_z else do_y do_z end # good if condition do_x else do_y end do_z # bad if condition do_z do_x else do_z do_y end # good do_z if condition do_x else do_y end # bad case foo when 1 do_x when 2 do_x else do_x end # good case foo when 1 do_x do_y when 2 # nothing else do_x do_z end # bad case foo in 1 do_x in 2 do_x else do_x end # good case foo in 1 do_x do_y in 2 # nothing else do_x do_z end
Constants
- MSG
Public Instance Methods
on_case(node)
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# File lib/rubocop/cop/style/identical_conditional_branches.rb, line 123 def on_case(node) return unless node.else? && node.else_branch branches = node.when_branches.map(&:body).push(node.else_branch) check_branches(node, branches) end
on_case_match(node)
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# File lib/rubocop/cop/style/identical_conditional_branches.rb, line 130 def on_case_match(node) return unless node.else? && node.else_branch branches = node.in_pattern_branches.map(&:body).push(node.else_branch) check_branches(node, branches) end
on_if(node)
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# File lib/rubocop/cop/style/identical_conditional_branches.rb, line 116 def on_if(node) return if node.elsif? branches = expand_elses(node.else_branch).unshift(node.if_branch) check_branches(node, branches) end
Private Instance Methods
check_branches(node, branches)
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# File lib/rubocop/cop/style/identical_conditional_branches.rb, line 139 def check_branches(node, branches) # return if any branch is empty. An empty branch can be an `if` # without an `else` or a branch that contains only comments. return if branches.any?(&:nil?) tails = branches.map { |branch| tail(branch) } check_expressions(node, tails, :after_condition) if duplicated_expressions?(node, tails) heads = branches.map { |branch| head(branch) } check_expressions(node, heads, :before_condition) if duplicated_expressions?(node, heads) end
check_expressions(node, expressions, insert_position)
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# File lib/rubocop/cop/style/identical_conditional_branches.rb, line 162 def check_expressions(node, expressions, insert_position) # rubocop:disable Metrics/MethodLength inserted_expression = false expressions.each do |expression| add_offense(expression) do |corrector| next if node.if_type? && node.ternary? range = range_by_whole_lines(expression.source_range, include_final_newline: true) corrector.remove(range) next if inserted_expression if insert_position == :after_condition corrector.insert_after(node, "\n#{expression.source}") else corrector.insert_before(node, "#{expression.source}\n") end inserted_expression = true end end end
duplicated_expressions?(node, expressions)
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# File lib/rubocop/cop/style/identical_conditional_branches.rb, line 151 def duplicated_expressions?(node, expressions) unique_expressions = expressions.uniq return false unless expressions.size >= 1 && unique_expressions.one? unique_expression = unique_expressions.first return true unless unique_expression.assignment? lhs = unique_expression.child_nodes.first node.condition.child_nodes.none? { |n| n.source == lhs.source if n.variable? } end
expand_elses(branch)
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‘elsif` branches show up in the if node as nested `else` branches. We need to recursively iterate over all `else` branches.
# File lib/rubocop/cop/style/identical_conditional_branches.rb, line 189 def expand_elses(branch) if branch.nil? [nil] elsif branch.if_type? _condition, elsif_branch, else_branch = *branch expand_elses(else_branch).unshift(elsif_branch) else [branch] end end
head(node)
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# File lib/rubocop/cop/style/identical_conditional_branches.rb, line 204 def head(node) node.begin_type? ? node.children.first : node end
message(node)
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# File lib/rubocop/cop/style/identical_conditional_branches.rb, line 183 def message(node) format(MSG, source: node.source) end
tail(node)
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# File lib/rubocop/cop/style/identical_conditional_branches.rb, line 200 def tail(node) node.begin_type? ? node.children.last : node end