Merge pull request #2 from segmentfault/utils/id

add utils id

utils/id.go

@@ -0,0 +1,40 @@
+package utils
+
+var ShortIDSwitch = false
+
+var AlphanumericSet = []rune{
+	'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',
+	'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',
+}
+
+var AlphanumericIndex map[rune]int
+
+func init() {
+	AlphanumericIndex = make(map[rune]int, len(AlphanumericSet))
+	for i, ru := range AlphanumericSet {
+		AlphanumericIndex[ru] = i
+	}
+}
+
+func EnShortID(id int64, salt int64) string {
+	id = id + salt
+	var code []rune
+	for id > 0 {
+		idx := id % int64(len(AlphanumericSet))
+		code = append(code, AlphanumericSet[idx])
+		id = id / int64(len(AlphanumericSet))
+	}
+	return string(code)
+}
+func DeShortID(code string, salt int64) int64 {
+	var id int64
+	runes := []rune(code)
+	for i := len(runes) - 1; i >= 0; i-- {
+		ru := runes[i]
+		idx := AlphanumericIndex[ru]
+		id = id*int64(len(AlphanumericSet)) + int64(idx)
+	}
+	id = id - salt
+	return id
+}

utils/id_test.go

@@ -0,0 +1,27 @@
+package utils
+
+import (
+	"fmt"
+	"testing"
+)
+
+func Test_ShortID(t *testing.T) {
+	nums := []int64{
+		10010000000000001, 10010000000000002, 10010000000000003, 10010000000000004,
+		10030000000000689, 10010000000000676, 10020000000000658, 10020000000000654,
+		10030000009000689, 10010000009000676, 10020000009000658, 10020000009999999,
+		10030000090000689, 10010000090000676, 10020000090000658, 10020000099999999,
+		10030000900000689, 10010000900000676, 10020000900000658, 10020000999999999,
+		10030009000000689, 10010009000000676, 10020009000000658, 10020009999999999,
+		10030090000000689, 10010090000000676, 10020090000000658, 10020099999999999,
+		10030900000000689, 10010900000000676, 10020900000000658, 10020999999999999,
+		10039000000000689, 10019000000000676, 10029000000000658, 10029999999999999,
+		10610000000000689, 10610000000000676, 10610000000000658, 10610000000000654,
+		19990000000000689, 19990000000000676, 19990000000000658, 19990000000000654,
+	}
+	for _, num := range nums {
+		code := EnShortID(num, 0)
+		denum := DeShortID(code, 0)
+		fmt.Println(num, code, denum)
+	}
+}