ErrorHighlight::Spotter#spot

# File tmp/rubies/ruby-4.1.0-preview1/lib/error_highlight/base.rb, line 147
def spot
  return nil unless @node

  # In Ruby 3.2 or later, a nested constant access (like `Foo::Bar::Baz`)
  # is compiled to one instruction (opt_getconstant_path).
  # @node points to the node of the whole `Foo::Bar::Baz` even if `Foo`
  # or `Foo::Bar` causes NameError.
  # So we try to spot the sub-node that causes the NameError by using
  # `NameError#name`.
  case @node.type
  when :COLON2
    subnodes = []
    node = @node
    while node.type == :COLON2
      node2, const = node.children
      subnodes << node if const == @name
      node = node2
    end
    if node.type == :CONST || node.type == :COLON3
      if node.children.first == @name
        subnodes << node
      end

      # If we found only one sub-node whose name is equal to @name, use it
      return nil if subnodes.size != 1
      @node = subnodes.first
    else
      # Do nothing; opt_getconstant_path is used only when the const base is
      # NODE_CONST (`Foo`) or NODE_COLON3 (`::Foo`)
    end
  when :constant_path_node
    subnodes = []
    node = @node

    begin
      subnodes << node if node.name == @name
    end while (node = node.parent)&.type == :constant_path_node

    if node&.type == :constant_read_node && node.name == @name
      subnodes << node
    end

    # If we found only one sub-node whose name is equal to @name, use it
    return nil if subnodes.size != 1
    @node = subnodes.first
  end

  case @node.type

  when :CALL, :QCALL
    case @point_type
    when :name
      spot_call_for_name
    when :args
      spot_call_for_args
    end

  when :ATTRASGN
    case @point_type
    when :name
      spot_attrasgn_for_name
    when :args
      spot_attrasgn_for_args
    end

  when :OPCALL
    case @point_type
    when :name
      spot_opcall_for_name
    when :args
      spot_opcall_for_args
    end

  when :FCALL
    case @point_type
    when :name
      spot_fcall_for_name
    when :args
      spot_fcall_for_args
    end

  when :VCALL
    spot_vcall

  when :OP_ASGN1
    case @point_type
    when :name
      spot_op_asgn1_for_name
    when :args
      spot_op_asgn1_for_args
    end

  when :OP_ASGN2
    case @point_type
    when :name
      spot_op_asgn2_for_name
    when :args
      spot_op_asgn2_for_args
    end

  when :CONST
    spot_vcall

  when :COLON2
    spot_colon2

  when :COLON3
    spot_vcall

  when :OP_CDECL
    spot_op_cdecl

  when :DEFN
    # There is nothing to highlight for the arguments of a method
    # definition, so just return nil instead of raising.
    return nil if @point_type != :name
    spot_defn

  when :DEFS
    return nil if @point_type != :name
    spot_defs

  when :LAMBDA
    return nil if @point_type != :name
    spot_lambda

  when :ITER
    return nil if @point_type != :name
    spot_iter

  when :call_node
    case @point_type
    when :name
      prism_spot_call_for_name
    when :args
      prism_spot_call_for_args
    end

  when :local_variable_operator_write_node
    case @point_type
    when :name
      prism_spot_local_variable_operator_write_for_name
    when :args
      prism_spot_local_variable_operator_write_for_args
    end

  when :call_operator_write_node
    case @point_type
    when :name
      prism_spot_call_operator_write_for_name
    when :args
      prism_spot_call_operator_write_for_args
    end

  when :index_operator_write_node
    case @point_type
    when :name
      prism_spot_index_operator_write_for_name
    when :args
      prism_spot_index_operator_write_for_args
    end

  when :constant_read_node
    prism_spot_constant_read

  when :constant_path_node
    prism_spot_constant_path

  when :constant_path_operator_write_node
    prism_spot_constant_path_operator_write

  when :def_node
    case @point_type
    when :name
      prism_spot_def_for_name
    when :args
      # There is nothing to highlight for the arguments of a method
      # definition (e.g. an ArgumentError for a missing required keyword
      # is spotted with point_type: :args). Return nil instead of raising
      # NotImplementedError, which would otherwise escape
      # Exception#detailed_message / #full_message.
      return nil
    end

  when :lambda_node
    case @point_type
    when :name
      prism_spot_lambda_for_name
    when :args
      # See the comment for :def_node above.
      return nil
    end

  when :block_node
    case @point_type
    when :name
      prism_spot_block_for_name
    when :args
      # See the comment for :def_node above.
      return nil
    end

  end

  if @snippet && @beg_column && @end_column && @beg_column < @end_column
    return {
      first_lineno: @beg_lineno,
      first_column: @beg_column,
      last_lineno: @end_lineno,
      last_column: @end_column,
      snippet: @snippet,
      script_lines: @node.script_lines,
    }
  else
    return nil
  end

rescue NonAscii
  nil
end