NamespacesImpl.java

/*
 * Copyright 2012 NGDATA nv
 *
 * 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 org.lilyproject.tools.import_.json;

import java.util.HashMap;
import java.util.Map;

public class NamespacesImpl implements Namespaces {
    // Each prefix can be used for only one namespace, and each namespace can be bound to only one prefix.
    private Map<String, String> nsToPrefix = new HashMap<String, String>();
    private Map<String, String> prefixToNs = new HashMap<String, String>();
    private int counter = 0;
    private boolean usePrefixes;
    public static boolean DEFAULT_USE_PREFIXES = true;

    public NamespacesImpl() {
        this.usePrefixes = DEFAULT_USE_PREFIXES;
    }

    public NamespacesImpl(boolean usePrefixes) {
        this.usePrefixes = usePrefixes;
    }

    @Override
    public boolean usePrefixes() {
        return usePrefixes;
    }

    @Override
    public String getOrMakePrefix(String namespace) {
        String prefix = nsToPrefix.get(namespace);
        if (prefix == null) {
            counter++;
            prefix = "ns" + counter;

            // This assumes we are the only one putting entries in here of the form ns+counter, otherwise
            // we would need to check if it is not already present.
            nsToPrefix.put(namespace, prefix);
            prefixToNs.put(prefix, namespace);
        }
        return prefix;
    }

    @Override
    public void addMapping(String prefix, String namespace) {
        if (nsToPrefix.containsKey(namespace) && !nsToPrefix.get(namespace).equals(prefix)) {
            throw new RuntimeException("Namespace is already bound to another prefix. Namespace: " + namespace +
                    ", existing prefix: " + nsToPrefix.get(namespace) + ", requested prefix: " + prefix);
        }

        if (prefixToNs.containsKey(prefix) && !prefixToNs.get(prefix).equals(namespace)) {
            throw new RuntimeException("Prefix is already bound to another namespace. Prefix: " + prefix +
                    ", existing namespace: " + prefixToNs.get(prefix) + ", requested namespace: " + namespace);
        }

        nsToPrefix.put(namespace, prefix);
        prefixToNs.put(prefix, namespace);
    }

    @Override
    public String getNamespace(String prefix) {
        return prefixToNs.get(prefix);
    }

    @Override
    public String getPrefix(String namespace) {
        return nsToPrefix.get(namespace);
    }

    @Override
    public Map<String, String> getNsToPrefixMapping() {
        return nsToPrefix;
    }

    public boolean isEmpty() {
        return prefixToNs.isEmpty();
    }

    public void clear() {
        prefixToNs.clear();
        nsToPrefix.clear();
        counter = 0;
    }
}