uk.ac.sheffield.vtts.model

Class Language

java.lang.Object

uk.ac.sheffield.vtts.model.Element

uk.ac.sheffield.vtts.model.Language

public class Language
extends Element

Language represents a set of sequences of various lengths. Formally, a language may consist of all sequences of uniform finite length, such as L0, L1, L2, ..., Ln, or may consist of sequences of mixed lengths, such as L*, the infinite set of all sequences of all possible lengths. In practice, we use languages that are finite subsets of L*, and denote these as Ln*, the language containing all finite sequences from L0..Ln, for some finite length n. We also refer to Ln+, the language containing all non-empty sequences up to length n. Ln* is the union of L0, the language containing just the empty sequence, and Ln+.

Version:

Broker@Cloud 1.0

Author:

Anthony J H Simons

Constructor Summary

Constructors

Constructor and Description
Language() Creates an empty language.

Method Summary

Methods

Modifier and Type	Method and Description
Language	addLanguage(Language language) Includes the set of sequences from another language in the set of sequences in this language.
Language	addSequence(Sequence sequence) Adds a sequence to the set of sequences in this language.
static Language	createBoundedPlus(Alphabet alphabet, int length) Creates a language containing all non-empty sequences up to a given length, chosen from an alphabet.
static Language	createBoundedStar(Alphabet alphabet, int length) Creates a language containing all sequences up to a given length, chosen from an alphabet.
static Language	createExactly(Alphabet alphabet, int length) Creates a language containing all sequences of a given length, chosen from an alphabet.
java.util.Set<Sequence>	getSequences() Returns the set of sequences that constitute this language.
Language	product(Alphabet alphabet) Creates the product of this language and every event in an alphabet.
Language	product(Language other) Creates the product of this language and every sequence in another language.
int	size() Returns the size of this language.

Methods inherited from class uk.ac.sheffield.vtts.model.Element

safeEquals, safeHashCode, semanticError

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Language

public Language()

Creates an empty language.

Method Detail

createExactly

public static Language createExactly(Alphabet alphabet,
                     int length)

Creates a language containing all sequences of a given length, chosen from an alphabet. A factory method, provided for convenience to create languages such as L1, L2, L3, ... Ln for some finite n.

Parameters:

alphabet - the alphabet.

length - the sequence length.

Returns:

the language containing all sequences of this length.

createBoundedPlus

public static Language createBoundedPlus(Alphabet alphabet,
                         int length)

Creates a language containing all non-empty sequences up to a given length, chosen from an alphabet. A factory method, provided for convenience to create Ln+, for some finite n.

Parameters:

alphabet - the alphabet.

length - the maximum sequence length.

Returns:

the language containing all non-empty sequences up to this length.

createBoundedStar

public static Language createBoundedStar(Alphabet alphabet,
                         int length)

Creates a language containing all sequences up to a given length, chosen from an alphabet. A factory method, provided for convenience to create Ln*, for some finite n.

Parameters:

alphabet - the alphabet.

length - the maximum sequence length

Returns:

the language containing all sequences up to this length, including the empty sequence.

size

public int size()

Returns the size of this language.

Returns:

the number of sequences in this language.

getSequences

public java.util.Set<Sequence> getSequences()

Returns the set of sequences that constitute this language.

Returns:

a set of sequences.

addSequence

public Language addSequence(Sequence sequence)

Adds a sequence to the set of sequences in this language. If this language does not already contain a sequence equal to the added sequence, it includes the new sequence in its set of sequences.

Parameters:

sequence - the sequence to add.

Returns:

this language.

addLanguage

public Language addLanguage(Language language)

Includes the set of sequences from another language in the set of sequences in this language. Modifies this language, such that it also includes all of the sequences in the other language.

Parameters:

language - the language to include.

Returns:

this language.

product

public Language product(Alphabet alphabet)

Creates the product of this language and every event in an alphabet. Creates a new language, in which every sequence from this language is extended by every event from the alphabet. This is a pure functional operation that does not modify any of its operands.

Parameters:

alphabet - the alphabet.

Returns:

the created product language.

product

public Language product(Language other)

Creates the product of this language and every sequence in another language. Creates a new language, in which every sequence from this language is extended by every sequence in the other language. This is a pure functional operation that does not modify any of its operands.

Parameters:

other - the other language.

Returns:

the created product language.