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.
55 lines
1.5 KiB
Go
55 lines
1.5 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 leveldb
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import (
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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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func (ts *TripleStore) OptimizeIterator(it graph.Iterator) (graph.Iterator, bool) {
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switch it.Type() {
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case graph.LinksTo:
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return ts.optimizeLinksTo(it.(*iterator.LinksTo))
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}
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return it, false
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}
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func (ts *TripleStore) optimizeLinksTo(it *iterator.LinksTo) (graph.Iterator, bool) {
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subs := it.SubIterators()
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if len(subs) != 1 {
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return it, false
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}
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primary := subs[0]
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if primary.Type() == graph.Fixed {
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size, _ := primary.Size()
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if size == 1 {
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val, ok := graph.Next(primary)
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if !ok {
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panic("Sizes lie")
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}
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newIt := ts.TripleIterator(it.Direction(), val)
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nt := newIt.Tagger()
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nt.CopyFrom(it)
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for _, tag := range primary.Tagger().Tags() {
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nt.AddFixed(tag, val)
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}
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it.Close()
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return newIt, true
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}
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}
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return it, false
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}
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