251 lines
7.2 KiB
Crystal
251 lines
7.2 KiB
Crystal
module Ameba::Rule::Style
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# This rule is used to identify usage of single expression blocks with
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# argument as a receiver, that can be collapsed into a short form.
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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..3).any? { |i| i.odd? }
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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..3).any?(&.odd?)
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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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# Style/VerboseBlock:
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# Enabled: true
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# ExcludeMultipleLineBlocks: true
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# ExcludeCallsWithBlock: true
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# ExcludePrefixOperators: true
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# ExcludeOperators: true
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# ExcludeSetters: false
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# MaxLineLength: ~
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# MaxLength: 50 # use ~ to disable
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# ```
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class VerboseBlock < Base
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include AST::Util
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properties do
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description "Identifies usage of collapsible single expression blocks"
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exclude_multiple_line_blocks true
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exclude_calls_with_block true
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exclude_prefix_operators true
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exclude_operators true
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exclude_setters false
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max_line_length : Int32? = nil # 100
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max_length : Int32? = 50
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end
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MSG = "Use short block notation instead: `%s`"
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CALL_PATTERN = "%s(%s&.%s)"
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protected def same_location_lines?(a, b)
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return unless a_location = name_location(a)
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return unless b_location = b.location
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a_location.line_number == b_location.line_number
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end
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private PREFIX_OPERATORS = {"+", "-", "~"}
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private OPERATOR_CHARS =
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{'[', ']', '!', '=', '>', '<', '~', '+', '-', '*', '/', '%', '^', '|', '&'}
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protected def prefix_operator?(node)
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node.name.in?(PREFIX_OPERATORS) && node.args.empty?
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end
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protected def operator?(name)
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!name.empty? && name[0].in?(OPERATOR_CHARS)
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end
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protected def setter?(name)
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!name.empty? && name[0].letter? && name.ends_with?('=')
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end
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protected def valid_length?(code)
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if max_length = self.max_length
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return code.size <= max_length
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end
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true
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end
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protected def valid_line_length?(node, code)
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if max_line_length = self.max_line_length
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if location = name_location(node)
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final_line_length = location.column_number + code.size
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return final_line_length <= max_line_length
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end
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end
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true
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end
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protected def reference_count(node, obj : Crystal::Var)
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i = 0
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case node
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when Crystal::Call
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i += reference_count(node.obj, obj)
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i += reference_count(node.block, obj)
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node.args.each do |arg|
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i += reference_count(arg, obj)
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end
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node.named_args.try &.each do |arg|
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i += reference_count(arg.value, obj)
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end
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when Crystal::BinaryOp
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i += reference_count(node.left, obj)
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i += reference_count(node.right, obj)
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when Crystal::Block
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i += reference_count(node.body, obj)
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when Crystal::Var
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i += 1 if node == obj
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end
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i
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end
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protected def args_to_s(io : IO, node : Crystal::Call, short_block = nil, skip_last_arg = false)
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node.args.dup.tap do |args|
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args.pop? if skip_last_arg
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args.join io, ", "
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named_args = node.named_args
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if named_args
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io << ", " unless args.empty? || named_args.empty?
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named_args.join io, ", " do |arg, inner_io|
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inner_io << arg.name << ": " << arg.value
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end
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end
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if short_block
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io << ", " unless args.empty? && (named_args.nil? || named_args.empty?)
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io << short_block
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end
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end
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end
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protected def node_to_s(source, node : Crystal::Call)
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String.build do |str|
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case name = node.name
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when "[]"
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str << '['
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args_to_s(str, node)
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str << ']'
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when "[]?"
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str << '['
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args_to_s(str, node)
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str << "]?"
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when "[]="
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str << '['
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args_to_s(str, node, skip_last_arg: true)
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str << "]=(" << node.args.last? << ')'
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else
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short_block = short_block_code(source, node)
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str << name
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if !node.args.empty? || (node.named_args && !node.named_args.try(&.empty?)) || short_block
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str << '('
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args_to_s(str, node, short_block)
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str << ')'
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end
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str << " {...}" if node.block && short_block.nil?
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end
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end
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end
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protected def short_block_code(source, node : Crystal::Call)
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return unless block = node.block
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return unless block_location = block.location
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return unless block_end_location = block.body.end_location
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block_code = source_between(block_location, block_end_location, source.lines)
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return unless block_code.try(&.starts_with?("&."))
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block_code
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end
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protected def call_code(source, call, body)
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args = String.build { |io| args_to_s(io, call) }.presence
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args += ", " if args
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call_chain = %w[].tap do |arr|
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obj = body.obj
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while obj.is_a?(Crystal::Call)
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arr << node_to_s(source, obj)
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obj = obj.obj
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end
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arr.reverse!
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arr << node_to_s(source, body)
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end
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name =
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call_chain.join('.')
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CALL_PATTERN % {call.name, args, name}
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end
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# ameba:disable Metrics/CyclomaticComplexity
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protected def issue_for_valid(source, call : Crystal::Call, block : Crystal::Block, body : Crystal::Call)
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return if exclude_calls_with_block? && body.block
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return if exclude_multiple_line_blocks? && !same_location_lines?(call, body)
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return if exclude_prefix_operators? && prefix_operator?(body)
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return if exclude_operators? && operator?(body.name)
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return if exclude_setters? && setter?(body.name)
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call_code =
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call_code(source, call, body)
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return unless valid_line_length?(call, call_code)
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return unless valid_length?(call_code)
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return unless location = name_location(call)
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return unless end_location = block.end_location
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if call_code.includes?("{...}")
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issue_for location, end_location, MSG % call_code
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else
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issue_for location, end_location, MSG % call_code do |corrector|
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corrector.replace(location, end_location, call_code)
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end
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end
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end
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def test(source, node : Crystal::Call)
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# we are interested only in calls with block taking a single argument
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#
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# ```
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# (1..3).any? { |i| i.to_i64.odd? }
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# ^--- ^ ^------------
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# block arg body
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# ```
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return unless (block = node.block) && block.args.size == 1
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arg = block.args.first
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# we filter out the blocks that are of call type - `i.to_i64.odd?`
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return unless (body = block.body).is_a?(Crystal::Call)
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# we need to "unwind" the chain calls, so the final receiver object
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# ends up being a variable - `i`
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obj = body.obj
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while obj.is_a?(Crystal::Call)
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obj = obj.obj
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end
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# only calls with a first argument used as a receiver are the valid game
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return unless obj == arg
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# we bail out if the block node include the block argument
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return if reference_count(body, arg) > 1
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# add issue if the given nodes pass all of the checks
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issue_for_valid source, node, block, body
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end
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end
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end
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