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Commit 82c4c3c6 authored by didi's avatar didi
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refactoring of contract according to the Solidity Style Guide, refs #2

parent 45cd76b4
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backend/contracts/Streem.sol
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......@@ -42,12 +42,36 @@ contract Streem {
// constructor
function Streem(uint initialSupply) {
assert(totalSupply > 0);
owner = msg.sender;
settledBalances[msg.sender] = int(initialSupply);
totalSupply = initialSupply;
streams.push(Stream(0,0,0,0)); // empty first element for implicit null-like semantics
}
// ################## Public functions ###################
// ERC-20 compliant function for discrete transfers
function transfer(address _to, uint256 _value) {
assert(_value > 0 && balanceOf(msg.sender) >= _value);
// if the settled balance doesn't suffice, settle the available funds of the ingoing stream.
// this would potentially reduce the dependency graph, but make the logic more complex
/*
if (settledBalances[msg.sender] < int(_value)) {
var inS = getInStreamOf(msg.sender);
settleStream(inS);
// lets check again! TODO: once the logic was validated / proofed, this checks should be superfluous
assert(balanceOf(msg.sender) >= _value);
}
*/
settledBalances[msg.sender] -= int(_value);
settledBalances[_to] += int(_value);
Transfer(msg.sender, _to, _value);
}
/*
* opens a stream from the transaction sender to the given receiver with the given speed.
* Will succeed only if the sender has no stream open and isn't underfunded
......@@ -64,6 +88,37 @@ contract Streem {
StreamOpened(msg.sender, receiver, perSecond);
}
// settle and close the outgoing stream
function closeStream() {
var outS = getOutStreamOf(msg.sender);
assert(exists(outS));
var (settleBal, outstandingBal) = settleStream(outS);
StreamClosed(msg.sender, outS.receiver, outS.perSecond, settleBal, outstandingBal);
// make sure this remains the last statement because the stream handle is a reference
deleteOutStreamOf(msg.sender);
}
// TODO: implement the fallback function?
// ################## Public constant functions ###################
function balanceOf(address _owner) constant returns (uint256) {
var inS = getInStreamOf(_owner);
// no prettier null check possible? https://ethereum.stackexchange.com/questions/871/what-is-the-zero-empty-or-null-value-of-a-struct
uint256 inStreamBal = exists(inS) ? streamBalance(inS, inS, 1) : 0;
var outS = getOutStreamOf(_owner);
uint256 outStreamBal = exists(outS) ? streamBalance(outS, outS, 1) : 0;
// TODO: check overflow before casting
assert(settledBalances[_owner] + int(inStreamBal) - int(outStreamBal) >= 0);
return uint(settledBalances[_owner] + int(inStreamBal) - int(outStreamBal));
}
// ################## Internal functions ###################
// returns the settled balance and the outstanding balance (> 0 if underfunded)
function settleStream(Stream s) internal returns (uint, uint) {
var bal = streamBalance(s, s, 1);
......@@ -86,37 +141,13 @@ contract Streem {
return (settleBal, naiveBal - settleBal);
}
// settle and close the outgoing stream
function closeStream() {
var outS = getOutStreamOf(msg.sender);
assert(exists(outS));
var (settleBal, outstandingBal) = settleStream(outS);
StreamClosed(msg.sender, outS.receiver, outS.perSecond, settleBal, outstandingBal);
// make sure this remains the last statement because the stream handle is a reference
deleteOutStreamOf(msg.sender);
// as long as only senders can close a stream, this is only needed for outstreams
function deleteOutStreamOf(address addr) internal {
var sid = outStreamPtrs[addr];
delete streams[sid];
}
// ERC-20 compliant function for discrete transfers
function transfer(address _to, uint256 _value) {
assert(_value > 0 && balanceOf(msg.sender) >= _value);
// if the settled balance doesn't suffice, settle the available funds of the ingoing stream.
/*
if(settledBalances[msg.sender] < int(_value)) {
var inS = getInStreamOf(msg.sender);
settleStream(inS);
// lets check again! TODO: once the logic was validated / proofed, this checks should be superfluous
assert(balanceOf(msg.sender) >= _value);
}
*/
settledBalances[msg.sender] -= int(_value);
settledBalances[_to] += int(_value);
Transfer(msg.sender, _to, _value);
}
// ################## Internal constant functions ###################
// Solidity (so far) has no simple null check, using startTimestamp as guard (assuming 1970 will not come back).
function exists(Stream s) internal constant returns (bool) {
......@@ -137,12 +168,6 @@ contract Streem {
return streams[inStreamPtrs[addr]];
}
// as long as only senders can close a stream, this is only needed for outstreams
function deleteOutStreamOf(address addr) internal {
var sid = outStreamPtrs[addr];
delete streams[sid];
}
function equals(Stream s1, Stream s2) internal constant returns (bool) {
// TODO: not multi-stream ready
return s1.sender == s2.sender && s1.receiver == s2.receiver;
......@@ -163,7 +188,7 @@ contract Streem {
// naming: osb -> outgoingStreamBalance, isb -> incomingStreamBalance, sb -> static balance
uint256 osb = naiveStreamBalance(s);
if(equals(s, origin) && hops > 1) { // special case: break on circular dependency. TODO: proof correctness
if (equals(s, origin) && hops > 1) { // special case: break on circular dependency. TODO: proof correctness
return osb;
} else {
var inS = getInStreamOf(s.sender);
......@@ -178,46 +203,7 @@ contract Streem {
}
}
// this balance function can return a negative value if an outgoing stream went "under water"
// and a higher than real balance if an incoming stream went "under water".
// note that this is NOT the actual balance, just a theoretical value
// TODO: refactor
// function owedBalanceOf(address _owner) constant returns (int256 balance) {
// uint256 inStreamBal = 0;
// var inStream = inStreams[_owner];
// // no prettier null check possible? https://ethereum.stackexchange.com/questions/871/what-is-the-zero-empty-or-null-value-of-a-struct
// if(inStream.startTimestamp != 0) {
// inStreamBal = (now - inStream.startTimestamp) * inStream.perSecond;
// }
//
// uint256 outStreamBal = 0;
// var outStream = outStreams[_owner];
// if(outStream.startTimestamp != 0) {
// outStreamBal = (now - outStream.startTimestamp) * outStream.perSecond;
// }
//
// // TODO: check overflow before casting
// balance = int256(settledBalances[_owner] + inStreamBal - outStreamBal);
// return balance;
// }
function balanceOf(address _owner) constant returns (uint256) {
var inS = getInStreamOf(_owner);
// no prettier null check possible? https://ethereum.stackexchange.com/questions/871/what-is-the-zero-empty-or-null-value-of-a-struct
uint256 inStreamBal = exists(inS) ? streamBalance(inS, inS, 1) : 0;
var outS = getOutStreamOf(_owner);
uint256 outStreamBal = exists(outS) ? streamBalance(outS, outS, 1) : 0;
// TODO: check overflow before casting
assert(settledBalances[_owner] + int(inStreamBal) - int(outStreamBal) >= 0);
return uint(settledBalances[_owner] + int(inStreamBal) -int(outStreamBal));
}
// TODO: implement the empty function?
// ####################### dev / testing helpers #############################
// ####################### dev / testing helpers #########################
// TODO: this is just for the test token. Issuance mechanism for mainnet token to be decided.
function dev_issueTo(address receiver, uint256 amount) {
......@@ -233,7 +219,7 @@ contract Streem {
outStreamPtrs[msg.sender] = 0;
inStreamPtrs[msg.sender] = 0;
if(msg.sender == owner) {
if (msg.sender == owner) {
settledBalances[msg.sender] = int(totalSupply);
delete streams;
......
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