Go Implementation

Go/shortUrl.go

@@ -0,0 +1,53 @@
+/**
+ * ShortURL: Bijective conversion between natural numbers (IDs) and short strings
+ * Licensed under the MIT License (https://opensource.org/licenses/MIT)
+ *
+ * ShortURL::encode() takes an ID and turns it into a short string
+ * ShortURL::decode() takes a short string and turns it into an ID
+ *
+ * Features:
+ * + large alphabet (51 chars) and thus very short resulting strings
+ * + proof against offensive words (removed 'a', 'e', 'i', 'o' and 'u')
+ * + unambiguous (removed 'I', 'l', '1', 'O' and '0')
+ **/
+package ShortURL
+
+import (
+	"fmt"
+	"strings"
+)
+
+const (
+	Alphabets = "23456789bcdfghjkmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ-_"
+	Base      = len(Alphabets)
+)
+
+type Codec struct{}
+
+func (c *Codec) Encode(n int) string {
+	var s string
+	for n > 0 {
+		s = string(Alphabets[n%Base]) + s
+		n /= Base
+	}
+	return s
+}
+
+func (c *Codec) Decode(path string) (int, error) {
+	n := 0
+	for _, c := range path {
+		i := strings.Index(Alphabets, string(c))
+		if i < 0 {
+			return 0, fmt.Errorf("Invalid character %s in input %s", string(c), path)
+		} else {
+			n = n*Base + i
+		}
+
+	}
+	return n, nil
+}
+
+func InitShorteningCodec() *Codec {
+	codec := Codec{}
+	return &codec
+}