`class Nested`

Represents nested sub-commands in a command.

A Nested parser allows you to define multiple sub-commands that can be invoked from the parent command.

Definitions

`def initialize(key, commands, default: nil, required: false)`

Initialize a new nested command parser.

Signature

parameter　key　Symbol: The name of the attribute to store the selected command in.
parameter　commands　Hash: A mapping of command names to command classes.
parameter　default　String | Nil: The default command name if none is provided.
parameter　required　Boolean: Whether a command is required.

Implementation

def initialize(key, commands, default: nil, required: false)
	@key = key
	@commands = commands
	
	# This is the default name [of a command], not the default command:
	@default = default
	
	@required = required
end

`attr :key`

The name of the attribute to store the selected command in.

Signature

attribute　Symbol

`attr :commands`

A mapping of command names to command classes.

Signature

attribute　Hash

`attr :default`

The default command name if none is provided.

Signature

attribute　String | Nil

`attr :required`

Whether a command is required.

Signature

attribute　Boolean

`def to_s`

Generate a string representation for usage output.

Signature

returns　String: The usage string.

Implementation

def to_s
	"<#{@key}>"
end

`def to_a`

Generate an array representation for usage output.

Signature

returns　Array: The usage array.

Implementation

def to_a
	usage = [self.to_s]
	
	if @commands.size == 0
		usage << "No commands available."
	elsif @commands.size == 1
		usage << "Only #{@commands.first}."
	else
		usage << "One of: #{@commands.keys.join(', ')}."
	end
	
	if @default
		usage << "(default: #{@default})"
	elsif @required
		usage << "(required)"
	end
	
	return usage
end

`def parse(input, parent = nil, default = nil)`

Parse a nested command from the input.

Signature

parameter　input　Array(String): The command-line arguments.
parameter　parent　Command | Nil: The parent command.
parameter　default　Command | Nil: The default command instance.
returns　Command | Object | Nil: The parsed command instance, or the default if no match.

Implementation

def parse(input, parent = nil, default = nil)
	if command = @commands[input.first]
		name = input.shift
		
		# puts "Instantiating #{command} with #{input}"
		command.new(input, name: name, parent: parent)
	elsif default
		return default
	elsif @default
		@commands[@default].new(input, name: @default, parent: parent)
	elsif @required
		raise MissingValueError.new(parent, @key)
	end
end

`def usage(rows)`

Generate usage information for this nested command.

Signature

parameter　rows　Output::Rows: The rows to append usage information to.

Implementation

def usage(rows)
	rows << self
	
	@commands.each do |key, klass|
		klass.usage(rows, key)
	end
end