java/8 : javax/management/ImmutableDescriptor.java

ImmutableDescriptor
https://openjdk.java.net/
GPLv2 + Classpath Exception
/*
 * Copyright (c) 2004, 2013, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package javax.management;

import com.sun.jmx.mbeanserver.Util;
import java.io.InvalidObjectException;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;

An immutable descriptor.
Since: 1.6/**
 * An immutable descriptor.
 * @since 1.6
 */
public class ImmutableDescriptor implements Descriptor {
    private static final long serialVersionUID = 8853308591080540165L;

    The names of the fields in this ImmutableDescriptor with their original case. The names must be in alphabetical order as determined by String.CASE_INSENSITIVE_ORDER. /**
     * The names of the fields in this ImmutableDescriptor with their
     * original case.  The names must be in alphabetical order as determined
     * by {@link String#CASE_INSENSITIVE_ORDER}.
     */
    private final String[] names;
    The values of the fields in this ImmutableDescriptor. The elements in this array match the corresponding elements in the names array. /**
     * The values of the fields in this ImmutableDescriptor.  The
     * elements in this array match the corresponding elements in the
     * {@code names} array.
     */
    private final Object[] values;

    private transient int hashCode = -1;

    An empty descriptor.
/**
     * An empty descriptor.
     */
    public static final ImmutableDescriptor EMPTY_DESCRIPTOR =
            new ImmutableDescriptor();

    Construct a descriptor containing the given fields and values.
Throws: IllegalArgumentException – if either array is null, or
if the arrays have different sizes, or
if a field name is null or empty, or if the same field name
appears more than once./**
     * Construct a descriptor containing the given fields and values.
     *
     * @throws IllegalArgumentException if either array is null, or
     * if the arrays have different sizes, or
     * if a field name is null or empty, or if the same field name
     * appears more than once.
     */
    public ImmutableDescriptor(String[] fieldNames, Object[] fieldValues) {
        this(makeMap(fieldNames, fieldValues));
    }

    Construct a descriptor containing the given fields. Each String must be of the form fieldName=fieldValue. The field name ends at the first = character; for example if the String is a=b=c then the field name is a and its value is b=c. 
Throws: IllegalArgumentException – if the parameter is null, or if a field name is empty, or if the same field name appears more than once, or if one of the strings does not contain an = character./**
     * Construct a descriptor containing the given fields.  Each String
     * must be of the form {@code fieldName=fieldValue}.  The field name
     * ends at the first {@code =} character; for example if the String
     * is {@code a=b=c} then the field name is {@code a} and its value
     * is {@code b=c}.
     *
     * @throws IllegalArgumentException if the parameter is null, or
     * if a field name is empty, or if the same field name appears
     * more than once, or if one of the strings does not contain
     * an {@code =} character.
     */
    public ImmutableDescriptor(String... fields) {
        this(makeMap(fields));
    }

    Construct a descriptor where the names and values of the fields
are the keys and values of the given Map.
Throws: IllegalArgumentException – if the parameter is null, or
if a field name is null or empty, or if the same field name appears
more than once (which can happen because field names are not case
sensitive)./**
     * <p>Construct a descriptor where the names and values of the fields
     * are the keys and values of the given Map.</p>
     *
     * @throws IllegalArgumentException if the parameter is null, or
     * if a field name is null or empty, or if the same field name appears
     * more than once (which can happen because field names are not case
     * sensitive).
     */
    public ImmutableDescriptor(Map<String, ?> fields) {
        if (fields == null)
            throw new IllegalArgumentException("Null Map");
        SortedMap<String, Object> map =
                new TreeMap<String, Object>(String.CASE_INSENSITIVE_ORDER);
        for (Map.Entry<String, ?> entry : fields.entrySet()) {
            String name = entry.getKey();
            if (name == null || name.equals(""))
                throw new IllegalArgumentException("Empty or null field name");
            if (map.containsKey(name))
                throw new IllegalArgumentException("Duplicate name: " + name);
            map.put(name, entry.getValue());
        }
        int size = map.size();
        this.names = map.keySet().toArray(new String[size]);
        this.values = map.values().toArray(new Object[size]);
    }

    This method can replace a deserialized instance of this class with another instance. For example, it might replace a deserialized empty ImmutableDescriptor with EMPTY_DESCRIPTOR. 
Throws: InvalidObjectException – if the read object has invalid fields.
Returns: the replacement object, which may be this./**
     * This method can replace a deserialized instance of this
     * class with another instance.  For example, it might replace
     * a deserialized empty ImmutableDescriptor with
     * {@link #EMPTY_DESCRIPTOR}.
     *
     * @return the replacement object, which may be {@code this}.
     *
     * @throws InvalidObjectException if the read object has invalid fields.
     */
    private Object readResolve() throws InvalidObjectException {

        boolean bad = false;
        if (names == null || values == null || names.length != values.length)
            bad = true;
        if (!bad) {
            if (names.length == 0 && getClass() == ImmutableDescriptor.class)
                return EMPTY_DESCRIPTOR;
            final Comparator<String> compare = String.CASE_INSENSITIVE_ORDER;
            String lastName = ""; // also catches illegal null name
            for (int i = 0; i < names.length; i++) {
                if (names[i] == null ||
                        compare.compare(lastName, names[i]) >= 0) {
                    bad = true;
                    break;
                }
                lastName = names[i];
            }
        }
        if (bad)
            throw new InvalidObjectException("Bad names or values");

        return this;
    }

    private static SortedMap<String, ?> makeMap(String[] fieldNames,
                                                Object[] fieldValues) {
        if (fieldNames == null || fieldValues == null)
            throw new IllegalArgumentException("Null array parameter");
        if (fieldNames.length != fieldValues.length)
            throw new IllegalArgumentException("Different size arrays");
        SortedMap<String, Object> map =
                new TreeMap<String, Object>(String.CASE_INSENSITIVE_ORDER);
        for (int i = 0; i < fieldNames.length; i++) {
            String name = fieldNames[i];
            if (name == null || name.equals(""))
                throw new IllegalArgumentException("Empty or null field name");
            Object old = map.put(name, fieldValues[i]);
            if (old != null) {
                throw new IllegalArgumentException("Duplicate field name: " +
                                                   name);
            }
        }
        return map;
    }

    private static SortedMap<String, ?> makeMap(String[] fields) {
        if (fields == null)
            throw new IllegalArgumentException("Null fields parameter");
        String[] fieldNames = new String[fields.length];
        String[] fieldValues = new String[fields.length];
        for (int i = 0; i < fields.length; i++) {
            String field = fields[i];
            int eq = field.indexOf('=');
            if (eq < 0) {
                throw new IllegalArgumentException("Missing = character: " +
                                                   field);
            }
            fieldNames[i] = field.substring(0, eq);
            // makeMap will catch the case where the name is empty
            fieldValues[i] = field.substring(eq + 1);
        }
        return makeMap(fieldNames, fieldValues);
    }

    Return an ImmutableDescriptor whose contents are the union of the given descriptors. Every field name that appears in any of the descriptors will appear in the result with the value that it has when the method is called. Subsequent changes to any of the descriptors do not affect the ImmutableDescriptor returned here.
In the simplest case, there is only one descriptor and the returned ImmutableDescriptor is a copy of its fields at the time this method is called:
Descriptor d = something();
ImmutableDescriptor copy = ImmutableDescriptor.union(d);

Params: descriptors – the descriptors to be combined.  Any of the
descriptors can be null, in which case it is skipped.
Throws: IllegalArgumentException – if two Descriptors contain the same field name with different associated values. Primitive array values are considered the same if they are of the same type with the same elements. Object array values are considered the same if Arrays.deepEquals(Object[], Object[]) returns true.
Returns: an ImmutableDescriptor that is the union of the given descriptors. The returned object may be identical to one of the input descriptors if it is an ImmutableDescriptor that contains all of the required fields./**
     * <p>Return an {@code ImmutableDescriptor} whose contents are the union of
     * the given descriptors.  Every field name that appears in any of
     * the descriptors will appear in the result with the
     * value that it has when the method is called.  Subsequent changes
     * to any of the descriptors do not affect the ImmutableDescriptor
     * returned here.</p>
     *
     * <p>In the simplest case, there is only one descriptor and the
     * returned {@code ImmutableDescriptor} is a copy of its fields at the
     * time this method is called:</p>
     *
     * <pre>
     * Descriptor d = something();
     * ImmutableDescriptor copy = ImmutableDescriptor.union(d);
     * </pre>
     *
     * @param descriptors the descriptors to be combined.  Any of the
     * descriptors can be null, in which case it is skipped.
     *
     * @return an {@code ImmutableDescriptor} that is the union of the given
     * descriptors.  The returned object may be identical to one of the
     * input descriptors if it is an ImmutableDescriptor that contains all of
     * the required fields.
     *
     * @throws IllegalArgumentException if two Descriptors contain the
     * same field name with different associated values.  Primitive array
     * values are considered the same if they are of the same type with
     * the same elements.  Object array values are considered the same if
     * {@link Arrays#deepEquals(Object[],Object[])} returns true.
     */
    public static ImmutableDescriptor union(Descriptor... descriptors) {
        // Optimize the case where exactly one Descriptor is non-Empty
        // and it is immutable - we can just return it.
        int index = findNonEmpty(descriptors, 0);
        if (index < 0)
            return EMPTY_DESCRIPTOR;
        if (descriptors[index] instanceof ImmutableDescriptor
                && findNonEmpty(descriptors, index + 1) < 0)
            return (ImmutableDescriptor) descriptors[index];

        Map<String, Object> map =
            new TreeMap<String, Object>(String.CASE_INSENSITIVE_ORDER);
        ImmutableDescriptor biggestImmutable = EMPTY_DESCRIPTOR;
        for (Descriptor d : descriptors) {
            if (d != null) {
                String[] names;
                if (d instanceof ImmutableDescriptor) {
                    ImmutableDescriptor id = (ImmutableDescriptor) d;
                    names = id.names;
                    if (id.getClass() == ImmutableDescriptor.class
                            && names.length > biggestImmutable.names.length)
                        biggestImmutable = id;
                } else
                    names = d.getFieldNames();
                for (String n : names) {
                    Object v = d.getFieldValue(n);
                    Object old = map.put(n, v);
                    if (old != null) {
                        boolean equal;
                        if (old.getClass().isArray()) {
                            equal = Arrays.deepEquals(new Object[] {old},
                                                      new Object[] {v});
                        } else
                            equal = old.equals(v);
                        if (!equal) {
                            final String msg =
                                "Inconsistent values for descriptor field " +
                                n + ": " + old + " :: " + v;
                            throw new IllegalArgumentException(msg);
                        }
                    }
                }
            }
        }
        if (biggestImmutable.names.length == map.size())
            return biggestImmutable;
        return new ImmutableDescriptor(map);
    }

    private static boolean isEmpty(Descriptor d) {
        if (d == null)
            return true;
        else if (d instanceof ImmutableDescriptor)
            return ((ImmutableDescriptor) d).names.length == 0;
        else
            return (d.getFieldNames().length == 0);
    }

    private static int findNonEmpty(Descriptor[] ds, int start) {
        for (int i = start; i < ds.length; i++) {
            if (!isEmpty(ds[i]))
                return i;
        }
        return -1;
    }

    private int fieldIndex(String name) {
        return Arrays.binarySearch(names, name, String.CASE_INSENSITIVE_ORDER);
    }

    public final Object getFieldValue(String fieldName) {
        checkIllegalFieldName(fieldName);
        int i = fieldIndex(fieldName);
        if (i < 0)
            return null;
        Object v = values[i];
        if (v == null || !v.getClass().isArray())
            return v;
        if (v instanceof Object[])
            return ((Object[]) v).clone();
        // clone the primitive array, could use an 8-way if/else here
        int len = Array.getLength(v);
        Object a = Array.newInstance(v.getClass().getComponentType(), len);
        System.arraycopy(v, 0, a, 0, len);
        return a;
    }

    public final String[] getFields() {
        String[] result = new String[names.length];
        for (int i = 0; i < result.length; i++) {
            Object value = values[i];
            if (value == null)
                value = "";
            else if (!(value instanceof String))
                value = "(" + value + ")";
            result[i] = names[i] + "=" + value;
        }
        return result;
    }

    public final Object[] getFieldValues(String... fieldNames) {
        if (fieldNames == null)
            return values.clone();
        Object[] result = new Object[fieldNames.length];
        for (int i = 0; i < fieldNames.length; i++) {
            String name = fieldNames[i];
            if (name != null && !name.equals(""))
                result[i] = getFieldValue(name);
        }
        return result;
    }

    public final String[] getFieldNames() {
        return names.clone();
    }

    Compares this descriptor to the given object.  The objects are equal if
the given object is also a Descriptor, and if the two Descriptors have
the same field names (possibly differing in case) and the same
associated values.  The respective values for a field in the two
Descriptors are equal if the following conditions hold:

If one value is null then the other must be too.
If one value is a primitive array then the other must be a primitive
array of the same type with the same elements.
If one value is an object array then the other must be too and Arrays.deepEquals(Object[], Object[]) must return true.
Otherwise Object.equals(Object) must return true.

Params: o – the object to compare with.
Returns: true if the objects are the same; false otherwise./**
     * Compares this descriptor to the given object.  The objects are equal if
     * the given object is also a Descriptor, and if the two Descriptors have
     * the same field names (possibly differing in case) and the same
     * associated values.  The respective values for a field in the two
     * Descriptors are equal if the following conditions hold:
     *
     * <ul>
     * <li>If one value is null then the other must be too.</li>
     * <li>If one value is a primitive array then the other must be a primitive
     * array of the same type with the same elements.</li>
     * <li>If one value is an object array then the other must be too and
     * {@link Arrays#deepEquals(Object[],Object[])} must return true.</li>
     * <li>Otherwise {@link Object#equals(Object)} must return true.</li>
     * </ul>
     *
     * @param o the object to compare with.
     *
     * @return {@code true} if the objects are the same; {@code false}
     * otherwise.
     *
     */
    // Note: this Javadoc is copied from javax.management.Descriptor
    //       due to 6369229.
    @Override
    public boolean equals(Object o) {
        if (o == this)
            return true;
        if (!(o instanceof Descriptor))
            return false;
        String[] onames;
        if (o instanceof ImmutableDescriptor) {
            onames = ((ImmutableDescriptor) o).names;
        } else {
            onames = ((Descriptor) o).getFieldNames();
            Arrays.sort(onames, String.CASE_INSENSITIVE_ORDER);
        }
        if (names.length != onames.length)
            return false;
        for (int i = 0; i < names.length; i++) {
            if (!names[i].equalsIgnoreCase(onames[i]))
                return false;
        }
        Object[] ovalues;
        if (o instanceof ImmutableDescriptor)
            ovalues = ((ImmutableDescriptor) o).values;
        else
            ovalues = ((Descriptor) o).getFieldValues(onames);
        return Arrays.deepEquals(values, ovalues);
    }

    Returns the hash code value for this descriptor. The hash code is computed as the sum of the hash codes for each field in the descriptor. The hash code of a field with name n and value v is n.toLowerCase().hashCode() ^ h. Here h is the hash code of v, computed as follows:

If v is null then h is 0.
If v is a primitive array then h is computed using the appropriate overloading of java.util.Arrays.hashCode.
If v is an object array then h is computed using Arrays.deepHashCode(Object[]).
Otherwise h is v.hashCode().

Returns: A hash code value for this object./**
     * <p>Returns the hash code value for this descriptor.  The hash
     * code is computed as the sum of the hash codes for each field in
     * the descriptor.  The hash code of a field with name {@code n}
     * and value {@code v} is {@code n.toLowerCase().hashCode() ^ h}.
     * Here {@code h} is the hash code of {@code v}, computed as
     * follows:</p>
     *
     * <ul>
     * <li>If {@code v} is null then {@code h} is 0.</li>
     * <li>If {@code v} is a primitive array then {@code h} is computed using
     * the appropriate overloading of {@code java.util.Arrays.hashCode}.</li>
     * <li>If {@code v} is an object array then {@code h} is computed using
     * {@link Arrays#deepHashCode(Object[])}.</li>
     * <li>Otherwise {@code h} is {@code v.hashCode()}.</li>
     * </ul>
     *
     * @return A hash code value for this object.
     *
     */
    // Note: this Javadoc is copied from javax.management.Descriptor
    //       due to 6369229.
    @Override
    public int hashCode() {
        if (hashCode == -1) {
            hashCode = Util.hashCode(names, values);
        }
        return hashCode;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder("{");
        for (int i = 0; i < names.length; i++) {
            if (i > 0)
                sb.append(", ");
            sb.append(names[i]).append("=");
            Object v = values[i];
            if (v != null && v.getClass().isArray()) {
                String s = Arrays.deepToString(new Object[] {v});
                s = s.substring(1, s.length() - 1); // remove [...]
                v = s;
            }
            sb.append(String.valueOf(v));
        }
        return sb.append("}").toString();
    }

    Returns true if all of the fields have legal values given their
names.  This method always returns true, but a subclass can
override it to return false when appropriate.
Throws: RuntimeOperationsException – if the validity checking fails.
The method returns false if the descriptor is not valid, but throws
this exception if the attempt to determine validity fails.
Returns: true if the values are legal./**
     * Returns true if all of the fields have legal values given their
     * names.  This method always returns true, but a subclass can
     * override it to return false when appropriate.
     *
     * @return true if the values are legal.
     *
     * @exception RuntimeOperationsException if the validity checking fails.
     * The method returns false if the descriptor is not valid, but throws
     * this exception if the attempt to determine validity fails.
     */
    public boolean isValid() {
        return true;
    }

    Returns a descriptor which is equal to this descriptor.
Changes to the returned descriptor will have no effect on this
descriptor, and vice versa.
This method returns the object on which it is called.
A subclass can override it
to return another object provided the contract is respected.
Throws: RuntimeOperationsException – for illegal value for field Names
or field Values.
If the descriptor construction fails for any reason, this exception will
be thrown./**
     * <p>Returns a descriptor which is equal to this descriptor.
     * Changes to the returned descriptor will have no effect on this
     * descriptor, and vice versa.</p>
     *
     * <p>This method returns the object on which it is called.
     * A subclass can override it
     * to return another object provided the contract is respected.
     *
     * @exception RuntimeOperationsException for illegal value for field Names
     * or field Values.
     * If the descriptor construction fails for any reason, this exception will
     * be thrown.
     */
    @Override
    public Descriptor clone() {
        return this;
    }

    This operation is unsupported since this class is immutable. If this call would change a mutable descriptor with the same contents, then a RuntimeOperationsException wrapping an UnsupportedOperationException is thrown. Otherwise, the behavior is the same as it would be for a mutable descriptor: either an exception is thrown because of illegal parameters, or there is no effect. /**
     * This operation is unsupported since this class is immutable.  If
     * this call would change a mutable descriptor with the same contents,
     * then a {@link RuntimeOperationsException} wrapping an
     * {@link UnsupportedOperationException} is thrown.  Otherwise,
     * the behavior is the same as it would be for a mutable descriptor:
     * either an exception is thrown because of illegal parameters, or
     * there is no effect.
     */
    public final void setFields(String[] fieldNames, Object[] fieldValues)
        throws RuntimeOperationsException {
        if (fieldNames == null || fieldValues == null)
            illegal("Null argument");
        if (fieldNames.length != fieldValues.length)
            illegal("Different array sizes");
        for (int i = 0; i < fieldNames.length; i++)
            checkIllegalFieldName(fieldNames[i]);
        for (int i = 0; i < fieldNames.length; i++)
            setField(fieldNames[i], fieldValues[i]);
    }

    This operation is unsupported since this class is immutable. If this call would change a mutable descriptor with the same contents, then a RuntimeOperationsException wrapping an UnsupportedOperationException is thrown. Otherwise, the behavior is the same as it would be for a mutable descriptor: either an exception is thrown because of illegal parameters, or there is no effect. /**
     * This operation is unsupported since this class is immutable.  If
     * this call would change a mutable descriptor with the same contents,
     * then a {@link RuntimeOperationsException} wrapping an
     * {@link UnsupportedOperationException} is thrown.  Otherwise,
     * the behavior is the same as it would be for a mutable descriptor:
     * either an exception is thrown because of illegal parameters, or
     * there is no effect.
     */
    public final void setField(String fieldName, Object fieldValue)
        throws RuntimeOperationsException {
        checkIllegalFieldName(fieldName);
        int i = fieldIndex(fieldName);
        if (i < 0)
            unsupported();
        Object value = values[i];
        if ((value == null) ?
                (fieldValue != null) :
                !value.equals(fieldValue))
            unsupported();
    }

    Removes a field from the descriptor.
Params: fieldName – String name of the field to be removed.
If the field name is illegal or the field is not found,
no exception is thrown.
Throws: RuntimeOperationsException – if a field of the given name exists and the descriptor is immutable. The wrapped exception will be an UnsupportedOperationException./**
     * Removes a field from the descriptor.
     *
     * @param fieldName String name of the field to be removed.
     * If the field name is illegal or the field is not found,
     * no exception is thrown.
     *
     * @exception RuntimeOperationsException if a field of the given name
     * exists and the descriptor is immutable.  The wrapped exception will
     * be an {@link UnsupportedOperationException}.
     */
    public final void removeField(String fieldName) {
        if (fieldName != null && fieldIndex(fieldName) >= 0)
            unsupported();
    }

    static Descriptor nonNullDescriptor(Descriptor d) {
        if (d == null)
            return EMPTY_DESCRIPTOR;
        else
            return d;
    }

    private static void checkIllegalFieldName(String name) {
        if (name == null || name.equals(""))
            illegal("Null or empty field name");
    }

    private static void unsupported() {
        UnsupportedOperationException uoe =
            new UnsupportedOperationException("Descriptor is read-only");
        throw new RuntimeOperationsException(uoe);
    }

    private static void illegal(String message) {
        IllegalArgumentException iae = new IllegalArgumentException(message);
        throw new RuntimeOperationsException(iae);
    }
}
Throws:	InvalidObjectException – if the read object has invalid fields.
Returns:	the replacement object, which may be `this`.
Params:	descriptors – the descriptors to be combined. Any of the descriptors can be null, in which case it is skipped.
Throws:	IllegalArgumentException – if two Descriptors contain the same field name with different associated values. Primitive array values are considered the same if they are of the same type with the same elements. Object array values are considered the same if `Arrays.deepEquals(Object[], Object[])` returns true.
Returns:	an `ImmutableDescriptor` that is the union of the given descriptors. The returned object may be identical to one of the input descriptors if it is an ImmutableDescriptor that contains all of the required fields.
Params:	o – the object to compare with.
Returns:	`true` if the objects are the same; `false` otherwise.
Throws:	RuntimeOperationsException – if the validity checking fails. The method returns false if the descriptor is not valid, but throws this exception if the attempt to determine validity fails.
Returns:	true if the values are legal.
Params:	fieldName – String name of the field to be removed. If the field name is illegal or the field is not found, no exception is thrown.
Throws:	RuntimeOperationsException – if a field of the given name exists and the descriptor is immutable. The wrapped exception will be an `UnsupportedOperationException`.
/

java/ 8/ javax/management/ImmutableDescriptor.java
