d6f94be514
This is done unsubtlely at the moment and there is plenty of room for optimisation of assertion location to prevent repeated reasserting as is done now.
163 lines
3.5 KiB
Go
163 lines
3.5 KiB
Go
// Copyright 2014 The Cayley Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package memstore
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import (
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"fmt"
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"math"
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"strings"
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"github.com/petar/GoLLRB/llrb"
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"github.com/google/cayley/graph"
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"github.com/google/cayley/graph/iterator"
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)
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type Iterator struct {
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uid uint64
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tags graph.Tagger
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tree *llrb.LLRB
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data string
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isRunning bool
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iterLast Int64
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result graph.Value
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}
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type Int64 int64
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func (i Int64) Less(than llrb.Item) bool {
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return i < than.(Int64)
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}
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func IterateOne(tree *llrb.LLRB, last Int64) Int64 {
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var next Int64
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tree.AscendGreaterOrEqual(last, func(i llrb.Item) bool {
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if i.(Int64) == last {
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return true
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} else {
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next = i.(Int64)
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return false
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}
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})
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return next
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}
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func NewLlrbIterator(tree *llrb.LLRB, data string) *Iterator {
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return &Iterator{
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uid: iterator.NextUID(),
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tree: tree,
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iterLast: Int64(-1),
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data: data,
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}
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}
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func (it *Iterator) UID() uint64 {
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return it.uid
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}
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func (it *Iterator) Reset() {
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it.iterLast = Int64(-1)
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}
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func (it *Iterator) Tagger() *graph.Tagger {
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return &it.tags
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}
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func (it *Iterator) TagResults(dst map[string]graph.Value) {
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for _, tag := range it.tags.Tags() {
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dst[tag] = it.Result()
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}
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for tag, value := range it.tags.Fixed() {
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dst[tag] = value
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}
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}
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func (it *Iterator) Clone() graph.Iterator {
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m := NewLlrbIterator(it.tree, it.data)
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m.tags.CopyFrom(it)
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return m
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}
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func (it *Iterator) Close() {}
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func (it *Iterator) Next() (graph.Value, bool) {
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graph.NextLogIn(it)
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if it.tree.Max() == nil || it.result == int64(it.tree.Max().(Int64)) {
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return graph.NextLogOut(it, nil, false)
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}
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it.iterLast = IterateOne(it.tree, it.iterLast)
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it.result = int64(it.iterLast)
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return graph.NextLogOut(it, it.result, true)
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}
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func (it *Iterator) ResultTree() *graph.ResultTree {
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return graph.NewResultTree(it.Result())
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}
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func (it *Iterator) Result() graph.Value {
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return it.result
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}
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func (it *Iterator) NextResult() bool {
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return false
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}
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// No subiterators.
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func (it *Iterator) SubIterators() []graph.Iterator {
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return nil
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}
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func (it *Iterator) Size() (int64, bool) {
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return int64(it.tree.Len()), true
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}
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func (it *Iterator) Check(v graph.Value) bool {
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graph.CheckLogIn(it, v)
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if it.tree.Has(Int64(v.(int64))) {
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it.result = v
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return graph.CheckLogOut(it, v, true)
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}
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return graph.CheckLogOut(it, v, false)
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}
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func (it *Iterator) DebugString(indent int) string {
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size, _ := it.Size()
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return fmt.Sprintf("%s(%s tags:%s size:%d %s)", strings.Repeat(" ", indent), it.Type(), it.tags.Tags(), size, it.data)
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}
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var memType graph.Type
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func init() {
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memType = graph.RegisterIterator("llrb")
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}
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func Type() graph.Type { return memType }
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func (it *Iterator) Type() graph.Type { return memType }
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func (it *Iterator) Sorted() bool { return true }
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func (it *Iterator) Optimize() (graph.Iterator, bool) {
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return it, false
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}
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func (it *Iterator) Stats() graph.IteratorStats {
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return graph.IteratorStats{
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CheckCost: int64(math.Log(float64(it.tree.Len()))) + 1,
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NextCost: 1,
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Size: int64(it.tree.Len()),
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}
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}
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