FilterConfigEncoder.java

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/*
 * Gridarta MMORPG map editor for Crossfire, Daimonin and similar games.
 * Copyright (C) 2000-2015 The Gridarta Developers.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

package net.sf.gridarta.model.filter;

import java.util.Map.Entry;
import java.util.TreeMap;
import java.util.TreeSet;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

public class FilterConfigEncoder {

    @NotNull
    private final StringBuilder sb = new StringBuilder();

    @NotNull
    private final FilterConfigVisitor visitor = new FilterConfigVisitor() {

        @Override
        public void visit(@NotNull final NamedFilterConfig filterConfig) {
            final int position = sb.length();
            sb.append("(");
            boolean first = true;

            if (filterConfig.isEnabled()) {
                sb.append("enabled");
                first = false;
            }

            if (filterConfig.isInverted()) {
                if (first) {
                    first = false;
                } else {
                    sb.append(",");
                }
                sb.append("inverted");
            }

            for (final Entry<String, FilterConfig<?, ?>> entry : new TreeMap<>(filterConfig.getEntries()).entrySet()) {
                final int savedPosition = sb.length();
                final boolean savedFirst = first;
                if (first) {
                    first = false;
                } else {
                    sb.append(",");
                }
                FilterCodecUtils.encodeString(sb, entry.getKey());
                sb.append("=");
                final int position2 = sb.length();
                encodeInternal(entry.getValue());
                if (position2 == sb.length()) {
                    sb.setLength(savedPosition);
                    first = savedFirst;
                }
            }
            if (first) {
                sb.setLength(position);
            } else {
                sb.append(")");
            }
        }

        @Override
        public void visit(@NotNull final NamedGameObjectMatcherFilterConfig filterConfig) {
            final int position = sb.length();
            sb.append("(");
            boolean first = true;

            if (filterConfig.isEnabled()) {
                sb.append("enabled");
                first = false;
            }

            for (final String key : new TreeSet<>(filterConfig.getProperties())) {
                if (first) {
                    first = false;
                } else {
                    sb.append(",");
                }
                FilterCodecUtils.encodeString(sb, key);
                sb.append("=");
                final String value = filterConfig.getProperty(key);
                if (value == null) {
                    throw new AssertionError("no value for key " + key);
                }
                FilterCodecUtils.encodeString(sb, value);
            }
            if (first) {
                sb.setLength(position);
            } else {
                sb.append(")");
            }
        }

    };

    @Nullable
    private FilterConfig<?, ?> filterConfig;

    @NotNull
    public String encode(@NotNull final FilterConfig<?, ?> filterConfig) {
        sb.setLength(0);
        encodeInternal(filterConfig);
        return sb.toString();
    }

    private void encodeInternal(@NotNull final FilterConfig<?, ?> filterConfig) {
        final FilterConfig<?, ?> prevFilterConfig = this.filterConfig;
        try {
            this.filterConfig = filterConfig;
            filterConfig.accept(visitor);
        } finally {
            this.filterConfig = prevFilterConfig;
        }
    }

}