mirror of
https://github.com/rclone/rclone.git
synced 2024-11-26 02:09:55 +08:00
292 lines
6.6 KiB
Go
292 lines
6.6 KiB
Go
package fs
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import (
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"crypto/md5"
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"crypto/sha1"
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"encoding/hex"
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"fmt"
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"hash"
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"io"
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"strings"
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"github.com/ncw/rclone/backend/dropbox/dbhash"
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"github.com/pkg/errors"
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"github.com/spf13/pflag"
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)
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// HashType indicates a standard hashing algorithm
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type HashType int
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// ErrHashUnsupported should be returned by filesystem,
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// if it is requested to deliver an unsupported hash type.
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var ErrHashUnsupported = errors.New("hash type not supported")
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const (
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// HashMD5 indicates MD5 support
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HashMD5 HashType = 1 << iota
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// HashSHA1 indicates SHA-1 support
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HashSHA1
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// HashDropbox indicates Dropbox special hash
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// https://www.dropbox.com/developers/reference/content-hash
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HashDropbox
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// HashNone indicates no hashes are supported
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HashNone HashType = 0
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)
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// SupportedHashes returns a set of all the supported hashes by
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// HashStream and MultiHasher.
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var SupportedHashes = NewHashSet(HashMD5, HashSHA1, HashDropbox)
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// HashWidth returns the width in characters for any HashType
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var HashWidth = map[HashType]int{
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HashMD5: 32,
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HashSHA1: 40,
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HashDropbox: 64,
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}
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// HashStream will calculate hashes of all supported hash types.
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func HashStream(r io.Reader) (map[HashType]string, error) {
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return HashStreamTypes(r, SupportedHashes)
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}
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// HashStreamTypes will calculate hashes of the requested hash types.
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func HashStreamTypes(r io.Reader, set HashSet) (map[HashType]string, error) {
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hashers, err := hashFromTypes(set)
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if err != nil {
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return nil, err
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}
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_, err = io.Copy(hashToMultiWriter(hashers), r)
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if err != nil {
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return nil, err
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}
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var ret = make(map[HashType]string)
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for k, v := range hashers {
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ret[k] = hex.EncodeToString(v.Sum(nil))
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}
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return ret, nil
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}
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// String returns a string representation of the hash type.
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// The function will panic if the hash type is unknown.
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func (h HashType) String() string {
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switch h {
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case HashNone:
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return "None"
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case HashMD5:
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return "MD5"
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case HashSHA1:
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return "SHA-1"
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case HashDropbox:
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return "DropboxHash"
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default:
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err := fmt.Sprintf("internal error: unknown hash type: 0x%x", int(h))
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panic(err)
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}
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}
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// Set a HashType from a flag
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func (h *HashType) Set(s string) error {
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switch s {
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case "None":
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*h = HashNone
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case "MD5":
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*h = HashMD5
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case "SHA-1":
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*h = HashSHA1
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case "DropboxHash":
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*h = HashDropbox
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default:
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return errors.Errorf("Unknown hash type %q", s)
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}
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return nil
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}
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// Type of the value
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func (h HashType) Type() string {
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return "string"
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}
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// Check it satisfies the interface
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var _ pflag.Value = (*HashType)(nil)
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// hashFromTypes will return hashers for all the requested types.
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// The types must be a subset of SupportedHashes,
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// and this function must support all types.
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func hashFromTypes(set HashSet) (map[HashType]hash.Hash, error) {
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if !set.SubsetOf(SupportedHashes) {
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return nil, errors.Errorf("requested set %08x contains unknown hash types", int(set))
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}
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var hashers = make(map[HashType]hash.Hash)
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types := set.Array()
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for _, t := range types {
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switch t {
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case HashMD5:
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hashers[t] = md5.New()
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case HashSHA1:
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hashers[t] = sha1.New()
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case HashDropbox:
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hashers[t] = dbhash.New()
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default:
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err := fmt.Sprintf("internal error: Unsupported hash type %v", t)
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panic(err)
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}
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}
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return hashers, nil
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}
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// hashToMultiWriter will return a set of hashers into a
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// single multiwriter, where one write will update all
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// the hashers.
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func hashToMultiWriter(h map[HashType]hash.Hash) io.Writer {
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// Convert to to slice
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var w = make([]io.Writer, 0, len(h))
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for _, v := range h {
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w = append(w, v)
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}
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return io.MultiWriter(w...)
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}
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// A MultiHasher will construct various hashes on
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// all incoming writes.
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type MultiHasher struct {
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w io.Writer
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size int64
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h map[HashType]hash.Hash // Hashes
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}
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// NewMultiHasher will return a hash writer that will write all
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// supported hash types.
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func NewMultiHasher() *MultiHasher {
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h, err := NewMultiHasherTypes(SupportedHashes)
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if err != nil {
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panic("internal error: could not create multihasher")
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}
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return h
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}
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// NewMultiHasherTypes will return a hash writer that will write
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// the requested hash types.
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func NewMultiHasherTypes(set HashSet) (*MultiHasher, error) {
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hashers, err := hashFromTypes(set)
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if err != nil {
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return nil, err
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}
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m := MultiHasher{h: hashers, w: hashToMultiWriter(hashers)}
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return &m, nil
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}
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func (m *MultiHasher) Write(p []byte) (n int, err error) {
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n, err = m.w.Write(p)
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m.size += int64(n)
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return n, err
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}
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// Sums returns the sums of all accumulated hashes as hex encoded
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// strings.
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func (m *MultiHasher) Sums() map[HashType]string {
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dst := make(map[HashType]string)
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for k, v := range m.h {
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dst[k] = hex.EncodeToString(v.Sum(nil))
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}
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return dst
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}
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// Size returns the number of bytes written
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func (m *MultiHasher) Size() int64 {
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return m.size
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}
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// A HashSet Indicates one or more hash types.
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type HashSet int
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// NewHashSet will create a new hash set with the hash types supplied
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func NewHashSet(t ...HashType) HashSet {
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h := HashSet(HashNone)
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return h.Add(t...)
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}
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// Add one or more hash types to the set.
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// Returns the modified hash set.
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func (h *HashSet) Add(t ...HashType) HashSet {
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for _, v := range t {
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*h |= HashSet(v)
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}
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return *h
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}
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// Contains returns true if the
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func (h HashSet) Contains(t HashType) bool {
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return int(h)&int(t) != 0
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}
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// Overlap returns the overlapping hash types
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func (h HashSet) Overlap(t HashSet) HashSet {
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return HashSet(int(h) & int(t))
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}
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// SubsetOf will return true if all types of h
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// is present in the set c
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func (h HashSet) SubsetOf(c HashSet) bool {
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return int(h)|int(c) == int(c)
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}
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// GetOne will return a hash type.
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// Currently the first is returned, but it could be
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// improved to return the strongest.
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func (h HashSet) GetOne() HashType {
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v := int(h)
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i := uint(0)
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for v != 0 {
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if v&1 != 0 {
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return HashType(1 << i)
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}
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i++
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v >>= 1
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}
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return HashType(HashNone)
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}
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// Array returns an array of all hash types in the set
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func (h HashSet) Array() (ht []HashType) {
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v := int(h)
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i := uint(0)
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for v != 0 {
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if v&1 != 0 {
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ht = append(ht, HashType(1<<i))
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}
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i++
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v >>= 1
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}
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return ht
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}
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// Count returns the number of hash types in the set
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func (h HashSet) Count() int {
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if int(h) == 0 {
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return 0
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}
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// credit: https://code.google.com/u/arnehormann/
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x := uint64(h)
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x -= (x >> 1) & 0x5555555555555555
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x = (x>>2)&0x3333333333333333 + x&0x3333333333333333
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x += x >> 4
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x &= 0x0f0f0f0f0f0f0f0f
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x *= 0x0101010101010101
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return int(x >> 56)
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}
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// String returns a string representation of the hash set.
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// The function will panic if it contains an unknown type.
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func (h HashSet) String() string {
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a := h.Array()
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var r []string
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for _, v := range a {
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r = append(r, v.String())
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}
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return "[" + strings.Join(r, ", ") + "]"
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}
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