github.com/Evanesco-Labs/go-evanesco@v1.0.1/common/bytes.go (about)

     1  // Copyright 2014 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  // Package common contains various helper functions.
    18  package common
    19  
    20  import (
    21  	"encoding/hex"
    22  )
    23  
    24  // FromHex returns the bytes represented by the hexadecimal string s.
    25  // s may be prefixed with "0x".
    26  func FromHex(s string) []byte {
    27  	if has0xPrefix(s) {
    28  		s = s[2:]
    29  	}
    30  	if len(s)%2 == 1 {
    31  		s = "0" + s
    32  	}
    33  	return Hex2Bytes(s)
    34  }
    35  
    36  // CopyBytes returns an exact copy of the provided bytes.
    37  func CopyBytes(b []byte) (copiedBytes []byte) {
    38  	if b == nil {
    39  		return nil
    40  	}
    41  	copiedBytes = make([]byte, len(b))
    42  	copy(copiedBytes, b)
    43  
    44  	return
    45  }
    46  
    47  // has0xPrefix validates str begins with '0x' or '0X'.
    48  func has0xPrefix(str string) bool {
    49  	return len(str) >= 2 && str[0] == '0' && (str[1] == 'x' || str[1] == 'X')
    50  }
    51  
    52  // isHexCharacter returns bool of c being a valid hexadecimal.
    53  func isHexCharacter(c byte) bool {
    54  	return ('0' <= c && c <= '9') || ('a' <= c && c <= 'f') || ('A' <= c && c <= 'F')
    55  }
    56  
    57  // isHex validates whether each byte is valid hexadecimal string.
    58  func isHex(str string) bool {
    59  	if len(str)%2 != 0 {
    60  		return false
    61  	}
    62  	for _, c := range []byte(str) {
    63  		if !isHexCharacter(c) {
    64  			return false
    65  		}
    66  	}
    67  	return true
    68  }
    69  
    70  // Bytes2Hex returns the hexadecimal encoding of d.
    71  func Bytes2Hex(d []byte) string {
    72  	return hex.EncodeToString(d)
    73  }
    74  
    75  // Hex2Bytes returns the bytes represented by the hexadecimal string str.
    76  func Hex2Bytes(str string) []byte {
    77  	h, _ := hex.DecodeString(str)
    78  	return h
    79  }
    80  
    81  // Hex2BytesFixed returns bytes of a specified fixed length flen.
    82  func Hex2BytesFixed(str string, flen int) []byte {
    83  	h, _ := hex.DecodeString(str)
    84  	if len(h) == flen {
    85  		return h
    86  	}
    87  	if len(h) > flen {
    88  		return h[len(h)-flen:]
    89  	}
    90  	hh := make([]byte, flen)
    91  	copy(hh[flen-len(h):flen], h)
    92  	return hh
    93  }
    94  
    95  // RightPadBytes zero-pads slice to the right up to length l.
    96  func RightPadBytes(slice []byte, l int) []byte {
    97  	if l <= len(slice) {
    98  		return slice
    99  	}
   100  
   101  	padded := make([]byte, l)
   102  	copy(padded, slice)
   103  
   104  	return padded
   105  }
   106  
   107  // LeftPadBytes zero-pads slice to the left up to length l.
   108  func LeftPadBytes(slice []byte, l int) []byte {
   109  	if l <= len(slice) {
   110  		return slice
   111  	}
   112  
   113  	padded := make([]byte, l)
   114  	copy(padded[l-len(slice):], slice)
   115  
   116  	return padded
   117  }
   118  
   119  // TrimLeftZeroes returns a subslice of s without leading zeroes
   120  func TrimLeftZeroes(s []byte) []byte {
   121  	idx := 0
   122  	for ; idx < len(s); idx++ {
   123  		if s[idx] != 0 {
   124  			break
   125  		}
   126  	}
   127  	return s[idx:]
   128  }
   129  
   130  // TrimRightZeroes returns a subslice of s without trailing zeroes
   131  func TrimRightZeroes(s []byte) []byte {
   132  	idx := len(s)
   133  	for ; idx > 0; idx-- {
   134  		if s[idx-1] != 0 {
   135  			break
   136  		}
   137  	}
   138  	return s[:idx]
   139  }