Initial project import

tools/v/vlib/encoding/base58/alphabet.v

@@ -0,0 +1,66 @@
+module base58
+
+const impossible = 'this should never happen'
+
+pub const btc_alphabet = new_alphabet('123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz') or {
+	panic(impossible)
+}
+
+pub const flickr_alphabet = new_alphabet('123456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ') or {
+	panic(impossible)
+}
+
+pub const ripple_alphabet = new_alphabet('rpshnaf39wBUDNEGHJKLM4PQRST7VWXYZ2bcdeCg65jkm8oFqi1tuvAxyz') or {
+	panic(impossible)
+}
+
+// alphabets is a map of common base58 alphabets:
+pub const alphabets = {
+	'btc':    btc_alphabet
+	'flickr': flickr_alphabet
+	'ripple': ripple_alphabet
+}
+
+// Alphabet is the series of characters that an input
+// will be encoded to and a decode table.
+struct Alphabet {
+mut:
+	decode []i8 = []i8{len: 128, init: -1}
+	encode []u8 = []u8{len: 58}
+}
+
+// str returns an Alphabet encode table byte array as a string
+pub fn (alphabet Alphabet) str() string {
+	// i guess i had a brain fart here. Why would I actually use this code?!
+	// mut str := []u8{}
+	// for entry in alphabet.encode {
+	// 	str << entry
+	// }
+	// return str.bytestr()
+	return alphabet.encode.bytestr()
+}
+
+// new_alphabet instantiates an Alphabet object based on
+// the provided characters
+pub fn new_alphabet(str string) !Alphabet {
+	if str.len != 58 {
+		return error(@MOD + '.' + @FN + ': string must be 58 characters in length')
+	}
+
+	mut ret := Alphabet{}
+	copy(mut ret.encode, str.bytes())
+
+	mut distinct := 0
+	for i, b in ret.encode {
+		if ret.decode[b] == -1 {
+			distinct++
+		}
+		ret.decode[b] = i8(i)
+	}
+
+	if distinct != 58 {
+		return error(@MOD + '.' + @FN + ': string must not contain repeating characters')
+	}
+
+	return ret
+}