nim-ethers/ethers/contract.nim

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import std/macros
import pkg/chronos
import pkg/contractabi
import ./basics
import ./provider
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import ./signer
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import ./events
import ./fields
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export basics
export provider
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export events
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type
Contract* = ref object of RootObj
provider: Provider
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signer: ?Signer
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address: Address
TransactionOverrides* = object
nonce*: ?UInt256
chainId*: ?UInt256
gasPrice*: ?UInt256
maxFee*: ?UInt256
maxPriorityFee*: ?UInt256
gasLimit*: ?UInt256
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ContractError* = object of EthersError
Confirmable* = ?TransactionResponse
EventHandler*[E: Event] = proc(event: E) {.gcsafe, upraises:[].}
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func new*(ContractType: type Contract,
address: Address,
provider: Provider): ContractType =
ContractType(provider: provider, address: address)
func new*(ContractType: type Contract,
address: Address,
signer: Signer): ContractType =
ContractType(signer: some signer, provider: signer.provider, address: address)
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func connect*[T: Contract](contract: T, provider: Provider | Signer): T =
T.new(contract.address, provider)
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func provider*(contract: Contract): Provider =
contract.provider
func signer*(contract: Contract): ?Signer =
contract.signer
func address*(contract: Contract): Address =
contract.address
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template raiseContractError(message: string) =
raise newException(ContractError, message)
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proc createTransaction(contract: Contract,
function: string,
parameters: tuple,
overrides = TransactionOverrides.default): Transaction =
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let selector = selector(function, typeof parameters).toArray
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let data = @selector & AbiEncoder.encode(parameters)
Transaction(
to: contract.address,
data: data,
nonce: overrides.nonce,
chainId: overrides.chainId,
gasPrice: overrides.gasPrice,
maxFee: overrides.maxFee,
maxPriorityFee: overrides.maxPriorityFee,
gasLimit: overrides.gasLimit,
)
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proc decodeResponse(T: type, multiple: static bool, bytes: seq[byte]): T =
when multiple:
without decoded =? AbiDecoder.decode(bytes, T):
raiseContractError "unable to decode return value as " & $T
return decoded
else:
return decodeResponse((T,), true, bytes)[0]
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proc call(contract: Contract,
function: string,
parameters: tuple,
blockTag = BlockTag.latest) {.async.} =
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let transaction = createTransaction(contract, function, parameters)
discard await contract.provider.call(transaction, blockTag)
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proc call(contract: Contract,
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function: string,
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parameters: tuple,
ReturnType: type,
returnMultiple: static bool,
blockTag = BlockTag.latest): Future[ReturnType] {.async.} =
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let transaction = createTransaction(contract, function, parameters)
let response = await contract.provider.call(transaction, blockTag)
return decodeResponse(ReturnType, returnMultiple, response)
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proc send(contract: Contract,
function: string,
parameters: tuple,
overrides = TransactionOverrides.default):
Future[?TransactionResponse] {.async.} =
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if signer =? contract.signer:
let transaction = createTransaction(contract, function, parameters, overrides)
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let populated = await signer.populateTransaction(transaction)
let txResp = await signer.sendTransaction(populated)
return txResp.some
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else:
await call(contract, function, parameters)
return TransactionResponse.none
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func getParameterTuple(procedure: NimNode): NimNode =
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let parameters = procedure[3]
var tupl = newNimNode(nnkTupleConstr, parameters)
for parameter in parameters[2..^1]:
for name in parameter[0..^3]:
tupl.add name
return tupl
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func isConstant(procedure: NimNode): bool =
let pragmas = procedure[4]
for pragma in pragmas:
if pragma.eqIdent "view":
return true
elif pragma.eqIdent "pure":
return true
false
func isMultipleReturn(returnType: NimNode): bool =
(returnType.kind == nnkPar and returnType.len > 1) or
(returnType.kind == nnkTupleConstr) or
(returnType.kind == nnkTupleTy)
func addOverrides(procedure: var NimNode) =
procedure[3].add(
newIdentDefs(
ident("overrides"),
newEmptyNode(),
quote do: TransactionOverrides.default
)
)
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func addContractCall(procedure: var NimNode) =
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let contract = procedure[3][1][0]
let function = $basename(procedure[0])
let parameters = getParameterTuple(procedure)
let returnType = procedure[3][0]
let returnMultiple = returnType.isMultipleReturn.newLit
procedure.addOverrides()
func call: NimNode =
if returnType.kind == nnkEmpty:
quote:
await call(`contract`, `function`, `parameters`)
else:
quote:
return await call(
`contract`, `function`, `parameters`, `returnType`, `returnMultiple`)
func send: NimNode =
if returnType.kind == nnkEmpty:
quote:
discard await send(`contract`, `function`, `parameters`, overrides)
else:
quote:
when typeof(result) isnot Confirmable:
{.error: "unexpected return type, missing {.view.} or {.pure.} ?".}
return await send(`contract`, `function`, `parameters`, overrides)
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procedure[6] =
if procedure.isConstant:
call()
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else:
send()
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func addFuture(procedure: var NimNode) =
let returntype = procedure[3][0]
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if returntype.kind != nnkEmpty:
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procedure[3][0] = quote: Future[`returntype`]
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func addAsyncPragma(procedure: var NimNode) =
let pragmas = procedure[4]
if pragmas.kind == nnkEmpty:
procedure[4] = newNimNode(nnkPragma)
procedure[4].add ident("async")
macro contract*(procedure: untyped{nkProcDef|nkMethodDef}): untyped =
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let parameters = procedure[3]
let body = procedure[6]
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parameters.expectMinLen(2) # at least return type and contract instance
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body.expectKind(nnkEmpty)
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var contractcall = copyNimTree(procedure)
contractcall.addContractCall()
contractcall.addFuture()
contractcall.addAsyncPragma()
contractcall
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template view* {.pragma.}
template pure* {.pragma.}
proc subscribe*[E: Event](contract: Contract,
_: type E,
handler: EventHandler[E]):
Future[Subscription] =
let topic = topic($E, E.fieldTypes).toArray
let filter = Filter(address: contract.address, topics: @[topic])
proc logHandler(log: Log) {.upraises: [].} =
if event =? E.decode(log.data, log.topics):
handler(event)
contract.provider.subscribe(filter, logHandler)