liblog4cxx-dev 0.10.0-10ubuntu1 / usr / include / log4cxx / patternlayout.h

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 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
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 *      http://www.apache.org/licenses/LICENSE-2.0
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#ifndef _LOG4CXX_PATTERN_LAYOUT_H
#define _LOG4CXX_PATTERN_LAYOUT_H

#if defined(_MSC_VER)
#pragma warning ( push )
#pragma warning ( disable: 4231 4251 4275 4786 )
#endif



#include <log4cxx/layout.h>
#include <log4cxx/pattern/loggingeventpatternconverter.h>
#include <log4cxx/pattern/formattinginfo.h>
#include <log4cxx/pattern/patternparser.h>

namespace log4cxx
{

        /**

        A flexible layout configurable with pattern string.

        <p>The goal of this class is to #format a {@link
        spi::LoggingEvent LoggingEvent} and return the results as a string.
        The results depend on the <em>conversion pattern</em>.

        <p>The conversion pattern is closely related to the conversion
        pattern of the printf function in C. A conversion pattern is
        composed of literal text and format control expressions called
        <em>conversion specifiers</em>.

        <p><i>You are free to insert any literal text within the conversion
        pattern.</i>

        <p>Each conversion specifier starts with a percent sign (\%) and is
        followed by optional <em>format modifiers</em> and a <em>conversion
        character</em>. The conversion character specifies the type of
        data, e.g. logger, level, date, thread name. The format
        modifiers control such things as field width, padding, left and
        right justification. The following is a simple example.

        <p>Let the conversion pattern be <b>"\%-5p [\%t]: \%m\%n"</b> and assume
        that the log4cxx environment was set to use a PatternLayout. Then the
        statements
        <pre>
        LoggerPtr root = Logger::getRoot();
        root->debug("Message 1");
        root->warn("Message 2");
        </pre>
        would yield the output
        <pre>
        DEBUG [main]: Message 1
        WARN  [main]: Message 2
        </pre>

        <p>Note that there is no explicit separator between text and
        conversion specifiers. The pattern parser knows when it has reached
        the end of a conversion specifier when it reads a conversion
        character. In the example above the conversion specifier
        <b>\%-5p</b> means the level of the logging event should be left
        justified to a width of five characters.

        The recognized conversion characters are

        <p>
        <table border="1" CELLPADDING="8">
        <tr>
        <td align=center><b>Conversion Character</b></td>
        <td align=center><b>Effect</b></td>
        </tr>

        <tr>
        <td align=center><b>c</b></td>

        <td>Used to output the logger of the logging event. The
        logger conversion specifier can be optionally followed by
        <em>precision specifier</em>, that is a decimal constant in
        brackets.

        <p>If a precision specifier is given, then only the corresponding
        number of right most components of the logger name will be
        printed. By default the logger name is printed in full.

        <p>For example, for the logger name "a.b.c" the pattern
        <b>\%c{2}</b> will output "b.c".

        </td>
        </tr>

   <tr> <td align=center><b>d</b></td> <td>Used to output the date of
         the logging event. The date conversion specifier may be
         followed by a set of braces containing a
         date and time pattern string compatible with java.text.SimpleDateFormat,
         <em>ABSOLUTE</em>, <em>DATE</em> or <em>ISO8601</em>.
         For example, <b>%d{HH:mm:ss,SSS}</b>,
         <b>%d{dd&nbsp;MMM&nbsp;yyyy&nbsp;HH:mm:ss,SSS}</b> or
         <b>%d{DATE}</b>.  If no date format specifier is given then
         ISO8601 format is assumed.
     </td>
   </tr>

        <tr>
        <td align=center><b>F</b></td>

        <td>Used to output the file name where the logging request was
        issued.

        </tr>

        <tr>
        <td align=center><b>l</b></td>

        <td>Used to output location information of the caller which generated
        the logging event.

        </td>
        </tr>

        <tr>
        <td align=center><b>L</b></td>

        <td>Used to output the line number from where the logging request
        was issued.
        </tr>


        <tr>
        <td align=center><b>m</b></td>
        <td>Used to output the application supplied message associated with
        the logging event.</td>
        </tr>

        <tr>
        <td align=center><b>n</b></td>

        <td>Outputs the platform dependent line separator character or
        characters.

        <p>This conversion character offers practically the same
        performance as using non-portable line separator strings such as
        "\n", or "\r\n". Thus, it is the preferred way of specifying a
        line separator.


        </tr>

        <tr>
        <td align=center><b>p</b></td>
        <td>Used to output the level of the logging event.</td>
        </tr>

        <tr>

        <td align=center><b>r</b></td>

        <td>Used to output the number of milliseconds elapsed since the start
        of the application until the creation of the logging event.</td>
        </tr>


        <tr>
        <td align=center><b>t</b></td>

        <td>Used to output the name of the thread that generated the
        logging event.</td>

        </tr>

        <tr>

        <td align=center><b>x</b></td>

        <td>Used to output the NDC (nested diagnostic context) associated
        with the thread that generated the logging event.
        </td>
        </tr>


        <tr>
        <td align=center><b>X</b></td>

        <td>

        <p>Used to output the MDC (mapped diagnostic context) associated
        with the thread that generated the logging event. The <b>X</b>
        conversion character <em>must</em> be followed by the key for the
        map placed between braces, as in <b>\%X{clientNumber}</b> where
        <code>clientNumber</code> is the key. The value in the MDC
        corresponding to the key will be output.</p>

        <p>See MDC class for more details.
        </p>

        </td>
        </tr>

        <tr>

        <td align=center><b>\%</b></td>

        <td>The sequence \%\% outputs a single percent sign.
        </td>
        </tr>

        </table>

        <p>By default the relevant information is output as is. However,
        with the aid of format modifiers it is possible to change the
        minimum field width, the maximum field width and justification.

        <p>The optional format modifier is placed between the percent sign
        and the conversion character.

        <p>The first optional format modifier is the <em>left justification
        flag</em> which is just the minus (-) character. Then comes the
        optional <em>minimum field width</em> modifier. This is a decimal
        constant that represents the minimum number of characters to
        output. If the data item requires fewer characters, it is padded on
        either the left or the right until the minimum width is
        reached. The default is to pad on the left (right justify) but you
        can specify right padding with the left justification flag. The
        padding character is space. If the data item is larger than the
        minimum field width, the field is expanded to accommodate the
        data. The value is never truncated.

        <p>This behavior can be changed using the <em>maximum field
        width</em> modifier which is designated by a period followed by a
        decimal constant. If the data item is longer than the maximum
        field, then the extra characters are removed from the
        <em>beginning</em> of the data item and not from the end. For
        example, it the maximum field width is eight and the data item is
        ten characters long, then the first two characters of the data item
        are dropped. This behavior deviates from the printf function in C
        where truncation is done from the end.

        <p>Below are various format modifier examples for the logger
        conversion specifier.

        <p>
        <TABLE BORDER=1 CELLPADDING=8>
        <tr>
        <td align=center><b>Format modifier</b></td>
        <td align=center><b>left justify</b></td>
        <td align=center><b>minimum width</b></td>
        <td align=center><b>maximum width</b></td>
        <td align=center><b>comment</b></td>
        </tr>

        <tr>
        <td align=center>\%20c</td>
        <td align=center>false</td>
        <td align=center>20</td>
        <td align=center>none</td>

        <td>Left pad with spaces if the logger name is less than 20
        characters long.

        <tr> <td align=center>\%-20c</td> <td align=center>true</td> <td
        align=center>20</td> <td align=center>none</td> <td>Right pad with
        spaces if the logger name is less than 20 characters long.

        <tr>
        <td align=center>\%.30c</td>
        <td align=center>NA</td>
        <td align=center>none</td>
        <td align=center>30</td>

        <td>Truncate from the beginning if the logger name is longer than 30
        characters.

        <tr>
        <td align=center>\%20.30c</td>
        <td align=center>false</td>
        <td align=center>20</td>
        <td align=center>30</td>

        <td>Left pad with spaces if the logger name is shorter than 20
        characters. However, if logger name is longer than 30 characters,
        then truncate from the beginning.

        <tr>
        <td align=center>\%-20.30c</td>
        <td align=center>true</td>
        <td align=center>20</td>
        <td align=center>30</td>

        <td>Right pad with spaces if the logger name is shorter than 20
        characters. However, if logger name is longer than 30 characters,
        then truncate from the beginning.

        </table>

        <p>Below are some examples of conversion patterns.

        <p><b>\%r [\%t] \%-5p \%c \%x - \%m\n</b>
        <p>This is essentially the TTCC layout.

        <p><b>\%-6r [\%15.15t] \%-5p \%30.30c \%x - \%m\n</b>

        <p>Similar to the TTCC layout except that the relative time is
        right padded if less than 6 digits, thread name is right padded if
        less than 15 characters and truncated if longer and the logger
        name is left padded if shorter than 30 characters and truncated if
        longer.

        <p>The above text is largely inspired from Peter A. Darnell and
        Philip E. Margolis' highly recommended book "C -- a Software
        Engineering Approach", ISBN 0-387-97389-3.
        */
        class LOG4CXX_EXPORT PatternLayout : public Layout
        {
                 /**
                  * Conversion pattern.
                  */
                LogString conversionPattern;

                /**
                 * Pattern converters.
                 */
                LOG4CXX_LIST_DEF(LoggingEventPatternConverterList, log4cxx::pattern::LoggingEventPatternConverterPtr);
                LoggingEventPatternConverterList patternConverters;

               /**
                * Field widths and alignment corresponding to pattern converters.
                */
                LOG4CXX_LIST_DEF(FormattingInfoList, log4cxx::pattern::FormattingInfoPtr);
                FormattingInfoList patternFields;


        public:
                DECLARE_LOG4CXX_OBJECT(PatternLayout)
                BEGIN_LOG4CXX_CAST_MAP()
                        LOG4CXX_CAST_ENTRY(PatternLayout)
                        LOG4CXX_CAST_ENTRY_CHAIN(Layout)
                END_LOG4CXX_CAST_MAP()

                /**
                Does nothing
                */
                PatternLayout();

                /**
                Constructs a PatternLayout using the supplied conversion pattern.
                */
                PatternLayout(const LogString& pattern);

                /**
                Set the <b>ConversionPattern</b> option. This is the string which
                controls formatting and consists of a mix of literal content and
                conversion specifiers.
                */
                void setConversionPattern(const LogString& conversionPattern);

                /**
                Returns the value of the <b>ConversionPattern</b> option.
                */
                inline LogString getConversionPattern() const
                        { return conversionPattern; }

                /**
                Call createPatternParser
                */
                virtual void activateOptions(log4cxx::helpers::Pool& p);

                virtual void setOption(const LogString& option, const LogString& value);

                /**
                The PatternLayout does not handle the throwable contained within
                {@link spi::LoggingEvent LoggingEvents}. Thus, it returns
                <code>true</code>.
                */
                virtual bool ignoresThrowable() const
                        { return true; }

                /**
                Produces a formatted string as specified by the conversion pattern.
                */
                virtual void format(LogString& output,
                     const spi::LoggingEventPtr& event, log4cxx::helpers::Pool& pool) const;

        protected:
                virtual log4cxx::pattern::PatternMap getFormatSpecifiers();
        };
      LOG4CXX_PTR_DEF(PatternLayout);
}  // namespace log4cxx

#if defined(_MSC_VER)
#pragma warning ( pop )
#endif


#endif //_LOG4CXX_PATTERN_LAYOUT_H