Examples of org.clapper.util.io.WordWrapWriter

org.clapper.util.io.WordWrapWriter
The WordWrapWriter class is a filter class. A WordWrapWriter object wraps a Writer or OutputStream object, filtering output to the wrapped object so that output lines are broken on word boundaries and fit nicely within the proscribed output width. Messages may be written with prefixes or without them, depending upon various settings in the WordWrapWriter object; the columnar width of the output object can be controlled, as well.

For example, the long message
```
Unable to open file /usr/local/etc/wombat: No such file or directory
```
might appear like this without a prefix:
```
 Unable to open file /usr/local/etc/wombat: No such file or directory 
```
and like this if the prefix is "myprog:"
```
 myprog: Unable to open file /usr/local/etc/wombat: No such file or directory 
```
Alternatively, if the output width is shortened, the same message can be made to wrap something like this:
```
 myprog: Unable to open file /usr/local/etc/wombat: No such file or directory 
```
Note how the WordWrapWriter output's logic will "tab" past the prefix on wrapped lines.

WordWrapWriter objects also support the notion of an indentation level, which is independent of the prefix. A non-zero indentation level causes each line, including the first line, to be indented that many characters. Thus, calling {@link #setIndentation(int) setIndentation()} with a value of4 will cause each output line to be preceded by 4 blanks. (It's also possible to change the indentation character from a blank to any other character. See {@link #setIndentationChar(char) setIndentationChar()}for details.)

The logic is predicated on the notion of a "message"; that is, a WordWrapWriter object has to know where a message begins and ends, so it can tell when to write the prefix, reset its internal column count, etc. The class's notion of a message is straightforward: A message consists of all characters written to the object via one of the write() methods, up to and including either an embedded newline or a call to the {@link #flush()} method. The println() methodsimplicitly call flush(), as does any write() method that encounters an embedded newline. Thus, it's rarely necessary to call flush() manually.

Notes
1. The class does not do any special processing of tab characters. Embedded tab characters can have surprising (and unwanted) effects on the rendered output.
2. Wrapping another WordWrapWriter object is an invitation to trouble.
3. Technically, this class probably ought to extend the java.io.FilterWriter class, since performs filtering of output written to another underlying Writer or OutputStream. However, I wanted WordWrapWriter to be polymorphically compatible with java.io.PrintWriter, so it could be passed to methods expecting a PrintWriter object; there are more methods that expect a PrintWriter than there are methods that expect a FilterWriter.
@see java.io.Writer @see java.io.PrintWriter @version $Revision$ @author Copyright © 2004-2007 Brian M. Clapper

     * @return the usage string, with embedded newlines
     */
    public String getUsageMessage(String prefixMsg, int maxLineLength)
    {
        StringWriter     buf = new StringWriter();
        WordWrapWriter   out;
        String[]         strings;
        int              i;
        int              maxParamLength = 0;
        int              maxOptionLength = 0;
        String           s;
        StringBuffer     usageLine = new StringBuffer();
        OptionInfo[]     options;
        OptionInfo       opt;
        Locale           locale = Locale.getDefault();


        if (maxLineLength <= 0)
            maxLineLength = Integer.MAX_VALUE;


        out = new WordWrapWriter(buf, maxLineLength);


        if (prefixMsg != null)
        {
            out.println();
            out.println(prefixMsg);
            out.println();
        }


        // Now, print the summary line.


        String commandName = usageInfo.getCommandName();
        if (commandName != null)
        {
            usageLine.append (commandName);
        }


        else
        {
            usageLine.append("java ");
            usageLine.append(getClass().getName());
        }


        usageLine.append(' ');
        usageLine.append(BundleUtil.getMessage(Package.BUNDLE_NAME,
                                               locale,
                                               "CommandLineUtility.options1",
                                               "[options]"));
        usageLine.append(' ');


        // Add the parameter placeholders. We'll also calculate the maximum
        // parameter name length in this loop, to save an iteration later.


        strings = usageInfo.getParameterNames();
        if (strings.length > 0)
        {
            for (i = 0; i < strings.length; i++)
            {
                usageLine.append(' ');


                boolean optional = true;
                if (usageInfo.parameterIsRequired(strings[i]))
                    optional = false;


                if (optional)
                    usageLine.append('[');
                usageLine.append(strings[i]);
                if (optional)
                    usageLine.append(']');
                maxParamLength = Math.max(maxParamLength,
                                          strings[i].length() + 1);
            }
        }


        if ( (s = usageInfo.getUsagePrologue()) != null)
            out.println(s);


        s = BundleUtil.getMessage(Package.BUNDLE_NAME,
                                  locale,
                                  "CommandLineUtility.usage",
                                  "Usage:");
        out.setPrefix(s + " ");
        out.println(usageLine.toString());
        out.setPrefix (null);
        out.println();


        // Find the largest option name.


        out.println(BundleUtil.getMessage(Package.BUNDLE_NAME,
                                          locale,
                                          "CommandLineUtility.options2",
                                          "OPTIONS:"));
        out.println();


        maxOptionLength = 2;
        options = usageInfo.getOptions();
        for (i = 0; i < options.length; i++)
        {
            opt = options[i];


            // An option with a null explanation is hidden.


            if (opt.explanation == null)
                continue;


            if (opt.longOption != null)
            {
                // Allow room for short option, long option and argument,
                // if any.
                //
                // -x, --long-x <arg>


                int    len = 0;
                String sep = "";
                if (opt.shortOption != UsageInfo.NO_SHORT_OPTION)
                {
                    len = 2;    // -x
                    sep = ", ";
                }


                if (opt.longOption != null)
                {
                    len += (sep.length()
                        + UsageInfo.LONG_OPTION_PREFIX.length()
                        + opt.longOption.length());
                }


                if (opt.argToken != null)
                    len += (opt.argToken.length() + 1);


                maxOptionLength = Math.max(maxOptionLength, len + 1);
            }
        }


        if (maxOptionLength > MAX_OPTION_STRING_LENGTH)
            maxOptionLength = MAX_OPTION_STRING_LENGTH;


        // Now, print the options.


        StringBuffer optString = new StringBuffer();
        for (i = 0; i < options.length; i++)
        {
            opt = options[i];


            // An option with a null explanation is hidden.


            if (opt.explanation == null)
                continue;


            // If there's a short option, print it first. Then do the
            // long one.


            optString.setLength (0);
            String sep = "";


            if (opt.shortOption != UsageInfo.NO_SHORT_OPTION)
            {
                optString.append(UsageInfo.SHORT_OPTION_PREFIX);
                optString.append(opt.shortOption);
                sep = ", ";
            }


            if (opt.longOption != null)
            {
                optString.append(sep);
                optString.append(UsageInfo.LONG_OPTION_PREFIX);
                optString.append(opt.longOption);
            }


            if (opt.argToken != null)
            {
                optString.append(' ');
                optString.append(opt.argToken);
            }


            s = optString.toString();
            if (s.length() > maxOptionLength)
            {
                out.println (s);
                out.setPrefix(padString(" ", maxOptionLength));
            }


            else
            {
                out.setPrefix(padString(optString.toString(),
                                        maxOptionLength));
            }


            out.println(opt.explanation);
            out.setPrefix(null);
        }


        // Print the parameters. We already have size of the the largest
        // parameter name.


        strings = usageInfo.getParameterNames();
        if (strings.length > 0)
        {
            out.println();
            out.println(BundleUtil.getMessage(Package.BUNDLE_NAME,
                                              locale,
                                              "CommandLineUtility.params",
                                              "PARAMETERS:"));
            out.println();


            // Now, print the parameters.


            for (i = 0; i < strings.length; i++)
            {
                out.setPrefix(padString(strings[i], maxParamLength));
                out.println(usageInfo.getParameterExplanation(strings[i]));
                out.setPrefix(null);
            }
        }


        if ( (s = usageInfo.getUsageTrailer()) != null)
        {
            out.println();
            out.println(s);
        }


        out.flush();


        return buf.toString();
    }

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org.clapper.util.cmdline.ParameterParser

java.io.OutputStreamWriter

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java.io.PrintWriter

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