Trait concordium_std::HasHost

pub trait HasHost<State>: Sized {
    type StateApiType: HasStateApi;
    type ReturnValueType: HasCallResponse + Debug;

    // Required methods
    fn invoke_transfer(
        &self,
        receiver: &AccountAddress,
        amount: Amount
    ) -> TransferResult;
    fn invoke_contract_raw(
        &mut self,
        to: &ContractAddress,
        parameter: Parameter<'_>,
        method: EntrypointName<'_>,
        amount: Amount
    ) -> CallContractResult<Self::ReturnValueType>;
    fn upgrade(&mut self, module: ModuleReference) -> UpgradeResult;
    fn invoke_contract_raw_read_only(
        &self,
        to: &ContractAddress,
        parameter: Parameter<'_>,
        method: EntrypointName<'_>,
        amount: Amount
    ) -> ReadOnlyCallContractResult<Self::ReturnValueType>;
    fn exchange_rates(&self) -> ExchangeRates;
    fn account_balance(
        &self,
        address: AccountAddress
    ) -> QueryAccountBalanceResult;
    fn contract_balance(
        &self,
        address: ContractAddress
    ) -> QueryContractBalanceResult;
    fn state(&self) -> &State;
    fn state_mut(&mut self) -> &mut State;
    fn commit_state(&mut self);
    fn state_builder(&mut self) -> &mut StateBuilder<Self::StateApiType>;
    fn state_and_builder(
        &mut self
    ) -> (&mut State, &mut StateBuilder<Self::StateApiType>);
    fn self_balance(&self) -> Amount;

    // Provided methods
    fn invoke_contract<P: Serial>(
        &mut self,
        to: &ContractAddress,
        parameter: &P,
        method: EntrypointName<'_>,
        amount: Amount
    ) -> CallContractResult<Self::ReturnValueType> { ... }
    fn invoke_contract_read_only<P: Serial>(
        &self,
        to: &ContractAddress,
        parameter: &P,
        method: EntrypointName<'_>,
        amount: Amount
    ) -> ReadOnlyCallContractResult<Self::ReturnValueType> { ... }
}

A type that can serve as the host, meaning that it supports interactions with the chain, such as querying balance of the contract, accessing its state, and invoking operations on other contracts and accounts.

The trait is parameterized by the State type. This is the type of the contract state that the particular contract operates on.

Required Associated Types

type StateApiType: HasStateApi

The type of low-level state that is associated with the host. This provides access to low-level state operations.

type ReturnValueType: HasCallResponse + Debug

The type of return values this host provides. This is the raw return value. The intention is that it will be deserialized by the consumer, via the Read implementation.

The Debug requirement exists so that consumers of this trait may use methods like ExpectReport::expect_report.

Required Methods

fn invoke_transfer( &self, receiver: &AccountAddress, amount: Amount ) -> TransferResult

Perform a transfer to the given account if the contract has sufficient balance.

fn invoke_contract_raw( &mut self, to: &ContractAddress, parameter: Parameter<'_>, method: EntrypointName<'_>, amount: Amount ) -> CallContractResult<Self::ReturnValueType>

Invoke a given method of a contract with the amount and parameter provided. If invocation succeeds then the return value is a pair of a boolean which indicates whether the state of the contract has changed or not, and a possible return value. The return value is present if and only if a V1 contract was invoked.

fn upgrade(&mut self, module: ModuleReference) -> UpgradeResult

Upgrade the module for this instance to a given module. The new module must contain a smart contract with a matching name. Invocations of this instance after the point of a successful upgrade, will use the new smart contract module. The remaining code after a successful upgrade in the same invokation is executed as normal.

This will fail if:

• The supplied module is not deployed.
• The supplied module does not contain a smart contract with a name matching this instance.
• The supplied module is a version 0 smart contract module.

fn invoke_contract_raw_read_only( &self, to: &ContractAddress, parameter: Parameter<'_>, method: EntrypointName<'_>, amount: Amount ) -> ReadOnlyCallContractResult<Self::ReturnValueType>

Invoke a given method of a contract with the amount and parameter provided. If invocation succeeds and the state of the contract instance is not modified then the return value is the return value of the contract that was invoked. The return value is present (i.e., not None) if and only if a V1 contract was invoked. If the invocation succeeds but the state of the contract is modified then this method will panic.

Warning: If the state of the contract was modified prior, i.e.,
if a mutable reference obtained via
state_mut was used to modify the state then
the state must be manually stored via the
commit_state function, otherwise it will not
be seen by the callee.

fn exchange_rates(&self) -> ExchangeRates

Get the current exchange rates used by the chain. That is a Euro per Energy rate and micro CCD per Euro rate.

fn account_balance(&self, address: AccountAddress) -> QueryAccountBalanceResult

Get the current public balance of an account. Here public means unencrypted or unshielded. See AccountBalance for more. This query will fail if the provided address does not exist on chain.

Any amount received by transfers during the transaction until the point of querying are reflected in this balance.

let balance_before = host.account_balance(account)?;
host.invoke_transfer(&account, amount)?;
let balance_after = host.account_balance(account)?; // balance_before + amount

Note: Querying the account invoking this transaction, will return the current account balance subtracted the amount of CCD reserved for paying the entire energy limit and the amount sent as part of update transaction.

fn contract_balance( &self, address: ContractAddress ) -> QueryContractBalanceResult

Get the current balance of a contract instance.

Any amount sent and received by transfers and invocations until the point of querying are reflected in this balance. This query will fail if the provided address does not exist on chain.

let balance_before = host.contract_balance(contract_address)?;
host.invoke_contract(&contract_address, ..., amount)?;
let balance_after = host.contract_balance(contract_address)?; // balance_before + amount

Note: Querying the contract itself returns the balance of the contract including the amount transferred as part of the invocation.

fn state(&self) -> &State

Get an immutable reference to the contract state.

fn state_mut(&mut self) -> &mut State

Get a mutable reference to the contract state.

fn commit_state(&mut self)

Make sure the contract state is fully written out, so that any changes that were done in-memory up to the point in contract execution are reflected in the actual contract state maintained by the node.

fn state_builder(&mut self) -> &mut StateBuilder<Self::StateApiType>

Get the state_builder for the contract state.

fn state_and_builder( &mut self ) -> (&mut State, &mut StateBuilder<Self::StateApiType>)

Get a mutable reference to both the state and the builder. This is required due to limitations of the Rust type system, since otherwise it is not possible to get the reference to the state and the state builder at the same time. Once some incarnation of “view types” is stable this will likely be possible to remove, and the types of state_builder and state_mut can be refined.

fn self_balance(&self) -> Amount

Get the contract’s own current balance. Upon entry to the entrypoint the balance that is returned is the sum of balance of the contract at the time of the invocation and the amount that is being transferred to the contract.

Provided Methods

fn invoke_contract<P: Serial>( &mut self, to: &ContractAddress, parameter: &P, method: EntrypointName<'_>, amount: Amount ) -> CallContractResult<Self::ReturnValueType>

Like invoke_contract_raw, except that the parameter is automatically serialized. If the parameter already implements AsRef<[u8]> or can be equivalently cheaply converted to a byte array, then invoke_contract_raw should be used, since it avoids intermediate allocations.

fn invoke_contract_read_only<P: Serial>( &self, to: &ContractAddress, parameter: &P, method: EntrypointName<'_>, amount: Amount ) -> ReadOnlyCallContractResult<Self::ReturnValueType>

Like invoke_contract_raw_read_only, except that the parameter is automatically serialized. If the parameter already implements AsRef<[u8]> or can be equivalently cheaply converted to a byte array, then invoke_contract_raw should be used, since it avoids intermediate allocations.

Warning: If the state of the contract was modified prior, i.e.,
if a mutable reference obtained via
state_mut was used to modify the state then
the state must be manually stored via the
commit_state function, otherwise it will not
be seen by the callee.

Implementors

impl<State: Serial + DeserialWithState<TestStateApi> + StateClone<TestStateApi>> HasHost<State> for TestHost<State>

type ReturnValueType = Cursor<Vec<u8, Global>>

type StateApiType = TestStateApi