# Check if a field is a valid ISBN
#
# ~~~
# var validator = new ObjectValidator
# validator.add new ISBNField("isbn")
# assert not validator.validate("""{ "isbn": "foo" }""")
# assert validator.validate("""{ "isbn": "ISBN 0-596-00681-0" }""")
# ~~~
class ISBNField
	super RegexField

	autoinit field, required

	redef var re = "(^ISBN [0-9]-[0-9]\{3\}-[0-9]\{5\}-[0-9]?$)".to_re
end