53 lines
1.4 KiB
Go
53 lines
1.4 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 graph_mongo
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import (
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"graph"
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)
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func (ts *MongoTripleStore) OptimizeIterator(it graph.Iterator) (graph.Iterator, bool) {
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switch it.Type() {
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case "linksto":
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return ts.optimizeLinksTo(it.(*graph.LinksToIterator))
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}
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return it, false
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}
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func (ts *MongoTripleStore) optimizeLinksTo(it *graph.LinksToIterator) (graph.Iterator, bool) {
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l := it.GetSubIterators()
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if l.Len() != 1 {
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return it, false
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}
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primaryIt := l.Front().Value.(graph.Iterator)
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if primaryIt.Type() == "fixed" {
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size, _ := primaryIt.Size()
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if size == 1 {
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val, ok := primaryIt.Next()
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if !ok {
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panic("Sizes lie")
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}
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newIt := ts.GetTripleIterator(it.Direction(), val)
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newIt.CopyTagsFrom(it)
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for _, tag := range primaryIt.Tags() {
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newIt.AddFixedTag(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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