1 files changed, 116 insertions, 0 deletions
diff --git a/vendor/github.com/couchbase/vellum/registry.go b/vendor/github.com/couchbase/vellum/registry.go
new file mode 100644
index 0000000000..3721a7c9c3
--- /dev/null
+++ b/vendor/github.com/couchbase/vellum/registry.go
@@ -0,0 +1,116 @@
+//  Copyright (c) 2017 Couchbase, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 		http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package vellum
+
+import (
+	"hash"
+	"hash/fnv"
+)
+
+type registryCell struct {
+	addr int
+	node *builderNode
+}
+
+type registry struct {
+	table     []registryCell
+	tableSize uint
+	mruSize   uint
+	hasher    hash.Hash64
+}
+
+func newRegistry(tableSize, mruSize int) *registry {
+	nsize := tableSize * mruSize
+	rv := &registry{
+		table:     make([]registryCell, nsize),
+		tableSize: uint(tableSize),
+		mruSize:   uint(mruSize),
+		hasher:    fnv.New64a(),
+	}
+	return rv
+}
+
+func (r *registry) Reset() {
+	for i := 0; i < len(r.table); i++ {
+		r.table[i] = registryCell{}
+	}
+	r.hasher.Reset()
+}
+
+func (r *registry) entry(node *builderNode) (bool, int, *registryCell) {
+	if len(r.table) == 0 {
+		return false, 0, nil
+	}
+	bucket := r.hash(node)
+	start := r.mruSize * uint(bucket)
+	end := start + r.mruSize
+	rc := registryCache(r.table[start:end])
+	return rc.entry(node)
+}
+
+const fnvPrime = 1099511628211
+
+func (r *registry) hash(b *builderNode) int {
+	var final uint64
+	if b.final {
+		final = 1
+	}
+
+	var h uint64 = 14695981039346656037
+	h = (h ^ final) * fnvPrime
+	h = (h ^ b.finalOutput) * fnvPrime
+	for _, t := range b.trans {
+		h = (h ^ uint64(t.in)) * fnvPrime
+		h = (h ^ t.out) * fnvPrime
+		h = (h ^ uint64(t.addr)) * fnvPrime
+	}
+	return int(h % uint64(r.tableSize))
+}
+
+type registryCache []registryCell
+
+func (r registryCache) entry(node *builderNode) (bool, int, *registryCell) {
+	if len(r) == 1 {
+		if r[0].node != nil && r[0].node.equiv(node) {
+			return true, r[0].addr, nil
+		}
+		r[0].node = node
+		return false, 0, &r[0]
+	}
+	for i := range r {
+		if r[i].node != nil && r[i].node.equiv(node) {
+			addr := r[i].addr
+			r.promote(i)
+			return true, addr, nil
+		}
+	}
+	// no match
+	last := len(r) - 1
+	r[last].node = node // discard LRU
+	r.promote(last)
+	return false, 0, &r[0]
+
+}
+
+func (r registryCache) promote(i int) {
+	for i > 0 {
+		r.swap(i-1, i)
+		i--
+	}
+}
+
+func (r registryCache) swap(i, j int) {
+	r[i], r[j] = r[j], r[i]
+}