This file is indexed.

/usr/lib/ruby/2.5.0/psych/handler.rb is in libruby2.5 2.5.1-1ubuntu1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
# frozen_string_literal: true
module Psych
  ###
  # Psych::Handler is an abstract base class that defines the events used
  # when dealing with Psych::Parser.  Clients who want to use Psych::Parser
  # should implement a class that inherits from Psych::Handler and define
  # events that they can handle.
  #
  # Psych::Handler defines all events that Psych::Parser can possibly send to
  # event handlers.
  #
  # See Psych::Parser for more details
  class Handler
    ###
    # Configuration options for dumping YAML.
    class DumperOptions
      attr_accessor :line_width, :indentation, :canonical

      def initialize
        @line_width  = 0
        @indentation = 2
        @canonical   = false
      end
    end

    # Default dumping options
    OPTIONS = DumperOptions.new

    # Events that a Handler should respond to.
    EVENTS = [ :alias,
               :empty,
               :end_document,
               :end_mapping,
               :end_sequence,
               :end_stream,
               :scalar,
               :start_document,
               :start_mapping,
               :start_sequence,
               :start_stream ]

    ###
    # Called with +encoding+ when the YAML stream starts.  This method is
    # called once per stream.  A stream may contain multiple documents.
    #
    # See the constants in Psych::Parser for the possible values of +encoding+.
    def start_stream encoding
    end

    ###
    # Called when the document starts with the declared +version+,
    # +tag_directives+, if the document is +implicit+.
    #
    # +version+ will be an array of integers indicating the YAML version being
    # dealt with, +tag_directives+ is a list of tuples indicating the prefix
    # and suffix of each tag, and +implicit+ is a boolean indicating whether
    # the document is started implicitly.
    #
    # === Example
    #
    # Given the following YAML:
    #
    #   %YAML 1.1
    #   %TAG ! tag:tenderlovemaking.com,2009:
    #   --- !squee
    #
    # The parameters for start_document must be this:
    #
    #   version         # => [1, 1]
    #   tag_directives  # => [["!", "tag:tenderlovemaking.com,2009:"]]
    #   implicit        # => false
    def start_document version, tag_directives, implicit
    end

    ###
    # Called with the document ends.  +implicit+ is a boolean value indicating
    # whether or not the document has an implicit ending.
    #
    # === Example
    #
    # Given the following YAML:
    #
    #   ---
    #     hello world
    #
    # +implicit+ will be true.  Given this YAML:
    #
    #   ---
    #     hello world
    #   ...
    #
    # +implicit+ will be false.
    def end_document implicit
    end

    ###
    # Called when an alias is found to +anchor+.  +anchor+ will be the name
    # of the anchor found.
    #
    # === Example
    #
    # Here we have an example of an array that references itself in YAML:
    #
    #   --- &ponies
    #   - first element
    #   - *ponies
    #
    # &ponies is the achor, *ponies is the alias.  In this case, alias is
    # called with "ponies".
    def alias anchor
    end

    ###
    # Called when a scalar +value+ is found.  The scalar may have an
    # +anchor+, a +tag+, be implicitly +plain+ or implicitly +quoted+
    #
    # +value+ is the string value of the scalar
    # +anchor+ is an associated anchor or nil
    # +tag+ is an associated tag or nil
    # +plain+ is a boolean value
    # +quoted+ is a boolean value
    # +style+ is an integer idicating the string style
    #
    # See the constants in Psych::Nodes::Scalar for the possible values of
    # +style+
    #
    # === Example
    #
    # Here is a YAML document that exercises most of the possible ways this
    # method can be called:
    #
    #   ---
    #   - !str "foo"
    #   - &anchor fun
    #   - many
    #     lines
    #   - |
    #     many
    #     newlines
    #
    # The above YAML document contains a list with four strings.  Here are
    # the parameters sent to this method in the same order:
    #
    #   # value               anchor    tag     plain   quoted  style
    #   ["foo",               nil,      "!str", false,  false,  3    ]
    #   ["fun",               "anchor", nil,    true,   false,  1    ]
    #   ["many lines",        nil,      nil,    true,   false,  1    ]
    #   ["many\nnewlines\n",  nil,      nil,    false,  true,   4    ]
    #
    def scalar value, anchor, tag, plain, quoted, style
    end

    ###
    # Called when a sequence is started.
    #
    # +anchor+ is the anchor associated with the sequence or nil.
    # +tag+ is the tag associated with the sequence or nil.
    # +implicit+ a boolean indicating whether or not the sequence was implicitly
    # started.
    # +style+ is an integer indicating the list style.
    #
    # See the constants in Psych::Nodes::Sequence for the possible values of
    # +style+.
    #
    # === Example
    #
    # Here is a YAML document that exercises most of the possible ways this
    # method can be called:
    #
    #   ---
    #   - !!seq [
    #     a
    #   ]
    #   - &pewpew
    #     - b
    #
    # The above YAML document consists of three lists, an outer list that
    # contains two inner lists.  Here is a matrix of the parameters sent
    # to represent these lists:
    #
    #   # anchor    tag                       implicit  style
    #   [nil,       nil,                      true,     1     ]
    #   [nil,       "tag:yaml.org,2002:seq",  false,    2     ]
    #   ["pewpew",  nil,                      true,     1     ]

    def start_sequence anchor, tag, implicit, style
    end

    ###
    # Called when a sequence ends.
    def end_sequence
    end

    ###
    # Called when a map starts.
    #
    # +anchor+ is the anchor associated with the map or +nil+.
    # +tag+ is the tag associated with the map or +nil+.
    # +implicit+ is a boolean indicating whether or not the map was implicitly
    # started.
    # +style+ is an integer indicating the mapping style.
    #
    # See the constants in Psych::Nodes::Mapping for the possible values of
    # +style+.
    #
    # === Example
    #
    # Here is a YAML document that exercises most of the possible ways this
    # method can be called:
    #
    #   ---
    #   k: !!map { hello: world }
    #   v: &pewpew
    #     hello: world
    #
    # The above YAML document consists of three maps, an outer map that contains
    # two inner maps.  Below is a matrix of the parameters sent in order to
    # represent these three maps:
    #
    #   # anchor    tag                       implicit  style
    #   [nil,       nil,                      true,     1     ]
    #   [nil,       "tag:yaml.org,2002:map",  false,    2     ]
    #   ["pewpew",  nil,                      true,     1     ]

    def start_mapping anchor, tag, implicit, style
    end

    ###
    # Called when a map ends
    def end_mapping
    end

    ###
    # Called when an empty event happens. (Which, as far as I can tell, is
    # never).
    def empty
    end

    ###
    # Called when the YAML stream ends
    def end_stream
    end

    ###
    # Called before each event with line/column information.
    def event_location(start_line, start_column, end_line, end_column)
    end

    ###
    # Is this handler a streaming handler?
    def streaming?
      false
    end
  end
end