Refactoring exercise.

From:

Roedy Green <see_website@mindprod.com.invalid>

Newsgroups:

comp.lang.java.help

Date:

Sat, 03 Nov 2012 01:37:20 -0700

Message-ID:

<ddl9989u8pc6vq1r0vaduqp8iamvcurn25@4ax.com>

This is a beginner's exercise in refactoring.

Below is posted the text for Amper.
You can get any other code it needs or find out more about what it is
for from http://mindprod.com/products1.html#AMPER

Notice how similar the methods ampifyPossiblyCommentedString and
ampifyPossiblyScriptedString are.

Your task is to refactor out that commonality in handling of text
inside/outside markers so that the logic appears only once.

Hint: see http://mindprod.com/jgloss/callback.html

This is aimed at newbies. If you are an old-timer, see if you could
come up with something clever to make the code more readable and
terse.

You don't have to show a complete working program, just the refactored
logic.

/*
* [Amper.java]
*
* Summary: amper, converts invalid & to & in html.
*
* Copyright: (c) 1999-2012 Roedy Green, Canadian Mind Products,
http://mindprod.com
*
* Licence: This software may be copied and used freely for any
purpose but military.
* http://mindprod.com/contact/nonmil.html
*
* Requires: JDK 1.5+
*
* Created with: JetBrains IntelliJ IDEA IDE
http://www.jetbrains.com/idea/
*
* Version History:
* 1.1 2006-03-05
* 1.2 2007-03-26 fix bug in StripEntities. Was not doing 
properly.
* 1.3 2007-04-07 recover from crash. Tidy code.
* 1.4 2007-05-10 add icon, PAD file.
* 1.5 2007-06-29 add -q command line support. New CommandLine
interface.
* 1.6 2008-08-03 change detail parameter so that you can request
three levels of detail, rather than two.
* 1.7 2012-01-25 now handles HTML5 entities. It now leaves any
unusual entities as is.
* 1.8 2012-02-09 fix bug. Now handles even very longest HTML5
entities. No longer extends DeEntifyStrings.
* 1.9 2012-06-18 allow you to ampify .htm and .csv files
* 2.0 2012-11-03 deal text inside <script is no longer ampified.
* new methods ampifyPossiblyScriptedString(String)
ampifyPossiblyCommentedString(String)
* deprecated ampifyCommented.
*/
package com.mindprod.amper;

import com.mindprod.commandline.CommandLine;
import com.mindprod.common11.Misc;
import com.mindprod.filter.AllButSVNDirectoriesFilter;
import com.mindprod.filter.ExtensionListFilter;
import com.mindprod.hunkio.HunkIO;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static java.lang.System.out;

/**
* amper, converts invalid & to & in html.
* <p/>
*
* @author Roedy Green, Canadian Mind Products
* @version 2.0 2012-11-03 deal text inside <script is no longer
ampified.
* new methods ampifyPossiblyScriptedString(String)
ampifyPossiblyCommentedString(String)
* deprecated ampifyCommented.
* @noinspection WeakerAccess
* @since 1999
*/
public final class Amper
    {
    // ------------------------------ CONSTANTS
------------------------------

    /**
     * true if want extra debug output
     */
    private static final boolean DEBUGGING = false;

    /**
     * Longest an HTML 5 entity can be, at least in our tables,
including the lead & and trail ;.
     */
    static final int LONGEST_HTML5_ENTITY =
"&CounterClockwiseContourIntegral;".length();

    /**
     * undisplayed copyright notice.
     *
     * @noinspection UnusedDeclaration
     */
    public static final String EMBEDDED_COPYRIGHT =
            "Copyright: (c) 1999-2012 Roedy Green, Canadian Mind
Products, http://mindprod.com";

    /**
     * date this version released.
     *
     * @noinspection UnusedDeclaration
     */
    private static final String RELEASE_DATE = "2012-06-18";

    /**
     * how to use the command line
     */
    private static final String USAGE = "Amper needs a filename.html
or a space-separated list of filenames, " +
                                        "with optional -s -q -v
switches";

    /**
     * embedded version string.
     *
     * @noinspection UnusedDeclaration
     */
    public static final String VERSION_STRING = "1.9";

    /**
     * pattern to detect entity less lead & with trail ; alpha, &#x
hex or &# numeric
     */
    private static final Pattern ENTITY_PATTERN = Pattern.compile(
"\\p{Alnum}{2," + ( LONGEST_HTML5_ENTITY - 2 ) +
"};|#x[0-9a-fA-F]{1,8};|#\\p{Digit}{1,10};" );

    // -------------------------- PUBLIC STATIC METHODS
--------------------------

    /**
     * convert all & except ones in comments to &.
     *
     * @param big string possibly containing & and comments, but no
<scripts
     *
     * @return compacted string.
     * @noinspection WeakerAccess
     * @see #ampifyPossiblyScriptedString(String)
     * @see #ampifyPossiblyCommentedString(String)
     * @see #ampifyUncommentedString(String)
     * @deprecated renamed to ampifyPossiblyCommentedString . You
probably really want
     * ampifyPossiblyScriptedString.
     */
    public static String ampifyCommented( String big )
        {
        return ampifyPossiblyCommentedString( big );
        }

    /**
     * fix amps in one file.
     *
     * @param fileBeingProcessed the file currently being processed.
     * @param detail 0=out output at all, 1=just files
changed, 2=all files.
     *
     * @throws IOException if trouble reading or writing file
     * @noinspection SameParameterValue, WeakerAccess
     * @see #ampifyPossiblyScriptedString(String)
     * @see #ampifyPossiblyCommentedString(String)
     * @see #ampifyUncommentedString(String)
     */
    public static void ampifyFile( File fileBeingProcessed,
                                   int detail ) throws IOException
        {
        if ( !( fileBeingProcessed.getName().endsWith( ".html" )
                || fileBeingProcessed.getName().endsWith( ".htm" )
                || fileBeingProcessed.getName().endsWith( ".csv" ) ) )
            {
            out.println( "Cannot amp: "
                         + fileBeingProcessed.getName()
                         + "not .html .htm .csv file" );
            return;
            }
        String big = HunkIO.readEntireFile( fileBeingProcessed );
        String result = ampifyPossiblyScriptedString( big );
        if ( result.equals( big ) )
            {
            // nothing changed. No need to write results.
            if ( detail >= 2 )
                {
                out.println( "- " + fileBeingProcessed.getName() );
                }
            return;
            }
        // generate output into a temporary file until we are sure all
is ok.
        // create a temp file in the same directory as filename
        if ( detail >= 1 )
            {
            // it changed
            out.println( "* " + fileBeingProcessed.getName() );
            }
        final File tempFile = HunkIO.createTempFile( "temp", ".tmp",
fileBeingProcessed );
        FileWriter emit = new FileWriter( tempFile );
        emit.write( result );
        emit.close();
        // successfully created output in same directory as input,
        // Now make it replace the input file.
        Misc.deleteAndRename( tempFile, fileBeingProcessed );
        }

    /**
     * convert all & except ones in comments to &.
     *
     * @param big string possibly containing & and comments, but no
<scripts
     *
     * @return tidied string.
     * @noinspection WeakerAccess
     * @see #ampifyPossiblyScriptedString(String)
     * @see #ampifyUncommentedString(String)
     */
    public static String ampifyPossiblyCommentedString( String big )
        {
        int originalLength = big.length();
        final StringBuilder sb = new StringBuilder( originalLength );
        // indexes which character we are working on
        int i = 0;
        while ( i < originalLength )
            {
            // search for start of comment
            int startCommentPlace = big.indexOf( "", startCommentPlace +
" on a
comment" );
                }
            endCommentPlace += "-->".length();
            String commentText = big.substring( startCommentPlace,
endCommentPlace );
            // make sure the comments not malformed. Should be no
embedded start
            // comment marker
            String commentGuts = commentText.substring(
"".length() );
            if ( commentGuts.contains( " not
balanced" );
                }
            // output the comment unchanged
            sb.append( commentText );
            i = endCommentPlace;
            }// end while
        return sb.toString();
        }

    /**
     * convert all & except ones in comments or inside <script to
&.
     *
     * @param big string possibly containing & and comments and
<scripts
     *
     * @return tidied string.
     * @noinspection WeakerAccess
     * @see #ampifyPossiblyCommentedString(String)
     * @see #ampifyUncommentedString(String)
     */
    public static String ampifyPossiblyScriptedString( String big )
        {
        int originalLength = big.length();
        final StringBuilder sb = new StringBuilder( originalLength );
        // indexes which character we are working on
        int i = 0;
        while ( i < originalLength )
            {
            // search for start of <script
            int startScriptPlace = big.indexOf( "<script", i );
            if ( startScriptPlace < 0 )
                {
                // no more scripts, finish off this last chunk
                sb.append( ampifyPossiblyCommentedString(
big.substring( i,
                        originalLength ) ) );
                break;
                }
            // we found the start of a <script
            // process html in front of <script, possibly empty
            sb.append( ampifyPossiblyCommentedString( big.substring(
i,
                    startScriptPlace ) ) );
            // find the end of script
            int endScriptPlace =
                    big.indexOf( "</script>", startScriptPlace +
"</script>".length() );
            if ( endScriptPlace < 0 )
                {
                throw new IllegalArgumentException( "missing
</script>" );
                }
            endScriptPlace += "</script>".length();
            String scriptText =
                    big.substring( startScriptPlace, endScriptPlace );
            // make sure the <scripts not malformed. Should be no
embedded start marker
            String scriptGuts = scriptText.substring(
"script".length(), scriptText.length() - "</script>".length() );
            if ( scriptGuts.contains( "script" ) )
                {
                throw new IllegalArgumentException( "<script ...
</script> not balanced" );
                }
            // output the script unchanged
            sb.append( scriptText );
            i = endScriptPlace;
            }// end while
        return sb.toString();
        }

    /**
     * convert all & to & unless it has been done already. Leaves
existing
     * entities as is.
     *
     * @param chunk the string to process
     *
     * @return tidied string
     * @noinspection WeakerAccess
     * * @see #ampifyPossiblyScriptedString(String)
     * @see #ampifyPossiblyCommentedString(String)
     */
    public static String ampifyUncommentedString( String chunk )
        {
        // do a quick check. If chunk contains no &, we have nothing
to do,
        // guaranteed
        if ( !chunk.contains( "&" ) )
            {
            return chunk;
            }
        int length = chunk.length();
        final StringBuilder sb2 = new StringBuilder( length + 20 );
        int i = 0;
        while ( i < length )
            {
            int ampPlace = chunk.indexOf( "&", i );
            if ( ampPlace < 0 )
                {
                // all done, copy over the remaining chunk.
                sb2.append( chunk.substring( i, length ) );
                // don't need to increment i
                break;
                }
            // we found an &
            // copy over stuff before the & we just found
            sb2.append( chunk.substring( i, ampPlace ) );
            i = ampPlace;
            // is it an & or < or some other entity already?

            // get string without lead & but with trailing ; if it
exists.
            final String candidate = chunk.substring( i + 1, Math.min(
i + LONGEST_HTML5_ENTITY, length ) );

            final Matcher m = ENTITY_PATTERN.matcher( candidate );
            // quick test. Just check pattern starting just after &
            if ( m.lookingAt() )
                {
                // this was an entity already, leave it alone.
                sb2.append( '&' );
                }
            else
                {
                // convert & to &
                sb2.append( "&" );
                }
            i++;
            }// end while
        return sb2.toString();
        }

    // --------------------------- CONSTRUCTORS
---------------------------

    /**
     * constructor, not used.
     *
     * @noinspection WeakerAccess
     */
    private Amper()
        {
        }

    // --------------------------- main() method
---------------------------

    /**
     * fixes ampersands in HTML files.
     *
     * @param args names of files to process, dirs, files, -s, *.*, no
wildcards.
     */
    public static void main( String[] args )
        {
        if ( DEBUGGING )
            {
            out.println( ENTITY_PATTERN.toString() );
            }
        // gather all the files mentioned on the command line.
        // either directories, files, with -s and subdirs option.
        // warning. Windows expands any wildcards in a nasty way.
        // do not use wildcards.
        // See http://mindprod.com/jgloss/wildcard.html
        out.println( "Gathering html files to &ampify..." );
        CommandLine commandLine = new CommandLine( args,
                new AllButSVNDirectoriesFilter(),
                new ExtensionListFilter( "html", "htm", "csv" ) );
        if ( commandLine.size() == 0 )
            {
            throw new IllegalArgumentException( "No files found to
process\n" + USAGE );
            }
        final boolean quiet = commandLine.isQuiet();
        for ( File file : commandLine )
            {
            try
                {
                // -q gives no output at all, otherwise just files
that changed.
                ampifyFile( file, quiet ? 0 : 1 );
                }
            catch ( FileNotFoundException e )
                {
                out.println( "Error: "
                             + file.getAbsolutePath()
                             + " not found." );
                }
            catch ( Exception e )
                {
                out.println( e.getMessage()
                             + " in file "
                             + file.getAbsolutePath() );
                }
            }// end for
        }// end main
    }

--
Roedy Green Canadian Mind Products http://mindprod.com
Ironically, even though the Internet was created by the US military
[DARPA (Defense Advanced Research Projects Agency)]
to withstand a nuclear attack, it is almost defenceless against malice
from any of its users