github.com/sberex/go-sberex@v1.8.2-0.20181113200658-ed96ac38f7d7/whisper/whisperv5/topic.go (about) 1 // This file is part of the go-sberex library. The go-sberex library is 2 // free software: you can redistribute it and/or modify it under the terms 3 // of the GNU Lesser General Public License as published by the Free 4 // Software Foundation, either version 3 of the License, or (at your option) 5 // any later version. 6 // 7 // The go-sberex library is distributed in the hope that it will be useful, 8 // but WITHOUT ANY WARRANTY; without even the implied warranty of 9 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser 10 // General Public License <http://www.gnu.org/licenses/> for more details. 11 12 // Contains the Whisper protocol Topic element. 13 14 package whisperv5 15 16 import ( 17 "github.com/Sberex/go-sberex/common" 18 "github.com/Sberex/go-sberex/common/hexutil" 19 ) 20 21 // Topic represents a cryptographically secure, probabilistic partial 22 // classifications of a message, determined as the first (left) 4 bytes of the 23 // SHA3 hash of some arbitrary data given by the original author of the message. 24 type TopicType [TopicLength]byte 25 26 func BytesToTopic(b []byte) (t TopicType) { 27 sz := TopicLength 28 if x := len(b); x < TopicLength { 29 sz = x 30 } 31 for i := 0; i < sz; i++ { 32 t[i] = b[i] 33 } 34 return t 35 } 36 37 // String converts a topic byte array to a string representation. 38 func (t *TopicType) String() string { 39 return common.ToHex(t[:]) 40 } 41 42 // MarshalText returns the hex representation of t. 43 func (t TopicType) MarshalText() ([]byte, error) { 44 return hexutil.Bytes(t[:]).MarshalText() 45 } 46 47 // UnmarshalText parses a hex representation to a topic. 48 func (t *TopicType) UnmarshalText(input []byte) error { 49 return hexutil.UnmarshalFixedText("Topic", input, t[:]) 50 }