entity.go

package flow

// Entity defines how flow entities should be defined
// Entities are flat data structures holding multiple data fields.
// Entities don't include nested entities, they only include pointers to
// other entities. For example, they keep a slice of entity commits instead
// of keeping a slice of entity object itself. This simplifies storage, signature and validation
// of entities.
type Entity interface {

	// ID returns a unique id for this entity using a hash of the immutable
	// fields of the entity.
	ID() Identifier

	// Checksum returns a unique checksum for the entity, including the mutable
	// data such as signatures.
	Checksum() Identifier
}

// Proof contains proof that an entity is part of a EntityList
type Proof []byte

// EntityList is a list of entities of the same type
type EntityList interface {
	EntitySet

	// HasIndex checks if the list has an entity at the given index.
	HasIndex(i uint) bool

	// ByIndex returns an entity from the list by index
	ByIndex(i uint) (Entity, bool)

	// ByIndexWithProof returns an entity from the list by index and proof of membership
	ByIndexWithProof(i uint) (Entity, Proof, bool)
}

// EntitySet holds a set of entities (order doesn't matter)
type EntitySet interface {

	// Insert adds an entity to the data structure.
	Insert(Entity) bool

	// Remove removes an entity from the data structure.
	Remove(Entity) bool

	// Items returns all items of the collection.
	Items() []Entity

	// Size returns the number of entities in the data structure.
	Size() uint

	// Fingerprint returns a unique identifier for all entities of the data
	// structure.
	Fingerprint() Identifier

	// ByID returns the entity with the given fingerprint.
	ByID(id Identifier) (Entity, bool)

	// if the set has an specific member providing proof of membership
	ByIDWithProof(id Identifier) (bool, Proof, error)
}