SpatialStrategy.cs

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

using System;
using Lucene.Net.Documents;
using Lucene.Net.Search;
using Lucene.Net.Search.Function;
using Lucene.Net.Spatial.Queries;
using Lucene.Net.Spatial.Util;
using Spatial4n.Core.Context;
using Spatial4n.Core.Shapes;

namespace Lucene.Net.Spatial
{
    public abstract class SpatialStrategy
    {
        protected readonly SpatialContext ctx;
        protected readonly string fieldName;

        protected SpatialStrategy(SpatialContext ctx, string fieldName)
        {
            if (ctx == null)
                throw new ArgumentException("ctx is required", "ctx");
            this.ctx = ctx;
            if (string.IsNullOrEmpty(fieldName))
                throw new ArgumentException("fieldName is required", "fieldName");
            this.fieldName = fieldName;
        }

        public SpatialContext GetSpatialContext()
        {
            return ctx;
        }

        public String GetFieldName()
        {
            return fieldName;
        }

        public abstract AbstractField[] CreateIndexableFields(Shape shape);

        public AbstractField CreateStoredField(Shape shape)
        {
            return new Field(GetFieldName(), ctx.ToString(shape), Field.Store.YES, Field.Index.NOT_ANALYZED_NO_NORMS, Field.TermVector.NO);
        }

        public abstract ValueSource MakeDistanceValueSource(Point queryPoint);

        public virtual ConstantScoreQuery MakeQuery(SpatialArgs args)
        {
            return new ConstantScoreQuery(MakeFilter(args));
        }

        public abstract Filter MakeFilter(SpatialArgs args);

        public ValueSource MakeRecipDistanceValueSource(Shape queryShape)
        {
            Rectangle bbox = queryShape.GetBoundingBox();
            double diagonalDist = ctx.GetDistCalc().Distance(
                ctx.MakePoint(bbox.GetMinX(), bbox.GetMinY()), bbox.GetMaxX(), bbox.GetMaxY());
            double distToEdge = diagonalDist*0.5;
            float c = (float) distToEdge*0.1f; //one tenth
            return new ReciprocalFloatFunction(MakeDistanceValueSource(queryShape.GetCenter()), 1f, c, c);
        }

        public override string ToString()
        {
            return GetType().Name + " field:" + fieldName + " ctx=" + ctx;
        }
    }
}