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Core processing architecture for json-schema-validator
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/*
 * Copyright (c) 2013, Francis Galiegue 
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the Lesser GNU General Public License as
 * published by the Free Software Foundation, either version 3 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
 * Lesser 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, see .
 */

package com.github.fge.jsonschema.library;

import com.github.fge.jsonschema.util.Frozen;
import com.google.common.collect.ImmutableMap;
import net.jcip.annotations.Immutable;

import java.util.Map;

/**
 * A dictionary
 *
 * This class is a wrapper over a {@link Map}, where keys are always {@link
 * String}s. The type of values is arbitrary.
 *
 * This class is immutable. If you want to build a dictionary, you
 * have two options:
 *
 * 
 *     create a new builder using {@link #newBuilder()};
 *     create a builder with all elements from an existing dictionary using
 *     {@link #thaw()}.
 * 
 *
 * For instance:
 *
 *  *     // New builder
 *     final DictionaryBuilder<Foo> builder = Dictionary.newBuilder();
 *     // From an existing dictionary
 *     final DictionaryBuilder<Foo> builder = dict.thaw();
 * 
 *
 * @param  the type of values for this dictionary
 *
 * @see DictionaryBuilder
 */
@Immutable
public final class Dictionary
    implements Frozen>
{
    /**
     * Entries of this dictionary
     *
     * This map is immutable.
     *
     * @see ImmutableMap
     */
    final Map entries;

    /**
     * Return a new, empty builder for a dictionary of this type
     *
     * @param  the type of values
     * @return a new, empty builder
     */
    public static  DictionaryBuilder newBuilder()
    {
        return new DictionaryBuilder();
    }

    /**
     * Package local constructor to generate a dictionary from a builder
     *
     * @param builder the builder
     * @see DictionaryBuilder#freeze()
     */
    Dictionary(final DictionaryBuilder builder)
    {
        entries = ImmutableMap.copyOf(builder.entries);
    }

    /**
     * Return the entries from this dictionary as a map
     *
     * The returned map is immutable.
     *
     * @return an immutable map of entries
     * @see ImmutableMap
     */
    public Map entries()
    {
        return entries;
    }

    /**
     * Return a builder with a copy of all entries from this dictionary
     *
     * @return a {@link DictionaryBuilder}
     */
    @Override
    public DictionaryBuilder thaw()
    {
        return new DictionaryBuilder(this);
    }
}