/*
* 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 System.Collections.Generic;
using Spatial4n.Core.Context;
using Spatial4n.Core.Distance;
namespace Lucene.Net.Spatial.Prefix.Tree
{
///
/// Abstract Factory for creating {@link SpatialPrefixTree} instances with useful
/// defaults and passed on configurations defined in a Map.
///
public abstract class SpatialPrefixTreeFactory
{
private const double DEFAULT_GEO_MAX_DETAIL_KM = 0.001; //1m
public static readonly String PREFIX_TREE = "prefixTree";
public static readonly String MAX_LEVELS = "maxLevels";
public static readonly String MAX_DIST_ERR = "maxDistErr";
protected Dictionary args;
protected SpatialContext ctx;
protected int? maxLevels;
///
/// The factory is looked up via "prefixTree" in args, expecting "geohash" or "quad".
/// If its neither of these, then "geohash" is chosen for a geo context, otherwise "quad" is chosen.
///
///
///
///
public static SpatialPrefixTree MakeSPT(Dictionary args, SpatialContext ctx)
{
SpatialPrefixTreeFactory instance;
String cname;
if (!args.TryGetValue(PREFIX_TREE, out cname) || cname == null)
cname = ctx.IsGeo() ? "geohash" : "quad";
if ("geohash".Equals(cname, StringComparison.InvariantCultureIgnoreCase))
instance = new GeohashPrefixTree.Factory();
else if ("quad".Equals(cname, StringComparison.InvariantCultureIgnoreCase))
instance = new QuadPrefixTree.Factory();
else
{
Type t = Type.GetType(cname);
instance = (SpatialPrefixTreeFactory)Activator.CreateInstance(t);
}
instance.Init(args, ctx);
return instance.NewSPT();
}
protected void Init(Dictionary args, SpatialContext ctx)
{
this.args = args;
this.ctx = ctx;
InitMaxLevels();
}
protected void InitMaxLevels()
{
String mlStr;
if (args.TryGetValue(MAX_LEVELS, out mlStr) && mlStr != null)
{
maxLevels = int.Parse(mlStr);
return;
}
double degrees;
if (!args.TryGetValue(MAX_DIST_ERR, out mlStr) || mlStr == null)
{
if (!ctx.IsGeo())
return; //let default to max
degrees = DistanceUtils.Dist2Degrees(DEFAULT_GEO_MAX_DETAIL_KM, DistanceUtils.EARTH_MEAN_RADIUS_KM);
}
else
{
degrees = Double.Parse(mlStr);
}
maxLevels = GetLevelForDistance(degrees);
}
/* Calls {@link SpatialPrefixTree#getLevelForDistance(double)}. */
protected abstract int GetLevelForDistance(double degrees);
protected abstract SpatialPrefixTree NewSPT();
}
}