SecureBPMN/GenericBreakGlass-XACML/src/com.sun.xacml/src/main/java/com/sun/xacml/attr/YearMonthDurationAttribute.java

/*
 * @(#)YearMonthDurationAttribute.java
 *
 * Copyright 2003-2004 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *   2. Redistribution in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
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package com.sun.xacml.attr;

import com.sun.xacml.Constants;
import com.sun.xacml.ParsingException;

import java.math.BigInteger;

import java.net.URI;

import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
import java.util.regex.Matcher;

import org.w3c.dom.Node;


/**
 * Representation of an xf:yearMonthDuration value. This class supports parsing
 * xd:yearMonthDuration values. All objects of this class are immutable and
 * thread-safe. The <code>Date</code> objects returned are not, but
 * these objects are cloned before being returned.
 * 
 * @since 1.0
 * @author Steve Hanna
 */
public class YearMonthDurationAttribute extends AttributeValue
{
    /**
     * Official name of this type
     */
    public static final String identifier =
        TypeIdentifierConstants.YEARMONTHDURATION;
 
    /**
     * URI version of name for this type
     * <p>
     * This field is initialized by a static initializer so that
     * we can catch any exceptions thrown by URI(String) and
     * transform them into a RuntimeException, since this should
     * never happen but should be reported properly if it ever does.
     */
    private static URI identifierURI;

    /**
     * RuntimeException that wraps an Exception thrown during the
     * creation of identifierURI, null if none.
     */
    private static RuntimeException earlyException;

    /**
     * Static initializer that initializes the identifierURI
     * class field so that we can catch any exceptions thrown
     * by URI(String) and transform them into a RuntimeException.
     * Such exceptions should never happen but should be reported
     * properly if they ever do.
     */
    static {
        try {
            identifierURI = URI.create(identifier);
        } catch (IllegalArgumentException e) {
            earlyException = e;
        }
    }

    /**
     * Regular expression for yearMonthDuration (a la java.util.regex)
     */
    private static final String patternString = 
        "(\\-)?P((\\d+)?Y)?((\\d+)?M)?";

    /**
     * The index of the capturing group for the negative sign.
     */
    private static final int GROUP_SIGN = 1;

    /**
     * The index of the capturing group for the number of years.
     */
    private static final int GROUP_YEARS = 3;

    /**
     * The index of the capturing group for the number of months.
     */
    private static final int GROUP_MONTHS = 5;

    /**
     * Static BigInteger values. We only use these if one of
     * the components is bigger than Integer.MAX_LONG and we
     * want to detect overflow.
     */
    private static BigInteger big12 = BigInteger.valueOf(12);
    private static BigInteger bigMaxLong = BigInteger.valueOf(Long.MAX_VALUE);

    /**
     * A shared Pattern object, only initialized if needed
     */
    private static Pattern pattern;

    /**
     * Negative flag. true if duration is negative, false otherwise
     */
    private boolean negative;

    /**
     * Number of years
     */
    private long years;

    /**
     * Number of months
     */
    private long months;

    /**
     * Total number of months (used for equals)
     */
    private long totalMonths;

    /**
     * Cached encoded value (null if not cached yet).
     */
    private String encodedValue = null;

    /**
     * Creates a new <code>YearMonthDurationAttribute</code> that represents
     * the duration supplied.
     *
     * @param negative true if the duration is negative, false otherwise
     * @param years the number of years in the duration (must be positive)
     * @param months the number of months in the duration (must be positive)
     * @throws IllegalArgumentException if the total number of months
     *                                  exceeds Long.MAX_LONG or the number
     *                                  of months or years is negative
     */
    public YearMonthDurationAttribute(boolean negative, long years,
                                      long months)
        throws IllegalArgumentException {
        super(identifierURI);

        // Shouldn't happen, but just in case...
        if (earlyException != null) {
            throw earlyException;
        }

        this.negative = negative;
        this.years = years;
        this.months = months;

        // Convert all the components except nanoseconds to milliseconds

        // If any of the components is big (too big to be an int),
        // use the BigInteger class to do the math so we can detect
        // overflow.
        if ((years > Integer.MAX_VALUE) || (months > Integer.MAX_VALUE)) {
            BigInteger bigMonths = BigInteger.valueOf(months);
            BigInteger bigYears = BigInteger.valueOf(years);

            BigInteger bigTotal = bigYears.multiply(big12).add(bigMonths);

            // If the result is bigger than Long.MAX_VALUE, we have an
            // overflow. Indicate an error (should be a processing error,
            // since it can be argued that we should handle gigantic
            // values for this).
            if (bigTotal.compareTo(bigMaxLong) == 1) {
                throw new IllegalArgumentException("total number of " +
                                                   "months " +
                                                   "exceeds Long.MAX_VALUE");
            }
            // If no overflow, convert to a long.
            this.totalMonths = bigTotal.longValue();
            if (negative) {
                this.totalMonths = - this.totalMonths;
            }
        } else {
            // The numbers are small, so do it the fast way.
            this.totalMonths = ((years * 12) + months) * (negative ? -1 : 1);
        }
    }

    /**
     * Returns a new <code>YearMonthDurationAttribute</code> that represents
     * the xf:yearMonthDuration at a particular DOM node.
     *
     * @param root the <code>Node</code> that contains the desired value
     * @return a new <code>YearMonthDurationAttribute</code> representing the
     *         appropriate value
     * @throws ParsingException if any problems occurred while parsing
     */
    public static YearMonthDurationAttribute getInstance(Node root)
            throws ParsingException {
        if (root.getFirstChild() != null) {
            return getInstance(root.getFirstChild().getNodeValue());
        }
        throw new ParsingException("Error while parsing a "
                + "YearMonthDurationAttribute");
    }

    /**
     * Returns the long value for the capturing group groupNumber.
     * This method takes a Matcher that has been used to match a
     * Pattern against a String, fetches the value for the specified
     * capturing group, converts that value to an long, and returns
     * the value. If that group did not match, 0 is returned.
     * If the matched value is not a valid long, NumberFormatException
     * is thrown.
     *
     * @param matcher the Matcher from which to fetch the group
     * @param groupNumber the group number to fetch
     * @return the long value for that groupNumber
     * @throws NumberFormatException if the string value for that
     * groupNumber is not a valid long
     */
    private static long parseGroup(Matcher matcher, int groupNumber)
        throws NumberFormatException {
        long groupLong = 0;

        if (matcher.start(groupNumber) != -1) {
            String groupString = matcher.group(groupNumber);
            groupLong = Long.parseLong(groupString);
        }
        return groupLong;
    }

    /**
     * Returns a new <code>YearMonthDurationAttribute</code> that represents
     * the xf:yearMonthDuration value indicated by the string provided.
     *
     * @param value a string representing the desired value
     *
     * @return a new <code>YearMonthDurationAttribute</code> representing the
     *         desired value
     *
     * @throws ParsingException if any problems occurred while parsing
     */
    public static YearMonthDurationAttribute getInstance(String value)
            throws ParsingException {
        if (value == null) {
            throw new ParsingException("Can't create a " 
                    + "YearMonthDurationAttribute from empty input");
        }
        boolean negative = false;
        long years = 0;
        long months = 0;

        // Compile the pattern, if not already done.
        if (pattern == null) {
            try {
                pattern = Pattern.compile(patternString);
            } catch (PatternSyntaxException e) {
                // This should never happen
                throw new ParsingException("unexpected pattern syntax error");
            }
        }

        // See if the value matches the pattern.
        Matcher matcher = pattern.matcher(value);
        boolean matches = matcher.matches();

        // If not, syntax error!
        if (!matches) {
            throw new ParsingException("Syntax error in yearMonthDuration");
        }

        // If the negative group matched, the value is negative.
        if (matcher.start(GROUP_SIGN) != -1) {
            negative = true;
        }

        try {
            // If the years group matched, parse that value.
            years = parseGroup(matcher, GROUP_YEARS);

            // If the months group matched, parse that value.
            months = parseGroup(matcher, GROUP_MONTHS);
        } catch (NumberFormatException e) {
            // If we run into a number that's too big to be a long
            // that's an error. Really, it's a processing error,
            // since one can argue that we should handle that.
            throw new ParsingException("Unable to handle number size");
        }

        // If parsing went OK, create a new YearMonthDurationAttribute
        // object and return it.
        return new YearMonthDurationAttribute(negative, years, months);
    }

    /**
     * Returns true if the duration is negative.
     *
     * @return true if the duration is negative, false otherwise
     */
    public boolean isNegative() {
        return this.negative;
    }

    /**
     * Gets the number of years.
     *
     * @return the number of years
     */
    public long getYears() {
        return this.years;
    }

    /**
     * Gets the number of months.
     *
     * @return the number of months
     */
    public long getMonths() {
        return this.months;
    }

    /**
     * Returns true if the input is an instance of this class and if its
     * value equals the value contained in this class.
     *
     * @param o the object to compare
     *
     * @return true if this object and the input represent the same value
     */
    public boolean equals(Object o) {
        if (! (o instanceof YearMonthDurationAttribute)) {
            return false;
        }

        YearMonthDurationAttribute other = (YearMonthDurationAttribute)o;

        return (this.totalMonths == other.totalMonths);
    }

    /**
     * Returns the hashcode value used to index and compare this object with
     * others of the same type. Typically this is the hashcode of the backing
     * data object.
     *
     * @return the object's hashcode value
     */
    public int hashCode() {
        return (int) this.totalMonths ^ (int) (this.totalMonths >> 32);
    }

    /**
     * Converts to a String representation.
     *
     * @return the String representation
     */
    public String toString() {
        StringBuffer sb = new StringBuffer();
        sb.append("YearMonthDurationAttribute: [" + Constants.nl);
        sb.append("  Negative: " + this.negative);
        sb.append("  Years: " + this.years);
        sb.append("  Months: " + this.months);
        sb.append("]");

        return sb.toString();
    }

    /**
     * Encodes the value in a form suitable for including in XML data like
     * a request or an obligation. This must return a value that could in
     * turn be used by the factory to create a new instance with the same
     * value.
     *
     * @return a <code>String</code> form of the value
     */
    public String encode() {
        if (this.encodedValue != null) {
            return this.encodedValue;
        }

        // Length is variable
        StringBuffer buf = new StringBuffer(10);

        if (this.negative) {
            buf.append('-');
        }
        buf.append('P');
        if ((this.years != 0) || (this.months == 0)) {
            buf.append(Long.toString(this.years));
            buf.append('Y');
        }
        if (this.months != 0) {
            buf.append(Long.toString(this.months));
            buf.append('M');
        }

        this.encodedValue = buf.toString();

        return this.encodedValue;
    }
}