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Emit events for all transfers #88

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merged 3 commits into from
Jul 15, 2024
Merged

Emit events for all transfers #88

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1bdd370
Emit events for all transfers
kantp Jul 8, 2024
5331d82
Properly filter balance change events that use the token
kantp Jul 12, 2024
8a677c6
Use `emitEventIf()`
kantp Jul 15, 2024
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16 changes: 10 additions & 6 deletions FungibleToken.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ import {
Int64,
MerkleList,
method,
Option,
Permissions,
Provable,
PublicKey,
Expand Down Expand Up @@ -60,7 +61,7 @@ export class FungibleToken extends TokenContract {
Pause: PauseEvent,
Mint: MintEvent,
Burn: BurnEvent,
Transfer: TransferEvent,
BalanceChange: BalanceChangeEvent,
}

// We use actions and reducers for changing the circulating supply. That is to allow multiple mints/burns in a single block, which would not work if those would alter the contract state directly.
Expand Down Expand Up @@ -149,7 +150,6 @@ export class FungibleToken extends TokenContract {
async transfer(from: PublicKey, to: PublicKey, amount: UInt64) {
this.paused.getAndRequireEquals().assertFalse()
this.internal.send({ from, to, amount })
this.emitEvent("Transfer", new TransferEvent({ from, to, amount }))
}

private checkPermissionsUpdate(update: AccountUpdate) {
Expand All @@ -169,6 +169,11 @@ export class FungibleToken extends TokenContract {
let totalBalance = Int64.from(0)
this.forEachUpdate(updates, (update, usesToken) => {
this.checkPermissionsUpdate(update)
this.emitEventIf(
usesToken,
"BalanceChange",
new BalanceChangeEvent({ address: update.publicKey, amount: update.balanceChange }),
)
totalBalance = Provable.if(usesToken, totalBalance.add(update.balanceChange), totalBalance)
totalBalance.isPositiveV2().assertFalse(
"Flash-minting detected. Please make sure that your `AccountUpdate`s are ordered properly, so that tokens are not received before they are sent.",
Expand Down Expand Up @@ -254,8 +259,7 @@ export class BurnEvent extends Struct({
amount: UInt64,
}) {}

export class TransferEvent extends Struct({
from: PublicKey,
to: PublicKey,
amount: UInt64,
export class BalanceChangeEvent extends Struct({
address: PublicKey,
amount: Int64,
}) {}
16 changes: 8 additions & 8 deletions documentation/api.md
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Original file line number Diff line number Diff line change
Expand Up @@ -94,7 +94,7 @@ events = {
Pause: PauseEvent,
Mint: MintEvent,
Burn: BurnEvent,
Transfer: TransferEvent,
BalanceChange: BalanceChangeEvent,
}

export class SetAdminEvent extends Struct({
Expand All @@ -115,13 +115,13 @@ class BurnEvent extends Struct({
amount: UInt64,
}) {}

class TransferEvent extends Struct({
from: PublicKey,
to: PublicKey,
amount: UInt64,
export class BalanceChangeEvent extends Struct({
address: PublicKey,
amount: Int64,
}) {}
```

Note that `approveBase` does not emit an event. Thus, transfers where the account updates have been
constructed externally to `FungibleToken` will not have an event emitted by the `FungibleToken`
contract.
Note that `MintEvent`, `BurnEvent`, and `BalanceChangeEvent` each signal that the balance of an
account changes. The difference is that `MintEvent` and `BurnEvent` are emitted when tokens are
minted/burned, and `BalanceChangeEvent` is emitted when a transaction takes tokens from some
addresses, and sends them to others.
14 changes: 7 additions & 7 deletions package-lock.json
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2 changes: 1 addition & 1 deletion package.json
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@
"check": "tsc --noEmit"
},
"peerDependencies": {
"o1js": "https://pkg.pr.new/o1-labs/o1js@9549719"
"o1js": "https://pkg.pr.new/o1-labs/o1js@8d95222"
},
"devDependencies": {
"ts-node": "^10.9.2",
Expand Down