management/openmbean/CompositeType.java

/*
 * Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package javax.management.openmbean;


// java import
//
import java.util.Set;
import java.util.TreeMap;
import java.util.Collections;
import java.util.Iterator;

// jmx import
//


/**
 * The <code>CompositeType</code> class is the <i>open type</i> class
 * whose instances describe the types of {@link CompositeData CompositeData} values.
 *
 *
 * @since 1.5
 */
public class CompositeType extends OpenType<CompositeData> {

    /* Serial version */
    static final long serialVersionUID = -5366242454346948798L;

    /**
     * @serial Sorted mapping of the item names to their descriptions
     */
    private TreeMap<String,String> nameToDescription;

    /**
     * @serial Sorted mapping of the item names to their open types
     */
    private TreeMap<String,OpenType<?>> nameToType;

    /* As this instance is immutable, following three values need only
     * be calculated once.  */
    private transient Integer myHashCode = null;
    private transient String  myToString = null;
    private transient Set<String> myNamesSet = null;


    /* *** Constructor *** */

    /**
     * Constructs a <code>CompositeType</code> instance, checking for the validity of the given parameters.
     * The validity constraints are described below for each parameter.
     * <p>
     * Note that the contents of the three array parameters
     * <var>itemNames</var>, <var>itemDescriptions</var> and <var>itemTypes</var>
     * are internally copied so that any subsequent modification of these arrays by the caller of this constructor
     * has no impact on the constructed <code>CompositeType</code> instance.
     * <p>
     * The Java class name of composite data values this composite type represents
     * (ie the class name returned by the {@link OpenType#getClassName() getClassName} method)
     * is set to the string value returned by <code>CompositeData.class.getName()</code>.
     *
     * @param  typeName  The name given to the composite type this instance represents; cannot be a null or empty string.
     *
     * @param  description  The human readable description of the composite type this instance represents;
     *                      cannot be a null or empty string.
     *
     * @param  itemNames  The names of the items contained in the
     *                    composite data values described by this <code>CompositeType</code> instance;
     *                    cannot be null and should contain at least one element; no element can be a null or empty string.
     *                    Note that the order in which the item names are given is not important to differentiate a
     *                    <code>CompositeType</code> instance from another;
     *                    the item names are internally stored sorted in ascending alphanumeric order.
     *
     * @param  itemDescriptions  The descriptions, in the same order as <var>itemNames</var>, of the items contained in the
     *                           composite data values described by this <code>CompositeType</code> instance;
     *                           should be of the same size as <var>itemNames</var>;
     *                           no element can be null or an empty string.
     *
     * @param  itemTypes  The open type instances, in the same order as <var>itemNames</var>, describing the items contained
     *                    in the composite data values described by this <code>CompositeType</code> instance;
     *                    should be of the same size as <var>itemNames</var>;
     *                    no element can be null.
     *
     * @throws IllegalArgumentException  If <var>typeName</var> or <var>description</var> is a null or empty string,
     *                                   or <var>itemNames</var> or <var>itemDescriptions</var> or <var>itemTypes</var> is null,
     *                                   or any element of <var>itemNames</var> or <var>itemDescriptions</var>
     *                                   is a null or empty string,
     *                                   or any element of <var>itemTypes</var> is null,
     *                                   or <var>itemNames</var> or <var>itemDescriptions</var> or <var>itemTypes</var>
     *                                   are not of the same size.
     *
     * @throws OpenDataException  If <var>itemNames</var> contains duplicate item names
     *                            (case sensitive, but leading and trailing whitespaces removed).
     */
    public CompositeType(String        typeName,
                         String        description,
                         String[]      itemNames,
                         String[]      itemDescriptions,
                         OpenType<?>[] itemTypes) throws OpenDataException {

        // Check and construct state defined by parent
        //
        super(CompositeData.class.getName(), typeName, description, false);

        // Check the 3 arrays are not null or empty (ie length==0) and that there is no null element or empty string in them
        //
        checkForNullElement(itemNames, "itemNames");
        checkForNullElement(itemDescriptions, "itemDescriptions");
        checkForNullElement(itemTypes, "itemTypes");
        checkForEmptyString(itemNames, "itemNames");
        checkForEmptyString(itemDescriptions, "itemDescriptions");

        // Check the sizes of the 3 arrays are the same
        //
        if ( (itemNames.length != itemDescriptions.length) || (itemNames.length != itemTypes.length) ) {
            throw new IllegalArgumentException("Array arguments itemNames[], itemDescriptions[] and itemTypes[] "+
                                               "should be of same length (got "+ itemNames.length +", "+
                                               itemDescriptions.length +" and "+ itemTypes.length +").");
        }

        // Initialize internal "names to descriptions" and "names to types" sorted maps,
        // and, by doing so, check there are no duplicate item names
        //
        nameToDescription = new TreeMap<String,String>();
        nameToType        = new TreeMap<String,OpenType<?>>();
        String key;
        for (int i=0; i<itemNames.length; i++) {
            key = itemNames[i].trim();
            if (nameToDescription.containsKey(key)) {
                throw new OpenDataException("Argument's element itemNames["+ i +"]=\""+ itemNames[i] +
                                            "\" duplicates a previous item names.");
            }
            nameToDescription.put(key, itemDescriptions[i].trim());
            nameToType.put(key, itemTypes[i]);
        }
    }

    private static void checkForNullElement(Object[] arg, String argName) {
        if ( (arg == null) || (arg.length == 0) ) {
            throw new IllegalArgumentException("Argument "+ argName +"[] cannot be null or empty.");
        }
        for (int i=0; i<arg.length; i++) {
            if (arg[i] == null) {
                throw new IllegalArgumentException("Argument's element "+ argName +"["+ i +"] cannot be null.");
            }
        }
    }

    private static void checkForEmptyString(String[] arg, String argName) {
        for (int i=0; i<arg.length; i++) {
            if (arg[i].trim().equals("")) {
                throw new IllegalArgumentException("Argument's element "+ argName +"["+ i +"] cannot be an empty string.");
            }
        }
    }

    /* *** Composite type specific information methods *** */

    /**
     * Returns <code>true</code> if this <code>CompositeType</code> instance defines an item
     * whose name is <var>itemName</var>.
     *
     * @param itemName the name of the item.
     *
     * @return true if an item of this name is present.
     */
    public boolean containsKey(String itemName) {

        if (itemName == null) {
            return false;
        }
        return nameToDescription.containsKey(itemName);
    }

    /**
     * Returns the description of the item whose name is <var>itemName</var>,
     * or <code>null</code> if this <code>CompositeType</code> instance does not define any item
     * whose name is <var>itemName</var>.
     *
     * @param itemName the name of the item.
     *
     * @return the description.
     */
    public String getDescription(String itemName) {

        if (itemName == null) {
            return null;
        }
        return nameToDescription.get(itemName);
    }

    /**
     * Returns the <i>open type</i> of the item whose name is <var>itemName</var>,
     * or <code>null</code> if this <code>CompositeType</code> instance does not define any item
     * whose name is <var>itemName</var>.
     *
     * @param itemName the name of the time.
     *
     * @return the type.
     */
    public OpenType<?> getType(String itemName) {

        if (itemName == null) {
            return null;
        }
        return (OpenType<?>) nameToType.get(itemName);
    }

    /**
     * Returns an unmodifiable Set view of all the item names defined by this <code>CompositeType</code> instance.
     * The set's iterator will return the item names in ascending order.
     *
     * @return a {@link Set} of {@link String}.
     */
    public Set<String> keySet() {

        // Initializes myNamesSet on first call
        if (myNamesSet == null) {
            myNamesSet = Collections.unmodifiableSet(nameToDescription.keySet());
        }

        return myNamesSet; // always return the same value
    }


    /**
     * Tests whether <var>obj</var> is a value which could be
     * described by this <code>CompositeType</code> instance.
     *
     * <p>If <var>obj</var> is null or is not an instance of
     * <code>javax.management.openmbean.CompositeData</code>,
     * <code>isValue</code> returns <code>false</code>.</p>
     *
     * <p>If <var>obj</var> is an instance of
     * <code>javax.management.openmbean.CompositeData</code>, then let
     * {@code ct} be its {@code CompositeType} as returned by {@link
     * CompositeData#getCompositeType()}.  The result is true if
     * {@code this} is <em>assignable from</em> {@code ct}.  This
     * means that:</p>
     *
     * <ul>
     * <li>{@link #getTypeName() this.getTypeName()} equals
     * {@code ct.getTypeName()}, and
     * <li>there are no item names present in {@code this} that are
     * not also present in {@code ct}, and
     * <li>for every item in {@code this}, its type is assignable from
     * the type of the corresponding item in {@code ct}.
     * </ul>
     *
     * <p>A {@code TabularType} is assignable from another {@code
     * TabularType} if they have the same {@linkplain
     * TabularType#getTypeName() typeName} and {@linkplain
     * TabularType#getIndexNames() index name list}, and the
     * {@linkplain TabularType#getRowType() row type} of the first is
     * assignable from the row type of the second.
     *
     * <p>An {@code ArrayType} is assignable from another {@code
     * ArrayType} if they have the same {@linkplain
     * ArrayType#getDimension() dimension}; and both are {@linkplain
     * ArrayType#isPrimitiveArray() primitive arrays} or neither is;
     * and the {@linkplain ArrayType#getElementOpenType() element
     * type} of the first is assignable from the element type of the
     * second.
     *
     * <p>In every other case, an {@code OpenType} is assignable from
     * another {@code OpenType} only if they are equal.</p>
     *
     * <p>These rules mean that extra items can be added to a {@code
     * CompositeData} without making it invalid for a {@code CompositeType}
     * that does not have those items.</p>
     *
     * @param  obj  the value whose open type is to be tested for compatibility
     * with this <code>CompositeType</code> instance.
     *
     * @return <code>true</code> if <var>obj</var> is a value for this
     * composite type, <code>false</code> otherwise.
     */
    public boolean isValue(Object obj) {

        // if obj is null or not CompositeData, return false
        //
        if (!(obj instanceof CompositeData)) {
            return false;
        }

        // if obj is not a CompositeData, return false
        //
        CompositeData value = (CompositeData) obj;

        // test value's CompositeType is assignable to this CompositeType instance
        //
        CompositeType valueType = value.getCompositeType();
        return this.isAssignableFrom(valueType);
    }

    /**
     * Tests whether values of the given type can be assigned to this
     * open type.  The result is true if the given type is also a
     * CompositeType with the same name ({@link #getTypeName()}), and
     * every item in this type is also present in the given type with
     * the same name and assignable type.  There can be additional
     * items in the given type, which are ignored.
     *
     * @param ot the type to be tested.
     *
     * @return true if {@code ot} is assignable to this open type.
     */
    @Override
    boolean isAssignableFrom(OpenType<?> ot) {
        if (!(ot instanceof CompositeType))
            return false;
        CompositeType ct = (CompositeType) ot;
        if (!ct.getTypeName().equals(getTypeName()))
            return false;
        for (String key : keySet()) {
            OpenType<?> otItemType = ct.getType(key);
            OpenType<?> thisItemType = getType(key);
            if (otItemType == null ||
                    !thisItemType.isAssignableFrom(otItemType))
                return false;
        }
        return true;
    }


    /* *** Methods overriden from class Object *** */

    /**
     * Compares the specified <code>obj</code> parameter with this <code>CompositeType</code> instance for equality.
     * <p>
     * Two <code>CompositeType</code> instances are equal if and only if all of the following statements are true:
     * <ul>
     * <li>their type names are equal</li>
     * <li>their items' names and types are equal</li>
     * </ul>
     *
     * @param  obj  the object to be compared for equality with this <code>CompositeType</code> instance;
     *              if <var>obj</var> is <code>null</code>, <code>equals</code> returns <code>false</code>.
     *
     * @return  <code>true</code> if the specified object is equal to this <code>CompositeType</code> instance.
     */
    public boolean equals(Object obj) {

        // if obj is null, return false
        //
        if (obj == null) {
            return false;
        }

        // if obj is not a CompositeType, return false
        //
        CompositeType other;
        try {
            other = (CompositeType) obj;
        } catch (ClassCastException e) {
            return false;
        }

        // Now, really test for equality between this CompositeType instance and the other
        //

        // their names should be equal
        if ( ! this.getTypeName().equals(other.getTypeName()) ) {
            return false;
        }

        // their items names and types should be equal
        if ( ! this.nameToType.equals(other.nameToType) ) {
            return false;
        }

        // All tests for equality were successfull
        //
        return true;
    }

    /**
     * Returns the hash code value for this <code>CompositeType</code> instance.
     * <p>
     * The hash code of a <code>CompositeType</code> instance is the sum of the hash codes
     * of all elements of information used in <code>equals</code> comparisons
     * (ie: name, items names, items types).
     * This ensures that <code> t1.equals(t2) </code> implies that <code> t1.hashCode()==t2.hashCode() </code>
     * for any two <code>CompositeType</code> instances <code>t1</code> and <code>t2</code>,
     * as required by the general contract of the method
     * {@link Object#hashCode() Object.hashCode()}.
     * <p>
     * As <code>CompositeType</code> instances are immutable, the hash code for this instance is calculated once,
     * on the first call to <code>hashCode</code>, and then the same value is returned for subsequent calls.
     *
     * @return  the hash code value for this <code>CompositeType</code> instance
     */
    public int hashCode() {

        // Calculate the hash code value if it has not yet been done (ie 1st call to hashCode())
        //
        if (myHashCode == null) {
            int value = 0;
            value += this.getTypeName().hashCode();
            for (String key : nameToDescription.keySet()) {
                value += key.hashCode();
                value += this.nameToType.get(key).hashCode();
            }
            myHashCode = Integer.valueOf(value);
        }

        // return always the same hash code for this instance (immutable)
        //
        return myHashCode.intValue();
    }

    /**
     * Returns a string representation of this <code>CompositeType</code> instance.
     * <p>
     * The string representation consists of
     * the name of this class (ie <code>javax.management.openmbean.CompositeType</code>), the type name for this instance,
     * and the list of the items names and types string representation of this instance.
     * <p>
     * As <code>CompositeType</code> instances are immutable, the string representation for this instance is calculated once,
     * on the first call to <code>toString</code>, and then the same value is returned for subsequent calls.
     *
     * @return  a string representation of this <code>CompositeType</code> instance
     */
    public String toString() {

        // Calculate the string representation if it has not yet been done (ie 1st call to toString())
        //
        if (myToString == null) {
            final StringBuilder result = new StringBuilder();
            result.append(this.getClass().getName());
            result.append("(name=");
            result.append(getTypeName());
            result.append(",items=(");
            int i=0;
            Iterator<String> k=nameToType.keySet().iterator();
            String key;
            while (k.hasNext()) {
                key = k.next();
                if (i > 0) result.append(",");
                result.append("(itemName=");
                result.append(key);
                result.append(",itemType=");
                result.append(nameToType.get(key).toString() +")");
                i++;
            }
            result.append("))");
            myToString = result.toString();
        }

        // return always the same string representation for this instance (immutable)
        //
        return myToString;
    }

}