Class: Samovar::One

Inherits:
Object
  • Object
show all
Defined in:
lib/samovar/one.rb

Overview

Represents a single positional argument in a command.

A ‘One` parser extracts exactly one argument from the command line that matches the specified pattern.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(key, description, pattern: //, default: nil, required: false) ⇒ One

Initialize a new positional argument parser.



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# File 'lib/samovar/one.rb', line 18

def initialize(key, description, pattern: //, default: nil, required: false)
	@key = key
	@description = description
	@pattern = pattern
	@default = default
	@required = required
end

Instance Attribute Details

#default ⇒ Object

The default value if no argument is provided.



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# File 'lib/samovar/one.rb', line 44

def default
  @default
end

#description ⇒ Object (readonly)

A description of the argument for help output.



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# File 'lib/samovar/one.rb', line 34

def description
  @description
end

#key ⇒ Object

The name of the attribute to store the value in.



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# File 'lib/samovar/one.rb', line 29

def key
  @key
end

#pattern ⇒ Object

A pattern to match valid values.



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# File 'lib/samovar/one.rb', line 39

def pattern
  @pattern
end

#required ⇒ Object

Whether the argument is required.



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# File 'lib/samovar/one.rb', line 49

def required
  @required
end

Instance Method Details

#parse(input, parent = nil, default = nil) ⇒ Object

Parse a single argument from the input.



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# File 'lib/samovar/one.rb', line 79

def parse(input, parent = nil, default = nil)
	if input.first =~ @pattern
		input.shift
	elsif default ||= @default
		return default
	elsif @required
		raise MissingValueError.new(parent, @key)
	end
end

#to_a ⇒ Object

Generate an array representation for usage output.



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# File 'lib/samovar/one.rb', line 61

def to_a
	usage = [to_s, @description]
	
	if @default
		usage << "(default: #{@default.inspect})"
	elsif @required
		usage << "(required)"
	end
	
	return usage
end

#to_s ⇒ Object

Generate a string representation for usage output.



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# File 'lib/samovar/one.rb', line 54

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