dict
Dictionary. A dictionary-like data structure that maps felt252 keys to values of any type. The Felt252Dict provides efficient key-value storage with operations for inserting, retrieving, and updating values. Each operation creates a new entry that can be validated through a process called squashing. # Examples One can create a new dictionary using the Default::default method:
use core::dict::Felt252Dict;
let mut dict: Felt252Dict<u8> = Default::default();
... then insert new values corresponding to a given key with the Felt252DictTrait::insert method, and retrieve any value given a key with the Felt252DictTrait::get method.
dict.insert(0, 10);
dict.insert(1, 20);
assert!(dict.get(0) == 10);
assert!(dict.get(1) == 20);
dict.insert(0, 20);
assert!(dict.get(0) == 20
It is also possible to use the Felt252DictTrait::entry method to retrieve the last entry given a certain key. In this case, the method takes ownership of the dictionary and returns the entry to update. After that, using the Felt252DictEntryTrait::finalize allows to create a new entry in the dictionary. Using entry and finalize methods can be very useful given that it does not require the type in the dictionary to be copyable, meaning that we can use non-copyable types like arrays as dictionary values.
use core::dict::Felt252Dict;
let mut dict: Felt252Dict<u8> = Default::default();
dict.insert(0, 10);
let (entry, prev_value) = dict.entry(0);
let new_value: u8 = 20;
dict = entry.finalize(new_value);
Fully qualified path: core::dict