library.java

hsql是很有名的嵌入式数据库

/* Copyright (c) 1995-2000, The Hypersonic SQL Group.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions 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 the Hypersonic SQL Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE HYPERSONIC SQL GROUP,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals 
 * on behalf of the Hypersonic SQL Group.
 *
 *
 * For work added by the HSQL Development Group:
 *
 * Copyright (c) 2001-2005, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions 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 the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


package org.hsqldb;

import java.sql.Connection;
import java.sql.Date;
import java.sql.Time;
import java.sql.Timestamp;
import java.text.FieldPosition;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Locale;
import java.util.Random;

import org.hsqldb.lib.HashMap;
import org.hsqldb.lib.IntValueHashMap;
import org.hsqldb.persist.HsqlDatabaseProperties;
import org.hsqldb.store.ValuePool;

// fredt@users 20020210 - patch 513005 by sqlbob@users (RMP) - ABS function
// fredt@users 20020305 - patch 1.7.0 - change to 2D string arrays
// sqlbob@users 20020420- patch 1.7.0 - added HEXTORAW and RAWTOHEX.
// boucherb@user 20020918 - doc 1.7.2 - added JavaDoc  and code comments
// fredt@user 20021021 - doc 1.7.2 - modified JavaDoc
// boucherb@users 20030201 - patch 1.7.2 - direct calls for org.hsqldb.Library
// fredt@users - patch 1.8.0 - new functions added

/**
 * fredt - todo - since the introduction of SQL built-in functions and
 * evaluation of several session-dependent methods outside this class,
 * several methods here are dummies. These methods are still reported in
 * system tables incorrectly as corresponding to the SQL function names.
 */

/**
 * Provides the HSQLDB implementation of standard Open Group SQL CLI
 * <em>Extended Scalar Functions</em> and other public HSQLDB SQL functions.<p>
 *
 * All methods here that have a Connection parameter are dummies and should
 * not be called from user supplied Java procedure or trigger code. Use real
 * SQL functions should be called instead in these instances.
 *
 * Extensively rewritten and extended in successive versions of HSQLDB.
 *
 * @author Thomas Mueller (Hypersonic SQL Group)
 * @version 1.8.0
 * @since Hypersonic SQL
 */
public class Library {

    static final SimpleDateFormat tocharFormat = new SimpleDateFormat();
    static final SimpleDateFormat daynameFormat = new SimpleDateFormat("EEEE",
        Locale.ENGLISH);
    static final SimpleDateFormat monthnameFormat =
        new SimpleDateFormat("MMMM", Locale.ENGLISH);
    static final StringBuffer daynameBuffer   = new StringBuffer();
    static final StringBuffer monthnameBuffer = new StringBuffer();
    static final FieldPosition monthPosition =
        new FieldPosition(SimpleDateFormat.MONTH_FIELD);
    static final FieldPosition dayPosition =
        new FieldPosition(SimpleDateFormat.DAY_OF_WEEK_FIELD);
    public static final String[][] sNumeric = {
        {
            "ABS", "org.hsqldb.Library.abs"
        }, {
            "ACOS", "java.lang.Math.acos"
        }, {
            "ASIN", "java.lang.Math.asin"
        }, {
            "ATAN", "java.lang.Math.atan"
        }, {
            "ATAN2", "java.lang.Math.atan2"
        }, {
            "CEILING", "java.lang.Math.ceil"
        }, {
            "COS", "java.lang.Math.cos"
        }, {
            "COT", "org.hsqldb.Library.cot"
        }, {
            "DEGREES", "java.lang.Math.toDegrees"
        }, {
            "EXP", "java.lang.Math.exp"
        }, {
            "FLOOR", "java.lang.Math.floor"
        }, {
            "LOG", "java.lang.Math.log"
        }, {
            "LOG10", "org.hsqldb.Library.log10"
        }, {
            "MOD", "org.hsqldb.Library.mod"
        }, {
            "PI", "org.hsqldb.Library.pi"
        }, {
            "POWER", "java.lang.Math.pow"
        }, {
            "RADIANS", "java.lang.Math.toRadians"
        }, {
            "RAND", "java.lang.Math.random"
        }, {
            "ROUND", "org.hsqldb.Library.round"
        }, {
            "SIGN", "org.hsqldb.Library.sign"
        }, {
            "SIN", "java.lang.Math.sin"
        }, {
            "SQRT", "java.lang.Math.sqrt"
        }, {
            "TAN", "java.lang.Math.tan"
        }, {
            "TRUNCATE", "org.hsqldb.Library.truncate"
        }, {
            "BITAND", "org.hsqldb.Library.bitand"
        }, {
            "BITOR", "org.hsqldb.Library.bitor"
        }, {
            "BITXOR", "org.hsqldb.Library.bitxor"
        }, {
            "ROUNDMAGIC", "org.hsqldb.Library.roundMagic"
        }
    };

// fredt@users 20010701 - patch 418023 by deforest@users
// the definition for SUBSTR was added
    public static final String[][] sString   = {
        {
            "ASCII", "org.hsqldb.Library.ascii"
        }, {
            "BIT_LENGTH", "org.hsqldb.Library.bitLength"
        }, {
            "CHAR", "org.hsqldb.Library.character"
        }, {
            "CHAR_LENGTH", "org.hsqldb.Library.length"
        }, {
            "CHARACTER_LENGTH", "org.hsqldb.Library.length"
        }, {
            "CONCAT", "org.hsqldb.Library.concat"
        }, {
            "DIFFERENCE", "org.hsqldb.Library.difference"
        }, {
            "HEXTORAW", "org.hsqldb.Library.hexToRaw"
        }, {
            "INSERT", "org.hsqldb.Library.insert"
        }, {
            "LCASE", "org.hsqldb.Library.lcase"
        }, {
            "LEFT", "org.hsqldb.Library.left"
        }, {
            "LENGTH", "org.hsqldb.Library.length"
        }, {
            "LOCATE", "org.hsqldb.Library.locate"
        }, {
            "LTRIM", "org.hsqldb.Library.ltrim"
        }, {
            "OCTET_LENGTH", "org.hsqldb.Library.octetLength"
        }, {
            "RAWTOHEX", "org.hsqldb.Library.rawToHex"
        }, {
            "REPEAT", "org.hsqldb.Library.repeat"
        }, {
            "REPLACE", "org.hsqldb.Library.replace"
        }, {
            "RIGHT", "org.hsqldb.Library.right"
        }, {
            "RTRIM", "org.hsqldb.Library.rtrim"
        }, {
            "SOUNDEX", "org.hsqldb.Library.soundex"
        }, {
            "SPACE", "org.hsqldb.Library.space"
        }, {
            "SUBSTR", "org.hsqldb.Library.substring"
        }, {
            "SUBSTRING", "org.hsqldb.Library.substring"
        }, {
            "UCASE", "org.hsqldb.Library.ucase"
        }, {
            "LOWER", "org.hsqldb.Library.lcase"
        }, {
            "UPPER", "org.hsqldb.Library.ucase"
        }
    };
    public static final String[][] sTimeDate = {
        {
            "CURDATE", "org.hsqldb.Library.curdate"
        }, {
            "CURTIME", "org.hsqldb.Library.curtime"
        }, {
            "DATEDIFF", "org.hsqldb.Library.datediff"
        }, {
            "DAYNAME", "org.hsqldb.Library.dayname"
        }, {
            "DAY", "org.hsqldb.Library.dayofmonth"
        }, {
            "DAYOFMONTH", "org.hsqldb.Library.dayofmonth"
        }, {
            "DAYOFWEEK", "org.hsqldb.Library.dayofweek"
        }, {
            "DAYOFYEAR", "org.hsqldb.Library.dayofyear"
        }, {
            "HOUR", "org.hsqldb.Library.hour"
        }, {
            "MINUTE", "org.hsqldb.Library.minute"
        }, {
            "MONTH", "org.hsqldb.Library.month"
        }, {
            "MONTHNAME", "org.hsqldb.Library.monthname"
        }, {
            "NOW", "org.hsqldb.Library.now"
        }, {
            "QUARTER", "org.hsqldb.Library.quarter"
        }, {
            "SECOND", "org.hsqldb.Library.second"
        }, {
            "WEEK", "org.hsqldb.Library.week"
        }, {
            "YEAR", "org.hsqldb.Library.year"
        }, {
            "TO_CHAR", "org.hsqldb.Library.to_char"
        }
    };
    public static final String[][] sSystem   = {
        {
            "DATABASE", "org.hsqldb.Library.database"
        }, {
            "USER", "org.hsqldb.Library.user"
        }, {
            "IDENTITY", "org.hsqldb.Library.identity"
        }
    };

    private Library() {}

    static HashMap getAliasMap() {

        HashMap h = new HashMap(83, 1);

        register(h, sNumeric);
        register(h, sString);
        register(h, sTimeDate);
        register(h, sSystem);

        return h;
    }

    private static void register(HashMap h, String[][] s) {

        for (int i = 0; i < s.length; i++) {
            h.put(s[i][0], s[i][1]);
        }
    }

    private static final Random rRandom = new Random();

    // NUMERIC FUNCTIONS
// fredt@users 20020220 - patch 489184 by xclayl@users - thread safety

    /**
     * Returns the next pseudorandom, uniformly distributed <code>double</code> value
     * between 0.0 and 1.0 from a single, system-wide random number generator's
     * sequence, optionally re-seeding (and thus resetting) the generator sequence.
     *
     * If the seed value is <code>null</code>, then the underlying random number
     * generator retrieves the next value in its current sequence, else the seed
     * alters the state of the generator object so as to be in exactly the same state
     * as if it had just been created with the seed value.
     * @param seed an optional parameter with which to reseed the underlying
     * pseudorandom number generator
     * @return the next pseudorandom, uniformly distributed <code>double</code> value between
     *      0.0 and 1.0
     */
    public static double rand(Integer seed) {

        // boucherb@users 20020918
        // CHECKME: perhaps rRandom should be a member of Session,
        // since otherwise connections are *not* guranteed to get the
        // same pseudorandom sequence, given the same set of calls to this
        // SQL function.  This makes comparitive analysis difficult.
        // In fact, rRandom will be shared across multiple in-process
        // database instances, so it is not even guaranteed that the
        // sole connection to one instance will get the same sequence given
        // the same set of calls to this SQL function.
        synchronized (rRandom) {
            if (seed != null) {
                rRandom.setSeed(seed.intValue());
            }

            return rRandom.nextDouble();
        }
    }

    /**
     * Returns the absolute value of the given <code>double</code> value.
     * @param d the number for which to determine the absolute value
     * @return the absolute value of <code>d</code>, as a <code>double</code>
     */
    public static double abs(double d) {
        return Math.abs(d);
    }

    // this magic number works for 100000000000000; but not for 0.1 and 0.01
    private static final double LOG10_FACTOR = 0.43429448190325183;

    /**
     * Returns the base 10 logarithm of the given <code>double</code> value.
     * @param x the value for which to calculate the base 10 logarithm
     * @return the base 10 logarithm of <code>x</code>, as a <code>double</code>
     */
    public static double log10(double x) {
        return roundMagic(Math.log(x) * LOG10_FACTOR);
    }

    /**
     * Retrieves a <em>magically</em> rounded </code>double</code> value produced
     * from the given <code>double</code> value.  This method provides special
     * handling for numbers close to zero and performs rounding only for
     * numbers within a specific range, returning  precisely the given value
     * if it does not lie in this range. <p>
     *
     * Special handling includes: <p>
     *
     * <UL>
     * <LI> input in the interval -0.0000000000001..0.0000000000001 returns 0.0
     * <LI> input outside the interval -1000000000000..1000000000000 returns
     *      input unchanged