Allow calls to non-constant functions

ethers/contract.nim

@@ -3,6 +3,7 @@ import pkg/chronos
 import pkg/contractabi
 import ./basics
 import ./provider
+import ./signer
 
 export basics
 export provider
@@ -10,9 +11,19 @@ export provider
 type
   Contract* = ref object of RootObj
     provider: Provider
+    signer: ?Signer
     address: Address
   ContractError* = object of EthersError
 
+func provider*(contract: Contract): Provider =
+  contract.provider
+
+func signer*(contract: Contract): ?Signer =
+  contract.signer
+
+func address*(contract: Contract): Address =
+  contract.address
+
 template raiseContractError(message: string) =
   raise newException(ContractError, message)
 
@@ -30,13 +41,32 @@ proc decodeResponse(T: type, bytes: seq[byte]): T =
     raiseContractError "unable to decode return value as " & $T
   return decoded
 
-proc call[ContractType: Contract, ResultType](
+proc call[ContractType: Contract, ReturnType](
           contract: ContractType,
           function: string,
-          parameters: tuple):Future[ResultType] {.async.} =
+          parameters: tuple): Future[ReturnType] {.async.} =
   let transaction = createTx(contract, function, parameters)
   let response = await contract.provider.call(transaction)
-  return decodeResponse(ResultType, response)
+  return decodeResponse(ReturnType, response)
+
+proc callNoResult[ContractType: Contract](
+                  contract: ContractType,
+                  function: string,
+                  parameters: tuple) {.async.} =
+  let transaction = createTx(contract, function, parameters)
+  discard await contract.provider.call(transaction)
+
+proc send[ContractType: Contract](
+          contract: ContractType,
+          function: string,
+          parameters: tuple) {.async.} =
+
+  without signer =? contract.signer:
+    raiseContractError "trying to send transaction without a signer"
+
+  let transaction = createTx(contract, function, parameters)
+  let populated = await signer.populateTransaction(transaction)
+  await signer.sendTransaction(populated)
 
 func getParameterTuple(procedure: var NimNode): NimNode =
   let parameters = procedure[3]
@@ -46,22 +76,46 @@ func getParameterTuple(procedure: var NimNode): NimNode =
       tupl.add name
   return tupl
 
+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
+    elif pragma.eqIdent "constant":
+      return true
+  false
+
 func addContractCall(procedure: var NimNode) =
   let name = procedure[0]
   let function = if name.kind == nnkPostfix: $name[1] else: $name
   let parameters = procedure[3]
   let contract = parameters[1][0]
   let contracttype = parameters[1][1]
-  let resulttype = parameters[0]
+  let returntype = parameters[0]
   let tupl = getParameterTuple(procedure)
+  if procedure.isConstant:
+    if returntype.kind == nnkEmpty:
       procedure[6] = quote do:
-    return await call[`contracttype`,`resulttype`](`contract`, `function`, `tupl`)
+        await callNoResult[`contracttype`](
+          `contract`, `function`, `tupl`
+        )
+    else:
+      procedure[6] = quote do:
+        return await call[`contracttype`,`returntype`](
+          `contract`, `function`, `tupl`
+        )
+  else:
+    procedure[6] = quote do:
+      if `contract`.signer.isSome:
+        await send[`contracttype`](`contract`, `function`, `tupl`)
+      else:
+        await callNoResult[`contracttype`](`contract`, `function`, `tupl`)
 
 func addFuture(procedure: var NimNode) =
   let returntype = procedure[3][0]
-  if returntype.kind == nnkEmpty:
+  if returntype.kind != nnkEmpty:
-    procedure[3][0] = quote do: Future[void]
-  else:
     procedure[3][0] = quote do: Future[`returntype`]
 
 func addAsyncPragma(procedure: var NimNode) =
@@ -75,11 +129,30 @@ func new*(ContractType: type Contract,
           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)
+
+template view* {.pragma.}
+template pure* {.pragma.}
+template constant* {.pragma.}
+
+func checkReturnType(procedure: NimNode) =
+  let parameters = procedure[3]
+  let returntype = parameters[0]
+  if returntype.kind != nnkEmpty and not procedure.isConstant:
+    const message =
+      "only contract functions with {.constant.}, {.pure.} or {.view.} " &
+      "can have a return type"
+    error(message, returntype)
+
 macro contract*(procedure: untyped{nkProcDef|nkMethodDef}): untyped =
   let parameters = procedure[3]
   let body = procedure[6]
   parameters.expectMinLen(2)
   body.expectKind(nnkEmpty)
+  procedure.checkReturnType()
   var contractcall = copyNimTree(procedure)
   contractcall.addContractCall()
   contractcall.addFuture()

ethers/providers/jsonrpc.nim

@@ -101,3 +101,8 @@ method getAddress*(signer: JsonRpcSigner): Future[Address] {.async.} =
     return accounts[0]
 
   raiseProviderError "no address found"
+
+method sendTransaction*(signer: JsonRpcSigner,
+                        transaction: Transaction) {.async.} =
+  let client = await signer.provider.client
+  discard await client.eth_sendTransaction(transaction)

ethers/signer.nim

@@ -15,6 +15,10 @@ method provider*(signer: Signer): Provider {.base.} =
 method getAddress*(signer: Signer): Future[Address] {.base.} =
   doAssert false, "not implemented"
 
+method sendTransaction*(signer: Signer,
+                        transaction: Transaction) {.base, async.} =
+  doAssert false, "not implemented"
+
 method getGasPrice*(signer: Signer): Future[UInt256] {.base.} =
   signer.provider.getGasPrice()
 

testmodule/testContracts.nim

@@ -8,27 +8,51 @@ type
   Erc20* = ref object of Contract
   TestToken = ref object of Erc20
 
-method totalSupply*(erc20: Erc20): UInt256 {.base, contract.}
+method totalSupply*(erc20: Erc20): UInt256 {.base, contract, view.}
-method balanceOf*(erc20: Erc20, account: Address): UInt256 {.base, contract.}
+method balanceOf*(erc20: Erc20, account: Address): UInt256 {.base, contract, view.}
-method allowance*(erc20: Erc20, owner, spender: Address): UInt256 {.base, contract.}
+method allowance*(erc20: Erc20, owner, spender: Address): UInt256 {.base, contract, view.}
+
+method mint(token: TestToken, holder: Address, amount: UInt256) {.base, contract.}
 
 suite "Contracts":
 
   var token: TestToken
   var provider: JsonRpcProvider
   var snapshot: JsonNode
+  var accounts: seq[Address]
 
   setup:
     provider = JsonRpcProvider.new()
     snapshot = await provider.send("evm_snapshot")
+    accounts = await provider.listAccounts()
     let deployment = readDeployment()
     token = TestToken.new(!deployment.address(TestToken), provider)
 
   teardown:
     discard await provider.send("evm_revert", @[snapshot])
 
-  test "can call view methods":
+  test "can call constant functions":
-    let accounts = await provider.listAccounts()
     check (await token.totalSupply()) == 0.u256
     check (await token.balanceOf(accounts[0])) == 0.u256
     check (await token.allowance(accounts[0], accounts[1])) == 0.u256
+
+  test "can call non-constant functions":
+    token = TestToken.new(token.address, provider.getSigner())
+    await token.mint(accounts[1], 100.u256)
+    check (await token.totalSupply()) == 100.u256
+    check (await token.balanceOf(accounts[1])) == 100.u256
+
+  test "can call non-constant functions without a signer":
+    await token.mint(accounts[1], 100.u256)
+    check (await token.balanceOf(accounts[1])) == 0.u256
+
+  test "can call constant functions without a return type":
+    token = TestToken.new(token.address, provider.getSigner())
+    proc mint(token: TestToken, holder: Address, amount: UInt256) {.contract, view.}
+    await mint(token, accounts[1], 100.u256)
+    check (await balanceOf(token, accounts[1])) == 0.u256
+
+  test "fails to compile when non-constant function has a return type":
+    let works = compiles:
+      proc foo(token: TestToken, bar: Address): UInt256 {.contract.}
+    check not works