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package contracts
import (
"encoding/binary"
"errors"
"fmt"
"math/big"
"github.com/ethereum/go-ethereum/accounts/abi"
"github.com/ethereum/go-ethereum/core/types"
)
// DecodeVersionNonce is an re-implementation of Encoding.sol#decodeVersionedNonce.
// If the nonce is greater than 32 bytes (solidity uint256), bytes [32:] are ignored
func DecodeVersionedNonce(nonce *big.Int) (uint16, *big.Int) {
nonceBytes := nonce.Bytes()
nonceByteLen := len(nonceBytes)
if nonceByteLen < 30 {
// version is 0x0000
return 0, nonce
} else if nonceByteLen == 31 {
// version is 0x00[01..ff]
return uint16(nonceBytes[0]), new(big.Int).SetBytes(nonceBytes[1:])
} else {
// fully specified
version := binary.BigEndian.Uint16(nonceBytes[:2])
return version, new(big.Int).SetBytes(nonceBytes[2:])
}
}
func UnpackLog(out interface{}, log *types.Log, name string, contractAbi *abi.ABI) error {
eventAbi, ok := contractAbi.Events[name]
if !ok {
return fmt.Errorf("event %s not present in supplied ABI", name)
} else if len(log.Topics) == 0 {
return errors.New("anonymous events are not supported")
} else if log.Topics[0] != eventAbi.ID {
return errors.New("event signature mismatch")
}
err := contractAbi.UnpackIntoInterface(out, name, log.Data)
if err != nil {
return err
}
// handle topics if present
if len(log.Topics) > 1 {
var indexedArgs abi.Arguments
for _, arg := range eventAbi.Inputs {
if arg.Indexed {
indexedArgs = append(indexedArgs, arg)
}
}
// The first topic (event signature) is omitted
err := abi.ParseTopics(out, indexedArgs, log.Topics[1:])
if err != nil {
return err
}
}
return nil
}