mirror of https://github.com/go-gitea/gitea.git
111 lines
3.3 KiB
Go
111 lines
3.3 KiB
Go
// Copyright (c) 2019 Couchbase, Inc.
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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 searcher
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import (
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"github.com/blevesearch/bleve/geo"
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"github.com/blevesearch/bleve/index"
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"github.com/blevesearch/bleve/numeric"
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"github.com/blevesearch/bleve/search"
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"math"
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)
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func NewGeoBoundedPolygonSearcher(indexReader index.IndexReader,
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polygon []geo.Point, field string, boost float64,
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options search.SearcherOptions) (search.Searcher, error) {
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// compute the bounding box enclosing the polygon
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topLeftLon, topLeftLat, bottomRightLon, bottomRightLat, err :=
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geo.BoundingRectangleForPolygon(polygon)
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if err != nil {
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return nil, err
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}
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// build a searcher for the bounding box on the polygon
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boxSearcher, err := boxSearcher(indexReader,
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topLeftLon, topLeftLat, bottomRightLon, bottomRightLat,
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field, boost, options, true)
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if err != nil {
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return nil, err
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}
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dvReader, err := indexReader.DocValueReader([]string{field})
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if err != nil {
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return nil, err
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}
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// wrap it in a filtering searcher that checks for the polygon inclusivity
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return NewFilteringSearcher(boxSearcher,
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buildPolygonFilter(dvReader, field, polygon)), nil
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}
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const float64EqualityThreshold = 1e-6
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func almostEqual(a, b float64) bool {
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return math.Abs(a-b) <= float64EqualityThreshold
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}
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// buildPolygonFilter returns true if the point lies inside the
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// polygon. It is based on the ray-casting technique as referred
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// here: https://wrf.ecse.rpi.edu/nikola/pubdetails/pnpoly.html
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func buildPolygonFilter(dvReader index.DocValueReader, field string,
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polygon []geo.Point) FilterFunc {
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return func(d *search.DocumentMatch) bool {
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var lon, lat float64
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var found bool
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err := dvReader.VisitDocValues(d.IndexInternalID, func(field string, term []byte) {
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// only consider the values which are shifted 0
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prefixCoded := numeric.PrefixCoded(term)
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shift, err := prefixCoded.Shift()
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if err == nil && shift == 0 {
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i64, err := prefixCoded.Int64()
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if err == nil {
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lon = geo.MortonUnhashLon(uint64(i64))
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lat = geo.MortonUnhashLat(uint64(i64))
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found = true
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}
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}
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})
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// Note: this approach works for points which are strictly inside
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// the polygon. ie it might fail for certain points on the polygon boundaries.
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if err == nil && found {
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nVertices := len(polygon)
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var inside bool
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// check for a direct vertex match
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if almostEqual(polygon[0].Lat, lat) &&
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almostEqual(polygon[0].Lon, lon) {
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return true
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}
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for i := 1; i < nVertices; i++ {
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if almostEqual(polygon[i].Lat, lat) &&
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almostEqual(polygon[i].Lon, lon) {
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return true
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}
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if (polygon[i].Lat > lat) != (polygon[i-1].Lat > lat) &&
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lon < (polygon[i-1].Lon-polygon[i].Lon)*(lat-polygon[i].Lat)/
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(polygon[i-1].Lat-polygon[i].Lat)+polygon[i].Lon {
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inside = !inside
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}
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}
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return inside
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}
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return false
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}
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}
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