SumType

A tagged union that can hold a single value from any of a specified set of types.

The value in a SumType can be operated on using pattern matching.

To avoid ambiguity, duplicate types are not allowed (but see the "basic usage" example for a workaround).

The special type This can be used as a placeholder to create self-referential types, just like with Algebraic. See the "Arithmetic expression evaluator" example for usage.

A SumType is initialized by default to hold the .init value of its first member type, just like a regular union. The version identifier SumTypeNoDefaultCtor can be used to disable this behavior.

struct SumType (

Types...

) if (

is(NoDuplicates!Types == Types) &&

Types.length > 0

) {

alias Types = AliasSeq!(ReplaceTypeUnless!(isSumTypeInstance, This, typeof(this), TemplateArgsOf!SumType));

this(T value);

this(const(T) value);

this(immutable(T) value);

this(Value value);

this(inout(SumType) other);

this(SumType other);

this(const(SumType) other);

this(immutable(SumType) other);

static if(isAssignableTo!T)

SumType opAssign(T rhs);

static if(allSatisfy!(isAssignableTo, Types))
static if(allSatisfy!(isCopyable, Types))

SumType opAssign(SumType rhs);

static if(allSatisfy!(isAssignableTo, Types))

SumType opAssign(SumType rhs);

bool opEquals(Rhs rhs);

void toString(Sink sink, FormatSpec!Char fmt);

static if(allSatisfy!(isHashable, Map!(ConstOf, Types)))
version(!D_BetterC)

size_t toHash();

size_t typeIndex();

}

Constructors

this this(T value)
this(const(T) value)
this(immutable(T) value)
this(Value value): Constructs a SumType holding a specific value.
this this(inout(SumType) other)
this(SumType other)
this(const(SumType) other)
this(immutable(SumType) other): Constructs a SumType that's a copy of another SumType.

Destructor

~this ~this(): Calls the destructor of the SumType's current value.

Members

Aliases

Types alias Types = AliasSeq!(ReplaceTypeUnless!(isSumTypeInstance, This, typeof(this), TemplateArgsOf!SumType)): The types a SumType can hold.

Functions

opAssign SumType opAssign(T rhs): Assigns a value to a SumType.
opAssign SumType opAssign(SumType rhs): Copies the value from another SumType into this one.
opAssign SumType opAssign(SumType rhs): Moves the value from another SumType into this one.
opEquals bool opEquals(Rhs rhs): Compares two SumTypes for equality.
toHash size_t toHash(): Returns the hash of the SumType's current value.
toString string toString(): Returns a string representation of the SumType's current value.
toString void toString(Sink sink, FormatSpec!Char fmt): Handles formatted writing of the SumType's current value.
typeIndex size_t typeIndex(): Returns the index of the type of the SumType's current value in the SumType's Types.

SumType

Constructors

Destructor

Members

Aliases

Functions

See Also

Meta

Source