Struct Optional<T>

A container object which may or may not contain a value.

Implements

IEquatable<Optional<T>>

IEquatable<T>

IStructuralEquatable

ISerializable

Namespace: DotNext

Assembly: DotNext.dll

Syntax

public struct Optional<T> : IEquatable<Optional<T>>, IEquatable<T>, IStructuralEquatable, ISerializable

Type Parameters

Name	Description
T	Type of value.

Constructors

Optional(T)

Constructs non-empty container.

Declaration

public Optional(T value)

Parameters

Type	Name	Description
T	value	A value to be placed into container.

Properties

Empty

Represents optional container without value.

Declaration

public static Optional<T> Empty { get; }

Property Value

Type	Description
Optional<T>

IsPresent

Indicates whether the value is present.

Declaration

public bool IsPresent { get; }

Property Value

Type	Description
Boolean

Value

If a value is present, returns the value, otherwise throw exception.

Declaration

public T Value { get; }

Property Value

Type	Description
T

Methods

Convert<U>(Converter<T, U>)

If a value is present, apply the provided mapping function to it, and if the result is non-null, return an Optional describing the result. Otherwise returns Empty.

Declaration

public Optional<U> Convert<U>(Converter<T, U> mapper)

Parameters

Type	Name	Description
DotNext.Converter<T, U>	mapper	A mapping function to be applied to the value, if present.

Returns

Type	Description
Optional<U>	An Optional describing the result of applying a mapping function to the value of this Optional, if a value is present, otherwise Empty.

Type Parameters

Name	Description
U	The type of the result of the mapping function.

Convert<U>(Converter<T, Optional<U>>)

If a value is present, apply the provided mapping function to it, and if the result is non-null, return an Optional describing the result. Otherwise returns Empty.

Declaration

public Optional<U> Convert<U>(Converter<T, Optional<U>> mapper)

Parameters

Type	Name	Description
DotNext.Converter<T, Optional<U>>	mapper	A mapping function to be applied to the value, if present.

Returns

Type	Description
Optional<U>	An Optional describing the result of applying a mapping function to the value of this Optional, if a value is present, otherwise Empty.

Type Parameters

Name	Description
U	The type of the result of the mapping function.

Convert<U>(ValueFunc<T, U>)

If a value is present, apply the provided mapping function to it, and if the result is non-null, return an Optional describing the result. Otherwise returns Empty.

Declaration

public Optional<U> Convert<U>(in ValueFunc<T, U> mapper)

Parameters

Type	Name	Description
ValueFunc<T, U>	mapper	A mapping function to be applied to the value, if present.

Returns

Type	Description
Optional<U>	An Optional describing the result of applying a mapping function to the value of this Optional, if a value is present, otherwise Empty.

Type Parameters

Name	Description
U	The type of the result of the mapping function.

Convert<U>(ValueFunc<T, Optional<U>>)

If a value is present, apply the provided mapping function to it, and if the result is non-null, return an Optional describing the result. Otherwise returns Empty.

Declaration

public Optional<U> Convert<U>(in ValueFunc<T, Optional<U>> mapper)

Parameters

Type	Name	Description
ValueFunc<T, Optional<U>>	mapper	A mapping function to be applied to the value, if present.

Returns

Type	Description
Optional<U>	An Optional describing the result of applying a mapping function to the value of this Optional, if a value is present, otherwise Empty.

Type Parameters

Name	Description
U	The type of the result of the mapping function.

Equals(T)

Determines whether this container stored the same value as the specified value.

Declaration

public bool Equals(T other)

Parameters

Type	Name	Description
T	other	Other value to compare.

Returns

Type	Description
Boolean	true if Value is equal to other; otherwise, false.

Equals(Optional<T>)

Determines whether this container stores the same value as other.

Declaration

public bool Equals(Optional<T> other)

Parameters

Type	Name	Description
Optional<T>	other	Other container to compare.

Returns

Type	Description
Boolean	true if this container stores the same value as other; otherwise, false.

Equals(Object)

Determines whether this container stores the same value as other.

Declaration

public override bool Equals(object other)

Parameters

Type	Name	Description
Object	other	Other container to compare.

Returns

Type	Description
Boolean	true if this container stores the same value as other; otherwise, false.

Equals(Object, IEqualityComparer)

Performs equality check between stored value and the specified value using method .

Declaration

public bool Equals(object other, IEqualityComparer comparer)

Parameters

Type	Name	Description
Object	other	Other object to compare with Value.
IEqualityComparer	comparer	The comparer implementing custom equality check.

Returns

Type	Description
Boolean	true if other is equal to Value using custom check; otherwise, false.

GetHashCode()

Computes hash code of the stored value.

Declaration

public override int GetHashCode()

Returns

Type	Description
Int32	The hash code of the stored value.

Remarks

This method calls for the object Value.

GetHashCode(IEqualityComparer)

Computes hash code for the stored value using method .

Declaration

public int GetHashCode(IEqualityComparer comparer)

Parameters

Type	Name	Description
IEqualityComparer	comparer	The comparer implementing hash code function.

Returns

Type	Description
Int32	The hash code of Value.

If(Predicate<T>)

If a value is present, and the value matches the given predicate, return an Optional describing the value, otherwise return an empty Optional.

Declaration

public Optional<T> If(Predicate<T> condition)

Parameters

Type	Name	Description
DotNext.Predicate<T>	condition	A predicate to apply to the value, if present.

Returns

Type	Description
Optional<T>	An Optional describing the value of this Optional if a value is present and the value matches the given predicate, otherwise an empty Optional

If(ValueFunc<T, Boolean>)

If a value is present, and the value matches the given predicate, return an Optional describing the value, otherwise return an empty Optional.

Declaration

public Optional<T> If(in ValueFunc<T, bool> condition)

Parameters

Type	Name	Description
ValueFunc<T, Boolean>	condition	A predicate to apply to the value, if present.

Returns

Type	Description
Optional<T>	An Optional describing the value of this Optional if a value is present and the value matches the given predicate, otherwise an empty Optional

Or(T)

Returns the value if present; otherwise return default value.

Declaration

public T Or(T defaultValue)

Parameters

Type	Name	Description
T	defaultValue	The value to be returned if there is no value present.

Returns

Type	Description
T	The value, if present, otherwise defaultValue.

OrDefault()

If a value is present, returns the value, otherwise return default value.

Declaration

public T OrDefault()

Returns

Type	Description
T	The value, if present, otherwise default

OrInvoke(Func<T>)

Returns the value if present; otherwise invoke delegate.

Declaration

public T OrInvoke(Func<T> defaultFunc)

Parameters

Type	Name	Description
DotNext.Func<T>	defaultFunc	A delegate to be invoked if value is not present.

Returns

Type	Description
T	The value, if present, otherwise returned from delegate.

OrInvoke(ValueFunc<T>)

Returns the value if present; otherwise invoke delegate.

Declaration

public T OrInvoke(in ValueFunc<T> defaultFunc)

Parameters

Type	Name	Description
ValueFunc<T>	defaultFunc	A delegate to be invoked if value is not present.

Returns

Type	Description
T	The value, if present, otherwise returned from delegate.

OrThrow<E>()

If a value is present, returns the value, otherwise throw exception.

Declaration

public T OrThrow<E>()

    where E : Exception, new()

Returns

Type	Description
T	The value, if present.

Type Parameters

Name	Description
E	Type of exception to throw.

OrThrow<E>(Func<E>)

If a value is present, returns the value, otherwise throw exception.

Declaration

public T OrThrow<E>(Func<E> exceptionFactory)

    where E : Exception

Parameters

Type	Name	Description
DotNext.Func<E>	exceptionFactory	Exception factory.

Returns

Type	Description
T	The value, if present.

Type Parameters

Name	Description
E

OrThrow<E>(ValueFunc<E>)

If a value is present, returns the value, otherwise throw exception.

Declaration

public T OrThrow<E>(in ValueFunc<E> exceptionFactory)

    where E : Exception

Parameters

Type	Name	Description
ValueFunc<E>	exceptionFactory	Exception factory.

Returns

Type	Description
T	The value, if present.

Type Parameters

Name	Description
E

ToString()

Returns textual representation of this object.

Declaration

public override string ToString()

Returns

Type	Description
String	The textual representation of this object.

TryGet(out T)

Attempts to extract value from container if it is present.

Declaration

public bool TryGet(out T value)

Parameters

Type	Name	Description
T	value	Extracted value.

Returns

Type	Description
Boolean	true if value is present; otherwise, false.

Operators

BitwiseOr(Optional<T>, Optional<T>)

Returns non-empty container.

Declaration

public static Optional<T> operator |(in Optional<T> first, in Optional<T> second)

Parameters

Type	Name	Description
Optional<T>	first	The first container.
Optional<T>	second	The second container.

Returns

Type	Description
Optional<T>	The first non-empty container.

See Also

Coalesce<T>(Optional<T>, Optional<T>)

Equality(Optional<T>, Optional<T>)

Determines whether two containers store the same value.

Declaration

public static bool operator ==(in Optional<T> first, in Optional<T> second)

Parameters

Type	Name	Description
Optional<T>	first	The first container to compare.
Optional<T>	second	The second container to compare.

Returns

Type	Description
Boolean	true, if both containers store the same value; otherwise, false.

ExclusiveOr(Optional<T>, Optional<T>)

Determines whether two containers are empty or have values.

Declaration

public static Optional<T> operator ^(in Optional<T> first, in Optional<T> second)

Parameters

Type	Name	Description
Optional<T>	first	The first container.
Optional<T>	second	The second container.

Returns

Type	Description
Optional<T>	true, if both containers are empty or have values; otherwise, false.

Explicit(Optional<T> to T)

Extracts value stored in the Optional container.

Declaration

public static explicit operator T(in Optional<T> optional)

Parameters

Type	Name	Description
Optional<T>	optional	The container.

Returns

Type	Description
T

False(Optional<T>)

Checks whether the container has no value.

Declaration

public static bool operator false (in Optional<T> optional)

Parameters

Type	Name	Description
Optional<T>	optional	The container to check.

Returns

Type	Description
Boolean	true if this container has no value; otherwise, false.

Implicit(T to Optional<T>)

Wraps value into Optional container.

Declaration

public static implicit operator Optional<T>(T value)

Parameters

Type	Name	Description
T	value	The value to convert.

Returns

Type	Description
Optional<T>

Inequality(Optional<T>, Optional<T>)

Determines whether two containers store the different values.

Declaration

public static bool operator !=(in Optional<T> first, in Optional<T> second)

Parameters

Type	Name	Description
Optional<T>	first	The first container to compare.
Optional<T>	second	The second container to compare.

Returns

Type	Description
Boolean	true, if both containers store the different values; otherwise, false.

True(Optional<T>)

Checks whether the container has value.

Declaration

public static bool operator true (in Optional<T> optional)

Parameters

Type	Name	Description
Optional<T>	optional	The container to check.

Returns

Type	Description
Boolean	true if this container has value; otherwise, false.

Implements

IEquatable<>

IEquatable<>

IStructuralEquatable

ISerializable

Extension Methods

ExpressionBuilder.Const<T>(T)

Optional.Coalesce<T>(Optional<T>, Optional<T>)