class RuboCop::Cop::Style::GuardClause
Use a guard clause instead of wrapping the code inside a conditional expression
A condition with an ‘elsif` or `else` branch is allowed unless one of `return`, `break`, `next`, `raise`, or `fail` is used in the body of the conditional expression.
NOTE: Autocorrect works in most cases except with if-else statements
that contain logical operators such as `foo || raise('exception')`
@example
# bad def test if something work end end # good def test return unless something work end # also good def test work if something end # bad if something raise 'exception' else ok end # good raise 'exception' if something ok # bad if something foo || raise('exception') else ok end # good foo || raise('exception') if something ok # bad define_method(:test) do if something work end end # good define_method(:test) do return unless something work end # also good define_method(:test) do work if something end
@example AllowConsecutiveConditionals: false (default)
# bad def test if foo? work end if bar? # <- reports an offense work end end
@example AllowConsecutiveConditionals: true
# good def test if foo? work end if bar? work end end # bad def test if foo? work end do_something if bar? # <- reports an offense work end end
Constants
- MSG
Public Instance Methods
on_block(node)
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# File lib/rubocop/cop/style/guard_clause.rb, line 132 def on_block(node) return unless node.method?(:define_method) || node.method?(:define_singleton_method) on_def(node) end
Also aliased as: on_numblock
on_def(node)
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# File lib/rubocop/cop/style/guard_clause.rb, line 123 def on_def(node) body = node.body return unless body check_ending_body(body) end
Also aliased as: on_defs
on_if(node)
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# File lib/rubocop/cop/style/guard_clause.rb, line 139 def on_if(node) return if accepted_form?(node) if (guard_clause = node.if_branch&.guard_clause?) kw = node.loc.keyword.source guard = :if elsif (guard_clause = node.else_branch&.guard_clause?) kw = node.inverse_keyword guard = :else else return end guard = nil if and_or_guard_clause?(guard_clause) register_offense(node, guard_clause_source(guard_clause), kw, guard) end
Private Instance Methods
accepted_form?(node, ending: false)
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# File lib/rubocop/cop/style/guard_clause.rb, line 275 def accepted_form?(node, ending: false) accepted_if?(node, ending) || node.condition.multiline? || node.parent&.assignment? end
accepted_if?(node, ending)
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# File lib/rubocop/cop/style/guard_clause.rb, line 285 def accepted_if?(node, ending) return true if node.modifier_form? || node.ternary? || node.elsif_conditional? || assigned_lvar_used_in_if_branch?(node) if ending node.else? else !node.else? || node.elsif? end end
allowed_consecutive_conditionals?()
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# File lib/rubocop/cop/style/guard_clause.rb, line 312 def allowed_consecutive_conditionals? cop_config.fetch('AllowConsecutiveConditionals', false) end
and_or_guard_clause?(guard_clause)
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# File lib/rubocop/cop/style/guard_clause.rb, line 265 def and_or_guard_clause?(guard_clause) parent = guard_clause.parent parent.and_type? || parent.or_type? end
assigned_lvar_used_in_if_branch?(node)
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# File lib/rubocop/cop/style/guard_clause.rb, line 296 def assigned_lvar_used_in_if_branch?(node) return false unless (if_branch = node.if_branch) assigned_lvars_in_condition = node.condition.each_descendant(:lvasgn).map do |lvasgn| lvar_name, = *lvasgn lvar_name.to_s end used_lvars_in_branch = if_branch.each_descendant(:lvar).map(&:source) || [] (assigned_lvars_in_condition & used_lvars_in_branch).any? end
autocorrect(corrector, node, condition, replacement, guard)
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rubocop:disable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
# File lib/rubocop/cop/style/guard_clause.rb, line 210 def autocorrect(corrector, node, condition, replacement, guard) corrector.replace(node.loc.keyword.join(condition.source_range), replacement) if_branch = node.if_branch else_branch = node.else_branch corrector.replace(node.loc.begin, "\n") if node.loc.begin&.is?('then') if if_branch&.send_type? && heredoc?(if_branch.last_argument) autocorrect_heredoc_argument(corrector, node, if_branch, else_branch, guard) elsif else_branch&.send_type? && heredoc?(else_branch.last_argument) autocorrect_heredoc_argument(corrector, node, else_branch, if_branch, guard) else corrector.remove(node.loc.end) return unless node.else? corrector.remove(node.loc.else) corrector.remove(range_of_branch_to_remove(node, guard)) end end
autocorrect_heredoc_argument(corrector, node, heredoc_branch, leave_branch, guard)
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# File lib/rubocop/cop/style/guard_clause.rb, line 236 def autocorrect_heredoc_argument(corrector, node, heredoc_branch, leave_branch, guard) remove_whole_lines(corrector, node.loc.end) return unless node.else? remove_whole_lines(corrector, leave_branch.source_range) remove_whole_lines(corrector, node.loc.else) remove_whole_lines(corrector, range_of_branch_to_remove(node, guard)) corrector.insert_after( heredoc_branch.last_argument.loc.heredoc_end, "\n#{leave_branch.source}" ) end
check_ending_body(body)
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# File lib/rubocop/cop/style/guard_clause.rb, line 159 def check_ending_body(body) return if body.nil? if body.if_type? check_ending_if(body) elsif body.begin_type? final_expression = body.children.last check_ending_if(final_expression) if final_expression&.if_type? end end
check_ending_if(node)
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# File lib/rubocop/cop/style/guard_clause.rb, line 170 def check_ending_if(node) return if accepted_form?(node, ending: true) || !min_body_length?(node) return if allowed_consecutive_conditionals? && consecutive_conditionals?(node.parent, node) register_offense(node, 'return', node.inverse_keyword) check_ending_body(node.if_branch) end
consecutive_conditionals?(parent, node)
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# File lib/rubocop/cop/style/guard_clause.rb, line 180 def consecutive_conditionals?(parent, node) parent.each_child_node.inject(false) do |if_type, child| break if_type if node == child child.if_type? end end
guard_clause_source(guard_clause)
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# File lib/rubocop/cop/style/guard_clause.rb, line 257 def guard_clause_source(guard_clause) if and_or_guard_clause?(guard_clause) guard_clause.parent.source else guard_clause.source end end
heredoc?(argument)
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rubocop:enable Metrics/AbcSize, Metrics/CyclomaticComplexity, Metrics/PerceivedComplexity
# File lib/rubocop/cop/style/guard_clause.rb, line 232 def heredoc?(argument) argument.respond_to?(:heredoc?) && argument.heredoc? end
range_of_branch_to_remove(node, guard)
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# File lib/rubocop/cop/style/guard_clause.rb, line 248 def range_of_branch_to_remove(node, guard) branch = case guard when :if then node.if_branch when :else then node.else_branch end branch.source_range end
register_offense(node, scope_exiting_keyword, conditional_keyword, guard = nil)
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# File lib/rubocop/cop/style/guard_clause.rb, line 188 def register_offense(node, scope_exiting_keyword, conditional_keyword, guard = nil) condition, = node.node_parts example = [scope_exiting_keyword, conditional_keyword, condition.source].join(' ') if too_long_for_single_line?(node, example) return if trivial?(node) example = "#{conditional_keyword} #{condition.source}; #{scope_exiting_keyword}; end" replacement = <<~RUBY.chomp #{conditional_keyword} #{condition.source} #{scope_exiting_keyword} end RUBY end add_offense(node.loc.keyword, message: format(MSG, example: example)) do |corrector| next if node.else? && guard.nil? autocorrect(corrector, node, condition, replacement || example, guard) end end
remove_whole_lines(corrector, range)
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# File lib/rubocop/cop/style/guard_clause.rb, line 308 def remove_whole_lines(corrector, range) corrector.remove(range_by_whole_lines(range, include_final_newline: true)) end
too_long_for_single_line?(node, example)
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# File lib/rubocop/cop/style/guard_clause.rb, line 270 def too_long_for_single_line?(node, example) max = max_line_length max && node.source_range.column + example.length > max end
trivial?(node)
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# File lib/rubocop/cop/style/guard_clause.rb, line 279 def trivial?(node) return false unless node.if_branch node.branches.one? && !node.if_branch.if_type? && !node.if_branch.begin_type? end