Class: Typisch::Type::String

Inherits:
Constructor show all
Defined in:
lib/typisch/string.rb

Overview

String types support refinement types, specifying a set of allowed values, or a maximum length.

About ruby Symbols: these are a pain in the arse. For now I’m allowing them to type-check interchangably with Strings. Since Typisch isn’t specifically designed for Ruby’s quirks but for more general data interchange, I don’t think Symbol should have a special priviledged type of its own.

Nevertheless if we ever allow custom type tags on String types (as we do for Object types at the moment) we could perhaps allow Symbol as a specially-tagged psuedo string like type. Although it’s not a subclass of String, so hmm.

Constant Summary collapse

Infinity = 
1.0/0

Constants inherited from Constructor

Constructor::CONSTRUCTOR_TYPE_SUBCLASSES

Instance Attribute Summary

Attributes inherited from Typisch::Type

#name

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Constructor

#alternative_types, #check_type, inherited, #type_lattice

Methods inherited from Typisch::Type

#<, #<=, #<=>, #==, #===, #>, #>=, #alternative_types, #annotations, #annotations=, #canonicalize!, #excluding_null, #inspect, #recursive?, #subexpression_types, subtype?, #target, #to_string

Constructor Details

#initialize(refinements = {}) ⇒ String

Returns a new instance of String.



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# File 'lib/typisch/string.rb', line 32

def initialize(refinements={})
  @refinements = refinements
  if @refinements[:values] && !@refinements[:values].is_a?(::Set)
    @refinements[:values] = ::Set.new(refinements[:values])
  end
end

Class Method Details

.check_subtype(x, y) ⇒ Object 



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# File 'lib/typisch/string.rb', line 24

def check_subtype(x, y)
  x.equal?(y) || (
    (x.max_length || Infinity) <= (y.max_length || Infinity) &&
    (!y.values || (x.values && x.values.subset?(y.values)))
  )
end

.tag ⇒ Object 



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# File 'lib/typisch/string.rb', line 16

def tag
  "String"
end

.top_type ⇒ Object 



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# File 'lib/typisch/string.rb', line 20

def top_type(*)
  @top_type ||= new
end

Instance Method Details

#max_length ⇒ Object 



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# File 'lib/typisch/string.rb', line 41

def max_length
  @refinements[:max_length]
end

#shallow_check_type(instance) ⇒ Object 



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# File 'lib/typisch/string.rb', line 61

def shallow_check_type(instance)
  (::String === instance || ::Symbol === instance) &&
  (!values     || values.include?(instance.to_s)) &&
  (!max_length || instance.to_s.length <= max_length)
end

#tag ⇒ Object 



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# File 'lib/typisch/string.rb', line 49

def tag
  self.class.tag
end

#to_s ⇒ Object 



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# File 'lib/typisch/string.rb', line 53

def to_s(*)
  @name ? @name.inspect : "string(#{@refinements.inspect})"
end

#values ⇒ Object 



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# File 'lib/typisch/string.rb', line 45

def values
  @refinements[:values]
end