class RuboCop::Cop::Performance::RedundantMerge

hash = 2<br>hash = 1
# good
hash.merge!(a: 1, b: 2)
# bad
@example MaxKeyValuePairs: 2 (default)<br><br>hash = ‘value’<br>hash = 1
# good
hash.merge!({‘key’ => ‘value’})
hash.merge!(a: 1)
# bad
@example
receiver of ‘merge!` is actually a hash or not.
This cop is unsafe because RuboCop cannot determine if the
@safety
an offense with `MaxKeyValuePairs`.
You can set the maximum number of key-value pairs to consider
Identifies places where `Hash#merge!` can be replaced by `Hash#[]=`.

def correct_multiple_elements(corrector, node, parent, new_source) 

def correct_multiple_elements(corrector, node, parent, new_source)
  if modifier_flow_control?(parent)
    new_source = rewrite_with_modifier(node, parent, new_source)
    node = parent
  else
    padding = "\n#{leading_spaces(node)}"
    new_source.gsub!("\n", padding)
  end
  corrector.replace(node, new_source)
end

def correct_single_element(corrector, node, new_source) 

def correct_single_element(corrector, node, new_source)
  corrector.replace(node, new_source)
end

def each_redundant_merge(node) 

def each_redundant_merge(node)
  redundant_merge_candidate(node) do |receiver, pairs|
    next if non_redundant_merge?(node, receiver, pairs)
    yield node
  end
end

def kwsplat_used?(pairs) 

def kwsplat_used?(pairs)
  pairs.any?(&:kwsplat_type?)
end

def leading_spaces(node) 

def leading_spaces(node)
  node.source_range.source_line[/\A\s*/]
end

def max_key_value_pairs 

def max_key_value_pairs
  Integer(cop_config['MaxKeyValuePairs'] || 2)
end

def message(node) 

def message(node)
  redundant_merge_candidate(node) do |receiver, pairs|
    assignments = to_assignments(receiver, pairs).join('; ')
    format(MSG, prefer: assignments, current: node.source)
  end
end

def non_redundant_merge?(node, receiver, pairs) 

def non_redundant_merge?(node, receiver, pairs)
  pairs.empty? ||
    non_redundant_pairs?(receiver, pairs) ||
    kwsplat_used?(pairs) ||
    non_redundant_value_used?(receiver, node)
end

def non_redundant_pairs?(receiver, pairs) 

def non_redundant_pairs?(receiver, pairs)
  (pairs.size > 1 && !receiver.pure?) || pairs.size > max_key_value_pairs
end

def non_redundant_value_used?(receiver, node) 

def non_redundant_value_used?(receiver, node)
  node.value_used? && !EachWithObjectInspector.new(node, receiver).value_used?
end

def on_send(node) 

def on_send(node)
  each_redundant_merge(node) do |redundant_merge_node|
    message = message(node)
    add_offense(redundant_merge_node, message: message) do |corrector|
      redundant_merge_candidate(node) do |receiver, pairs|
        new_source = to_assignments(receiver, pairs).join("\n")
        if node.parent && pairs.size > 1
          correct_multiple_elements(corrector, node, node.parent, new_source)
        else
          correct_single_element(corrector, node, new_source)
        end
      end
    end
  end
end

def rewrite_with_modifier(node, parent, new_source) 

def rewrite_with_modifier(node, parent, new_source)
  indent = ' ' * configured_indentation_width
  padding = "\n#{indent + leading_spaces(node)}"
  new_source.gsub!("\n", padding)
  format(WITH_MODIFIER_CORRECTION, keyword: parent.loc.keyword.source,
                                   condition: parent.condition.source,
                                   leading_space: leading_spaces(node),
                                   indent: indent,
                                   body: new_source).chomp
end

def to_assignments(receiver, pairs) 

def to_assignments(receiver, pairs)
  pairs.map do |pair|
    key, value = *pair
    key = key.sym_type? && pair.colon? ? ":#{key.source}" : key.source
    format(AREF_ASGN, receiver: receiver.source, key: key, value: value.source)
  end
end