Many resources are needed to download a project. Please understand that we have to compensate our server costs. Thank you in advance. Project price only 1 $
You can buy this project and download/modify it how often you want.
package net.corda.contracts.asset
import net.corda.contracts.clause.AbstractConserveAmount
import net.corda.contracts.clause.AbstractIssue
import net.corda.contracts.clause.NoZeroSizedOutputs
import net.corda.core.contracts.*
import net.corda.core.contracts.clauses.AllOf
import net.corda.core.contracts.clauses.FirstOf
import net.corda.core.contracts.clauses.GroupClauseVerifier
import net.corda.core.contracts.clauses.verifyClause
import net.corda.core.crypto.*
import net.corda.core.schemas.MappedSchema
import net.corda.core.schemas.PersistentState
import net.corda.core.schemas.QueryableState
import net.corda.core.transactions.TransactionBuilder
import net.corda.core.utilities.Emoji
import net.corda.schemas.CashSchemaV1
import java.math.BigInteger
import java.util.*
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//
// Cash
//
// Just a fake program identifier for now. In a real system it could be, for instance, the hash of the program bytecode.
val CASH_PROGRAM_ID = Cash()
/**
* A cash transaction may split and merge money represented by a set of (issuer, depositRef) pairs, across multiple
* input and output states. Imagine a Bitcoin transaction but in which all UTXOs had a colour
* (a blend of issuer+depositRef) and you couldn't merge outputs of two colours together, but you COULD put them in
* the same transaction.
*
* The goal of this design is to ensure that money can be withdrawn from the ledger easily: if you receive some money
* via this contract, you always know where to go in order to extract it from the R3 ledger, no matter how many hands
* it has passed through in the intervening time.
*
* At the same time, other contracts that just want money and don't care much who is currently holding it in their
* vaults can ignore the issuer/depositRefs and just examine the amount fields.
*/
class Cash : OnLedgerAsset() {
/**
* TODO:
* 1) hash should be of the contents, not the URI
* 2) allow the content to be specified at time of instance creation?
*
* Motivation: it's the difference between a state object referencing a programRef, which references a
* legalContractReference and a state object which directly references both. The latter allows the legal wording
* to evolve without requiring code changes. But creates a risk that users create objects governed by a program
* that is inconsistent with the legal contract.
*/
override val legalContractReference: SecureHash = SecureHash.sha256("https://www.big-book-of-banking-law.gov/cash-claims.html")
override val conserveClause: AbstractConserveAmount = Clauses.ConserveAmount()
override fun extractCommands(commands: Collection>): List>
= commands.select()
interface Clauses {
class Group : GroupClauseVerifier>(AllOf>(
NoZeroSizedOutputs(),
FirstOf>(
Issue(),
ConserveAmount())
)
) {
override fun groupStates(tx: TransactionForContract): List>>
= tx.groupStates> { it.amount.token }
}
class Issue : AbstractIssue(
sum = { sumCash() },
sumOrZero = { sumCashOrZero(it) }
) {
override val requiredCommands: Set> = setOf(Commands.Issue::class.java)
}
class ConserveAmount : AbstractConserveAmount()
}
/** A state representing a cash claim against some party. */
data class State(
override val amount: Amount>,
/** There must be a MoveCommand signed by this key to claim the amount. */
override val owner: CompositeKey
) : FungibleAsset, QueryableState {
constructor(deposit: PartyAndReference, amount: Amount, owner: CompositeKey)
: this(Amount(amount.quantity, Issued(deposit, amount.token)), owner)
override val exitKeys = setOf(owner, amount.token.issuer.party.owningKey)
override val contract = CASH_PROGRAM_ID
override val participants = listOf(owner)
override fun move(newAmount: Amount>, newOwner: CompositeKey): FungibleAsset
= copy(amount = amount.copy(newAmount.quantity, amount.token), owner = newOwner)
override fun toString() = "${Emoji.bagOfCash}Cash($amount at ${amount.token.issuer} owned by $owner)"
override fun withNewOwner(newOwner: CompositeKey) = Pair(Commands.Move(), copy(owner = newOwner))
/** Object Relational Mapping support. */
override fun generateMappedObject(schema: MappedSchema): PersistentState {
return when (schema) {
is CashSchemaV1 -> CashSchemaV1.PersistentCashState(
owner = this.owner.toBase58String(),
pennies = this.amount.quantity,
currency = this.amount.token.product.currencyCode,
issuerParty = this.amount.token.issuer.party.owningKey.toBase58String(),
issuerRef = this.amount.token.issuer.reference.bytes
)
else -> throw IllegalArgumentException("Unrecognised schema $schema")
}
}
/** Object Relational Mapping support. */
override fun supportedSchemas(): Iterable = listOf(CashSchemaV1)
}
// Just for grouping
interface Commands : FungibleAsset.Commands {
/**
* A command stating that money has been moved, optionally to fulfil another contract.
*
* @param contractHash the contract this move is for the attention of. Only that contract's verify function
* should take the moved states into account when considering whether it is valid. Typically this will be
* null.
*/
data class Move(override val contractHash: SecureHash? = null) : FungibleAsset.Commands.Move, Commands
/**
* Allows new cash states to be issued into existence: the nonce ("number used once") ensures the transaction
* has a unique ID even when there are no inputs.
*/
data class Issue(override val nonce: Long = newSecureRandom().nextLong()) : FungibleAsset.Commands.Issue, Commands
/**
* A command stating that money has been withdrawn from the shared ledger and is now accounted for
* in some other way.
*/
data class Exit(override val amount: Amount>) : Commands, FungibleAsset.Commands.Exit
}
/**
* Puts together an issuance transaction from the given template, that starts out being owned by the given pubkey.
*/
fun generateIssue(tx: TransactionBuilder, tokenDef: Issued, pennies: Long, owner: CompositeKey, notary: Party)
= generateIssue(tx, Amount(pennies, tokenDef), owner, notary)
/**
* Puts together an issuance transaction for the specified amount that starts out being owned by the given pubkey.
*/
fun generateIssue(tx: TransactionBuilder, amount: Amount>, owner: CompositeKey, notary: Party) {
check(tx.inputStates().isEmpty())
check(tx.outputStates().map { it.data }.sumCashOrNull() == null)
val at = amount.token.issuer
tx.addOutputState(TransactionState(State(amount, owner), notary))
tx.addCommand(generateIssueCommand(), at.party.owningKey)
}
override fun deriveState(txState: TransactionState, amount: Amount>, owner: CompositeKey)
= txState.copy(data = txState.data.copy(amount = amount, owner = owner))
override fun generateExitCommand(amount: Amount>) = Commands.Exit(amount)
override fun generateIssueCommand() = Commands.Issue()
override fun generateMoveCommand() = Commands.Move()
override fun verify(tx: TransactionForContract)
= verifyClause(tx, Clauses.Group(), extractCommands(tx.commands))
}
// Small DSL extensions.
/**
* Sums the cash states in the list belonging to a single owner, throwing an exception
* if there are none, or if any of the cash states cannot be added together (i.e. are
* different currencies or issuers).
*/
fun Iterable.sumCashBy(owner: CompositeKey): Amount> = filterIsInstance().filter { it.owner == owner }.map { it.amount }.sumOrThrow()
/**
* Sums the cash states in the list, throwing an exception if there are none, or if any of the cash
* states cannot be added together (i.e. are different currencies or issuers).
*/
fun Iterable.sumCash(): Amount> = filterIsInstance().map { it.amount }.sumOrThrow()
/** Sums the cash states in the list, returning null if there are none. */
fun Iterable.sumCashOrNull(): Amount>? = filterIsInstance().map { it.amount }.sumOrNull()
/** Sums the cash states in the list, returning zero of the given currency+issuer if there are none. */
fun Iterable.sumCashOrZero(currency: Issued): Amount> {
return filterIsInstance().map { it.amount }.sumOrZero(currency)
}
fun Cash.State.ownedBy(owner: CompositeKey) = copy(owner = owner)
fun Cash.State.issuedBy(party: Party) = copy(amount = Amount(amount.quantity, amount.token.copy(issuer = amount.token.issuer.copy(party = party))))
fun Cash.State.issuedBy(deposit: PartyAndReference) = copy(amount = Amount(amount.quantity, amount.token.copy(issuer = deposit)))
fun Cash.State.withDeposit(deposit: PartyAndReference): Cash.State = copy(amount = amount.copy(token = amount.token.copy(issuer = deposit)))
infix fun Cash.State.`owned by`(owner: CompositeKey) = ownedBy(owner)
infix fun Cash.State.`issued by`(party: Party) = issuedBy(party)
infix fun Cash.State.`issued by`(deposit: PartyAndReference) = issuedBy(deposit)
infix fun Cash.State.`with deposit`(deposit: PartyAndReference): Cash.State = withDeposit(deposit)
// Unit testing helpers. These could go in a separate file but it's hardly worth it for just a few functions.
/** A randomly generated key. */
val DUMMY_CASH_ISSUER_KEY by lazy { entropyToKeyPair(BigInteger.valueOf(10)) }
/** A dummy, randomly generated issuer party by the name of "Snake Oil Issuer" */
val DUMMY_CASH_ISSUER by lazy { Party("Snake Oil Issuer", DUMMY_CASH_ISSUER_KEY.public.composite).ref(1) }
/** An extension property that lets you write 100.DOLLARS.CASH */
val Amount.CASH: Cash.State get() = Cash.State(Amount(quantity, Issued(DUMMY_CASH_ISSUER, token)), NullCompositeKey)
/** An extension property that lets you get a cash state from an issued token, under the [NullPublicKey] */
val Amount>.STATE: Cash.State get() = Cash.State(this, NullCompositeKey)
