001package votorola.g.lang; // Copyright 2008, Michael Allan.  Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Votorola Software"), to deal in the Votorola Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicence, and/or sell copies of the Votorola Software, and to permit persons to whom the Votorola Software is furnished to do so, subject to the following conditions: The preceding copyright notice and this permission notice shall be included in all copies or substantial portions of the Votorola Software. THE VOTOROLA SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE VOTOROLA SOFTWARE OR THE USE OR OTHER DEALINGS IN THE VOTOROLA SOFTWARE.
002
003
004/** StringBuilder utilities.
005  */
006public @ThreadSafe final class StringBuilderX
007{
008
009    private StringBuilderX() {}
010
011
012
013    /** Clears the string builder.
014      *
015      *     @return the same string builder.
016      */
017    public static StringBuilder clear( final StringBuilder b )
018    {
019        b.delete( 0, b.length() );
020        return b;
021    }
022
023
024
025    /** Collapses contiguous runs of whitespace to a single space each, and trims all
026      * whitepace from the ends.
027      *
028      *     @return the same string builder.
029      */
030    public static StringBuilder collapseAndTrim( final StringBuilder b )
031    {
032        boolean wasWhitespaceLast = true; // thus to trim all trailing spaces
033        for( int c = b.length() - 1; c >= 0; --c )
034        {
035            final char ch = b.charAt( c );
036            final boolean isWhitespace = Character.isWhitespace( ch );
037            if( isWhitespace )
038            {
039                if( wasWhitespaceLast ) b.deleteCharAt( c ); // collapse all whitespace
040                else if( ch != ' ' ) b.setCharAt( c, ' ' ); // to single space char
041            }
042            wasWhitespaceLast = isWhitespace;
043        }
044        if( b.length() > 0 && wasWhitespaceLast ) b.deleteCharAt( 0 ); // trim leading space, if any (can only be one left)
045
046        return b;
047    }
048
049
050
051    /** Trims all whitepace from the ends.
052      *
053      *     @return the same string builder.
054      */
055    public static StringBuilder trim( final StringBuilder b )
056    {
057        for( ;; )
058        {
059            final int length = b.length();
060            if( length == 0 ) return b;
061
062            final char ch = b.charAt( 0 );
063            if( !Character.isWhitespace( ch ))
064            {
065                if( length == 1 ) return b;
066
067                break;
068            }
069
070            b.deleteCharAt( 0 );
071        }
072
073        for( ;; )
074        {
075            final int last = b.length() - 1;
076            final char ch = b.charAt( last );
077            if( !Character.isWhitespace( ch )) break;
078
079            b.deleteCharAt( last );
080            if( last == 0 ) break;
081        }
082
083        return b;
084    }
085
086
087
088}