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/*
Copyright 2018 ZeroEx Intl.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
pragma solidity ^0.4.21;
import "../IAssetProxy.sol";
import "../../../utils/LibBytes/LibBytes.sol";
import "../../../utils/Authorizable/Authorizable.sol";
import "/zeppelin/contracts/token/ERC721/ERC721Token.sol";
contract ERC721TransferProxy is
LibBytes,
Authorizable,
IAssetProxy
{
/// @dev Transfers ERC20 tokens.
/// @param assetMetadata Byte array encoded for the respective asset proxy.
/// @param from Address to transfer token from.
/// @param to Address to transfer token to.
/// @param amount Amount of token to transfer.
function transferFrom(
bytes assetMetadata,
address from,
address to,
uint256 amount)
public
onlyAuthorized
{
// Decode metadata
address token;
uint256 tokenId;
(token, tokenId) = decodeMetadata(assetMetadata);
// There exists only 1 of each token.
require(amount == 1);
// Call ERC721 contract. Either succeeds or throws.
ERC721Token(token).transferFrom(from, to, tokenId);
}
/// @dev Encodes ERC721 byte array for the ERC20 asset proxy.
/// @param assetProxyId Id of the asset proxy.
/// @param tokenAddress Address of the asset.
/// @param tokenId Id of ERC721 token.
/// @return assetMetadata Byte array encoded for the ERC721 asset proxy.
function encodeMetadata(
uint8 assetProxyId,
address tokenAddress,
uint256 tokenId)
public pure
returns (bytes assetMetadata)
{
// 0 is reserved as invalid proxy id
require(assetProxyId != 0);
// Encode fields into a byte array
assetMetadata = new bytes(53);
assetMetadata[0] = byte(assetProxyId);
writeAddress(assetMetadata, 1, tokenAddress);
writeUint256(assetMetadata, 21, tokenId);
return assetMetadata;
}
/// @dev Decodes ERC721-encoded byte array for the ERC721 asset proxy.
/// @param assetMetadata Byte array encoded for the ERC721 asset proxy.
/// @return tokenAddress Address of ERC721 token.
/// @return tokenId Id of ERC721 token.
function decodeMetadata(bytes assetMetadata)
public pure
returns (address tokenAddress, uint256 tokenId)
{
require(assetMetadata.length == 53);
tokenAddress = readAddress(assetMetadata, 1);
tokenId = readUint256(assetMetadata, 21);
return (tokenAddress, tokenId);
}
}
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