summaryrefslogtreecommitdiff
path: root/lib/slop/parser.rb
blob: 00b7e3330dfc50b9eb6b66d184ccab4d5294a4d9 (plain)
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
module Slop
  class Parser

    # Our Options instance.
    attr_reader :options

    # A Hash of configuration options.
    attr_reader :config

    # Returns an Array of String arguments that were not parsed.
    attr_reader :arguments

    def initialize(options, **config)
      @options = options
      @config  = config
      reset
    end

    # Reset the parser, useful to use the same instance to parse a second
    # time without duplicating state.
    def reset
      @arguments = []
      @options.each(&:reset)
      self
    end

    # Traverse `strings` and process options one by one. Anything after
    # `--` is ignored. If a flag includes a equals (=) it will be split
    # so that `flag, argument = s.split('=')`.
    #
    # The `call` method will be executed immediately for each option found.
    # Once all options have been executed, any found options will have
    # the `finish` method called on them.
    #
    # Returns a Slop::Result.
    def parse(strings)
      reset # reset before every parse

      # ignore everything after "--"
      strings, ignored_args = partition(strings)

      pairs = strings.each_cons(2).to_a
      # this ensures we still support the last string being a flag,
      # otherwise it'll only be used as an argument.
      pairs << [strings.last, nil]

      @arguments = strings.dup

      pairs.each_with_index do |pair, idx|
        flag, arg = pair
        break if !flag

        # support `foo=bar`
        orig_flag = flag.dup
        if match = flag.match(/([^=]+)=([^=]+)/)
          flag, arg = match.captures
        end

        if opt = try_process(flag, arg)
          # since the option was parsed, we remove it from our
          # arguments (plus the arg if necessary)
          # delete argument first while we can find its index.
          if opt.expects_argument?

            # if we consumed the argument, remove the next pair
            if consume_next_argument?(orig_flag)
              pairs.delete_at(idx + 1)
            end

            arguments.each_with_index do |argument, i|
              if argument == orig_flag && !orig_flag.include?("=")
                arguments.delete_at(i + 1)
              end
            end
          end
          arguments.delete(orig_flag)
        end
      end

      @arguments += ignored_args

      if !suppress_errors?
        unused_options.each do |o|
          if o.config[:required]
            pretty_flags = o.flags.map { |f| "`#{f}'" }.join(", ")
            raise MissingRequiredOption, "missing required option #{pretty_flags}"
          end
        end
      end

      Result.new(self).tap do |result|
        used_options.each { |o| o.finish(result) }
      end
    end

    # Returns an Array of Option instances that were used.
    def used_options
      options.select { |o| o.count > 0 }
    end

    # Returns an Array of Option instances that were not used.
    def unused_options
      options.to_a - used_options
    end

    private

    def consume_next_argument?(flag)
      return false if flag.include?("=")
      return true if flag.start_with?("--")
      return true if /\A-[a-zA-Z]\z/ === flag
      false
    end

    # We've found an option, process and return it
    def process(option, arg)
      option.ensure_call(arg)
      option
    end

    # Try and find an option to process
    def try_process(flag, arg)
      if option = matching_option(flag)
        process(option, arg)
      elsif flag.start_with?("--no-") && option = matching_option(flag.sub("no-", ""))
        process(option, false)
      elsif flag =~ /\A-[^-]{2,}/
        try_process_smashed_arg(flag) || try_process_grouped_flags(flag, arg)
      else
        if flag.start_with?("-") && !suppress_errors?
          raise UnknownOption.new("unknown option `#{flag}'", "#{flag}")
        end
      end
    end

    # try and process a flag with a "smashed" argument, e.g.
    # -nFoo or -i5
    def try_process_smashed_arg(flag)
      option = matching_option(flag[0, 2])
      if option && option.expects_argument?
        process(option, flag[2..-1])
      end
    end

    # try and process as a set of grouped short flags. drop(1) removes
    # the prefixed -, then we add them back to each flag separately.
    def try_process_grouped_flags(flag, arg)
      flags = flag.split("").drop(1).map { |f| "-#{f}" }
      last  = flags.pop

      flags.each { |f| try_process(f, nil) }
      try_process(last, arg) # send the argument to the last flag
    end

    def suppress_errors?
      config[:suppress_errors]
    end

    def matching_option(flag)
      options.find { |o| o.flags.include?(flag) }
    end

    def partition(strings)
      if strings.include?("--")
        partition_idx = strings.index("--")
        return [[], strings[1..-1]] if partition_idx.zero?
        [strings[0..partition_idx-1], strings[partition_idx+1..-1]]
      else
        [strings, []]
      end
    end
  end
end