v

1
module base58
2

3
const impossible = 'this should never happen'
4

5
pub const btc_alphabet = new_alphabet('123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz') or {
6
	panic(impossible)
7
}
8

9
pub const flickr_alphabet = new_alphabet('123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ') or {
10
	panic(impossible)
11
}
12

13
pub const ripple_alphabet = new_alphabet('rpshnaf39wBUDNEGHJKLM4PQRST7VWXYZ2bcdeCg65jkm8oFqi1tuvAxyz') or {
14
	panic(impossible)
15
}
16

17
// alphabets is a map of common base58 alphabets:
18
pub const alphabets = {
19
	'btc':    btc_alphabet
20
	'flickr': flickr_alphabet
21
	'ripple': ripple_alphabet
22
}
23

24
// Alphabet is the series of characters that an input
25
// will be encoded to and a decode table.
26
struct Alphabet {
27
mut:
28
	decode []i8 = []i8{len: 128, init: -1}
29
	encode []u8 = []u8{len: 58}
30
}
31

32
// str returns an Alphabet encode table byte array as a string
33
pub fn (alphabet Alphabet) str() string {
34
	// i guess i had a brain fart here. Why would I actually use this code?!
35
	// mut str := []u8{}
36
	// for entry in alphabet.encode {
37
	// 	str << entry
38
	// }
39
	// return str.bytestr()
40
	return alphabet.encode.bytestr()
41
}
42

43
// new_alphabet instantiates an Alphabet object based on
44
// the provided characters
45
pub fn new_alphabet(str string) !Alphabet {
46
	if str.len != 58 {
47
		return error(@MOD + '.' + @FN + ': string must be 58 characters in length')
48
	}
49

50
	mut ret := Alphabet{}
51
	copy(mut ret.encode, str.bytes())
52

53
	mut distinct := 0
54
	for i, b in ret.encode {
55
		if ret.decode[b] == -1 {
56
			distinct++
57
		}
58
		ret.decode[b] = i8(i)
59
	}
60

61
	if distinct != 58 {
62
		return error(@MOD + '.' + @FN + ': string must not contain repeating characters')
63
	}
64

65
	return ret
66
}
67