Subversion Repositories mkgmap

/*
 * Copyright (C) 2014.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 3 or
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */
package uk.me.parabola.mkgmap.reader.osm;

import java.util.ArrayList;
import java.util.HashMap;

import it.unimi.dsi.fastutil.shorts.ShortArrayList;
import uk.me.parabola.imgfmt.MapFailedException;


/**
 * A dictionary for tag names. Allows to translate a tag name to a unique Short value.
 * @author GerdP
 *
 */
public class TagDict{
        private static final TagDict INSTANCE = new TagDict();
        private final HashMap<String,Short>  map = new HashMap<>();
        private final ArrayList<String>  list = new ArrayList<>();

        public static final short INVALID_TAG_VALUE = 0;

        /**
         * create an empty dictionary
         */
        private TagDict() {
                map.put("invalid tag", INVALID_TAG_VALUE);
                list.add("invalid tag");
        }
       
        /**
         * give access to the singleton instance  
         * @return
         */
        public static TagDict getInstance() {
                return INSTANCE;
        }              
       
        /**
         * translate a tag name to a short value
         * @param keyString the tag name
         * @return a Short > 0 that can be used to retrieve
         * the tag name with the get() method
         */
        public synchronized  short xlate (String keyString){
                Short tagKey = map.get(keyString);
                if (tagKey == null) {
                        short size = (short) list.size();
                        if (size == Short.MAX_VALUE){
                                // very unlikely, typically we have a few hundred tag names
                                throw new MapFailedException("Fatal: Too many different tags in style");
                        }
                        String s = keyString;
                        map.put(s, size);
                        list.add(s);
                        return size;
                }
                return tagKey.shortValue();
        }

        /**
         * get the tagName for a tagKey. The caller has
         * to make sure that the key is valid.
         * @param key the tagKey (returned by xlate()
         * @return the tagName
         */
        public String get(short key){
                if (key == INVALID_TAG_VALUE) return null;
                       
                return list.get(key);
        }
       
        /**
         * The size of the dictionary. The highest known tagKey is
         * size() - 1.
         * @return
         */
        public int size(){
                return list.size();
        }
       
        /**
         * Return list of compiled tag keys for given array of key strings.
         * @param keys the keys
         * @return a ShortArrayList which might be empty but will not be null.
         */
        public static ShortArrayList compileTags(String ...keys) {
                ShortArrayList compiled = new ShortArrayList();
                if (keys != null) {
                        for (String key : keys) {
                                compiled.add(getInstance().xlate(key));
                        }
                }
                return compiled;
        }
}