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Module 0x2::coin

Defines the Coin type - platform wide representation of fungible tokens and coins. Coin can be described as a secure wrapper around Balance type.

use 0x1::ascii;
use 0x1::option;
use 0x1::string;
use 0x1::type_name;
use 0x2::balance;
use 0x2::deny_list;
use 0x2::object;
use 0x2::transfer;
use 0x2::tx_context;
use 0x2::types;
use 0x2::url;

Resource Coin​

A coin of type T worth value. Transferable and storable

struct Coin<T> has store, key
Fields

Resource CoinMetadata​

Each Coin type T created through create_currency function will have a unique instance of CoinMetadata<T> that stores the metadata for this coin type.

struct CoinMetadata<T> has store, key
Fields
id: object::UID
decimals: u8

Number of decimal places the coin uses. A coin with value N and decimals D should be shown as N / 10^D E.g., a coin with value 7002 and decimals 3 should be displayed as 7.002 This is metadata for display usage only.

name: string::String

Name for the token

symbol: ascii::String

Symbol for the token

description: string::String

Description of the token

icon_url: option::Option<url::Url>

URL for the token logo

Resource RegulatedCoinMetadata​

Similar to CoinMetadata, but created only for regulated coins that use the DenyList. This object is always immutable.

struct RegulatedCoinMetadata<T> has key
Fields
id: object::UID
coin_metadata_object: object::ID

The ID of the coin's CoinMetadata object.

deny_cap_object: object::ID

The ID of the coin's DenyCap object.

Resource TreasuryCap​

Capability allowing the bearer to mint and burn coins of type T. Transferable

struct TreasuryCap<T> has store, key
Fields
id: object::UID
total_supply: balance::Supply<T>

Resource DenyCapV1​

Capability allowing the bearer to deny addresses from using the currency's coins-- immediately preventing those addresses from interacting with the coin as an input to a transaction and at the start of the next preventing them from receiving the coin. If allow_global_pause is true, the bearer can enable a global pause that behaves as if all addresses were added to the deny list.

struct DenyCapV1<T> has store, key
Fields
id: object::UID
allow_global_pause: bool

Constants​

Trying to split a coin more times than its balance allows.

const ENotEnough: u64 = 2;

The index into the deny list vector for the iota::coin::Coin type.

const DENY_LIST_COIN_INDEX: u64 = 0;

A type passed to create_supply is not a one-time witness.

const EBadWitness: u64 = 0;
const EGlobalPauseNotAllowed: u64 = 3;

Invalid arguments are passed to a function.

const EInvalidArg: u64 = 1;

Function total_supply​

Return the total number of T's in circulation.

public fun total_supply<T>(cap: &coin::TreasuryCap<T>): u64
Implementation
public fun total_supply<T>(cap: &TreasuryCap<T>): u64 {
balance::supply_value(&cap.total_supply)
}

Function treasury_into_supply​

Unwrap TreasuryCap getting the Supply.

Operation is irreversible. Supply cannot be converted into a TreasuryCap due to different security guarantees (TreasuryCap can be created only once for a type)

public fun treasury_into_supply<T>(treasury: coin::TreasuryCap<T>): balance::Supply<T>
Implementation
public fun treasury_into_supply<T>(treasury: TreasuryCap<T>): Supply<T> {
let TreasuryCap { id, total_supply } = treasury;
id.delete();
total_supply
}

Function supply_immut​

Get immutable reference to the treasury's Supply.

public fun supply_immut<T>(treasury: &coin::TreasuryCap<T>): &balance::Supply<T>
Implementation
public fun supply_immut<T>(treasury: &TreasuryCap<T>): &Supply<T> {
&treasury.total_supply
}

Function supply_mut​

Get mutable reference to the treasury's Supply.

public fun supply_mut<T>(treasury: &mut coin::TreasuryCap<T>): &mut balance::Supply<T>
Implementation
public fun supply_mut<T>(treasury: &mut TreasuryCap<T>): &mut Supply<T> {
&mut treasury.total_supply
}

Function value​

Public getter for the coin's value

public fun value<T>(self: &coin::Coin<T>): u64
Implementation
public fun value<T>(self: &Coin<T>): u64 {
self.balance.value()
}

Function balance​

Get immutable reference to the balance of a coin.

public fun balance<T>(coin: &coin::Coin<T>): &balance::Balance<T>
Implementation
public fun balance<T>(coin: &Coin<T>): &Balance<T> {
&coin.balance
}

Function balance_mut​

Get a mutable reference to the balance of a coin.

public fun balance_mut<T>(coin: &mut coin::Coin<T>): &mut balance::Balance<T>
Implementation
public fun balance_mut<T>(coin: &mut Coin<T>): &mut Balance<T> {
&mut coin.balance
}

Function from_balance​

Wrap a balance into a Coin to make it transferable.

public fun from_balance<T>(balance: balance::Balance<T>, ctx: &mut tx_context::TxContext): coin::Coin<T>
Implementation
public fun from_balance<T>(balance: Balance<T>, ctx: &mut TxContext): Coin<T> {
Coin { id: object::new(ctx), balance }
}

Function into_balance​

Destruct a Coin wrapper and keep the balance.

public fun into_balance<T>(coin: coin::Coin<T>): balance::Balance<T>
Implementation
public fun into_balance<T>(coin: Coin<T>): Balance<T> {
let Coin { id, balance } = coin;
id.delete();
balance
}

Function take​

Take a Coin worth of value from Balance. Aborts if value > balance.value

public fun take<T>(balance: &mut balance::Balance<T>, value: u64, ctx: &mut tx_context::TxContext): coin::Coin<T>
Implementation
public fun take<T>(
balance: &mut Balance<T>, value: u64, ctx: &mut TxContext,
): Coin<T> {
Coin {
id: object::new(ctx),
balance: balance.split(value)
}
}

Function put​

Put a Coin<T> to the Balance<T>.

public fun put<T>(balance: &mut balance::Balance<T>, coin: coin::Coin<T>)
Implementation
public fun put<T>(balance: &mut Balance<T>, coin: Coin<T>) {
balance.join(into_balance(coin));
}

Function join​

Consume the coin c and add its value to self. Aborts if c.value + self.value > U64_MAX

public entry fun join<T>(self: &mut coin::Coin<T>, c: coin::Coin<T>)
Implementation
public entry fun join<T>(self: &mut Coin<T>, c: Coin<T>) {
let Coin { id, balance } = c;
id.delete();
self.balance.join(balance);
}

Function split​

Split coin self to two coins, one with balance split_amount, and the remaining balance is left is self.

public fun split<T>(self: &mut coin::Coin<T>, split_amount: u64, ctx: &mut tx_context::TxContext): coin::Coin<T>
Implementation
public fun split<T>(
self: &mut Coin<T>, split_amount: u64, ctx: &mut TxContext
): Coin<T> {
take(&mut self.balance, split_amount, ctx)
}

Function divide_into_n​

Split coin self into n - 1 coins with equal balances. The remainder is left in self. Return newly created coins.

public fun divide_into_n<T>(self: &mut coin::Coin<T>, n: u64, ctx: &mut tx_context::TxContext): vector<coin::Coin<T>>
Implementation
public fun divide_into_n<T>(
self: &mut Coin<T>, n: u64, ctx: &mut TxContext
): vector<Coin<T>> {
assert!(n > 0, EInvalidArg);
assert!(n <= value(self), ENotEnough);
let mut vec = vector[];
let mut i = 0;
let split_amount = value(self) / n;
while (i < n - 1) {
vec.push_back(self.split(split_amount, ctx));
i = i + 1;
};
vec
}

Function zero​

Make any Coin with a zero value. Useful for placeholding bids/payments or preemptively making empty balances.

public fun zero<T>(ctx: &mut tx_context::TxContext): coin::Coin<T>
Implementation
public fun zero<T>(ctx: &mut TxContext): Coin<T> {
Coin { id: object::new(ctx), balance: balance::zero() }
}

Function destroy_zero​

Destroy a coin with value zero

public fun destroy_zero<T>(c: coin::Coin<T>)
Implementation
public fun destroy_zero<T>(c: Coin<T>) {
let Coin { id, balance } = c;
id.delete();
balance.destroy_zero()
}

Function create_currency​

Create a new currency type T as and return the TreasuryCap for T to the caller. Can only be called with a one-time-witness type, ensuring that there's only one TreasuryCap per T.

public fun create_currency<T: drop>(witness: T, decimals: u8, symbol: vector<u8>, name: vector<u8>, description: vector<u8>, icon_url: option::Option<url::Url>, ctx: &mut tx_context::TxContext): (coin::TreasuryCap<T>, coin::CoinMetadata<T>)
Implementation
public fun create_currency<T: drop>(
witness: T,
decimals: u8,
symbol: vector<u8>,
name: vector<u8>,
description: vector<u8>,
icon_url: Option<Url>,
ctx: &mut TxContext
): (TreasuryCap<T>, CoinMetadata<T>) {
// Make sure there's only one instance of the type T
assert!(iota::types::is_one_time_witness(&witness), EBadWitness);
(
TreasuryCap {
id: object::new(ctx),
total_supply: balance::create_supply(witness)
},
CoinMetadata {
id: object::new(ctx),
decimals,
name: string::utf8(name),
symbol: ascii::string(symbol),
description: string::utf8(description),
icon_url
}
)
}

Function create_regulated_currency_v1​

This creates a new currency, via create_currency, but with an extra capability that allows for specific addresses to have their coins frozen. When an address is added to the deny list, it is immediately unable to interact with the currency's coin as input objects. Additionally at the start of the next epoch, they will be unable to receive the currency's coin. The allow_global_pause flag enables an additional API that will cause all addresses to be denied. Note however, that this doesn't affect per-address entries of the deny list and will not change the result of the "contains" APIs.

public fun create_regulated_currency_v1<T: drop>(witness: T, decimals: u8, symbol: vector<u8>, name: vector<u8>, description: vector<u8>, icon_url: option::Option<url::Url>, allow_global_pause: bool, ctx: &mut tx_context::TxContext): (coin::TreasuryCap<T>, coin::DenyCapV1<T>, coin::CoinMetadata<T>)
Implementation
public fun create_regulated_currency_v1<T: drop>(
witness: T,
decimals: u8,
symbol: vector<u8>,
name: vector<u8>,
description: vector<u8>,
icon_url: Option<Url>,
allow_global_pause: bool,
ctx: &mut TxContext,
): (TreasuryCap<T>, DenyCapV1<T>, CoinMetadata<T>) {
let (treasury_cap, metadata) = create_currency(
witness,
decimals,
symbol,
name,
description,
icon_url,
ctx
);
let deny_cap = DenyCapV1 {
id: object::new(ctx),
allow_global_pause,
};
transfer::freeze_object(RegulatedCoinMetadata<T> {
id: object::new(ctx),
coin_metadata_object: object::id(&metadata),
deny_cap_object: object::id(&deny_cap),
});
(treasury_cap, deny_cap, metadata)
}

Function mint​

Create a coin worth value and increase the total supply in cap accordingly.

public fun mint<T>(cap: &mut coin::TreasuryCap<T>, value: u64, ctx: &mut tx_context::TxContext): coin::Coin<T>
Implementation
public fun mint<T>(
cap: &mut TreasuryCap<T>, value: u64, ctx: &mut TxContext,
): Coin<T> {
Coin {
id: object::new(ctx),
balance: cap.total_supply.increase_supply(value)
}
}

Function mint_balance​

Mint some amount of T as a Balance and increase the total supply in cap accordingly. Aborts if value + cap.total_supply >= U64_MAX

public fun mint_balance<T>(cap: &mut coin::TreasuryCap<T>, value: u64): balance::Balance<T>
Implementation
public fun mint_balance<T>(
cap: &mut TreasuryCap<T>, value: u64
): Balance<T> {
cap.total_supply.increase_supply(value)
}

Function burn​

Destroy the coin c and decrease the total supply in cap accordingly.

public entry fun burn<T>(cap: &mut coin::TreasuryCap<T>, c: coin::Coin<T>): u64
Implementation
public entry fun burn<T>(cap: &mut TreasuryCap<T>, c: Coin<T>): u64 {
let Coin { id, balance } = c;
id.delete();
cap.total_supply.decrease_supply(balance)
}

Function deny_list_v1_add​

Adds the given address to the deny list, preventing it from interacting with the specified coin type as an input to a transaction. Additionally at the start of the next epoch, the address will be unable to receive objects of this coin type.

public fun deny_list_v1_add<T>(deny_list: &mut deny_list::DenyList, _deny_cap: &mut coin::DenyCapV1<T>, addr: address, ctx: &mut tx_context::TxContext)
Implementation
public fun deny_list_v1_add<T>(
deny_list: &mut DenyList,
_deny_cap: &mut DenyCapV1<T>,
addr: address,
ctx: &mut TxContext,
) {
let ty = type_name::get_with_original_ids<T>().into_string().into_bytes();
deny_list.add(DENY_LIST_COIN_INDEX, ty, addr, ctx)
}

Function deny_list_v1_remove​

Removes an address from the deny list. Similar to deny_list_v1_add, the effect for input objects will be immediate, but the effect for receiving objects will be delayed until the next epoch.

public fun deny_list_v1_remove<T>(deny_list: &mut deny_list::DenyList, _deny_cap: &mut coin::DenyCapV1<T>, addr: address, ctx: &mut tx_context::TxContext)
Implementation
public fun deny_list_v1_remove<T>(
deny_list: &mut DenyList,
_deny_cap: &mut DenyCapV1<T>,
addr: address,
ctx: &mut TxContext,
) {
let ty = type_name::get_with_original_ids<T>().into_string().into_bytes();
deny_list.remove(DENY_LIST_COIN_INDEX, ty, addr, ctx)
}

Function deny_list_v1_contains_current_epoch​

Check if the deny list contains the given address for the current epoch. Denied addresses in the current epoch will be unable to receive objects of this coin type.

public fun deny_list_v1_contains_current_epoch<T>(deny_list: &deny_list::DenyList, addr: address, ctx: &tx_context::TxContext): bool
Implementation
public fun deny_list_v1_contains_current_epoch<T>(
deny_list: &DenyList,
addr: address,
ctx: &TxContext,
): bool {
let ty = type_name::get_with_original_ids<T>().into_string().into_bytes();
deny_list.contains_current_epoch(DENY_LIST_COIN_INDEX, ty, addr, ctx)
}

Function deny_list_v1_contains_next_epoch​

Check if the deny list contains the given address for the next epoch. Denied addresses in the next epoch will immediately be unable to use objects of this coin type as inputs. At the start of the next epoch, the address will be unable to receive objects of this coin type.

public fun deny_list_v1_contains_next_epoch<T>(deny_list: &deny_list::DenyList, addr: address): bool
Implementation
public fun deny_list_v1_contains_next_epoch<T>(
deny_list: &DenyList,
addr: address,
): bool {
let ty = type_name::get_with_original_ids<T>().into_string().into_bytes();
deny_list.contains_next_epoch(DENY_LIST_COIN_INDEX, ty, addr)
}

Function deny_list_v1_enable_global_pause​

Enable the global pause for the given coin type. This will immediately prevent all addresses from using objects of this coin type as inputs. At the start of the next epoch, all addresses will be unable to receive objects of this coin type.

public fun deny_list_v1_enable_global_pause<T>(deny_list: &mut deny_list::DenyList, deny_cap: &mut coin::DenyCapV1<T>, ctx: &mut tx_context::TxContext)
Implementation
public fun deny_list_v1_enable_global_pause<T>(
deny_list: &mut DenyList,
deny_cap: &mut DenyCapV1<T>,
ctx: &mut TxContext,
) {
assert!(deny_cap.allow_global_pause, EGlobalPauseNotAllowed);
let ty = type_name::get_with_original_ids<T>().into_string().into_bytes();
deny_list.enable_global_pause(DENY_LIST_COIN_INDEX, ty, ctx)
}

Function deny_list_v1_disable_global_pause​

Disable the global pause for the given coin type. This will immediately allow all addresses to resume using objects of this coin type as inputs. However, receiving objects of this coin type will still be paused until the start of the next epoch.

public fun deny_list_v1_disable_global_pause<T>(deny_list: &mut deny_list::DenyList, deny_cap: &mut coin::DenyCapV1<T>, ctx: &mut tx_context::TxContext)
Implementation
public fun deny_list_v1_disable_global_pause<T>(
deny_list: &mut DenyList,
deny_cap: &mut DenyCapV1<T>,
ctx: &mut TxContext,
) {
assert!(deny_cap.allow_global_pause, EGlobalPauseNotAllowed);
let ty = type_name::get_with_original_ids<T>().into_string().into_bytes();
deny_list.disable_global_pause(DENY_LIST_COIN_INDEX, ty, ctx)
}

Function deny_list_v1_is_global_pause_enabled_current_epoch​

Check if the global pause is enabled for the given coin type in the current epoch.

public fun deny_list_v1_is_global_pause_enabled_current_epoch<T>(deny_list: &deny_list::DenyList, ctx: &tx_context::TxContext): bool
Implementation
public fun deny_list_v1_is_global_pause_enabled_current_epoch<T>(
deny_list: &DenyList,
ctx: &TxContext,
): bool {
let ty = type_name::get_with_original_ids<T>().into_string().into_bytes();
deny_list.is_global_pause_enabled_current_epoch(DENY_LIST_COIN_INDEX, ty, ctx)
}

Function deny_list_v1_is_global_pause_enabled_next_epoch​

Check if the global pause is enabled for the given coin type in the next epoch.

public fun deny_list_v1_is_global_pause_enabled_next_epoch<T>(deny_list: &deny_list::DenyList): bool
Implementation
public fun deny_list_v1_is_global_pause_enabled_next_epoch<T>(
deny_list: &DenyList,
): bool {
let ty = type_name::get_with_original_ids<T>().into_string().into_bytes();
deny_list.is_global_pause_enabled_next_epoch(DENY_LIST_COIN_INDEX, ty)
}

Function mint_and_transfer​

Mint amount of Coin and send it to recipient. Invokes mint().

public entry fun mint_and_transfer<T>(c: &mut coin::TreasuryCap<T>, amount: u64, recipient: address, ctx: &mut tx_context::TxContext)
Implementation
public entry fun mint_and_transfer<T>(
c: &mut TreasuryCap<T>, amount: u64, recipient: address, ctx: &mut TxContext
) {
transfer::public_transfer(mint(c, amount, ctx), recipient)
}

Function update_name​

Update name of the coin in CoinMetadata

public entry fun update_name<T>(_treasury: &coin::TreasuryCap<T>, metadata: &mut coin::CoinMetadata<T>, name: string::String)
Implementation
public entry fun update_name<T>(
_treasury: &TreasuryCap<T>, metadata: &mut CoinMetadata<T>, name: string::String
) {
metadata.name = name;
}

Function update_symbol​

Update the symbol of the coin in CoinMetadata

public entry fun update_symbol<T>(_treasury: &coin::TreasuryCap<T>, metadata: &mut coin::CoinMetadata<T>, symbol: ascii::String)
Implementation
public entry fun update_symbol<T>(
_treasury: &TreasuryCap<T>, metadata: &mut CoinMetadata<T>, symbol: ascii::String
) {
metadata.symbol = symbol;
}

Function update_description​

Update the description of the coin in CoinMetadata

public entry fun update_description<T>(_treasury: &coin::TreasuryCap<T>, metadata: &mut coin::CoinMetadata<T>, description: string::String)
Implementation
public entry fun update_description<T>(
_treasury: &TreasuryCap<T>, metadata: &mut CoinMetadata<T>, description: string::String
) {
metadata.description = description;
}

Function update_icon_url​

Update the url of the coin in CoinMetadata

public entry fun update_icon_url<T>(_treasury: &coin::TreasuryCap<T>, metadata: &mut coin::CoinMetadata<T>, url: ascii::String)
Implementation
public entry fun update_icon_url<T>(
_treasury: &TreasuryCap<T>, metadata: &mut CoinMetadata<T>, url: ascii::String
) {
metadata.icon_url = option::some(url::new_unsafe(url));
}

Function get_decimals​

public fun get_decimals<T>(metadata: &coin::CoinMetadata<T>): u8
Implementation
public fun get_decimals<T>(metadata: &CoinMetadata<T>): u8 {
metadata.decimals
}

Function get_name​

public fun get_name<T>(metadata: &coin::CoinMetadata<T>): string::String
Implementation
public fun get_name<T>(metadata: &CoinMetadata<T>): string::String {
metadata.name
}

Function get_symbol​

public fun get_symbol<T>(metadata: &coin::CoinMetadata<T>): ascii::String
Implementation
public fun get_symbol<T>(metadata: &CoinMetadata<T>): ascii::String {
metadata.symbol
}

Function get_description​

public fun get_description<T>(metadata: &coin::CoinMetadata<T>): string::String
Implementation
public fun get_description<T>(metadata: &CoinMetadata<T>): string::String {
metadata.description
}

Function get_icon_url​

public fun get_icon_url<T>(metadata: &coin::CoinMetadata<T>): option::Option<url::Url>
Implementation
public fun get_icon_url<T>(metadata: &CoinMetadata<T>): Option<Url> {
metadata.icon_url
}