path: root/accounts/abi/bind/backend.go

// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package bind

import (
    "context"
    "errors"
    "math/big"

    "github.com/ethereum/go-ethereum"
    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core/types"
)

var (
    // ErrNoCode is returned by call and transact operations for which the requested
    // recipient contract to operate on does not exist in the state db or does not
    // have any code associated with it (i.e. suicided).
    ErrNoCode = errors.New("no contract code at given address")

    // This error is raised when attempting to perform a pending state action
    // on a backend that doesn't implement PendingContractCaller.
    ErrNoPendingState = errors.New("backend does not support pending state")

    // This error is returned by WaitDeployed if contract creation leaves an
    // empty contract behind.
    ErrNoCodeAfterDeploy = errors.New("no contract code after deployment")
)

// ContractCaller defines the methods needed to allow operating with contract on a read
// only basis.
type ContractCaller interface {
    // CodeAt returns the code of the given account. This is needed to differentiate
    // between contract internal errors and the local chain being out of sync.
    CodeAt(ctx context.Context, contract common.Address, blockNumber *big.Int) ([]byte, error)
    // ContractCall executes an Ethereum contract call with the specified data as the
    // input.
    CallContract(ctx context.Context, call ethereum.CallMsg, blockNumber *big.Int) ([]byte, error)
}

// PendingContractCaller defines methods to perform contract calls on the pending state.
// Call will try to discover this interface when access to the pending state is requested.
// If the backend does not support the pending state, Call returns ErrNoPendingState.
type PendingContractCaller interface {
    // PendingCodeAt returns the code of the given account in the pending state.
    PendingCodeAt(ctx context.Context, contract common.Address) ([]byte, error)
    // PendingCallContract executes an Ethereum contract call against the pending state.
    PendingCallContract(ctx context.Context, call ethereum.CallMsg) ([]byte, error)
}

// ContractTransactor defines the methods needed to allow operating with contract
// on a write only basis. Beside the transacting method, the remainder are helpers
// used when the user does not provide some needed values, but rather leaves it up
// to the transactor to decide.
type ContractTransactor interface {
    // PendingCodeAt returns the code of the given account in the pending state.
    PendingCodeAt(ctx context.Context, account common.Address) ([]byte, error)
    // PendingNonceAt retrieves the current pending nonce associated with an account.
    PendingNonceAt(ctx context.Context, account common.Address) (uint64, error)
    // SuggestGasPrice retrieves the currently suggested gas price to allow a timely
    // execution of a transaction.
    SuggestGasPrice(ctx context.Context) (*big.Int, error)
    // EstimateGas tries to estimate the gas needed to execute a specific
    // transaction based on the current pending state of the backend blockchain.
    // There is no guarantee that this is the true gas limit requirement as other
    // transactions may be added or removed by miners, but it should provide a basis
    // for setting a reasonable default.
    EstimateGas(ctx context.Context, call ethereum.CallMsg) (gas uint64, err error)
    // SendTransaction injects the transaction into the pending pool for execution.
    SendTransaction(ctx context.Context, tx *types.Transaction) error
}

// ContractFilterer defines the methods needed to access log events using one-off
// queries or continuous event subscriptions.
type ContractFilterer interface {
    // FilterLogs executes a log filter operation, blocking during execution and
    // returning all the results in one batch.
    //
    // TODO(karalabe): Deprecate when the subscription one can return past data too.
    FilterLogs(ctx context.Context, query ethereum.FilterQuery) ([]types.Log, error)

    // SubscribeFilterLogs creates a background log filtering operation, returning
    // a subscription immediately, which can be used to stream the found events.
    SubscribeFilterLogs(ctx context.Context, query ethereum.FilterQuery, ch chan<- types.Log) (ethereum.Subscription, error)
}

// DeployBackend wraps the operations needed by WaitMined and WaitDeployed.
type DeployBackend interface {
    TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error)
    CodeAt(ctx context.Context, account common.Address, blockNumber *big.Int) ([]byte, error)
}

// ContractBackend defines the methods needed to work with contracts on a read-write basis.
type ContractBackend interface {
    ContractCaller
    ContractTransactor
    ContractFilterer
}