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110 lines
2.6 KiB
110 lines
2.6 KiB
package cache
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import (
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"fmt"
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"github.com/segmentio/fasthash/fnv1a"
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)
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const (
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hashTypeInt uint64 = 1 << iota
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hashTypeSignedInt
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hashTypeBool
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hashTypeString
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hashTypeHashable
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hashTypeNil
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)
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type hasher struct {
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t uint64
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v interface{}
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}
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func (h *hasher) Hash() uint64 {
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return NewHash(h.t, h.v)
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}
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func NewHashable(t uint64, v interface{}) Hashable {
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return &hasher{t: t, v: v}
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}
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func InitHash(t uint64) uint64 {
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return fnv1a.AddUint64(fnv1a.Init64, t)
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}
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func NewHash(t uint64, in ...interface{}) uint64 {
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return AddToHash(InitHash(t), in...)
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}
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func AddToHash(h uint64, in ...interface{}) uint64 {
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for i := range in {
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if in[i] == nil {
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continue
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}
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h = addToHash(h, in[i])
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}
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return h
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}
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func addToHash(h uint64, in interface{}) uint64 {
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switch v := in.(type) {
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case uint64:
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeInt), v)
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case uint32:
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeInt), uint64(v))
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case uint16:
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeInt), uint64(v))
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case uint8:
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeInt), uint64(v))
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case uint:
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeInt), uint64(v))
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case int64:
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if v < 0 {
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeSignedInt), uint64(-v))
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} else {
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeInt), uint64(v))
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}
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case int32:
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if v < 0 {
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeSignedInt), uint64(-v))
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} else {
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeInt), uint64(v))
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}
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case int16:
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if v < 0 {
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeSignedInt), uint64(-v))
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} else {
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeInt), uint64(v))
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}
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case int8:
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if v < 0 {
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeSignedInt), uint64(-v))
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} else {
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeInt), uint64(v))
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}
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case int:
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if v < 0 {
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeSignedInt), uint64(-v))
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} else {
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeInt), uint64(v))
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}
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case bool:
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if v {
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeBool), 1)
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} else {
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeBool), 2)
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}
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case string:
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return fnv1a.AddString64(fnv1a.AddUint64(h, hashTypeString), v)
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case Hashable:
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if in == nil {
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panic(fmt.Sprintf("could not hash nil element %T", in))
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}
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeHashable), v.Hash())
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case nil:
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return fnv1a.AddUint64(fnv1a.AddUint64(h, hashTypeNil), 0)
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default:
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panic(fmt.Sprintf("unsupported value type %T", in))
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}
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}
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