Class Alphabet

An alphabet associated with a finite state automaton.

Inheritance

object

Alphabet

Implements

IEquatable<Alphabet>

Inherited Members

object.Equals(object, object)

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

Namespace: Automata.Core

Assembly: Automata.Core.dll

Syntax

public class Alphabet : IEquatable<Alphabet>

Remarks

An Alphabet is a collection of symbols used by a finite state automaton. It can be extended with new symbols, but symbols cannot be removed. This enables multiple automata to share the same alphabet. Furthermore, automata never needs to deals with strings, but can use integer indices instead for all operations. Default behavior for operations that create new automata is to use the existing alphabet of the input automata. If a new alphabet is needed, an explicit creation of a new alphabet is typically required.

Constructors

Alphabet()

Initializes a new empty instance of the Alphabet class.

Declaration

public Alphabet()

Alphabet(Alphabet)

Initializes a new cloned instance of the Alphabet class from the specified alphabet.

Declaration

public Alphabet(Alphabet alphabet)

Parameters

Type	Name	Description
Alphabet	alphabet	Alphabet to initialize the alphabet with.

Alphabet(IEnumerable<string>)

Initializes a new instance of the Alphabet class with the specified symbols.

Declaration

public Alphabet(IEnumerable<string> symbols)

Parameters

Type	Name	Description
IEnumerable<string>	symbols	Symbols to initialize the alphabet with.

Alphabet(params string[])

Initializes a new instance of the Alphabet class with the specified symbols.

Symbols to initialize the alphabet with.

Declaration

public Alphabet(params string[] symbols)

Parameters

Type	Name	Description
string[]	symbols

Properties

Count

Number of symbols in the alphabet.

Declaration

public int Count { get; }

Property Value

Type	Description
int

this[int]

Symbol at the specified index.

Declaration

public string this[int index] { get; }

Parameters

Type	Name	Description
int	index	Index of the symbol to get.

Property Value

Type	Description
string	Symbol at the specified index.

Exceptions

Type	Condition
ArgumentOutOfRangeException	Thrown when the index is out of range.

this[string]

Index of the specified symbol.

Declaration

public int this[string symbol] { get; }

Parameters

Type	Name	Description
string	symbol	Symbol whose index to get.

Property Value

Type	Description
int	Index of the specified symbol, or InvalidSymbolIndex if not found.

SymbolIndices

Returns an enumerable collection of indices of the symbols in the alphabet. This is effectively the integers in range [0 .. Count).

Declaration

public IEnumerable<int> SymbolIndices { get; }

Property Value

Type	Description
IEnumerable<int>

Symbols

Readonly collection of symbols in the alphabet.

Declaration

public IReadOnlyCollection<string> Symbols { get; }

Property Value

Type	Description
IReadOnlyCollection<string>

Methods

AddAll(IEnumerable<string>)

Adds all the specified symbols to the alphabet that are not already present.

Declaration

public void AddAll(IEnumerable<string> symbols)

Parameters

Type	Name	Description
IEnumerable<string>	symbols	Symbols to add.

Contains(int)

Indicates whether the alphabet contains the specified symbol as an integer.

Declaration

public bool Contains(int symbol)

Parameters

Type	Name	Description
int	symbol	Symbol index to locate in the alphabet.

Returns

Type	Description
bool	true iff the symbol is found; otherwise, false.

Contains(string)

Indicates whether the alphabet contains the specified symbol as a string.

Declaration

public bool Contains(string symbol)

Parameters

Type	Name	Description
string	symbol	Symbol string to locate in the alphabet.

Returns

Type	Description
bool	true iff the symbol is found; otherwise, false.

Equals(Alphabet?)

Indicates whether the current object is equal to another object of the same type.

Declaration

public bool Equals(Alphabet? other)

Parameters

Type	Name	Description
Alphabet	other	An object to compare with this object.

Returns

Type	Description
bool	true if the current object is equal to the other parameter; otherwise, false.

Equals(object?)

Determines whether the specified object is equal to the current object.

Declaration

public override bool Equals(object? obj)

Parameters

Type	Name	Description
object	obj	The object to compare with the current object.

Returns

Type	Description
bool	true if the specified object is equal to the current object; otherwise, false.

Overrides

object.Equals(object)

GetHashCode()

Serves as the default hash function.

Declaration

public override int GetHashCode()

Returns

Type	Description
int	A hash code for the current object.

Overrides

object.GetHashCode()

GetOrAdd(string)

Index of the specified symbol or adds it if it does not exist.

Declaration

public int GetOrAdd(string symbol)

Parameters

Type	Name	Description
string	symbol	Symbol to get or add.

Returns

Type	Description
int	Index of the specified symbol.

ToString()

String that represents the current alphabet, including its size.

Declaration

public override string ToString()

Returns

Type	Description
string	A string representation of the alphabet.

Overrides

object.ToString()

ToStringExpanded()

String with each symbol and its index, separated by a newline.

Declaration

public string ToStringExpanded()

Returns

Type	Description
string	A string with each symbol and its index, separated by a newline.

TryGetIndex(string, out int)

Tries to get the index of the specified symbol.

Declaration

public bool TryGetIndex(string symbol, out int index)

Parameters

Type	Name	Description
string	symbol	Symbol whose index to get.
int	index	When this method returns, contains the index of the specified symbol, if the symbol is found; otherwise, -1.

Returns

Type	Description
bool	true iff the symbol is found; otherwise, false.

UnionWith(Alphabet)

Add another alphabet to the current alphabet.

Declaration

public Dictionary<int, int> UnionWith(Alphabet other)

Parameters

Type	Name	Description
Alphabet	other	The other alphabet to merge into this.

Returns

Type	Description
Dictionary<int, int>	A dictionary mapping indices from the other alphabet to the current alphabet.

Operators

operator ==(Alphabet, Alphabet)

Declaration

public static bool operator ==(Alphabet left, Alphabet right)

Parameters

Type	Name	Description
Alphabet	left
Alphabet	right

Returns

Type	Description
bool

operator !=(Alphabet, Alphabet)

Declaration

public static bool operator !=(Alphabet left, Alphabet right)

Parameters

Type	Name	Description
Alphabet	left
Alphabet	right

Returns

Type	Description
bool

Implements

IEquatable<T>