Class: Finitio::Attribute

Inherits:
Object
  • Object
show all
Includes:
Metadata
Defined in:
lib/finitio/support/attribute.rb

Overview

Helper class for tuple and relation attributes.

An attribute is simply a ‘(name: AttrName, type: Type)` pair, where the type is a Finitio type.

Constant Summary

Constants included from Metadata

Metadata::EMPTY_METADATA

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Metadata

#metadata, #metadata=, #metadata?

Constructor Details

#initialize(name, type, required = true, metadata = nil) ⇒ Attribute

Returns a new instance of Attribute.



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# File 'lib/finitio/support/attribute.rb', line 11

def initialize(name, type, required = true, metadata = nil)
  unless name.is_a?(Symbol)
    raise ArgumentError, "Symbol expected for attribute name, got `#{name}`"
  end

  unless type.is_a?(Type)
    raise ArgumentError, "Type expected for attribute domain, got `#{type}`"
  end

  @name, @type, @required, @metadata = name, type, required, metadata
end

Instance Attribute Details

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/finitio/support/attribute.rb', line 22

def name
  @name
end

#required ⇒ Object (readonly) Also known as: required?

Returns the value of attribute required.



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# File 'lib/finitio/support/attribute.rb', line 22

def required
  @required
end

#type ⇒ Object (readonly)

Returns the value of attribute type.



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# File 'lib/finitio/support/attribute.rb', line 22

def type
  @type
end

Instance Method Details

#==(other) ⇒ Object Also known as: eql? 



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# File 'lib/finitio/support/attribute.rb', line 48

def ==(other)
  other.is_a?(Attribute) && name==other.name && \
  type==other.type && required==other.required
end

#fetch_on(arg, &bl) ⇒ Object

Fetch the attribute on ‘arg`, which is expected to be a Hash object.

This method allows working with ruby hashes having either Symbols or Strings as keys. It ensures that no Symbol is created by the rest of the code, since this would provide a DoS attack vector under MRI.



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# File 'lib/finitio/support/attribute.rb', line 35

def fetch_on(arg, &bl)
  unless arg.respond_to?(:fetch)
    raise ArgumentError, "Object responding to `fetch` expected"
  end
  arg.fetch(name) do
    arg.fetch(name.to_s, &bl)
  end
end

#hash ⇒ Object 



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# File 'lib/finitio/support/attribute.rb', line 54

def hash
  name.hash ^ type.hash ^ required.hash
end

#optional? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/finitio/support/attribute.rb', line 25

def optional?
  !required?
end

#resolve_proxies(system) ⇒ Object 



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# File 'lib/finitio/support/attribute.rb', line 58

def resolve_proxies(system)
  Attribute.new(name, type.resolve_proxies(system), required, metadata)
end

#to_name ⇒ Object 



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# File 'lib/finitio/support/attribute.rb', line 44

def to_name
  required ? "#{name}: #{type}" : "#{name} :? #{type}"
end

#unconstrained ⇒ Object 



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# File 'lib/finitio/support/attribute.rb', line 62

def unconstrained
  Attribute.new(name, type.unconstrained, required, metadata)
end