pronounced jasopts

jsopts.rb

require 'json'

class Cell < Struct.new(:item); end

class Args
  attr_reader :pos, :top
  def initialize()
    @pos = []
    @top = {}
    @stack = [Cell.new(@top)]
  end

  def current_hash()
    c = @stack.last
    return c.item if c.item.is_a?(Hash)
    return c.item = {} if c.item == nil
    if c.item.is_a?(Array)
      h = Cell.new({})
      c.item << h
      @stack.push h
      return h.item
    end
    raise "stack top is weird"
  end

  def current_array()
    c = @stack.last
    return c.item if c.item.is_a?(Array)
    return c.item = [] if c.item == nil
    @pos
  end

  def parse(arg)
    if @stack.empty?
      @pos << arg
      return
    end

    if arg == '--'
      @stack = []
      return
    end

    if m = arg.match(/^-(\/+)$/)
      m[1].length.times do
        @stack.pop
      end
      return
    end

    if m = arg.match(/^-(,+)$/)
      m[1].length.times do
        if @stack.last.item == nil
          @stack.last.item = []
        else
          v = Cell.new([])
          current_array << v
          @stack << v
        end
      end
      return
    end

    if m = arg.match(/^-\/(.*)$/)
      literal(JSON.load(m[1]))
      return
    end

    if m = arg.match(/^--([^:=]+):$/)
      v = Cell.new(nil)
      current_hash[m[1]] = v
      @stack << v
      return
    end

    if m = arg.match(/^--([^=]+)(?:=(.*))?$/)
      current_hash[m[1]] = m[2] || true
      return
    end

    current_array << arg
  end

  def literal(v)
    if @stack.last.item == nil
      @stack.pop.item = cell(v)
    else
      current_array << cell(v)
    end
    return
  end
end

def uncell(v)
  if v.is_a?(Hash)
    v.transform_values { |i| uncell(i) }
  elsif v.is_a?(Array)
    v.map { |i| uncell(i) }
  elsif v.is_a?(Cell)
    uncell(v.item)
  else
    v
  end
end

def cell(v)
  if v.is_a?(Hash)
    v.transform_values { |i| cell(i) }
  elsif v.is_a?(Array)
    v.map { |i| cell(i) }
  elsif v.is_a?(Cell)
    v
  else
    Cell.new(v)
  end
end

args = Args.new
ARGV.each do |v| args.parse(v) end
puts JSON.dump(uncell(args.top))
puts JSON.dump(uncell(args.pos))

$ ruby jsopts.rb leading positional args --toplevel=value --nested: --inner=value -/ --toplevel2=value --some-array: 1 2 3 4 --object-in-array -// --nested-array: -,,,, lol -//// --explicit-null: -/null --a-number: -/42 -- trailing positional args | jq .
{
  "toplevel": "value",
  "nested": {
    "inner": "value"
  },
  "toplevel2": "value",
  "some-array": [
    "1",
    "2",
    "3",
    "4",
    {
      "object-in-array": true
    }
  ],
  "nested-array": [
    [
      [
        [
          "lol"
        ]
      ]
    ]
  ],
  "explicit-null": null,
  "a-number": 42
}
[
  "leading",
  "positional",
  "args",
  "trailing",
  "positional",
  "args"
]