text: // Protocol Buffers for Go with Gadgets
  //
  // Copyright (c) 2013, The GoGo Authors. All rights reserved.
  // http://github.com/gogo/protobuf
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  package test
  
  import (
  	"bytes"
  	"encoding/hex"
  	"encoding/json"
  )
  
  func PutLittleEndianUint64(b []byte, offset int, v uint64) {
  	b[offset] = byte(v)
  	b[offset+1] = byte(v >> 8)
  	b[offset+2] = byte(v >> 16)
  	b[offset+3] = byte(v >> 24)
  	b[offset+4] = byte(v >> 32)
  	b[offset+5] = byte(v >> 40)
  	b[offset+6] = byte(v >> 48)
  	b[offset+7] = byte(v >> 56)
  }
  
  type Uuid []byte
  
  func (uuid Uuid) Marshal() ([]byte, error) {
  	if len(uuid) == 0 {
  		return nil, nil
  	}
  	return []byte(uuid), nil
  }
  
  func (uuid Uuid) MarshalTo(data []byte) (n int, err error) {
  	if len(uuid) == 0 {
  		return 0, nil
  	}
  	copy(data, uuid)
  	return 16, nil
  }
  
  func (uuid *Uuid) Unmarshal(data []byte) error {
  	if len(data) == 0 {
  		uuid = nil
  		return nil
  	}
  	id := Uuid(make([]byte, 16))
  	copy(id, data)
  	*uuid = id
  	return nil
  }
  
  func (uuid *Uuid) Size() int {
  	if uuid == nil {
  		return 0
  	}
  	if len(*uuid) == 0 {
  		return 0
  	}
  	return 16
  }
  
  func (uuid Uuid) MarshalJSON() ([]byte, error) {
  	s := hex.EncodeToString([]byte(uuid))
  	return json.Marshal(s)
  }
  
  func (uuid *Uuid) UnmarshalJSON(data []byte) error {
  	var s string
  	err := json.Unmarshal(data, &s)
  	if err != nil {
  		return err
  	}
  	d, err := hex.DecodeString(s)
  	if err != nil {
  		return err
  	}
  	*uuid = Uuid(d)
  	return nil
  }
  
  func (uuid Uuid) Equal(other Uuid) bool {
  	return bytes.Equal(uuid[0:], other[0:])
  }
  
  func (uuid Uuid) Compare(other Uuid) int {
  	return bytes.Compare(uuid[0:], other[0:])
  }
  
  type int63 interface {
  	Int63() int64
  }
  
  func NewPopulatedUuid(r int63) *Uuid {
  	u := RandV4(r)
  	return &u
  }
  
  func RandV4(r int63) Uuid {
  	uuid := make(Uuid, 16)
  	uuid.RandV4(r)
  	return uuid
  }
  
  func (uuid Uuid) RandV4(r int63) {
  	PutLittleEndianUint64(uuid, 0, uint64(r.Int63()))
  	PutLittleEndianUint64(uuid, 8, uint64(r.Int63()))
  	uuid[6] = (uuid[6] & 0xf) | 0x40
  	uuid[8] = (uuid[8] & 0x3f) | 0x80
  }
  