ComparableVersion.java

package org.apache.maven.artifact.versioning;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

import java.math.BigInteger;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Properties;

/**
 * <p>
 * Generic implementation of version comparison.
 * </p>
 *
 * Features:
 * <ul>
 * <li>mixing of '<code>-</code>' (hyphen) and '<code>.</code>' (dot) separators,</li>
 * <li>transition between characters and digits also constitutes a separator:
 *     <code>1.0alpha1 =&gt; [1, 0, alpha, 1]</code></li>
 * <li>unlimited number of version components,</li>
 * <li>version components in the text can be digits or strings,</li>
 * <li>strings are checked for well-known qualifiers and the qualifier ordering is used for version ordering.
 *     Well-known qualifiers (case insensitive) are:<ul>
 *     <li><code>alpha</code> or <code>a</code></li>
 *     <li><code>beta</code> or <code>b</code></li>
 *     <li><code>milestone</code> or <code>m</code></li>
 *     <li><code>rc</code> or <code>cr</code></li>
 *     <li><code>snapshot</code></li>
 *     <li><code>(the empty string)</code> or <code>ga</code> or <code>final</code></li>
 *     <li><code>sp</code></li>
 *     </ul>
 *     Unknown qualifiers are considered after known qualifiers, with lexical order (always case insensitive),
 *   </li>
 * <li>a hyphen usually precedes a qualifier, and is always less important than something preceded with a dot.</li>
 * </ul>
 *
 * @see <a href="https://cwiki.apache.org/confluence/display/MAVENOLD/Versioning">"Versioning" on Maven Wiki</a>
 * @author <a href="mailto:kenney@apache.org">Kenney Westerhof</a>
 * @author <a href="mailto:hboutemy@apache.org">Hervé Boutemy</a>
 */
public class ComparableVersion
    implements Comparable<ComparableVersion>
{
    private static final int MAX_INTITEM_LENGTH = 9;

    private static final int MAX_LONGITEM_LENGTH = 18;

    private String value;

    private String canonical;

    private ListItem items;

    private interface Item
    {
        int INT_ITEM = 3;
        int LONG_ITEM = 4;
        int BIGINTEGER_ITEM = 0;
        int STRING_ITEM = 1;
        int LIST_ITEM = 2;

        int compareTo( Item item );

        int getType();

        boolean isNull();
    }

    /**
     * Represents a numeric item in the version item list that can be represented with an int.
     */
    private static class IntItem
        implements Item
    {
        private final int value;

        public static final IntItem ZERO = new IntItem();

        private IntItem()
        {
            this.value = 0;
        }

        IntItem( String str )
        {
            this.value = Integer.parseInt( str );
        }

        @Override
        public int getType()
        {
            return INT_ITEM;
        }

        @Override
        public boolean isNull()
        {
            return value == 0;
        }

        @Override
        public int compareTo( Item item )
        {
            if ( item == null )
            {
                return ( value == 0 ) ? 0 : 1; // 1.0 == 1, 1.1 > 1
            }

            switch ( item.getType() )
            {
                case INT_ITEM:
                    int itemValue = ( (IntItem) item ).value;
                    return ( value < itemValue ) ? -1 : ( ( value == itemValue ) ? 0 : 1 );
                case LONG_ITEM:
                case BIGINTEGER_ITEM:
                    return -1;

                case STRING_ITEM:
                    return 1; // 1.1 > 1-sp

                case LIST_ITEM:
                    return 1; // 1.1 > 1-1

                default:
                    throw new IllegalStateException( "invalid item: " + item.getClass() );
            }
        }

        @Override
        public boolean equals( Object o )
        {
            if ( this == o )
            {
                return true;
            }
            if ( o == null || getClass() != o.getClass() )
            {
                return false;
            }

            IntItem intItem = (IntItem) o;

            return value == intItem.value;

        }

        @Override
        public int hashCode()
        {
            return value;
        }

        @Override
        public String toString()
        {
            return Integer.toString( value );
        }
    }

    /**
     * Represents a numeric item in the version item list that can be represented with a long.
     */
    private static class LongItem
        implements Item
    {
        private final long value;

        LongItem( String str )
        {
            this.value = Long.parseLong( str );
        }

        @Override
        public int getType()
        {
            return LONG_ITEM;
        }

        @Override
        public boolean isNull()
        {
            return value == 0;
        }

        @Override
        public int compareTo( Item item )
        {
            if ( item == null )
            {
                return ( value == 0 ) ? 0 : 1; // 1.0 == 1, 1.1 > 1
            }

            switch ( item.getType() )
            {
                case INT_ITEM:
                    return 1;
                case LONG_ITEM:
                    long itemValue = ( (LongItem) item ).value;
                    return ( value < itemValue ) ? -1 : ( ( value == itemValue ) ? 0 : 1 );
                case BIGINTEGER_ITEM:
                    return -1;

                case STRING_ITEM:
                    return 1; // 1.1 > 1-sp

                case LIST_ITEM:
                    return 1; // 1.1 > 1-1

                default:
                    throw new IllegalStateException( "invalid item: " + item.getClass() );
            }
        }

        @Override
        public boolean equals( Object o )
        {
            if ( this == o )
            {
                return true;
            }
            if ( o == null || getClass() != o.getClass() )
            {
                return false;
            }

            LongItem longItem = (LongItem) o;

            return value == longItem.value;

        }

        @Override
        public int hashCode()
        {
            return (int) ( value ^ ( value >>> 32 ) );
        }

        @Override
        public String toString()
        {
            return Long.toString( value );
        }
    }

    /**
     * Represents a numeric item in the version item list.
     */
    private static class BigIntegerItem
        implements Item
    {
        private final BigInteger value;

        BigIntegerItem( String str )
        {
            this.value = new BigInteger( str );
        }

        @Override
        public int getType()
        {
            return BIGINTEGER_ITEM;
        }

        @Override
        public boolean isNull()
        {
            return BigInteger.ZERO.equals( value );
        }

        @Override
        public int compareTo( Item item )
        {
            if ( item == null )
            {
                return BigInteger.ZERO.equals( value ) ? 0 : 1; // 1.0 == 1, 1.1 > 1
            }

            switch ( item.getType() )
            {
                case INT_ITEM:
                case LONG_ITEM:
                    return 1;

                case BIGINTEGER_ITEM:
                    return value.compareTo( ( (BigIntegerItem) item ).value );

                case STRING_ITEM:
                    return 1; // 1.1 > 1-sp

                case LIST_ITEM:
                    return 1; // 1.1 > 1-1

                default:
                    throw new IllegalStateException( "invalid item: " + item.getClass() );
            }
        }

        @Override
        public boolean equals( Object o )
        {
            if ( this == o )
            {
                return true;
            }
            if ( o == null || getClass() != o.getClass() )
            {
                return false;
            }

            BigIntegerItem that = (BigIntegerItem) o;

            return value.equals( that.value );

        }

        @Override
        public int hashCode()
        {
            return value.hashCode();
        }

        public String toString()
        {
            return value.toString();
        }
    }

    /**
     * Represents a string in the version item list, usually a qualifier.
     */
    private static class StringItem
        implements Item
    {
        private static final List<String> QUALIFIERS =
                Arrays.asList( "alpha", "beta", "milestone", "rc", "snapshot", "", "sp"  );

        private static final Properties ALIASES = new Properties();
        static
        {
            ALIASES.put( "ga", "" );
            ALIASES.put( "final", "" );
            ALIASES.put("release", "");
            ALIASES.put( "cr", "rc" );
        }

        /**
         * A comparable value for the empty-string qualifier. This one is used to determine if a given qualifier makes
         * the version older than one without a qualifier, or more recent.
         */
        private static final String RELEASE_VERSION_INDEX = String.valueOf( QUALIFIERS.indexOf( "" ) );

        private final String value;

        StringItem( String value, boolean followedByDigit )
        {
            if ( followedByDigit && value.length() == 1 )
            {
                // a1 = alpha-1, b1 = beta-1, m1 = milestone-1
                switch ( value.charAt( 0 ) )
                {
                    case 'a':
                        value = "alpha";
                        break;
                    case 'b':
                        value = "beta";
                        break;
                    case 'm':
                        value = "milestone";
                        break;
                    default:
                }
            }
            this.value = ALIASES.getProperty( value , value );
        }

        @Override
        public int getType()
        {
            return STRING_ITEM;
        }

        @Override
        public boolean isNull()
        {
            return ( comparableQualifier( value ).compareTo( RELEASE_VERSION_INDEX ) == 0 );
        }

        /**
         * Returns a comparable value for a qualifier.
         *
         * This method takes into account the ordering of known qualifiers then unknown qualifiers with lexical
         * ordering.
         *
         * just returning an Integer with the index here is faster, but requires a lot of if/then/else to check for -1
         * or QUALIFIERS.size and then resort to lexical ordering. Most comparisons are decided by the first character,
         * so this is still fast. If more characters are needed then it requires a lexical sort anyway.
         *
         * @param qualifier
         * @return an equivalent value that can be used with lexical comparison
         */
        public static String comparableQualifier( String qualifier )
        {
            int i = QUALIFIERS.indexOf( qualifier );

            return i == -1 ? ( QUALIFIERS.size() + "-" + qualifier ) : String.valueOf( i );
        }

        @Override
        public int compareTo( Item item )
        {
            if ( item == null )
            {
                // 1-rc < 1, 1-ga > 1
                return comparableQualifier( value ).compareTo( RELEASE_VERSION_INDEX );
            }
            switch ( item.getType() )
            {
                case INT_ITEM:
                case LONG_ITEM:
                case BIGINTEGER_ITEM:
                    return -1; // 1.any < 1.1 ?

                case STRING_ITEM:
                    return comparableQualifier( value ).compareTo( comparableQualifier( ( (StringItem) item ).value ) );

                case LIST_ITEM:
                    return -1; // 1.any < 1-1

                default:
                    throw new IllegalStateException( "invalid item: " + item.getClass() );
            }
        }

        @Override
        public boolean equals( Object o )
        {
            if ( this == o )
            {
                return true;
            }
            if ( o == null || getClass() != o.getClass() )
            {
                return false;
            }

            StringItem that = (StringItem) o;

            return value.equals( that.value );

        }

        @Override
        public int hashCode()
        {
            return value.hashCode();
        }

        public String toString()
        {
            return value;
        }
    }

    /**
     * Represents a version list item. This class is used both for the global item list and for sub-lists (which start
     * with '-(number)' in the version specification).
     */
    private static class ListItem
        extends ArrayList<Item>
        implements Item
    {
        @Override
        public int getType()
        {
            return LIST_ITEM;
        }

        @Override
        public boolean isNull()
        {
            return ( size() == 0 );
        }

        void normalize()
        {
            for ( int i = size() - 1; i >= 0; i-- )
            {
                Item lastItem = get( i );

                if ( lastItem.isNull() )
                {
                    // remove null trailing items: 0, "", empty list
                    remove( i );
                }
                else if ( !( lastItem instanceof ListItem ) )
                {
                    break;
                }
            }
        }

        @Override
        public int compareTo( Item item )
        {
            if ( item == null )
            {
                if ( size() == 0 )
                {
                    return 0; // 1-0 = 1- (normalize) = 1
                }
                Item first = get( 0 );
                return first.compareTo( null );
            }
            switch ( item.getType() )
            {
                case INT_ITEM:
                case LONG_ITEM:
                case BIGINTEGER_ITEM:
                    return -1; // 1-1 < 1.0.x

                case STRING_ITEM:
                    return 1; // 1-1 > 1-sp

                case LIST_ITEM:
                    Iterator<Item> left = iterator();
                    Iterator<Item> right = ( (ListItem) item ).iterator();

                    while ( left.hasNext() || right.hasNext() )
                    {
                        Item l = left.hasNext() ? left.next() : null;
                        Item r = right.hasNext() ? right.next() : null;

                        // if this is shorter, then invert the compare and mul with -1
                        int result = l == null ? ( r == null ? 0 : -1 * r.compareTo( l ) ) : l.compareTo( r );

                        if ( result != 0 )
                        {
                            return result;
                        }
                    }

                    return 0;

                default:
                    throw new IllegalStateException( "invalid item: " + item.getClass() );
            }
        }

        @Override
        public String toString()
        {
            StringBuilder buffer = new StringBuilder();
            for ( Item item : this )
            {
                if ( buffer.length() > 0 )
                {
                    buffer.append( ( item instanceof ListItem ) ? '-' : '.' );
                }
                buffer.append( item );
            }
            return buffer.toString();
        }
    }

    public ComparableVersion( String version )
    {
        parseVersion( version );
    }

    @SuppressWarnings( "checkstyle:innerassignment" )
    public final void parseVersion( String version )
    {
        this.value = version;

        items = new ListItem();

        version = version.toLowerCase( Locale.ENGLISH );

        ListItem list = items;

        Deque<Item> stack = new ArrayDeque<>();
        stack.push( list );

        boolean isDigit = false;

        int startIndex = 0;

        for ( int i = 0; i < version.length(); i++ )
        {
            char c = version.charAt( i );

            if ( c == '.' )
            {
                if ( i == startIndex )
                {
                    list.add( IntItem.ZERO );
                }
                else
                {
                    list.add( parseItem( isDigit, version.substring( startIndex, i ) ) );
                }
                startIndex = i + 1;
            }
            else if ( c == '-' )
            {
                if ( i == startIndex )
                {
                    list.add( IntItem.ZERO );
                }
                else
                {
                    list.add( parseItem( isDigit, version.substring( startIndex, i ) ) );
                }
                startIndex = i + 1;

                list.add( list = new ListItem() );
                stack.push( list );
            }
            else if ( Character.isDigit( c ) )
            {
                if ( !isDigit && i > startIndex )
                {
                    list.add( new StringItem( version.substring( startIndex, i ), true ) );
                    startIndex = i;

                    list.add( list = new ListItem() );
                    stack.push( list );
                }

                isDigit = true;
            }
            else
            {
                if ( isDigit && i > startIndex )
                {
                    list.add( parseItem( true, version.substring( startIndex, i ) ) );
                    startIndex = i;

                    list.add( list = new ListItem() );
                    stack.push( list );
                }

                isDigit = false;
            }
        }

        if ( version.length() > startIndex )
        {
            list.add( parseItem( isDigit, version.substring( startIndex ) ) );
        }

        while ( !stack.isEmpty() )
        {
            list = (ListItem) stack.pop();
            list.normalize();
        }
    }

    private static Item parseItem( boolean isDigit, String buf )
    {
        if ( isDigit )
        {
            buf = stripLeadingZeroes( buf );
            if ( buf.length() <= MAX_INTITEM_LENGTH )
            {
                // lower than 2^31
                return new IntItem( buf );
            }
            else if ( buf.length() <= MAX_LONGITEM_LENGTH )
            {
                // lower than 2^63
                return new LongItem( buf );
            }
            return new BigIntegerItem( buf );
        }
        return new StringItem( buf, false );
    }

    private static String stripLeadingZeroes( String buf )
    {
        if ( buf == null || buf.isEmpty() )
        {
            return "0";
        }
        for ( int i = 0; i < buf.length(); ++i )
        {
            char c = buf.charAt( i );
            if ( c != '0' )
            {
                return buf.substring( i );
            }
        }
        return buf;
    }

    @Override
    public int compareTo( ComparableVersion o )
    {
        return items.compareTo( o.items );
    }

    @Override
    public String toString()
    {
        return value;
    }

    public String getCanonical()
    {
        if ( canonical == null )
        {
            canonical = items.toString();
        }
        return canonical;
    }

    @Override
    public boolean equals( Object o )
    {
        return ( o instanceof ComparableVersion ) && items.equals( ( (ComparableVersion) o ).items );
    }

    @Override
    public int hashCode()
    {
        return items.hashCode();
    }

    // CHECKSTYLE_OFF: LineLength
    /**
     * Main to test version parsing and comparison.
     * <p>
     * To check how "1.2.7" compares to "1.2-SNAPSHOT", for example, you can issue
     * <pre>java -jar ${maven.repo.local}/org/apache/maven/maven-artifact/${maven.version}/maven-artifact-${maven.version}.jar "1.2.7" "1.2-SNAPSHOT"</pre>
     * command to command line. Result of given command will be something like this:
     * <pre>
     * Display parameters as parsed by Maven (in canonical form) and comparison result:
     * 1. 1.2.7 == 1.2.7
     *    1.2.7 &gt; 1.2-SNAPSHOT
     * 2. 1.2-SNAPSHOT == 1.2-snapshot
     * </pre>
     *
     * @param args the version strings to parse and compare. You can pass arbitrary number of version strings and always
     * two adjacent will be compared
     */
    // CHECKSTYLE_ON: LineLength
    public static void main( String... args )
    {
        System.out.println( "Display parameters as parsed by Maven (in canonical form) and comparison result:" );
        if ( args.length == 0 )
        {
            return;
        }

        ComparableVersion prev = null;
        int i = 1;
        for ( String version : args )
        {
            ComparableVersion c = new ComparableVersion( version );

            if ( prev != null )
            {
                int compare = prev.compareTo( c );
                System.out.println( "   " + prev.toString() + ' '
                    + ( ( compare == 0 ) ? "==" : ( ( compare < 0 ) ? "<" : ">" ) ) + ' ' + version );
            }

            System.out.println( String.valueOf( i++ ) + ". " + version + " == " + c.getCanonical() );

            prev = c;
        }
    }
}