ObjectSerializationContext.java

package org.jolokia.converter.json;

import java.util.*;

import org.jolokia.converter.json.ValueFaultHandler;

/*
 * Copyright 2009-2011 Roland Huss
 *
 *  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.
 */

/**
 * Context class for holding and counting limits. It can also take care
 * about cycles, i.e. the context knows when an object is visited the second time.
 *
 * @author roland
 */
class ObjectSerializationContext {

    // =============================================================================
    // Context used for detecting call loops and the like
    private static final Set<Class> SIMPLE_TYPES = new HashSet<Class>(Arrays.asList(
            String.class,
            Number.class,
            Long.class,
            Integer.class,
            Boolean.class,
            Date.class
                                                                                   ));

    private Set   objectsInCallStack = new HashSet();
    private Stack callStack          = new Stack();
    private final JsonConvertOptions options;

    private int objectCount = 0;

    /**
     * Constructor for the stack context providing processing options
     *
     * @param pOpts options used for parsing
     */
    ObjectSerializationContext(JsonConvertOptions pOpts) {
        options = pOpts;
    }

    /**
     * Check, whether a given object has been already seen
     *
     * @param object to check
     * @return true if the object has been already visited
     */
    boolean alreadyVisited(Object object) {
        return objectsInCallStack.contains(object);
    }

    /**
     * Check whether the max depth of the call stack is exceeded
     *
     * @return true if the max depth limit has been reached
     */
    public boolean maxDepthReached() {
        return options.maxDepthReached(objectsInCallStack.size());
    }

    /**
     * Check whether the number of extracted objects exceeds the number of maximum objects to extract
     *
     * @return true if the number of extracted objects exceeds the maximum number of objects
     */
    public boolean maxObjectsExceeded() {
        return options.maxObjectExceeded(objectCount);
    }

    /**
     * Get the size of a collection trimmed to the maximum size of collections as configured
     *
     * @param pCollectionSize the original collection size
     * @return the original collection size if smalled than the maximum collection size,
     *         otherwise the maximum collection size
     */
    public int getCollectionSizeTruncated(int pCollectionSize) {
        return options.getCollectionSizeTruncated(pCollectionSize);
    }

    /**
     * The fault handler used for errors during serialization
     *
     * @return the value fault handler
     */
    public ValueFaultHandler getValueFaultHandler() {
        return options.getValueFaultHandler();
    }

    // =====================================================
    // Tracking methods

    /**
     * Push a new object on the stack
     *
     * @param object to push
     */
    void push(Object object) {
        callStack.push(object);

        if (object != null && !SIMPLE_TYPES.contains(object.getClass())) {
            objectsInCallStack.add(object);
        }
        objectCount++;
    }

    /**
     * Remove an object from top of the call stack
     * @return the object popped
     */
    Object pop() {
        Object ret = callStack.pop();
        if (ret != null && !SIMPLE_TYPES.contains(ret.getClass())) {
            objectsInCallStack.remove(ret);
        }
        return ret;
    }
}