com.xboxng.config.ReferenceResolver Maven / Gradle / Ivy

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A Java library that manages configurations for multiple environments
There is a newer version: 2.0
/*
 *  Copyright Qiang Yu (qiangyu #### gmail.com)
 *
 *  Licensed 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.
 */

package com.xboxng.config;

import com.xboxng.config.exception.XNConfigException;
import com.xboxng.config.tree.ConfigList;
import com.xboxng.config.tree.ConfigMap;
import com.xboxng.config.tree.Reference;
import com.xboxng.config.tree.Resolvable;

import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class ReferenceResolver {
    private XNConfig config;

    public ReferenceResolver(XNConfig config) {
        this.config = config;
    }

    protected Object resolve(Object value, Set pendingReference) {
        if (value instanceof Reference) {
            if (pendingReference.contains(value)) {
                throw new XNConfigException("cyclic references found: " + ((Reference) value).getName());
            }
            pendingReference.add((Reference) value);
            Object v = config.getValue(((Reference) value).getName(), pendingReference);
            v = resolve(v, pendingReference);
            pendingReference.remove(v);
            return v;
        } else if (value instanceof ConfigMap)
            return resolveMap((ConfigMap) value, pendingReference);
        else if (value instanceof ConfigList)
            return resolveList((ConfigList) value, pendingReference);
        else
            return value;
    }

    private Map resolveMap(ConfigMap map, Set pendingReference) {
        Map references = map.getReferences();
        Map elements = map.getElements();

        for (Map.Entry entry : references.entrySet()) {
            String key = entry.getKey();
            if (elements.get(key) == entry.getValue()) {
                elements.put(key, resolve(entry.getValue(), pendingReference));
            }
        }

        // all references have been resolved
        references.clear();
        return Collections.unmodifiableMap(elements);
    }

    private List resolveList(ConfigList list, Set pendingReference) {
        Map references = list.getReferences();
        List