From 3f8b0b0fa251a060ead95bb8ec08ac4f01d0f6c3 Mon Sep 17 00:00:00 2001
From: Maxim Bublis <b@codemonkey.ru>
Date: Wed, 4 Dec 2013 19:01:44 +0400
Subject: [PATCH] Added FromString parser

---
 benchmarks_test.go | 21 +++++++++++++++++++++
 uuid.go            | 29 +++++++++++++++++++++++++++++
 uuid_test.go       | 40 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 90 insertions(+)

diff --git a/benchmarks_test.go b/benchmarks_test.go
index 542e659..fd261d1 100644
--- a/benchmarks_test.go
+++ b/benchmarks_test.go
@@ -32,6 +32,27 @@ func BenchmarkFromBytes(b *testing.B) {
 	}
 }
 
+func BenchmarkFromString(b *testing.B) {
+	s := "6ba7b810-9dad-11d1-80b4-00c04fd430c8"
+	for i := 0; i < b.N; i++ {
+		FromString(s)
+	}
+}
+
+func BenchmarkFromStringUrn(b *testing.B) {
+	s := "urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8"
+	for i := 0; i < b.N; i++ {
+		FromString(s)
+	}
+}
+
+func BenchmarkFromStringWithBrackets(b *testing.B) {
+	s := "{6ba7b810-9dad-11d1-80b4-00c04fd430c8}"
+	for i := 0; i < b.N; i++ {
+		FromString(s)
+	}
+}
+
 func BenchmarkNewV1(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		NewV1()
diff --git a/uuid.go b/uuid.go
index ef7de47..4c90106 100644
--- a/uuid.go
+++ b/uuid.go
@@ -30,10 +30,12 @@ import (
 	"crypto/rand"
 	"crypto/sha1"
 	"encoding/binary"
+	"encoding/hex"
 	"fmt"
 	"hash"
 	"net"
 	"os"
+	"strings"
 	"time"
 )
 
@@ -192,6 +194,31 @@ func FromBytes(input []byte) (u UUID, err error) {
 	return
 }
 
+// FromString returns UUID parsed from string input.
+// Following formats are supported:
+// "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
+// "{6ba7b810-9dad-11d1-80b4-00c04fd430c8}",
+// "urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8"
+func FromString(input string) (u UUID, err error) {
+	s := strings.Replace(input, "-", "", -1)
+
+	if len(s) == 41 && s[:9] == "urn:uuid:" {
+		s = s[9:]
+	} else if len(s) == 34 && s[0] == '{' && s[33] == '}' {
+		s = s[1:33]
+	}
+
+	if len(s) != 32 {
+		err = fmt.Errorf("Invalid UUID string: %s", input)
+		return
+	}
+
+	b := []byte(s)
+	_, err = hex.Decode(u[:], b)
+
+	return
+}
+
 // NewV1 returns UUID based on current timestamp and MAC address.
 func NewV1() UUID {
 	u := UUID{}
@@ -228,7 +255,9 @@ func NewV2(domain byte) UUID {
 	binary.BigEndian.PutUint16(u[6:], uint16(timeNow>>48))
 	binary.BigEndian.PutUint16(u[8:], clockSequence)
 	u[9] = domain
+
 	copy(u[10:], hardwareAddr[:])
+
 	u.SetVersion(2)
 	u.SetVariant()
 
diff --git a/uuid_test.go b/uuid_test.go
index 7f3fc40..0dec83d 100644
--- a/uuid_test.go
+++ b/uuid_test.go
@@ -137,6 +137,46 @@ func TestFromBytes(t *testing.T) {
 	}
 }
 
+func TestFromString(t *testing.T) {
+	u := UUID{0x6b, 0xa7, 0xb8, 0x10, 0x9d, 0xad, 0x11, 0xd1, 0x80, 0xb4, 0x00, 0xc0, 0x4f, 0xd4, 0x30, 0xc8}
+
+	s1 := "6ba7b810-9dad-11d1-80b4-00c04fd430c8"
+	s2 := "{6ba7b810-9dad-11d1-80b4-00c04fd430c8}"
+	s3 := "urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8"
+
+	_, err := FromString("")
+	if err == nil {
+		t.Errorf("Should return error trying to parse empty string, got %s", err)
+	}
+
+	u1, err := FromString(s1)
+	if err != nil {
+		t.Errorf("Error parsing UUID from string: %s", err)
+	}
+
+	if !Equal(u, u1) {
+		t.Errorf("UUIDs should be equal: %s and %s", u, u1)
+	}
+
+	u2, err := FromString(s2)
+	if err != nil {
+		t.Errorf("Error parsing UUID from string: %s", err)
+	}
+
+	if !Equal(u, u2) {
+		t.Errorf("UUIDs should be equal: %s and %s", u, u2)
+	}
+
+	u3, err := FromString(s3)
+	if err != nil {
+		t.Errorf("Error parsing UUID from string: %s", err)
+	}
+
+	if !Equal(u, u3) {
+		t.Errorf("UUIDs should be equal: %s and %s", u, u3)
+	}
+}
+
 func TestNewV1(t *testing.T) {
 	u := NewV1()