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Switch from a cache to a query contract, cache is out of scope

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William Entriken 2018-02-20 17:33:49 -05:00 committed by GitHub
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1 changed files with 7 additions and 26 deletions
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EIPS/eip-165.md
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@ -115,48 +115,29 @@ Following is a caching contract that detects which interfaces other contracts im
```solidity
pragma solidity ^0.4.20;
contract ERC165Cache {
contract ERC165Query {
bytes4 constant InvalidID = 0xffffffff;
bytes4 constant ERC165ID = 0x01ffc9a7;
enum ImplStatus { Unknown, No, Yes }
mapping (address => mapping (bytes4 => ImplStatus)) cache;
// Return value from cache if available
function interfaceSupported(address _contract, bytes4 _interfaceId) external returns (bool) {
ImplStatus status = cache[_contract][_interfaceId];
if (status == ImplStatus.Unknown) {
return checkInterfaceSupported(_contract, _interfaceId);
}
return status == ImplStatus.Yes;
}
// Repull result into cache
function checkInterfaceSupported(address _contract, bytes4 _interfaceId) public returns (bool) {
ImplStatus status = determineInterfaceImplementationStatus(_contract, _interfaceId);
cache[_contract][_interfaceId] = status;
return status == ImplStatus.Yes;
}
function determineInterfaceImplementationStatus(address _contract, bytes4 _interfaceId) internal view returns (ImplStatus) {
function doesContractImplementInterface(address _contract, bytes4 _interfaceId) external view returns (bool) {
uint256 success;
uint256 result;
(success, result) = noThrowCall(_contract, ERC165ID);
if ((success==0)||(result==0)) {
return ImplStatus.No;
return false;
}
(success, result) = noThrowCall(_contract, InvalidID);
if ((success==0)||(result!=0)) {
return ImplStatus.No;
return false;
}
(success, result) = noThrowCall(_contract, _interfaceId);
if ((success==1)&&(result==1)) {
return ImplStatus.Yes;
return true;
}
return ImplStatus.No;
return false;
}
function noThrowCall(address _contract, bytes4 _interfaceId) constant internal returns (uint256 success, uint256 result) {
@ -171,7 +152,7 @@ contract ERC165Cache {
30000, // 30k gas
_contract, // To addr
x, // Inputs are stored at location x
0x20, // Inputs are 8 byes long
0x20, // Inputs are 8 byes long
x, // Store output over input (saves space)
0x20) // Outputs are 32 bytes long