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SmartContract

scrypt-ts-opcat v1.0.1

scrypt-ts-opcat / SmartContract

Class: SmartContract\<StateT>

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:54

The main contract class. To write a contract, extend this class as such:

Onchain​

Example​

class YourSmartContract extends SmartContract {
  // your smart contract code here
}

Extends​

  • AbstractContract

Type Parameters​

• StateT extends OpcatState = undefined

Constructors​

new SmartContract()​

new SmartContract\<StateT>(...args): SmartContract\<StateT>

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:106

Parameters​

args​

...SupportedParamType[]

Returns​

SmartContract\<StateT>

Overrides​

AbstractContract.constructor

Backtrace​

backtraceToOutpoint()​

backtraceToOutpoint(backtraceInfo, genesisOutpoint): boolean

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:654

Check whether the contract can be traced back to the genesis outpoint.

Parameters​

backtraceInfo​

BacktraceInfo

the backtrace info to verify, including prevTx and prevPrevTx informations

genesisOutpoint​

ByteString

expected genesis outpoint to be traced back to

Returns​

boolean

true if the contract can be backtraced to the genesis outpoint. Otherwise false.

Onchain​

Overrides​

AbstractContract.backtraceToOutpoint

backtraceToScript()​

backtraceToScript(backtraceInfo, genesisScript): boolean

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:666

Check whether the contract can be traced back to the genesis script.

Parameters​

backtraceInfo​

BacktraceInfo

the backtrace info to verify, including prevTx and prevPrevTx informations

genesisScript​

ByteString

expected genesis script to be traced back to

Returns​

boolean

true if the contract can be backtraced to the genesis script. Otherwise false.

Onchain​

Overrides​

AbstractContract.backtraceToScript

Other​

lockingScript​

readonly lockingScript: Script

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:89

Locking script corresponding to the SmartContract

state​

state: StateT

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:84

The state of the contract UTXO, usually committed to the first OP_RETURN output, is revealed when spending.

Onchain​

utxo?​

optional utxo: ExtUtxo

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:78

artifact​

static artifact: Artifact

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:60

Bitcoin Contract Artifact

changeInfo​

Get Signature​

get changeInfo(): TxOut

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:518

Get the change info of the change output for current psbt.

Onchain​
Returns​

TxOut

the change info of current psbt

ctx​

Get Signature​

get ctx(): IContext

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:319

Get the context details of the current PSBT input in which this contract is called or spent.

Onchain​
Returns​

IContext

Overrides​

AbstractContract.ctx

debug​

Get Signature​

get debug(): object

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:527

A set of functions for debugging contracts, which can only be called in @method methods.

Onchain​
Returns​

object

diffOutputs()​

diffOutputs: (outputsByte) => void

Parameters​
outputsByte​

ByteString

Returns​

void

inputContext​

Get Signature​

get inputContext(): InputContext

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:371

Get the context of the current PSBT input in which this contract is called or spent.

Returns​

InputContext

the context of the current PSBT input

spentPsbt​

Get Signature​

get spentPsbt(): Contextual

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:354

Gets the PSBT (Partially Signed Bitcoin Transaction) that was used to spend this contract. Returns undefined if no spending transaction exists.

Returns​

Contextual

bindToUtxo()​

bindToUtxo(utxo): this

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:690

Binds the smart contract to a UTXO by verifying and setting its script.

Parameters​

utxo​

The UTXO to bind to (script field is optional)

Optional\<ExtUtxo, "script"> | Optional\<UTXO, "script">

Returns​

this

The contract instance for chaining

Throws​

Error if the UTXO's script exists and doesn't match the contract's locking script

buildChangeOutput()​

buildChangeOutput(): ByteString

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:208

A built-in function to create an [change output][https://en.bitcoin.it/wiki/Change](https://en.bitcoin.it/wiki/Change).

Returns​

ByteString

Onchain​

Overrides​

AbstractContract.buildChangeOutput

checkInputState()​

checkInputState(inputIndex, serializedState): boolean

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:299

check state of the input. option in the @method() decorator to false.

Parameters​

inputIndex​

Int32

index of the input

serializedState​

ByteString

the state of the input

Returns​

boolean

success if stateHash is valid

Onchain​

Overrides​

AbstractContract.checkInputState

checkOutputs()​

checkOutputs(outputs): boolean

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:568

Check the outputs with the context of current transaction.

Parameters​

outputs​

ByteString

the expected serialized outputs of the current transaction

Returns​

boolean

true if the outputs are not consistent with the transaction context, otherwise false.

Onchain​

Overrides​

AbstractContract.checkOutputs

checkSHPreimage()​

checkSHPreimage(shPreimage): boolean

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:161

Using the [OP_PUSH_TX][https://medium.com/@xiaohuiliu/op-push-tx-3d3d279174c1](https://medium.com/@xiaohuiliu/op-push-tx-3d3d279174c1) technique, check if shPreimage is the preimage of the current transaction.

Parameters​

shPreimage​

SHPreimage

Returns​

boolean

true if shPreimage is the preimage of the current transaction. Otherwise false.

Onchain​

Overrides​

AbstractContract.checkSHPreimage

getCallData()​

getCallData(): MethodCallData

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:591

Gets the method call data for the current smart contract.

Returns​

MethodCallData

The method call data object.

Throws​

If no method call is found.

getUnlockingScript()​

getUnlockingScript(): Script

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:581

Returns the raw arguments from the call data of the smart contract.

Returns​

Script

The raw arguments extracted from the call data.

isPubFunction()​

isPubFunction(method): boolean

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:407

Checks if the given method is a public function in the smart contract.

Parameters​

method​

string

The method name to check.

Returns​

boolean

True if the method is a public function, false otherwise.

next()​

next(newState): this

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:676

Get a new contract instance with the new state.

Parameters​

newState​

StateT

the new state

Returns​

this

the new covenant

setSighashType()​

setSighashType(sigHashType): void

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:362

Sets the signature hash type for the current input in the PSBT.

Parameters​

sigHashType​

SigHashType

The signature hash type to set

Returns​

void

spentFromInput()​

spentFromInput(psbt, inputIndex): void

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:345

Mark the contract instance as spent from the input of the PSBT.

Parameters​

psbt​

Contextual

inputIndex​

number

Returns​

void

timeLock()​

timeLock(nLockTime): boolean

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:623

Checks a locktime parameter with the transaction's locktime. There are two times of nLockTime: lock-by-blockheight and lock-by-blocktime, distinguished by whether nLockTime < LOCKTIME_THRESHOLD = 500000000

See the corresponding code on bitcoin core: https://github.com/bitcoin/bitcoin/blob/ffd75adce01a78b3461b3ff05bcc2b530a9ce994/src/script/interpreter.cpp#L1129

See the bip65 for specification https://github.com/bitcoin/bips/blob/master/bip-0065.mediawiki#summary

Parameters​

nLockTime​

Int32

the locktime read from the script

Returns​

boolean

true if the transaction's locktime is less than or equal to the transaction's locktime

Onchain​

Overrides​

AbstractContract.timeLock

create()​

static create\<T>(this, ...args): InstanceType\<T>

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:144

Used to create an instance of a smart contract. If your smart contract has a base class, you must use this method to instantiate it.

Type Parameters​

• T extends (...args) => InstanceType\<T>

Parameters​

this​

T

args​

...ConstructorParameters\<T>

Returns​

InstanceType\<T>

deserializeState()​

static deserializeState\<T>(this, serializedState): T

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:258

Deserializes the contract state from a ByteString.

Type Parameters​

• T extends StructObject

The type of the contract state extending OpcatState

Parameters​

this​

(...args) => SmartContract\<T>

serializedState​

ByteString

The serialized state as a ByteString

Returns​

T

The deserialized state object of type T

Throws​

Error if artifact is not loaded or state type is not defined

isStateful()​

static isStateful(): boolean

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:708

Checks if the contract has state by verifying if the state object exists and is not empty.

Returns​

boolean

True if the contract has state, false otherwise.

loadArtifact()​

static loadArtifact(artifact): typeof SmartContract

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:96

This function is usually called on the frontend. The contract class needs to call this function before instantiating.

Parameters​

artifact​

Artifact

a contract artifact json object

Returns​

typeof SmartContract

serializeState()​

static serializeState\<T>(this, state): ByteString

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:232

Serializes the contract state into a ByteString.

Type Parameters​

• T extends StructObject

Type of the contract state extending OpcatState

Parameters​

this​

(...args) => SmartContract\<T>

Constructor reference for type inference

state​

T

The contract state object to serialize

Returns​

ByteString

Serialized state as ByteString

Throws​

Error if artifact is not loaded or state type is not defined

Overrides​

AbstractContract.serializeState

stateHash()​

static stateHash\<T>(this, state): ByteString

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:284

Computes the SHA-256 hash of the serialized contract state.

Type Parameters​

• T extends StructObject

Type extending OpcatState

Parameters​

this​

(...args) => SmartContract\<T>

state​

T

The contract state to hash

Returns​

ByteString

ByteString containing the SHA-256 hash of the serialized state

Overrides​

AbstractContract.stateHash

Signature Verification​

checkMultiSig()​

checkMultiSig(signatures, publickeys): boolean

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:199

Compares the first signature against each public key until it finds an ECDSA match. Starting with the subsequent public key, it compares the second signature against each remaining public key until it finds an ECDSA match. The process is repeated until all signatures have been checked or not enough public keys remain to produce a successful result. All signatures need to match a public key. Because public keys are not checked again if they fail any signature comparison, signatures must be placed in the scriptSig using the same order as their corresponding public keys were placed in the scriptPubKey or redeemScript. If all signatures are valid, 1 is returned, 0 otherwise. Due to a bug, one extra unused value is removed from the stack.

Parameters​

signatures​

Sig[]

publickeys​

PubKey[]

Returns​

boolean

Onchain​

checkSig()​

checkSig(signature, publickey, errorMsg): boolean

Defined in: packages/scrypt-ts-opcat/src/smart-contract/smartContract.ts:171

A built-in function verifies an Schnorr signature. It takes two inputs from the stack, a public key (on top of the stack) and an Schnorr signature in its DER_CANONISED format concatenated with sighash flags. It outputs true or false on the stack based on whether the signature check passes or fails. [see][https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki#specification](https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki#specification)

Parameters​

signature​

Sig

publickey​

PubKey

errorMsg​

string = 'signature check failed'

Returns​

boolean

Onchain​

Overrides​

AbstractContract.checkSig