9.9 CharacterClass

The CharacterClass domain allows classes of characters to be defined and manipulated efficiently. Character classes can be created by giving either a string or a list of characters.

cl1 := charClass [char "a", char "e", char "i", char "o", char "u", char

“y”]

\[\]

“aeiouy”

_{Type: CharacterClass}

cl2 := charClass "bcdfghjklmnpqrstvwxyz"

\[\]

“bcdfghjklmnpqrstvwxyz”

_{Type: CharacterClass}

A number of character classes are predefined for convenience.

digit()

\[\]

“0123456789”

_{Type: CharacterClass}

hexDigit()

\[\]

“0123456789ABCDEFabcdef”

_{Type: CharacterClass}

upperCase()

\[\]

“ABCDEFGHIJKLMNOPQRSTUVWXYZ”

_{Type: CharacterClass}

lowerCase()

\[\]

“abcdefghijklmnopqrstuvwxyz”

_{Type: CharacterClass}

alphabetic()

\[\]

“ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz”

_{Type: CharacterClass}

alphanumeric()

\[\]

“0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz”

_{Type: CharacterClass}

You can quickly test whether a character belongs to a class.

member?(char "a", cl1)

\[\]

true

_{Type: Boolean}

member?(char "a", cl2)

\[\]

false

_{Type: Boolean}

Classes have the usual set operations because the CharacterClass domain belongs to the category FiniteSetAggregate(Character).

intersect(cl1, cl2)

\[\]

“y”

_{Type: CharacterClass}

union(cl1,cl2)

\[\]

“abcdefghijklmnopqrstuvwxyz”

_{Type: CharacterClass}

difference(cl1,cl2)

\[\]

“aeiou”

_{Type: CharacterClass}

intersect(complement(cl1),cl2)

\[\]

“bcdfghjklmnpqrstvwxz”

_{Type: CharacterClass}

You can modify character classes by adding or removing characters.

insert!(char "a", cl2)

\[\]

“abcdfghjklmnpqrstvwxyz”

_{Type: CharacterClass}

remove!(char "b", cl2)

\[\]

“acdfghjklmnpqrstvwxyz”

_{Type: CharacterClass}

For more information on related topics, see CharacterXmpPage and StringXmpPage .