namespace Cobra.Core

	extend IDictionary<of TKey, TValue>

		def clone as IDictionary<of TKey, TValue>  # CC: as same
			"""
			Returns a new dictionary with the contents of this dictionary.
			Does not clone the contents themselves.
			This is sometimes known as a "shallow copy".
			"""
			ensure
				result is not this
				result.count == .count
				result.typeOf is .typeOf
			body
				type = .typeOf
				newDict = type(this)
				return newDict

		def get(key as TKey, default as TValue) as TValue
			"""
			Returns the value for the given key, or returns the default if the key is not found.
			"""
			ensure not .containsKey(key) implies result == default
			value as TValue
			if .tryGetValue(key, out value), return value
			else, return default


	class TestIDictionaryExtensions

		test
			a = Dictionary<of String, int>()
			
			b = a.clone
			assert b is not a
			assert b.count == 0
			
			a = {'x': 1, 'y': 2}
			b = a.clone
			assert b is not a
			assert b.count == 2
			assert b['x'] == 1 and b['y'] == 2

			d = {'a': 1, 'b': 2}
			assert d.get('a', 0) == 1
			assert d.get('c', 1) == 1