initial

2023-08-03 14:44:03 +02:00
commit 9adac9b32a
6 changed files with 291 additions and 0 deletions
--- a/go.mod
+++ b/go.mod
@@ -0,0 +1,11 @@
+module code.icod.de/dalu/oid36
+
+go 1.20
+
+require github.com/stretchr/testify v1.8.4
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
--- a/go.sum
+++ b/go.sum
@@ -0,0 +1,9 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
--- a/internal/base36/base36.go
+++ b/internal/base36/base36.go
@@ -0,0 +1,167 @@
+package base36
+
+import (
+	"math/big"
+	"strings"
+)
+
+var (
+	base36 = []byte{
+		'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+		'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
+		'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
+		'U', 'V', 'W', 'X', 'Y', 'Z'}
+
+	//index = map[byte]int{
+	//	'0': 0, '1': 1, '2': 2, '3': 3, '4': 4,
+	//	'5': 5, '6': 6, '7': 7, '8': 8, '9': 9,
+	//	'A': 10, 'B': 11, 'C': 12, 'D': 13, 'E': 14,
+	//	'F': 15, 'G': 16, 'H': 17, 'I': 18, 'J': 19,
+	//	'K': 20, 'L': 21, 'M': 22, 'N': 23, 'O': 24,
+	//	'P': 25, 'Q': 26, 'R': 27, 'S': 28, 'T': 29,
+	//	'U': 30, 'V': 31, 'W': 32, 'X': 33, 'Y': 34,
+	//	'Z': 35,
+	//	'a': 10, 'b': 11, 'c': 12, 'd': 13, 'e': 14,
+	//	'f': 15, 'g': 16, 'h': 17, 'i': 18, 'j': 19,
+	//	'k': 20, 'l': 21, 'm': 22, 'n': 23, 'o': 24,
+	//	'p': 25, 'q': 26, 'r': 27, 's': 28, 't': 29,
+	//	'u': 30, 'v': 31, 'w': 32, 'x': 33, 'y': 34,
+	//	'z': 35,
+	//}
+	uint8Index = []uint64{
+		0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 1, 2,
+		3, 4, 5, 6, 7, 8, 9, 0, 0, 0,
+		0, 0, 0, 0, 10, 11, 12, 13, 14,
+		15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
+		25, 26, 27, 28, 29, 30, 31, 32, 33, 34,
+		35, 0, 0, 0, 0, 0, 0, 10, 11, 12, 13,
+		14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
+		24, 25, 26, 27, 28, 29, 30, 31, 32, 33,
+		34, 35, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+		0, 0, 0, 0, 0, // 256
+	}
+	pow36Index = []uint64{
+		1, 36, 1296, 46656, 1679616, 60466176,
+		2176782336, 78364164096, 2821109907456,
+		101559956668416, 3656158440062976,
+		131621703842267136, 4738381338321616896,
+		9223372036854775808,
+	}
+)
+
+// Encode encodes a number to base36.
+func Encode(value uint64) string {
+	var res [16]byte
+	var i int
+	for i = len(res) - 1; ; i-- {
+		res[i] = base36[value%36]
+		value /= 36
+		if value == 0 {
+			break
+		}
+	}
+
+	return string(res[i:])
+}
+
+// Decode decodes a base36-encoded string.
+func Decode(s string) uint64 {
+	if len(s) > 13 {
+		s = s[:12]
+	}
+	res := uint64(0)
+	l := len(s) - 1
+	for idx := 0; idx < len(s); idx++ {
+		c := s[l-idx]
+		res += uint8Index[c] * pow36Index[idx]
+	}
+	return res
+}
+
+var bigRadix = big.NewInt(36)
+var bigZero = big.NewInt(0)
+
+// EncodeBytesAsBytes encodes a byte slice to base36.
+func EncodeBytesAsBytes(b []byte) []byte {
+	x := new(big.Int)
+	x.SetBytes(b)
+
+	answer := make([]byte, 0, len(b)*136/100)
+	for x.Cmp(bigZero) > 0 {
+		mod := new(big.Int)
+		x.DivMod(x, bigRadix, mod)
+		answer = append(answer, base36[mod.Int64()])
+	}
+
+	// leading zero bytes
+	for _, i := range b {
+		if i != 0 {
+			break
+		}
+		answer = append(answer, base36[0])
+	}
+
+	// reverse
+	alen := len(answer)
+	for i := 0; i < alen/2; i++ {
+		answer[i], answer[alen-1-i] = answer[alen-1-i], answer[i]
+	}
+
+	return answer
+}
+
+// EncodeBytes encodes a byte slice to base36 string.
+func EncodeBytes(b []byte) string {
+	return string(EncodeBytesAsBytes(b))
+}
+
+// DecodeToBytes decodes a base36 string to a byte slice, using alphabet.
+func DecodeToBytes(b string) []byte {
+	alphabet := string(base36)
+	answer := big.NewInt(0)
+	j := big.NewInt(1)
+
+	for i := len(b) - 1; i >= 0; i-- {
+		tmp := strings.IndexAny(alphabet, string(b[i]))
+		if tmp == -1 {
+			return []byte("")
+		}
+		idx := big.NewInt(int64(tmp))
+		tmp1 := big.NewInt(0)
+		tmp1.Mul(j, idx)
+
+		answer.Add(answer, tmp1)
+		j.Mul(j, bigRadix)
+	}
+
+	tmpval := answer.Bytes()
+
+	var numZeros int
+	for numZeros = 0; numZeros < len(b); numZeros++ {
+		if b[numZeros] != alphabet[0] {
+			break
+		}
+	}
+	flen := numZeros + len(tmpval)
+	val := make([]byte, flen, flen)
+	copy(val[numZeros:], tmpval)
+
+	return val
+}
--- a/internal/base36/base36_test.go
+++ b/internal/base36/base36_test.go
@@ -0,0 +1,51 @@
+package base36
+
+import (
+	"math"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var raw = []uint64{0, 50, 100, 999, 1000, 1111, 5959, 99999,
+	123456789, 5481594952936519619, math.MaxInt64 / 2048, math.MaxInt64 / 512,
+	math.MaxInt64, math.MaxUint64}
+
+var encoded = []string{"0", "1E", "2S", "RR", "RS", "UV", "4LJ", "255R",
+	"21I3V9", "15N9Z8L3AU4EB", "18CE53UN18F", "4XDKKFEK4XR",
+	"1Y2P0IJ32E8E7", "3W5E11264SGSF"}
+
+func TestEncode(t *testing.T) {
+	for i, v := range raw {
+		assert.Equal(t, encoded[i], Encode(v))
+	}
+}
+
+func TestDecode(t *testing.T) {
+	for i, v := range encoded {
+		assert.Equal(t, raw[i], Decode(v))
+		assert.Equal(t, raw[i], Decode(strings.ToLower(v)))
+	}
+}
+
+func BenchmarkEncode(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Encode(5481594952936519619)
+	}
+}
+
+func BenchmarkEncodeBytesAsBytes(b *testing.B) {
+	data := []byte{
+		0x86, 0x4F, 0xD2, 0x6F, 0xB5, 0x59, 0xF7, 0x5B, 0x48, 0x4F, 0x2A, 0x48, 0x4F, 0x2A,
+	}
+	for i := 0; i < b.N; i++ {
+		EncodeBytesAsBytes(data)
+	}
+}
+
+func BenchmarkDecode(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Decode("1Y2P0IJ32E8E7")
+	}
+}
--- a/oid36.go
+++ b/oid36.go
@@ -0,0 +1,21 @@
+package oid36
+
+import (
+	"encoding/hex"
+
+	"code.icod.de/dalu/oid36/internal/base36"
+)
+
+func ObjectIDToBase36(oid string) (string, error) {
+	b, e := hex.DecodeString(oid)
+	if e != nil {
+		return "", e
+	}
+	s := base36.EncodeBytes(b)
+	return s, nil
+}
+
+func Base36ToObjectID(bid string) string {
+	b := base36.DecodeToBytes(bid)
+	return hex.EncodeToString(b)
+}
--- a/oid36_test.go
+++ b/oid36_test.go
@@ -0,0 +1,32 @@
+package oid36_test
+
+import (
+	"testing"
+
+	"code.icod.de/dalu/oid36"
+)
+
+func TestObjectIDToBase36(t *testing.T) {
+	oid := "617fc6a58149e807907dac6f"
+	exp := "2XBEMITFMZGGAZ8UC1B"
+	result, e := oid36.ObjectIDToBase36(oid)
+	if e != nil {
+		t.Error(e)
+		t.Fail()
+		return
+	}
+	if result != exp {
+		t.Fail()
+		return
+	}
+}
+
+func TestBase36ToObjectID(t *testing.T) {
+	bid := "2XBEMITFMZGGAZ8UC1B"
+	exp := "617fc6a58149e807907dac6f"
+	result := oid36.Base36ToObjectID(bid)
+	if result != exp {
+		t.Fail()
+		return
+	}
+}