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Contents
# frozen_string_literal: true
module RuboCop
module Cop
module Lint
# Checks for self-assignments.
#
# @example
# # bad
# foo = foo
# foo, bar = foo, bar
# Foo = Foo
#
# # good
# foo = bar
# foo, bar = bar, foo
# Foo = Bar
#
class SelfAssignment < Base
MSG = 'Self-assignment detected.'
ASSIGNMENT_TYPE_TO_RHS_TYPE = {
lvasgn: :lvar,
ivasgn: :ivar,
cvasgn: :cvar,
gvasgn: :gvar
}.freeze
def on_lvasgn(node)
lhs, rhs = *node
return unless rhs
rhs_type = ASSIGNMENT_TYPE_TO_RHS_TYPE[node.type]
add_offense(node) if rhs.type == rhs_type && rhs.source == lhs.to_s
end
alias on_ivasgn on_lvasgn
alias on_cvasgn on_lvasgn
alias on_gvasgn on_lvasgn
def on_casgn(node)
lhs_scope, lhs_name, rhs = *node
return unless rhs&.const_type?
rhs_scope, rhs_name = *rhs
add_offense(node) if lhs_scope == rhs_scope && lhs_name == rhs_name
end
def on_masgn(node)
add_offense(node) if multiple_self_assignment?(node)
end
def on_or_asgn(node)
lhs, rhs = *node
add_offense(node) if rhs_matches_lhs?(rhs, lhs)
end
alias on_and_asgn on_or_asgn
private
def multiple_self_assignment?(node)
lhs, rhs = *node
return false unless rhs.array_type?
return false unless lhs.children.size == rhs.children.size
lhs.children.zip(rhs.children).all? do |lhs_item, rhs_item|
rhs_matches_lhs?(rhs_item, lhs_item)
end
end
def rhs_matches_lhs?(rhs, lhs)
rhs.type == ASSIGNMENT_TYPE_TO_RHS_TYPE[lhs.type] &&
rhs.children.first == lhs.children.first
end
end
end
end
end
Version data entries
153 entries across 146 versions & 13 rubygems