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Module iota::token

The Token module which implements a Closed Loop Token with a configurable policy. The policy is defined by a set of rules that must be satisfied for an action to be performed on the token.

The module is designed to be used with a TreasuryCap to allow for minting and burning of the Tokens. And can act as a replacement / extension or a companion to existing open-loop (Coin) systems.

Module:      iota::balance       iota::coin             iota::token
Main type:   `Balance<T>`         `Coin<T>`               `Token<T>`
Capability:  `Supply<T>`  <---->  `TreasuryCap<T>` <----> `TreasuryCap<T>`
Abilities:   store              key + store           key

The Token system allows for fine-grained control over the actions performed on the token. And hence it is highly suitable for applications that require control over the currency which a simple open-loop system can't provide.

use iota::address;
use iota::bag;
use iota::balance;
use iota::coin;
use iota::config;
use iota::deny_list;
use iota::dynamic_field;
use iota::dynamic_object_field;
use iota::event;
use iota::hex;
use iota::object;
use iota::transfer;
use iota::tx_context;
use iota::types;
use iota::url;
use iota::vec_map;
use iota::vec_set;
use std::address;
use std::ascii;
use std::bcs;
use std::option;
use std::string;
use std::type_name;
use std::vector;

Struct Token​

A single Token with Balance inside. Can only be owned by an address, and actions performed on it must be confirmed in a matching TokenPolicy.

public struct Token<phantom T> has key
Fields

Struct TokenPolicyCap​

A Capability that manages a single TokenPolicy specified in the for field. Created together with TokenPolicy in the new function.

public struct TokenPolicyCap<phantom T> has key, store
Fields

Struct TokenPolicy​

TokenPolicy represents a set of rules that define what actions can be performed on a Token and which Rules must be satisfied for the action to succeed.

  • For the sake of availability, TokenPolicy is a key-only object.
  • Each TokenPolicy is managed by a matching TokenPolicyCap.
  • For an action to become available, there needs to be a record in the rules VecMap. To allow an action to be performed freely, there's an allow function that can be called by the TokenPolicyCap owner.
public struct TokenPolicy<phantom T> has key
Fields
id: iota::object::UID
spent_balance: iota::balance::Balance<T>

The balance that is effectively spent by the user on the "spend" action. However, actual decrease of the supply can only be done by the TreasuryCap owner when flush is called. This balance is effectively spent and cannot be accessed by anyone but the TreasuryCap owner.

rules: iota::vec_map::VecMap<std::string::String, iota::vec_set::VecSet<std::type_name::TypeName>>

The set of rules that define what actions can be performed on the token. For each "action" there's a set of Rules that must be satisfied for the ActionRequest to be confirmed.

Struct ActionRequest​

A request to perform an "Action" on a token. Stores the information about the action to be performed and must be consumed by the confirm_request or confirm_request_mut functions when the Rules are satisfied.

public struct ActionRequest<phantom T>
Fields
name: std::string::String

Name of the Action to look up in the Policy. Name can be one of the default actions: transfer, spend, to_coin, from_coin or a custom action.

amount: u64

Amount is present in all of the txs

sender: address

Sender is a permanent field always

recipient: std::option::Option<address>

Recipient is only available in transfer action.

spent_balance: std::option::Option<iota::balance::Balance<T>>

The balance to be "spent" in the TokenPolicy, only available in the spend action.

approvals: iota::vec_set::VecSet<std::type_name::TypeName>

Collected approvals (stamps) from completed Rules. They're matched against TokenPolicy.rules to determine if the request can be confirmed.

Struct RuleKey​

Dynamic field key for the TokenPolicy to store the Config for a specific action Rule. There can be only one configuration per Rule per TokenPolicy.

public struct RuleKey<phantom T> has copy, drop, store
Fields
is_protected: bool

Struct TokenPolicyCreated​

An event emitted when a TokenPolicy is created and shared. Because TokenPolicy can only be shared (and potentially frozen in the future), we emit this event in the share_policy function and mark it as mutable.

public struct TokenPolicyCreated<phantom T> has copy, drop
Fields
id: iota::object::ID

ID of the TokenPolicy that was created.

is_mutable: bool

Whether the TokenPolicy is "shared" (mutable) or "frozen" (immutable) - TBD.

Constants​

The balance is too low to perform the action.

const EBalanceTooLow: u64 = 3;

The balance is not zero when trying to confirm with TransferPolicyCap.

const ECantConsumeBalance: u64 = 5;

Rule is trying to access a missing config (with type).

const ENoConfig: u64 = 6;

The rule was not approved.

const ENotApproved: u64 = 1;

Trying to perform an admin action with a wrong cap.

const ENotAuthorized: u64 = 2;

The balance is not zero.

const ENotZero: u64 = 4;

The action is not allowed (defined) in the policy.

const EUnknownAction: u64 = 0;

Using confirm_request_mut without spent_balance. Immutable version of the function must be used instead.

const EUseImmutableConfirm: u64 = 7;

A Tag for the from_coin action.

const FROM_COIN: vector<u8> = vector[102, 114, 111, 109, 95, 99, 111, 105, 110];

A Tag for the spend action.

const SPEND: vector<u8> = vector[115, 112, 101, 110, 100];

A Tag for the to_coin action.

const TO_COIN: vector<u8> = vector[116, 111, 95, 99, 111, 105, 110];

A Tag for the transfer action.

const TRANSFER: vector<u8> = vector[116, 114, 97, 110, 115, 102, 101, 114];

Function new_policy​

Create a new TokenPolicy and a matching TokenPolicyCap. The TokenPolicy must then be shared using the share_policy method.

TreasuryCap guarantees full ownership over the currency, and is unique, hence it is safe to use it for authorization.

public fun new_policy<T>(_treasury_cap: &iota::coin::TreasuryCap<T>, ctx: &mut iota::tx_context::TxContext): (iota::token::TokenPolicy<T>, iota::token::TokenPolicyCap<T>)
Implementation
public fun new_policy<T>(
_treasury_cap: &TreasuryCap<T>,
ctx: &mut TxContext,
): (TokenPolicy<T>, TokenPolicyCap<T>) {
let policy = TokenPolicy {
id: object::new(ctx),
spent_balance: balance::zero(),
rules: vec_map::empty(),
};
let cap = TokenPolicyCap {
id: object::new(ctx),
<b>for</b>: object::id(&policy),
};
(policy, cap)
}

Function share_policy​

Share the TokenPolicy. Due to key-only restriction, it must be shared after initialization.

public fun share_policy<T>(policy: iota::token::TokenPolicy<T>)
Implementation
public fun share_policy<T>(policy: TokenPolicy<T>) {
event::emit(TokenPolicyCreated<T> {
id: object::id(&policy),
is_mutable: true,
});
transfer::share_object(policy)
}

Function transfer​

Transfer a Token to a recipient. Creates an ActionRequest for the "transfer" action. The ActionRequest contains the recipient field to be used in verification.

public fun transfer<T>(t: iota::token::Token<T>, recipient: address, ctx: &mut iota::tx_context::TxContext): iota::token::ActionRequest<T>
Implementation
public fun transfer<T>(t: Token<T>, recipient: address, ctx: &mut TxContext): ActionRequest<T> {
let amount = t.balance.value();
transfer::transfer(t, recipient);
new_request(
transfer_action(),
amount,
option::some(recipient),
option::none(),
ctx,
)
}

Function spend​

Spend a Token by unwrapping it and storing the Balance in the ActionRequest for the "spend" action. The ActionRequest contains the spent_balance field to be used in verification.

Spend action requires confirm_request_mut to be called to confirm the request and join the spent balance with the TokenPolicy.spent_balance.

public fun spend<T>(t: iota::token::Token<T>, ctx: &mut iota::tx_context::TxContext): iota::token::ActionRequest<T>
Implementation
public fun spend<T>(t: Token<T>, ctx: &mut TxContext): ActionRequest<T> {
let Token { id, balance } = t;
id.delete();
new_request(
spend_action(),
balance.value(),
option::none(),
option::some(balance),
ctx,
)
}

Function to_coin​

Convert Token into an open Coin. Creates an ActionRequest for the "to_coin" action.

public fun to_coin<T>(t: iota::token::Token<T>, ctx: &mut iota::tx_context::TxContext): (iota::coin::Coin<T>, iota::token::ActionRequest<T>)
Implementation
public fun to_coin<T>(t: Token<T>, ctx: &mut TxContext): (Coin<T>, ActionRequest<T>) {
let Token { id, balance } = t;
let amount = balance.value();
id.delete();
(
balance.into_coin(ctx),
new_request(
to_coin_action(),
amount,
option::none(),
option::none(),
ctx,
),
)
}

Function from_coin​

Convert an open Coin into a Token. Creates an ActionRequest for the "from_coin" action.

public fun from_coin<T>(coin: iota::coin::Coin<T>, ctx: &mut iota::tx_context::TxContext): (iota::token::Token<T>, iota::token::ActionRequest<T>)
Implementation
public fun from_coin<T>(coin: Coin<T>, ctx: &mut TxContext): (Token<T>, ActionRequest<T>) {
let amount = coin.value();
let token = Token {
id: object::new(ctx),
balance: coin.into_balance(),
};
(
token,
new_request(
from_coin_action(),
amount,
option::none(),
option::none(),
ctx,
),
)
}

Function join​

Join two Tokens into one, always available.

public fun join<T>(token: &mut iota::token::Token<T>, another: iota::token::Token<T>)
Implementation
public fun join<T>(token: &mut Token<T>, another: Token<T>) {
let Token { id, balance } = another;
token.balance.join(balance);
id.delete();
}

Function split​

Split a Token with amount. Aborts if the Token.balance is lower than amount.

public fun split<T>(token: &mut iota::token::Token<T>, amount: u64, ctx: &mut iota::tx_context::TxContext): iota::token::Token<T>
Implementation
public fun split<T>(token: &mut Token<T>, amount: u64, ctx: &mut TxContext): Token<T> {
assert!(token.balance.value() >= amount, EBalanceTooLow);
Token {
id: object::new(ctx),
balance: token.balance.split(amount),
}
}

Function zero​

Create a zero Token.

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

Function destroy_zero​

Destroy an empty Token, fails if the balance is non-zero. Aborts if the Token.balance is not zero.

public fun destroy_zero<T>(token: iota::token::Token<T>)
Implementation
public fun destroy_zero<T>(token: Token<T>) {
let Token { id, balance } = token;
assert!(balance.value() == 0, ENotZero);
balance.destroy_zero();
id.delete();
}

Function keep​

Transfer the Token to the transaction sender.

public fun keep<T>(token: iota::token::Token<T>, ctx: &mut iota::tx_context::TxContext)
Implementation
public fun keep<T>(token: Token<T>, ctx: &mut TxContext) {
transfer::transfer(token, ctx.sender())
}

Function new_request​

Create a new ActionRequest. Publicly available method to allow for custom actions.

public fun new_request<T>(name: std::string::String, amount: u64, recipient: std::option::Option<address>, spent_balance: std::option::Option<iota::balance::Balance<T>>, ctx: &iota::tx_context::TxContext): iota::token::ActionRequest<T>
Implementation
public fun new_request<T>(
name: String,
amount: u64,
recipient: Option<address>,
spent_balance: Option<Balance<T>>,
ctx: &TxContext,
): ActionRequest<T> {
ActionRequest {
name,
amount,
recipient,
spent_balance,
sender: ctx.sender(),
approvals: vec_set::empty(),
}
}

Function confirm_request​

Confirm the request against the TokenPolicy and return the parameters of the request: (Name, Amount, Sender, Recipient).

Cannot be used for spend and similar actions that deliver spent_balance to the TokenPolicy. For those actions use confirm_request_mut.

Aborts if:

public fun confirm_request<T>(policy: &iota::token::TokenPolicy<T>, request: iota::token::ActionRequest<T>, _ctx: &mut iota::tx_context::TxContext): (std::string::String, u64, address, std::option::Option<address>)
Implementation
public fun confirm_request<T>(
policy: &TokenPolicy<T>,
request: ActionRequest<T>,
_ctx: &mut TxContext,
): (String, u64, address, Option<address>) {
assert!(request.spent_balance.is_none(), ECantConsumeBalance);
assert!(policy.rules.contains(&request.name), EUnknownAction);
let ActionRequest {
name,
approvals,
spent_balance,
amount,
sender,
recipient,
} = request;
spent_balance.destroy_none();
let rules = &(*policy.rules.get(&name)).into_keys();
let rules_len = rules.length();
let mut i = 0;
while (i < rules_len) {
let rule = &rules[i];
assert!(approvals.contains(rule), ENotApproved);
i = i + 1;
};
(name, amount, sender, recipient)
}

Function confirm_request_mut​

Confirm the request against the TokenPolicy and return the parameters of the request: (Name, Amount, Sender, Recipient).

Unlike confirm_request this function requires mutable access to the TokenPolicy and must be used on spend action. After dealing with the spent balance it calls confirm_request internally.

See confirm_request for the list of abort conditions.

public fun confirm_request_mut<T>(policy: &mut iota::token::TokenPolicy<T>, request: iota::token::ActionRequest<T>, ctx: &mut iota::tx_context::TxContext): (std::string::String, u64, address, std::option::Option<address>)
Implementation
public fun confirm_request_mut<T>(
policy: &mut TokenPolicy<T>,
mut request: ActionRequest<T>,
ctx: &mut TxContext,
): (String, u64, address, Option<address>) {
assert!(policy.rules.contains(&request.name), EUnknownAction);
assert!(request.spent_balance.is_some(), EUseImmutableConfirm);
policy.spent_balance.join(request.spent_balance.extract());
confirm_request(policy, request, ctx)
}

Function confirm_with_policy_cap​

Confirm an ActionRequest as the TokenPolicyCap owner. This function allows TokenPolicy owner to perform Capability-gated actions ignoring the ruleset specified in the TokenPolicy.

Aborts if request contains spent_balance due to inability of the TokenPolicyCap to decrease supply. For scenarios like this a TreasuryCap is required (see confirm_with_treasury_cap).

public fun confirm_with_policy_cap<T>(_policy_cap: &iota::token::TokenPolicyCap<T>, request: iota::token::ActionRequest<T>, _ctx: &mut iota::tx_context::TxContext): (std::string::String, u64, address, std::option::Option<address>)
Implementation
public fun confirm_with_policy_cap<T>(
_policy_cap: &TokenPolicyCap<T>,
request: ActionRequest<T>,
_ctx: &mut TxContext,
): (String, u64, address, Option<address>) {
assert!(request.spent_balance.is_none(), ECantConsumeBalance);
let ActionRequest {
name,
amount,
sender,
recipient,
approvals: _,
spent_balance,
} = request;
spent_balance.destroy_none();
(name, amount, sender, recipient)
}

Function confirm_with_treasury_cap​

Confirm an ActionRequest as the TreasuryCap owner. This function allows TreasuryCap owner to perform Capability-gated actions ignoring the ruleset specified in the TokenPolicy.

Unlike confirm_with_policy_cap this function allows spent_balance to be consumed, decreasing the total_supply of the Token.

public fun confirm_with_treasury_cap<T>(treasury_cap: &mut iota::coin::TreasuryCap<T>, request: iota::token::ActionRequest<T>, _ctx: &mut iota::tx_context::TxContext): (std::string::String, u64, address, std::option::Option<address>)
Implementation
public fun confirm_with_treasury_cap<T>(
treasury_cap: &mut TreasuryCap<T>,
request: ActionRequest<T>,
_ctx: &mut TxContext,
): (String, u64, address, Option<address>) {
let ActionRequest {
name,
amount,
sender,
recipient,
approvals: _,
spent_balance,
} = request;
if (spent_balance.is_some()) {
treasury_cap.supply_mut().decrease_supply(spent_balance.destroy_some());
} else {
spent_balance.destroy_none();
};
(name, amount, sender, recipient)
}

Function add_approval​

Add an "approval" to the ActionRequest by providing a Witness. Intended to be used by Rules to add their own approvals, however, can be used to add arbitrary approvals to the request (not only the ones required by the TokenPolicy).

public fun add_approval<T, W: drop>(_t: W, request: &mut iota::token::ActionRequest<T>, _ctx: &mut iota::tx_context::TxContext)
Implementation
public fun add_approval<T, W: drop>(_t: W, request: &mut ActionRequest<T>, _ctx: &mut TxContext) {
request.approvals.insert(type_name::get<W>())
}

Function add_rule_config​

Add a Config for a Rule in the TokenPolicy. Rule configuration is independent from the TokenPolicy.rules and needs to be managed by the Rule itself. Configuration is stored per Rule and not per Rule per Action to allow reuse in different actions.

  • Rule witness guarantees that the Config is approved by the Rule.
  • TokenPolicyCap guarantees that the Config setup is initiated by the TokenPolicy owner.
public fun add_rule_config<T, Rule: drop, Config: store>(_rule: Rule, self: &mut iota::token::TokenPolicy<T>, cap: &iota::token::TokenPolicyCap<T>, config: Config, _ctx: &mut iota::tx_context::TxContext)
Implementation
public fun add_rule_config<T, Rule: drop, Config: store>(
_rule: Rule,
self: &mut TokenPolicy<T>,
cap: &TokenPolicyCap<T>,
config: Config,
_ctx: &mut TxContext,
) {
assert!(object::id(self) == cap.<b>for</b>, ENotAuthorized);
df::add(&mut self.id, key<Rule>(), config)
}

Function rule_config​

Get a Config for a Rule in the TokenPolicy. Requires Rule witness, hence can only be read by the Rule itself. This requirement guarantees safety of the stored Config and allows for simpler dynamic field management inside the Rule Config (custom type keys are not needed for access gating).

Aborts if the Config is not present.

public fun rule_config<T, Rule: drop, Config: store>(_rule: Rule, self: &iota::token::TokenPolicy<T>): &Config
Implementation
public fun rule_config<T, Rule: drop, Config: store>(_rule: Rule, self: &TokenPolicy<T>): &Config {
assert!(has_rule_config_with_type<T, Rule, Config>(self), ENoConfig);
df::borrow(&self.id, key<Rule>())
}

Function rule_config_mut​

Get mutable access to the Config for a Rule in the TokenPolicy. Requires Rule witness, hence can only be read by the Rule itself, as well as TokenPolicyCap to guarantee that the TokenPolicy owner is the one who initiated the Config modification.

Aborts if:

public fun rule_config_mut<T, Rule: drop, Config: store>(_rule: Rule, self: &mut iota::token::TokenPolicy<T>, cap: &iota::token::TokenPolicyCap<T>): &mut Config
Implementation
public fun rule_config_mut<T, Rule: drop, Config: store>(
_rule: Rule,
self: &mut TokenPolicy<T>,
cap: &TokenPolicyCap<T>,
): &mut Config {
assert!(has_rule_config_with_type<T, Rule, Config>(self), ENoConfig);
assert!(object::id(self) == cap.<b>for</b>, ENotAuthorized);
df::borrow_mut(&mut self.id, key<Rule>())
}

Function remove_rule_config​

Remove a Config for a Rule in the TokenPolicy. Unlike the add_rule_config, this function does not require a Rule witness, hence can be performed by the TokenPolicy owner on their own.

Rules need to make sure that the Config is present when performing verification of the ActionRequest.

Aborts if:

public fun remove_rule_config<T, Rule, Config: store>(self: &mut iota::token::TokenPolicy<T>, cap: &iota::token::TokenPolicyCap<T>, _ctx: &mut iota::tx_context::TxContext): Config
Implementation
public fun remove_rule_config<T, Rule, Config: store>(
self: &mut TokenPolicy<T>,
cap: &TokenPolicyCap<T>,
_ctx: &mut TxContext,
): Config {
assert!(has_rule_config_with_type<T, Rule, Config>(self), ENoConfig);
assert!(object::id(self) == cap.<b>for</b>, ENotAuthorized);
df::remove(&mut self.id, key<Rule>())
}

Function has_rule_config​

Check if a config for a Rule is set in the TokenPolicy without checking the type of the Config.

public fun has_rule_config<T, Rule>(self: &iota::token::TokenPolicy<T>): bool
Implementation
public fun has_rule_config<T, Rule>(self: &TokenPolicy<T>): bool {
df::exists_<RuleKey<Rule>>(&self.id, key<Rule>())
}

Function has_rule_config_with_type​

Check if a Config for a Rule is set in the TokenPolicy and that it matches the type provided.

public fun has_rule_config_with_type<T, Rule, Config: store>(self: &iota::token::TokenPolicy<T>): bool
Implementation
public fun has_rule_config_with_type<T, Rule, Config: store>(self: &TokenPolicy<T>): bool {
df::exists_with_type<RuleKey<Rule>, Config>(&self.id, key<Rule>())
}

Function allow​

Allows an action to be performed on the Token freely by adding an empty set of Rules for the action.

Aborts if the TokenPolicyCap is not matching the TokenPolicy.

public fun allow<T>(self: &mut iota::token::TokenPolicy<T>, cap: &iota::token::TokenPolicyCap<T>, action: std::string::String, _ctx: &mut iota::tx_context::TxContext)
Implementation
public fun allow<T>(
self: &mut TokenPolicy<T>,
cap: &TokenPolicyCap<T>,
action: String,
_ctx: &mut TxContext,
) {
assert!(object::id(self) == cap.<b>for</b>, ENotAuthorized);
self.rules.insert(action, vec_set::empty());
}

Function disallow​

Completely disallows an action on the Token by removing the record from the TokenPolicy.rules.

Aborts if the TokenPolicyCap is not matching the TokenPolicy.

public fun disallow<T>(self: &mut iota::token::TokenPolicy<T>, cap: &iota::token::TokenPolicyCap<T>, action: std::string::String, _ctx: &mut iota::tx_context::TxContext)
Implementation
public fun disallow<T>(
self: &mut TokenPolicy<T>,
cap: &TokenPolicyCap<T>,
action: String,
_ctx: &mut TxContext,
) {
assert!(object::id(self) == cap.<b>for</b>, ENotAuthorized);
self.rules.remove(&action);
}

Function add_rule_for_action​

Adds a Rule for an action with name in the TokenPolicy.

Aborts if the TokenPolicyCap is not matching the TokenPolicy.

public fun add_rule_for_action<T, Rule: drop>(self: &mut iota::token::TokenPolicy<T>, cap: &iota::token::TokenPolicyCap<T>, action: std::string::String, ctx: &mut iota::tx_context::TxContext)
Implementation
public fun add_rule_for_action<T, Rule: drop>(
self: &mut TokenPolicy<T>,
cap: &TokenPolicyCap<T>,
action: String,
ctx: &mut TxContext,
) {
assert!(object::id(self) == cap.<b>for</b>, ENotAuthorized);
if (!self.rules.contains(&action)) {
allow(self, cap, action, ctx);
};
self.rules.get_mut(&action).insert(type_name::get<Rule>())
}

Function remove_rule_for_action​

Removes a rule for an action with name in the TokenPolicy. Returns the config object to be handled by the sender (or a Rule itself).

Aborts if the TokenPolicyCap is not matching the TokenPolicy.

public fun remove_rule_for_action<T, Rule: drop>(self: &mut iota::token::TokenPolicy<T>, cap: &iota::token::TokenPolicyCap<T>, action: std::string::String, _ctx: &mut iota::tx_context::TxContext)
Implementation
public fun remove_rule_for_action<T, Rule: drop>(
self: &mut TokenPolicy<T>,
cap: &TokenPolicyCap<T>,
action: String,
_ctx: &mut TxContext,
) {
assert!(object::id(self) == cap.<b>for</b>, ENotAuthorized);
self.rules.get_mut(&action).remove(&type_name::get<Rule>())
}

Function mint​

Mint a Token with a given amount using the TreasuryCap.

public fun mint<T>(cap: &mut iota::coin::TreasuryCap<T>, amount: u64, ctx: &mut iota::tx_context::TxContext): iota::token::Token<T>
Implementation
public fun mint<T>(cap: &mut TreasuryCap<T>, amount: u64, ctx: &mut TxContext): Token<T> {
let balance = cap.supply_mut().increase_supply(amount);
Token { id: object::new(ctx), balance }
}

Function burn​

Burn a Token using the TreasuryCap.

public fun burn<T>(cap: &mut iota::coin::TreasuryCap<T>, token: iota::token::Token<T>)
Implementation
public fun burn<T>(cap: &mut TreasuryCap<T>, token: Token<T>) {
let Token { id, balance } = token;
cap.supply_mut().decrease_supply(balance);
id.delete();
}

Function flush​

Flush the TokenPolicy.spent_balance into the TreasuryCap. This action is only available to the TreasuryCap owner.

public fun flush<T>(self: &mut iota::token::TokenPolicy<T>, cap: &mut iota::coin::TreasuryCap<T>, _ctx: &mut iota::tx_context::TxContext): u64
Implementation
public fun flush<T>(
self: &mut TokenPolicy<T>,
cap: &mut TreasuryCap<T>,
_ctx: &mut TxContext,
): u64 {
let amount = self.spent_balance.value();
let balance = self.spent_balance.split(amount);
cap.supply_mut().decrease_supply(balance)
}

Function is_allowed​

Check whether an action is present in the rules VecMap.

public fun is_allowed<T>(self: &iota::token::TokenPolicy<T>, action: &std::string::String): bool
Implementation
public fun is_allowed<T>(self: &TokenPolicy<T>, action: &String): bool {
self.rules.contains(action)
}

Function rules​

Returns the rules required for a specific action.

public fun rules<T>(self: &iota::token::TokenPolicy<T>, action: &std::string::String): iota::vec_set::VecSet<std::type_name::TypeName>
Implementation
public fun rules<T>(self: &TokenPolicy<T>, action: &String): VecSet<TypeName> {
*self.rules.get(action)
}

Function spent_balance​

Returns the spent_balance of the TokenPolicy.

public fun spent_balance<T>(self: &iota::token::TokenPolicy<T>): u64
Implementation
public fun spent_balance<T>(self: &TokenPolicy<T>): u64 {
self.spent_balance.value()
}

Function value​

Returns the balance of the Token.

public fun value<T>(t: &iota::token::Token<T>): u64
Implementation
public fun value<T>(t: &Token<T>): u64 {
t.balance.value()
}

Function transfer_action​

Name of the Transfer action.

public fun transfer_action(): std::string::String
Implementation
public fun transfer_action(): String {
let transfer_str = TRANSFER;
transfer_str.to_string()
}

Function spend_action​

Name of the Spend action.

public fun spend_action(): std::string::String
Implementation
public fun spend_action(): String {
let spend_str = SPEND;
spend_str.to_string()
}

Function to_coin_action​

Name of the ToCoin action.

public fun to_coin_action(): std::string::String
Implementation
public fun to_coin_action(): String {
let to_coin_str = TO_COIN;
to_coin_str.to_string()
}

Function from_coin_action​

Name of the FromCoin action.

public fun from_coin_action(): std::string::String
Implementation
public fun from_coin_action(): String {
let from_coin_str = FROM_COIN;
from_coin_str.to_string()
}

Function action​

The Action in the ActionRequest.

public fun action<T>(self: &iota::token::ActionRequest<T>): std::string::String
Implementation
public fun action<T>(self: &ActionRequest<T>): String { self.name }

Function amount​

Amount of the ActionRequest.

public fun amount<T>(self: &iota::token::ActionRequest<T>): u64
Implementation
public fun amount<T>(self: &ActionRequest<T>): u64 { self.amount }

Function sender​

Sender of the ActionRequest.

public fun sender<T>(self: &iota::token::ActionRequest<T>): address
Implementation
public fun sender<T>(self: &ActionRequest<T>): address { self.sender }

Function recipient​

Recipient of the ActionRequest.

public fun recipient<T>(self: &iota::token::ActionRequest<T>): std::option::Option<address>
Implementation
public fun recipient<T>(self: &ActionRequest<T>): Option<address> {
self.recipient
}

Function approvals​

Approvals of the ActionRequest.

public fun approvals<T>(self: &iota::token::ActionRequest<T>): iota::vec_set::VecSet<std::type_name::TypeName>
Implementation
public fun approvals<T>(self: &ActionRequest<T>): VecSet<TypeName> {
self.approvals
}

Function spent​

Burned balance of the ActionRequest.

public fun spent<T>(self: &iota::token::ActionRequest<T>): std::option::Option<u64>
Implementation
public fun spent<T>(self: &ActionRequest<T>): Option<u64> {
if (self.spent_balance.is_some()) {
option::some(self.spent_balance.borrow().value())
} else {
option::none()
}
}

Function key​

Create a new RuleKey for a Rule. The is_protected field is kept for potential future use, if Rules were to have a freely modifiable storage as addition / replacement for the Config system.

The goal of is_protected is to potentially allow Rules store a mutable version of their configuration and mutate state on user action.

fun key<Rule>(): iota::token::RuleKey<Rule>
Implementation
fun key<Rule>(): RuleKey<Rule> { RuleKey { is_protected: true } }