github.com/gobitfly/go-ethereum@v1.8.12/whisper/whisperv5/topic.go (about)

     1  // Copyright 2016 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  // Contains the Whisper protocol Topic element.
    18  
    19  package whisperv5
    20  
    21  import (
    22  	"github.com/ethereum/go-ethereum/common"
    23  	"github.com/ethereum/go-ethereum/common/hexutil"
    24  )
    25  
    26  // TopicType represents a cryptographically secure, probabilistic partial
    27  // classifications of a message, determined as the first (left) 4 bytes of the
    28  // SHA3 hash of some arbitrary data given by the original author of the message.
    29  type TopicType [TopicLength]byte
    30  
    31  func BytesToTopic(b []byte) (t TopicType) {
    32  	sz := TopicLength
    33  	if x := len(b); x < TopicLength {
    34  		sz = x
    35  	}
    36  	for i := 0; i < sz; i++ {
    37  		t[i] = b[i]
    38  	}
    39  	return t
    40  }
    41  
    42  // String converts a topic byte array to a string representation.
    43  func (t *TopicType) String() string {
    44  	return common.ToHex(t[:])
    45  }
    46  
    47  // MarshalText returns the hex representation of t.
    48  func (t TopicType) MarshalText() ([]byte, error) {
    49  	return hexutil.Bytes(t[:]).MarshalText()
    50  }
    51  
    52  // UnmarshalText parses a hex representation to a topic.
    53  func (t *TopicType) UnmarshalText(input []byte) error {
    54  	return hexutil.UnmarshalFixedText("Topic", input, t[:])
    55  }