Module 0x2::object_bag
Similar to sui::bag, an ObjectBag is a heterogeneous map-like collection. But unlike sui::bag, the values bound to these dynamic fields must be objects themselves. This allows for the objects to still exist in storage, which may be important for external tools. The difference is otherwise not observable from within Move.
- Resource
ObjectBag
- Constants
- Function
new
- Function
add
- Function
borrow
- Function
borrow_mut
- Function
remove
- Function
contains
- Function
contains_with_type
- Function
length
- Function
is_empty
- Function
destroy_empty
- Function
value_id
use 0x1::option;
use 0x2::dynamic_object_field;
use 0x2::object;
use 0x2::tx_context;
Resource ObjectBag
struct ObjectBag has store, key
Fields
- id: object::UID
- the ID of this bag
- size: u64
- the number of key-value pairs in the bag
Constants
const EBagNotEmpty: u64 = 0;
Function new
Creates a new, empty bag
public fun new(ctx: &mut tx_context::TxContext): object_bag::ObjectBag
Implementation
public fun new(ctx: &mut TxContext): ObjectBag {
ObjectBag {
id: object::new(ctx),
size: 0,
}
}
Function add
Adds a key-value pair to the bag bag: &mut ObjectBag Aborts with sui::dynamic_field::EFieldAlreadyExists if the bag already has an entry with that key k: K.
public fun add<K: copy, drop, store, V: store, key>(bag: &mut object_bag::ObjectBag, k: K, v: V)
Function borrow
Immutably borrows the value associated with the key in the bag bag: &ObjectBag. Aborts with sui::dynamic_field::EFieldDoesNotExist if the bag does not have an entry with that key k: K. Aborts with sui::dynamic_field::EFieldTypeMismatch if the bag has an entry for the key, but the value does not have the specified type.
public fun borrow<K: copy, drop, store, V: store, key>(bag: &object_bag::ObjectBag, k: K): &V
Function borrow_mut
Mutably borrows the value associated with the key in the bag bag: &mut ObjectBag. Aborts with sui::dynamic_field::EFieldDoesNotExist if the bag does not have an entry with that key k: K. Aborts with sui::dynamic_field::EFieldTypeMismatch if the bag has an entry for the key, but the value does not have the specified type.
public fun borrow_mut<K: copy, drop, store, V: store, key>(bag: &mut object_bag::ObjectBag, k: K): &mut V
Implementation
public fun borrow_mut<K: copy + drop + store, V: key + store>(bag: &mut ObjectBag, k: K): &mut V {
ofield::borrow_mut(&mut bag.id, k)
}
Function remove
Mutably borrows the key-value pair in the bag bag: &mut ObjectBag and returns the value. Aborts with sui::dynamic_field::EFieldDoesNotExist if the bag does not have an entry with that key k: K. Aborts with sui::dynamic_field::EFieldTypeMismatch if the bag has an entry for the key, but the value does not have the specified type.
public fun remove<K: copy, drop, store, V: store, key>(bag: &mut object_bag::ObjectBag, k: K): V
Function contains
Returns true iff there is an value associated with the key k: K in the bag bag: &ObjectBag
public fun contains<K: copy, drop, store>(bag: &object_bag::ObjectBag, k: K): bool
Function contains_with_type
Returns true iff there is an value associated with the key k: K in the bag bag: &ObjectBag with an assigned value of type V
public fun contains_with_type<K: copy, drop, store, V: store, key>(bag: &object_bag::ObjectBag, k: K): bool
Implementation
public fun contains_with_type<K: copy + drop + store, V: key + store>(bag: &ObjectBag, k: K): bool {
ofield::exists_with_type<K, V>(&bag.id, k)
}
Function length
Returns the size of the bag, the number of key-value pairs
public fun length(bag: &object_bag::ObjectBag): u64
Function is_empty
Returns true iff the bag is empty (if length returns 0)
public fun is_empty(bag: &object_bag::ObjectBag): bool
Function destroy_empty
Destroys an empty bag Aborts with EBagNotEmpty if the bag still contains values
public fun destroy_empty(bag: object_bag::ObjectBag)
Implementation
public fun destroy_empty(bag: ObjectBag) {
let ObjectBag { id, size } = bag;
assert!(size == 0, EBagNotEmpty);
id.delete()
}
Function value_id
Returns the ID of the object associated with the key if the bag has an entry with key k: K Returns none otherwise
public fun value_id<K: copy, drop, store>(bag: &object_bag::ObjectBag, k: K): option::Option<object::ID>