shimatta
/
metrixpp


			
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                <h2>Multiple languages</h2>
                <p class="lead">&middot; C/C++, C# and Java.</p>
                <p class="lead">&middot; Recognises classes, interfaces, namespaces, functions, comments, preprocessor and much more.</p>
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                <h2>Multiple metrics</h2>
                <p class="lead">&middot; Complexity, size and other.</p>
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                <h2>High performance and scalability</h2>
                <p class="lead">&middot; Applicable to huge code bases: thousands of files per minute.</p>
                <p class="lead">&middot; Ultra-fast feedback on iterative re-run.</p>
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                <h2>Effortless application to legacy code</h2>
                <p class="lead">&middot; Recognises legacy, modified and new code.</p>
                <p class="lead">&middot; Prevents from negative trends. Encourages positive.</p>
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                <p class="lead">&middot; Define your custom metric.</p>
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            <h5 class="text-right">Management of source code quality is possible.</h5>
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            <h1>Overview</h1>
          </div>

          <h3>Highlights</h3>
          <p>Metrix++ is a tool to collect and analyse code metrics. Any metric is useless if it is not used.
             Metrix++ offers great usage capabilities and assists with variety of application use cases:</p>
          <ul>
            <li>Monitoring trends on <strong>daily</strong> basis. In order to take actions or make right decisions earlier.</li>
            <li>Enforcing trends on <strong>hourly</strong> basis, at every commit of code changes. In order to control quality in time, i.e. when it is not too late to redo.</li>
            <li>Assisiting on <strong>per minute</strong> basis during code refactoring and code development, where coding and quality standards matter.</li>
          </ul>

          <p>The workflow sections below demonstarate basic application usecases.</p>

          <h3>Languages supported</h3>
          <p>The tool can parse C/C++, C# and Java source code files. The parser identifies certain regions in the code,
             such as classes, functions, namespaces, interfaces, etc. It obviously detects comments, strings and code for preprocessor.
             The identified regions form a tree of nested source code blocks, which are refered after and additionally scanned by metrics plugins.
             This concept allows to attribute metrics per regions, what gives fine grained data and rich input to analysis tools.
             The following example demonstrates regions concept.</p>
             
          <table class="table">
            <thead>
              <tr>
                <th>Source code</th>
                <th>Regions tree [type: name: content type]</th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td>
<pre class="prettyprint linenums">
// simple C++ code

#include &lt;myapi.h&gt;

// I explain the following class
class MyClass {
public:
    int m_var; // some member

    // I explain the following function
    MyClass(): m_var(0) {
        char str[] = "unused string"
        
        // nested region for good measure
        struct MyStruct {};
    }
    
    // Do not judge ugly code below
#define get_max(a,b) ((a)>(b)?(a):(b))
    set_max(int b) {
        m_var = get_max(m_var, b);
    }
};
// this is the last line
</pre>
                </td>
                <td>
<pre class="prettyprint linenums">
file: __global__: comment
file: __global__: code
file: __global__: preprocessor
file: __global__: code
    class: MyClass: comment
    class: MyClass: code
    class: MyClass: code
    class: MyClass: code, comment
    class: MyClass: code
        function: MyClass: comment
        function: MyClass: code
        function: MyClass: code, string
        function: MyClass: code
            struct: MyStruct: comment
            struct: MyStruct: code
        function: MyClass: code
    class: MyClass: code
        function: set_max: comment
        function: set_max: preprocessor
        function: set_max: code
        function: set_max: code
        function: set_max: code
    class: MyClass: code
file: __global__: comment
</pre>
                </td>
              </tr>
            </tbody>
          </table>

          <h3>Metrics</h3>
          <p>Metrics highlighed in blue are <strong>per file</strong> metrics. Other metrics are <strong>per region</strong> metrics.
             Region term is explained in the previous chapter.</p>
          <table class="table table-bordered">
            <thead>
              <tr>
                <th>Metric (enable option)</th>
                <th>Brief description</th>
                <th>Motivation</th>
              </tr>
            </thead>
            <tbody>
              <tr class="info">
                <td>std.general.size</td>
                <td>Size of a file in bytes.</td>
                <td rowspan="4"><ul><li>Monitoring growth of source code base.</li>
                    <li>Normalizing other metrics.</li>
                    <li>Preventing large files and regions (large things difficult to maintain).</li>
                    <li>Predicting delivery dates by comparing
                        <a href="http://www.compaid.com/caiInternet/casestudies/kanarticle2.pdf">S-shaped code base growth / change curves</a>.</li></ul></td>
              </tr>
              <tr>
                <td>std.code.length.total</td>
                <td>The same as 'std.general.size' metric, but attributed to code regions.</td>
                <td></td>
              </tr>
              <tr>
                <td>std.code.lines.total</td>
                <td>Number of non-blank lines of code of any content type (exectuable, comments, etc.)</td>
                <td></td>
              </tr>
              <tr>
                <td>std.code.lines.code</td>
                <td>Number of non-blank lines of code excluding preprocessor and comments.</td>
                <td></td>
              </tr>
              <tr>
                <td>std.code.lines.preprocessor</td>
                <td>Number of non-blank lines of preprocessor code.</td>
                <td><ul><li>Enforcing localisation of preprocessor code in a single place.</li>
                    <li>Encouraging usage of safer code structures instead of preprocessor.</li></ul></td>
              </tr>
              <tr>
                <td>std.code.lines.comments</td>
                <td>Number of non-blank lines of comments.</td>
                <td><ul><li>Low number of comments may indicate about maintainability problems.</li></ul></td>
              </tr>
              <tr>
                <td>std.code.complexity.cyclomatic</td>
                <td>McCabe cyclomatic complexity metric.</td>
                <td colspan="2"><ul><li>Identification of highly complex code for review and refactoring.</li>
                    <li>Preventing complex functions (complexity is a reason of many defects and a reason of expensive maintaintenance).</li></ul></td>
              </tr>
              <tr>
                <td>std.code.complexity.maxindent</td>
                <td>Maximum level of indentation of blocks within a region. For example, the following class has got 
                	the metric equal to 1 and the function has got it equal to 2:
                	<pre class="prettyprint">
class WeekClass {
    int isWeekend(int day) {
        if (day == SATURDAY ||
            day == SUNDAY) {
            return true;
        }
        return false;
    }
}
</pre>
                	</td>
              </tr>
              <tr>
                <td>std.suppress</td>
                <td>An option enables collection of Metrix++ suppressions and 2 metrics: 'std.suppress:count' and 
                    'std.suppress.file:count'. The first is number of suppressions per region.
                    The second is the same but applies for file-scope metrics.</td>
                <td><ul><li>Suppressing false-positives.</li>
                    <li>Managing the amount of suppressions. Usually there are no false-positives to suppress with the right metric,
                        but could be exceptions in specific cases. Managing suppressions is about managing exceptions.
                        If there are many exceptional cases, maybe something is wrong with a metric or an application of a metric.</li></ul></td>
              </tr>
              <tr class="info">
                <td>std.general.procerrors</td>
                <td>Number of errors detected by Metrix++ code parser.
                    Errors, like mismatched brackets, may result in bad identification of regions.</td>
                <td><ul><li>Cleaning up errors to ensure reliable code scanning.</li></ul></td>
              </tr>
              <tr class="info">
                <td>std.general.proctime</td>
                <td>Seconds spent on processing a file.</td>
                <td><ul><li>Monitor and profile tool's performance.</li></ul></td>
              </tr>
            </tbody>
          </table>

        </section>

        <section id="download_section">
          <div class="page-header">
            <h1>Download &amp; Install</h1>
          </div>

          <p>In order to get the tool working, <a href="https://sourceforge.net/projects/metrixplusplus/files/latest/download">dowload the archive</a> with the latest stable version
             and unpack it to some folder. First run of the tool will trigger the installation within the folder,
             where it was launched.</p>

          <p>Corresponding checkout from the <a href="https://sourceforge.net/p/metrixplusplus/code">version control system</a> is the following:</p>
          <pre>svn checkout <a href="https://sourceforge.net/p/metrixplusplus/code">svn://svn.code.sf.net/p/metrixplusplus/code</a>/releases/latest Metrix++</pre>

          <p>In order to checkout the latest version under development, use this command:</p>
          <pre>svn checkout <a href="https://sourceforge.net/p/metrixplusplus/code">svn://svn.code.sf.net/p/metrixplusplus/code</a>/mainline Metrix++</pre>

          <h4>Prerequisites</h4>
          <p>Python Runtime Environment (version 2.7.* or later, version 3.* has not been tested)</p>

          <h4>License</h4>
          <p>This program is free software; you can redistribute it and/or modify it
             under the terms of the GNU General Public License as published by the
             Free Software Foundation; version 3 of the License.</p>
          <p>This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
             without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
             See the GNU General Public License for more details.</p>
          <p>You should have received a copy of the GNU General Public License along with the Metrix++;
             if not, contact <a href="mailto:avkonst@users.sourceforge.net?subject=Metrix%2B%2B License">Project Administrator</a></p>
             
        </section>

        <div class="page-header">
          <h1>Workflow</h1>
        </div>
        <p>The workflow and application usecases are demonstrated using source code of 
        	<a href="http://www.boost.org/doc/libs/1_54_0/doc/html/interprocess.html">boost/interprocess</a> library.
        	Boost versions 1.52 and 1.54 are used and refered below as 'previous' and 'current' accordingly.</p>
        <section id="workflow_collect_section">
          <h2>Collect data</h2>
          <p>The first obvious step is to collect the data.
             The 'collect' tool has got multiple options to enable various metrics plugins.
             Let's collect number of lines of code and cyclomatic complexity metrics
             for the previous (1.52.0 version) boost interprocess library. Assuming that 2 versions of boost library
             are unpacked in the current working directory:</p>
          <pre>
&gt; cd boost_1_52_0
&gt; python "/path/to/metrix++.py" collect --std.code.lines.code --std.code.complexity.cyclomatic -- boost/interprocess
&gt; cd ../ # return back to working directory
</pre>
          <p>The list of arguments after '--' enumerates paths where to read source files.
          	As a result of execution of this command, a file metrixpp.db will be written in the current working directory.
          	It can be redefined with help of --db-file option.</p>
          <p>Metrix++ has got rich functionality in comparing code bases and reducing processing scope to modified or new code.
          	So, let's collect the same data for the current (1.54.0 version) boost interprocess library.</p>
          <pre>
&gt; cd boost_1_54_0
&gt; python "/path/to/metrix++.py" collect --std.code.lines.code --std.code.complexity.cyclomatic -- boost/interprocess --db-file-prev=../boost_1_52_0/metrixpp.db
&gt; cd ../ # return back to working directory
</pre>
          <p>The option --db-file-prev points out to the file with data collected in the previous step.
          	So, eventually it executed iterative collection. It can speed up the exectuion significantly,
          	depending on amount of changes between two version.</p>
          <p>Check other options of the collect tool by executing:</p>
          <pre>
&gt; python "/path/to/metrix++.py" collect --help
</pre>
        </section>
        <section id="workflow_view_section">
          <h2>View data</h2>
        </section>
        <section id="workflow_view_summary_section">
          <h3>Summary metrics and distribution tables/graphs</h3>
          <p>It is time to look at the data files collected (step above). The command:</p>
          <pre>
&gt; python "/path/to/metrix++.py" view --db-file=boost_1_54_0/metrixpp.db
</pre>
          <p>prints summary metrics, like minimum/maximum, and distribution/frequency tables:</p>
          <pre>
:: info: Overall metrics for 'std.code.complexity:cyclomatic' metric
	Average        : 0.652902698283
	Minimum        : 0
	Maximum        : 37
	Total          : 1597.0
	Distribution   : 2446 regions in total (including 0 suppressed)
	  Metric value : Ratio : R-sum : Number of regions
	             0 : 0.771 : 0.771 : 1886	|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
	             1 : 0.110 : 0.881 :  268	|||||||||||
	             2 : 0.044 : 0.925 :  108	||||
	             3 : 0.025 : 0.949 :   60	||
	             4 : 0.016 : 0.966 :   40	||
	             5 : 0.007 : 0.973 :   18	|
	             6 : 0.006 : 0.979 :   14	|
	             7 : 0.004 : 0.983 :   10	
	             8 : 0.003 : 0.986 :    8	
	             9 : 0.002 : 0.988 :    4	
	            10 : 0.004 : 0.991 :    9	
	            11 : 0.002 : 0.993 :    4	
	            12 : 0.001 : 0.994 :    3	
	            13 : 0.001 : 0.995 :    2	
	            14 : 0.001 : 0.996 :    2	
	         15-16 : 0.001 : 0.997 :    3	
	         17-18 : 0.001 : 0.998 :    3	
	            20 : 0.000 : 0.999 :    1	
	         23-25 : 0.001 : 1.000 :    2	
	            37 : 0.000 : 1.000 :    1	

:: info: Overall metrics for 'std.code.lines:code' metric
	Average        : 6.64356984479
	Minimum        : 0
	Maximum        : 201
	Total          : 23970.0
	Distribution   : 3608 regions in total (including 0 suppressed)
	  Metric value : Ratio : R-sum : Number of regions
	           0-1 : 0.088 : 0.088 :  319	|||||||||
	             2 : 0.320 : 0.409 : 1155	||||||||||||||||||||||||||||||||
	             3 : 0.108 : 0.517 :  390	|||||||||||
	             4 : 0.081 : 0.598 :  294	||||||||
	             5 : 0.080 : 0.678 :  290	||||||||
	             6 : 0.061 : 0.739 :  220	||||||
	             7 : 0.049 : 0.788 :  176	|||||
	             8 : 0.030 : 0.818 :  109	|||
	             9 : 0.025 : 0.843 :   89	||
	         10-11 : 0.032 : 0.876 :  117	|||
	         12-13 : 0.020 : 0.895 :   71	||
	            14 : 0.012 : 0.907 :   43	|
	         15-16 : 0.017 : 0.924 :   61	||
	         17-19 : 0.015 : 0.939 :   55	||
	         20-22 : 0.013 : 0.952 :   46	|
	         23-26 : 0.011 : 0.963 :   40	|
	         27-30 : 0.009 : 0.972 :   33	|
	         31-39 : 0.009 : 0.981 :   33	|
	         40-65 : 0.009 : 0.991 :   34	|
	        66-201 : 0.009 : 1.000 :   33	|

:: info: Directory content:
	Directory      : .
</pre>
          <p>The same command with --db-file-prev option enables comparision and change trends are shown in [] brackets:</p>
          <pre>
&gt; python "/path/to/metrix++.py" view --db-file=boost_1_54_0/metrixpp.db --db-file-prev=boost_1_52_0/metrixpp.db
</pre>
          <pre>
:: info: Overall metrics for 'std.code.complexity:cyclomatic' metric
	Average        : 0.652902698283 [+0.00362138411453]
	Minimum        : 0 [+0]
	Maximum        : 37 [+1]
	Total          : 1597.0 [+16.0]
	Distribution   : 2446 [+11] regions in total (including 0 [+0] suppressed)
	  Metric value : Ratio : R-sum : Number of regions
	             0 : 0.771 : 0.771 : 1886 [+5   ]	|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
	             1 : 0.110 : 0.881 :  268 [+4   ]	|||||||||||
	             2 : 0.044 : 0.925 :  108 [+0   ]	||||
	             3 : 0.025 : 0.949 :   60 [+2   ]	||
	             4 : 0.016 : 0.966 :   40 [-1   ]	||
	             5 : 0.007 : 0.973 :   18 [-1   ]	|
	             6 : 0.006 : 0.979 :   14 [+1   ]	|
	             7 : 0.004 : 0.983 :   10 [+1   ]	
	             8 : 0.003 : 0.986 :    8 [+1   ]	
	             9 : 0.002 : 0.988 :    4 [+0   ]	
	            10 : 0.004 : 0.991 :    9 [-2   ]	
	            11 : 0.002 : 0.993 :    4 [+1   ]	
	            12 : 0.001 : 0.994 :    3 [+0   ]	
	            13 : 0.001 : 0.995 :    2 [+0   ]	
	            14 : 0.001 : 0.996 :    2 [+0   ]	
	         15-16 : 0.001 : 0.997 :    3 [-1   ]	
	         17-18 : 0.001 : 0.998 :    3 [+1   ]	
	            20 : 0.000 : 0.999 :    1 [+0   ]	
	         23-25 : 0.001 : 1.000 :    2 [+0   ]	
	         36-37 : 0.000 : 1.000 :    1 [+0   ]	

:: info: Overall metrics for 'std.code.lines:code' metric
	Average        : 6.64356984479 [+0.012181964309]
	Minimum        : 0 [+0]
	Maximum        : 201 [+4]
	Total          : 23970.0 [+223.0]
	Distribution   : 3608 [+27] regions in total (including 0 [+0] suppressed)
	  Metric value : Ratio : R-sum : Number of regions
	           0-1 : 0.088 : 0.088 :  319 [+3   ]	|||||||||
	             2 : 0.320 : 0.409 : 1155 [+9   ]	||||||||||||||||||||||||||||||||
	             3 : 0.108 : 0.517 :  390 [-3   ]	|||||||||||
	             4 : 0.081 : 0.598 :  294 [+7   ]	||||||||
	             5 : 0.080 : 0.678 :  290 [+7   ]	||||||||
	             6 : 0.061 : 0.739 :  220 [-1   ]	||||||
	             7 : 0.049 : 0.788 :  176 [-2   ]	|||||
	             8 : 0.030 : 0.818 :  109 [-1   ]	|||
	             9 : 0.025 : 0.843 :   89 [+4   ]	||
	         10-11 : 0.032 : 0.876 :  117 [+9   ]	|||
	         12-13 : 0.020 : 0.895 :   71 [-9   ]	||
	            14 : 0.012 : 0.907 :   43 [+0   ]	|
	         15-16 : 0.017 : 0.924 :   61 [+0   ]	||
	         17-19 : 0.015 : 0.939 :   55 [+6   ]	||
	         20-22 : 0.013 : 0.952 :   46 [-3   ]	|
	         23-26 : 0.011 : 0.963 :   40 [+2   ]	|
	         27-30 : 0.009 : 0.972 :   33 [-3   ]	|
	         31-39 : 0.009 : 0.981 :   33 [+0   ]	|
	         40-65 : 0.009 : 0.991 :   34 [+1   ]	|
	        66-201 : 0.009 : 1.000 :   33 [+1   ]	|

:: info: Directory content:
	Directory      : .
</pre>
          <h4>Reducing analysis scope</h4>
          <p>There are two ways to reduce the analysis scope for the view tool. The first is to enumerate paths of interest.
          	For example, the following command reduces scope to 'allocators' sub-directory within the processed code.</p>
          <pre>
&gt; python "/path/to/metrix++.py" view --db-file=boost_1_54_0/metrixpp.db -- ./boost/interprocess/allocators
</pre>
          <p>The second is to specify --scope-mode option, which instructs the tool to process only modified and/or new files/regions.
          	For example, view the summary metrics for all modified and new regions:</p>
          <pre>
&gt; python "/path/to/metrix++.py" view --db-file=boost_1_54_0/metrixpp.db  --db-file-prev=boost_1_52_0/metrixpp.db --scope-mode=touched
</pre>
          <pre>
:: info: Overall metrics for 'std.code.complexity:cyclomatic' metric
	Average        : 1.84924623116 [-0.0230941943761]
	Minimum        : 0 [+0]
	Maximum        : 37 [+1]
	Total          : 368.0 [+16.0]
	Distribution   : 199 [+11] regions in total (including 0 [+0] suppressed)
	  Metric value : Ratio : R-sum : Number of regions
	             0 : 0.608 : 0.608 : 121 [+5  ]	|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
	             1 : 0.131 : 0.739 :  26 [+4  ]	|||||||||||||
	             2 : 0.070 : 0.809 :  14 [+0  ]	|||||||
	             3 : 0.060 : 0.869 :  12 [+2  ]	||||||
	             4 : 0.015 : 0.884 :   3 [-1  ]	||
	             5 : 0.015 : 0.899 :   3 [-1  ]	||
	             6 : 0.005 : 0.905 :   1 [+1  ]	|
	             7 : 0.015 : 0.920 :   3 [+1  ]	||
	             8 : 0.015 : 0.935 :   3 [+1  ]	||
	             9 : 0.010 : 0.945 :   2 [+0  ]	|
	            10 : 0.010 : 0.955 :   2 [-2  ]	|
	            11 : 0.005 : 0.960 :   1 [+1  ]	|
	            12 : 0.005 : 0.965 :   1 [+0  ]	|
	            13 : 0.005 : 0.970 :   1 [+0  ]	|
	            16 : 0.005 : 0.975 :   1 [-1  ]	|
	            17 : 0.005 : 0.980 :   1 [+0  ]	|
	            18 : 0.010 : 0.990 :   2 [+1  ]	|
	            20 : 0.005 : 0.995 :   1 [+0  ]	|
	         36-37 : 0.005 : 1.000 :   1 [+0  ]	|

:: info: Overall metrics for 'std.code.lines:code' metric
	Average        : 15.9645390071 [-0.815853149771]
	Minimum        : 0 [+0]
	Maximum        : 201 [+6]
	Total          : 4502.0 [+223.0]
	Distribution   : 282 [+27] regions in total (including 0 [+0] suppressed)
	  Metric value : Ratio : R-sum : Number of regions
	           0-1 : 0.053 : 0.053 :  15 [+3  ]	|||||
	             2 : 0.124 : 0.177 :  35 [+9  ]	||||||||||||
	             3 : 0.053 : 0.230 :  15 [-3  ]	|||||
	             4 : 0.060 : 0.291 :  17 [+7  ]	||||||
	             5 : 0.089 : 0.379 :  25 [+7  ]	|||||||||
	             6 : 0.060 : 0.440 :  17 [-1  ]	||||||
	             7 : 0.050 : 0.489 :  14 [-2  ]	|||||
	           8-9 : 0.074 : 0.564 :  21 [+3  ]	|||||||
	            10 : 0.035 : 0.599 :  10 [+5  ]	||||
	            11 : 0.082 : 0.681 :  23 [+4  ]	||||||||
	         12-13 : 0.043 : 0.723 :  12 [-9  ]	||||
	         14-15 : 0.039 : 0.762 :  11 [-1  ]	||||
	         16-18 : 0.028 : 0.791 :   8 [+4  ]	|||
	         19-22 : 0.039 : 0.830 :  11 [+0  ]	||||
	         23-26 : 0.039 : 0.869 :  11 [+2  ]	||||
	         27-32 : 0.028 : 0.897 :   8 [-3  ]	|||
	         38-50 : 0.025 : 0.922 :   7 [+0  ]	||
	         51-69 : 0.025 : 0.947 :   7 [+1  ]	||
	        71-100 : 0.032 : 0.979 :   9 [+2  ]	|||
	       101-201 : 0.021 : 1.000 :   6 [-1  ]	||

:: info: Directory content:
	Directory      : .
</pre>
        </section>
        <section id="workflow_view_details_section">
          <h3>Detailed metrics per file/region</h3>
          <p>The same view tool can print detailed metrics per file and per every region in the specified file.
          	In order to get detailed metrics, enumerate files of interest after '--'. For example:</p>
          <pre>
&gt; python "/path/to/metrix++.py" view --db-file=boost_1_54_0/metrixpp.db --db-file-prev=boost_1_52_0/metrixpp.db -- ./boost/interprocess/detail/managed_open_or_create_impl.hpp
</pre>
          <p>produces output similar to this (truncated to make the page shorter):</p>
          <pre>
./interprocess/detail/managed_open_or_create_impl.hpp:302: info: Metrics per 'priv_open_or_create' region
	Region name    : priv_open_or_create
	Region type    : function
	Offsets        : 8314-14526
	Line numbers   : 301-467
	Modified       : True
	std.code.complexity:cyclomatic: 37 [+1]
	std.code.lines:code: 148 [+4]
</pre>
        </section>
        <section>
          <h3>More about the viewer</h3>
          <p>The 'view' command has got an option to alter the output format. It is possible to get the same data
          	in xml pr python disctionary formats. This can be particularly useful for integration of the tool with
          	other applications. For example, an editor may re-collect and show context based metrics when a file is saved.</p>
          <pre>
&gt; python "/path/to/metrix++.py" view --db-file=boost_1_54_0/metrixpp.db --format=xml
</pre>
          <p>Check other options of the view tool by executing:</p>
          <pre>
&gt; python "/path/to/metrix++.py" view --help
</pre>
        </section>
        <section id="workflow_limit_section">
          <h2>Apply thresholds</h2>
          <p>The viewer shows (above) that there are function with quite large value of cyclomatic complexity metric.
          	 Growth of this metric can be considered as negative trend. Metrix++ 'limit' tool offers the capability
          	 to organise the control over trends by applying limits to metric values.
          	 Exceeded limites are alarms in the quality management and control.</p>
        </section>
        <section id="workflow_limit_hotspots_section">
          <h3>Hotspots</h3>
          <p>Hotspots mode of the limit tool helps to identify top files/regions exceeding a metric threshold.
          	Let's identify top 3 functions in boost interprocess library, which exceed limit of 15 points of
          	cyclomatic complexity metric:</p>
          <pre>
&gt; python "/path/to/metrix++.py" limit --db-file=boost_1_54_0/metrixpp.db --max-limit=std.code.complexity:cyclomatic:15 --hotspots=3
</pre>
          <pre>
./interprocess/detail/managed_open_or_create_impl.hpp:302: warning: Metric 'std.code.complexity:cyclomatic' for region 'priv_open_or_create' exceeds the limit.
	Metric name    : std.code.complexity:cyclomatic
	Region name    : priv_open_or_create
	Metric value   : 37
	Modified       : None
	Change trend   : None
	Limit          : 15.0
	Suppressed     : False

./interprocess/streams/vectorstream.hpp:284: warning: Metric 'std.code.complexity:cyclomatic' for region 'seekoff' exceeds the limit.
	Metric name    : std.code.complexity:cyclomatic
	Region name    : seekoff
	Metric value   : 25
	Modified       : None
	Change trend   : None
	Limit          : 15.0
	Suppressed     : False

./interprocess/streams/bufferstream.hpp:174: warning: Metric 'std.code.complexity:cyclomatic' for region 'seekoff' exceeds the limit.
	Metric name    : std.code.complexity:cyclomatic
	Region name    : seekoff
	Metric value   : 23
	Modified       : None
	Change trend   : None
	Limit          : 15.0
	Suppressed     : False
</pre>
        </section>
        <section id="workflow_limit_control_section">
          <h3>Controlling trends</h3>
          <p>Exit code of the 'limit' tool is equal to number of warnings printed. This allows to use the tool
          	as a static analysis tool during software build process. In this case, non-zero exit code means
          	that there are violations to the agreed standards and it may fail the build. So, the same command
          	without --hotspots option will print all regions/files exceeding the specified limit:</p>
          <pre>
&gt; python "/path/to/metrix++.py" limit --db-file=boost_1_54_0/metrixpp.db --max-limit=std.code.complexity:cyclomatic:15
</pre>
          <h4>Modes to exclude old code from the considiration</h4>
          <p>However, it is likely there are many warnings printed in this mode, especially if very old or legacy code is profiled 
          	against new metrics and coding rules. Although all warnings can be removed 
          	by re-factoring in scope of big task force activity, it is where many tools are rejected,
          	because it is difficult to justify the initial cost of applying and integrating them.
          	Metrix++ 'limit' tool has got an option --warn-mode, which helps to overcome this problem.</p>
          <p>--warn-mode=touched encourages re-factoring only for new and modified regions. It enables
          	continuous refactoring. It does not matter how late the rule is applied or 
          	coding standard is modified. It is possible to do it anytime with zero initial investment.
          	For example, applying it to boost interprocess library for a changes between 1.52 and 1.54 versions
          	results in only 6 warnings:</p>
          <pre>
&gt; python "/path/to/metrix++.py" limit --db-file=boost_1_54_0/metrixpp.db --db-file-prev=boost_1_52_0/metrixpp.db --max-limit=std.code.complexity:cyclomatic:15 --warn-mode=touched
</pre>
          <pre>
./interprocess/detail/managed_open_or_create_impl.hpp:302: warning: Metric 'std.code.complexity:cyclomatic' for region 'priv_open_or_create' exceeds the limit.
	Metric name    : std.code.complexity:cyclomatic
	Region name    : priv_open_or_create
	Metric value   : 37
	Modified       : True
	Change trend   : +1
	Limit          : 15.0
	Suppressed     : False

./interprocess/ipc/message_queue.hpp:375: warning: Metric 'std.code.complexity:cyclomatic' for region 'insert_at' exceeds the limit.
	Metric name    : std.code.complexity:cyclomatic
	Region name    : insert_at
	Metric value   : 16
	Modified       : True
	Change trend   : 0
	Limit          : 15.0
	Suppressed     : False

./interprocess/mapped_region.hpp:575: warning: Metric 'std.code.complexity:cyclomatic' for region 'mapped_region' exceeds the limit.
	Metric name    : std.code.complexity:cyclomatic
	Region name    : mapped_region
	Metric value   : 18
	Modified       : True
	Change trend   : +2
	Limit          : 15.0
	Suppressed     : False

./interprocess/mem_algo/detail/mem_algo_common.hpp:452: warning: Metric 'std.code.complexity:cyclomatic' for region 'priv_allocate_many' exceeds the limit.
	Metric name    : std.code.complexity:cyclomatic
	Region name    : priv_allocate_many
	Metric value   : 20
	Modified       : True
	Change trend   : 0
	Limit          : 15.0
	Suppressed     : False

./interprocess/mem_algo/rbtree_best_fit.hpp:787: warning: Metric 'std.code.complexity:cyclomatic' for region 'priv_expand_both_sides' exceeds the limit.
	Metric name    : std.code.complexity:cyclomatic
	Region name    : priv_expand_both_sides
	Metric value   : 17
	Modified       : True
	Change trend   : 0
	Limit          : 15.0
	Suppressed     : False

./interprocess/sync/windows/named_sync.hpp:98: warning: Metric 'std.code.complexity:cyclomatic' for region 'open_or_create' exceeds the limit.
	Metric name    : std.code.complexity:cyclomatic
	Region name    : open_or_create
	Metric value   : 18
	Modified       : True
	Change trend   : 0
	Limit          : 15.0
	Suppressed     : False
</pre>
          <p>If it is challenging or not beneficial to refactor everything touched, 
          	--warn-mode=trends simplifies the control over modified regions and only makes sure
          	that there are no regressions in modified code. In other words, a warning is printed about modified region/file
          	only if a metric exceeds the specified limit and the value of the metric has got negative trend in modification.
          	It is possible to apply it anytime with zero initial investment and almost zero on-going investment around old code.
          	For example, applying it to boost interprocess library for a changes between 1.52 and 1.54 versions
          	results in only 2 warnings:</p>
          <pre>
&gt; python "/path/to/metrix++.py" limit --db-file=boost_1_54_0/metrixpp.db --db-file-prev=boost_1_52_0/metrixpp.db --max-limit=std.code.complexity:cyclomatic:15 --warn-mode=trend
</pre>
          <pre>
./interprocess/detail/managed_open_or_create_impl.hpp:302: warning: Metric 'std.code.complexity:cyclomatic' for region 'priv_open_or_create' exceeds the limit.
	Metric name    : std.code.complexity:cyclomatic
	Region name    : priv_open_or_create
	Metric value   : 37
	Modified       : True
	Change trend   : +1
	Limit          : 15.0
	Suppressed     : False

./interprocess/mapped_region.hpp:575: warning: Metric 'std.code.complexity:cyclomatic' for region 'mapped_region' exceeds the limit.
	Metric name    : std.code.complexity:cyclomatic
	Region name    : mapped_region
	Metric value   : 18
	Modified       : True
	Change trend   : +2
	Limit          : 15.0
	Suppressed     : False
</pre>
          <p>--warn-mode=new drops control over existing code and ensures that warnings are only about new code.
          	For example, applying it to boost interprocess library for a changes between 1.52 and 1.54 versions
          	results in 0 warnings, so new code is totally compliant with the standard required in the example.</p>
          <pre>
&gt; python "/path/to/metrix++.py" limit --db-file=boost_1_54_0/metrixpp.db --db-file-prev=boost_1_52_0/metrixpp.db --max-limit=std.code.complexity:cyclomatic:15 --warn-mode=new
</pre>
          <h4>Suppressions</h4>
          <p>It is possible to suppress warnings on exceptional basis. Suppressions are collected from comments in code
             and used by the 'limit' tool to filter out unnecessary (suppressed) warnings.
             It allows to take fine grained control over false-positive warnings, if there are.</p>
          <p>In order to suppress a warning:</p>
          <ul>
          	<li>per region metrics: put the metrix++ instruction in the comments before the region, for example:</li>
          <pre class="prettyprint linenums">
// This function returns string typed
// representation of a name of a color,
// requested by color's id
// metrix++: suppress std.code.complexity:cyclomatic
std::string getColorName(int color_id)
{
	switch (color_id)
	{
	case COLOR_RED:
		return std::string("red")
	case COLOR_GREEN:
		return std::string("green")
	case COLOR_BLUE:
		return std::string("blue")
	/* and so on */
	}
}
</pre>
          	<li>per file metrics: put the metrix++ instruction in the comments at the beginning of a file, for example:</li>
          <pre class="prettyprint linenums">
//
// This file does processing of colors and brushes
// Copyright is my company, 2013
// 
// However, it is too long and big file, and there is no time
// to split it into multiple file, so shut up the metrix++ warnings:
// metrix++: suppress std.general:size
//

std::string getColorName(int color_id)
{
	...
...
</pre>
          	<li>activate collection of suppressions:</li>
          <pre>
&gt; python "/path/to/metrix++.py" collect --std.suppress
</pre>
          	<li>run the 'limit' tool WITHOUT --disable-suppressions option:</li>
          <pre>
&gt; python "/path/to/metrix++.py" limit ...
</pre>
             </ul>
          <h5>Important notice:</h5>
             <ul><li>--std.suppress option enables collection of 2 metrics as well: 'std.suppress:count' and 
                'std.suppress.file:count'. The first is number of suppressions per region.
                The second is the same but applies to file-scope metrics.
                It allows to manage the amount of suppressions.
                Usually there are no false-positives to suppress with the <strong>right</strong> metric,
                but could be exceptions in specific cases. Managing suppressions is about managing exceptions.
                If there are many exceptional cases, maybe something is wrong with a metric or an application of a metric.
                Two code examples about colors above do not demonstrate the technically exceptional case,
                they likely demonstrate a case of a process exception, like "there is no time to do it proper now", or
                a case of wrong application of a metric, like "shut up the useless tool". So, be careful.
                The 'view' tool shows number of suppressions and its change trends on per metric basis.</li></ul>
        </section>

        <section id="workflow_other_section">
          <h2>Other applications</h2>
          <h3>Checking data file properties</h3>
          <p>Metrix++ 'info' tool is helpful to check properties of a data file, like settings used to write it,  
          	colected metrics and files processed. For example:</p>
          <pre>
&gt; python "/path/to/metrix++.py" info --db-file=boost_1_54_0/metrixpp.db
</pre>
          <pre>
boost_1_54_0/metrixpp.db:: info: Created using plugins and settings:
	version        : 1.0
	std.code.complexity:version: 1.1
	std.code.cpp:version: 1.1
	std.code.cpp:files: *.c,*.cc,*.cpp,*.cxx,*.h,*.hh,*.hpp,*.hxx
	std.code.cs:version: 1.0
	std.code.cs:files: *.cs
	std.code.java:version: 1.1
	std.code.java:files: *.java
	std.code.lines:version: 1.1

test_workflow.db:: info: Collected metrics:
	std.code.complexity:cyclomatic: 
	std.code.lines:code: 

:: info: Processed files and checksums:
	./interprocess/allocators/detail/node_pool.hpp: 0xb099a7c3
	./interprocess/allocators/detail/node_tools.hpp: 0xaaf5044d
	./interprocess/anonymous_shared_memory.hpp: 0x2bf06cb0
	./interprocess/containers/allocation_type.hpp: 0x8e95cda0
	./interprocess/containers/containers_fwd.hpp: 0xa4d0d9f7
	./interprocess/containers/deque.hpp: 0x6dbb77af
	./interprocess/containers/flat_map.hpp: 0x6750338c
	...
</pre>
          <h3>Exporting results</h3>
          <p>Metrix++ 'export' tool exports data files to csv formated files. For example:</p>
          <pre>
&gt; python "/path/to/metrix++.py" export --db-file=boost_1_54_0/metrixpp.db > boost_1_54_0/metrixpp.csv
</pre>
          <pre>
file,region,type,modified,line start,line end,std.code.complexity:cyclomatic,std.code.lines:code
./interprocess/allocators/detail/node_pool.hpp,__global__,global,,1,110,,0
./interprocess/allocators/detail/node_pool.hpp,boost,namespace,,33,105,,2
./interprocess/allocators/detail/node_pool.hpp,interprocess,namespace,,34,104,,2
./interprocess/allocators/detail/node_pool.hpp,ipcdetail,namespace,,35,103,,4
./interprocess/allocators/detail/node_pool.hpp,SegmentManager,class,,39,72,,16
...
</pre>
          <p>Files with csv format can be opened by applications, like Microsoft Office Excel, with advanced analysis capabilities.
          	For example, to draw this distribution graph:</p>
          <p align="center"><img src="assets/img/piechart.png"/></p>
          <p>It is not recommended to use export tool to implement custom post-analysis Metrix++ extensions.
          	  The main reason is non granted backward compatibility support for csv columns. Another main reason is that
          	  exporting is relatively slow process. It is recommended to use Metrix++ extensions API instead.</p>
        </section>
        <section id="extend_section">
          <div class="page-header">
            <h1>Create plugin</h1>
            <p>There are 3 types of plugins considered in this chapter:</p>
            <ul>
            	<li>Metric plugin</li>
            	<li>Language parser</li>
            	<li>Post-processing / Analysis tool</li>
            </ul>
            <p>Tutorial for metric plugin is generic at the beginning and large portion of this is applied to
            	all other plugins. You need to know python and python regular expressions library to write Metrix++ extensions.</p>
          </div>
          <h2>Metric plugin</h2>
          <p>The tutorial will explain how to create a plugin to count magic numbers in source code.
             It will be relatively simple at first and will be extended with additional configuration
             options and smarter counting logic.</p>
          <h4>Create placeholder for new plugin</h4>
          <ol>
             <li>All plugins are loaded by Metrix++ from standard places within the tool installation directory and
                 from custom places specified in the METRIXPLUSPLUS_PATH environment variable.
                 METRIXPLUSPLUS_PATH has got the same format as system PATH environment variable.
                 So, the first step in plugin development is to set the METRIXPLUSPLUS_PATH to point out to
                 the directory (or directories) where plugin is located.</li>
             <li>Create new python package 'myext', python lib 'magic.py' and 'magic.ini' file.</li>
             <pre>
+ working_directory (set in METRIXPLUSPLUS_PATH variable)
\--+ myext
   \--- __init__.py
   \--- magic.py
   \--- magic.ini
</pre>
            <li>__init__.py is empty file to make myext considered by python as a package.</li>
            <li>Edit magic.py to have the following content:
             <pre class="prettyprint linenums">
import mpp.api

class Plugin(mpp.api.Plugin):
    
    def initialize(self):
        print "Hello world"
</pre>
            mpp.api package include Metrix++ API classes. mpp.api.Plugin is the base class, which can be loaded
            by Metrix++ engine and does nothing by default. In the code sample above it is extended to print
            "Hello world" on initialization.</li>
            <li>Edit magic.ini to have the following content:
             <pre class="prettyprint linenums">
[Plugin]
version: 1.0
package: myext
module:  magic
class:   Plugin
depends: None
actions: collect
enabled: True
</pre>
            This file is a manifest for Metrix++ plugin loader. The fields in Plugin section are:
            <dl class="dl-horizontal">
            	<dt>version</dt>
            	<dd>a string representing the version, step up it every time when behaviour of a plugin
            		or backward compatibility in api or data scope is changed</dd>
            	<dt>package</dt>
            	<dd>python package name where to load from</dd>
            	<dt>module</dt>
            	<dd>python module name (filename of *.py file) to load</dd>
            	<dt>class</dt>
            	<dd>name of a plugin class to instanciate</dd>
            	<dt>depends</dt>
            	<dd>list of plugin names to load, if it this plugin is loaded</dd>
            	<dt>actions</dt>
            	<dd>list of Metrix++ actions affected by this plugin</dd>
            	<dt>enabled</dt>
            	<dd>True or False, working status of a plugin</dd>
            </dl>
            </li>
            <li>Now run Metrix++ to see how this new plugin works:</li>
          <pre>&gt; python "/path/to/metrix++.py" collect</pre>
          <pre>Hello world</pre>
          </ol>
          <h4>Toogle option for the plugin</h4>
          <ol>
             <li>It is recommended to follow the convention for all plugins: 'run only if enabled'.
             	So, let's extend the magic.py file to make it configurable
             <pre class="prettyprint linenums">
import mpp.api

class Plugin(mpp.api.Plugin,
             # make this instance configurable...
             mpp.api.IConfigurable):
    # ... and implement 2 interfaces
    
    def declare_configuration(self, parser):
        parser.add_option("--myext.magic.numbers", "--mmn",
            action="store_true", default=False,
            help="Enables collection of magic numbers metric [default: %default]")
        
    def configure(self, options):
        self.is_active_numbers = options.__dict__['myext.magic.numbers']
    
    def initialize(self):
        # use configuration option here
        if self.is_active_numbers == True:
            print "Hello world"
</pre>
            parser argument is an instance of optparse.OptionParser class. It has got an extension to
            accept multiple options of the same argument. Check std.tools.limit to see how to declare multiopt options, if you need.</li>
            <li>Now run Metrix++ to see how this works:</li>
          <pre>&gt; python "/path/to/metrix++.py" collect --myext.magic.numbers</pre>
          <pre>Hello world</pre>
          </ol>
          <h4>Subscribe to notifications from parent plugins (or code parsers)</h4>
          <ol>
             <li>Every plugin works in a callback functions called by parent plugins.
             	Callback receives a reference to parent plugin, data object where to store metrics data,
             	and a flag indicating if there are changes in file or parent's settings since the previous collection.</li>
             <pre class="prettyprint linenums">
import mpp.api

class Plugin(mpp.api.Plugin,
             mpp.api.IConfigurable,
             # declare that it can subscribe on notifications
             mpp.api.Child):
    
    def declare_configuration(self, parser):
        parser.add_option("--myext.magic.numbers", "--mmn",
            action="store_true", default=False,
            help="Enables collection of magic numbers metric [default: %default]")
    
    def configure(self, options):
        self.is_active_numbers = options.__dict__['myext.magic.numbers']
    
    def initialize(self):
        if self.is_active_numbers == True:
            # subscribe to notifications from all code parsers
            self.subscribe_by_parents_interface(mpp.api.ICode, 'callback')

    # parents (code parsers) will call the callback declared
    def callback(self, parent, data, is_updated):
        print parent.get_name(), data.get_path(), is_updated
</pre>
            <li>Now run Metrix++ to see how this works. Try to do iterative scans (--db-file-prev option) to see how the
            	state of arguments is changed</li>
          <pre>&gt; python "/path/to/metrix++.py" collect --myext.magic.numbers</pre>
          <pre>std.code.cpp ./test.cpp True</pre>
          </ol>
          <h4>Implement simple metric based on regular expression pattern</h4>
          <ol>
             <li>Callback may execute counting, searcing and additional parsing and store results, using data argument.
             	'data' argument is an instance of mpp.api.FileData class.
             	However, most metrics can be implemented
             	simplier, if mpp.api.MetricPluginMixin routines are used. MetricPluginMixin implements
             	declarative style for metrics based on searches by regular expression. It
             	cares about initialisation of database fields and properties.
             	It implements default callback which counts number of matches by regular expression for all
             	active declared metrics. So, let's utilise that:
             	</li>
             <pre class="prettyprint linenums">
import mpp.api
import re

class Plugin(mpp.api.Plugin,
             mpp.api.IConfigurable,
             mpp.api.Child,
             # reuse by inheriting standard metric facilities
             mpp.api.MetricPluginMixin):
    
    def declare_configuration(self, parser):
        parser.add_option("--myext.magic.numbers", "--mmn",
            action="store_true", default=False,
            help="Enables collection of magic numbers metric [default: %default]")
    
    def configure(self, options):
        self.is_active_numbers = options.__dict__['myext.magic.numbers']
    
    def initialize(self):
        # declare metric rules
        self.declare_metric(
            self.is_active_numbers, # to count if active in callback
            self.Field('numbers', int), # field name and type in the database
            re.compile(r'''[0-9]+'''), # pattern to search
            marker_type_mask=mpp.api.Marker.T.CODE, # search in code
            region_type_mask=mpp.api.Region.T.ANY) # search in all types of regions
        
        # use superclass facilities to initialize everything from declared fields
        super(Plugin, self).initialize(fields=self.get_fields())
        
        # subscribe to all code parsers if at least one metric is active
        if self.is_active() == True:
            self.subscribe_by_parents_interface(mpp.api.ICode)
</pre>
            <li>Now run Metrix++ to count numbers in code files.</li>
          <pre>&gt; python "/path/to/metrix++.py" collect --myext.magic.numbers</pre>
            <li>Now view the results. At this stage it is fully working simple metric.</li>
          <pre>&gt; python "/path/to/metrix++.py" view</pre>
          <pre>
:: info: Overall metrics for 'myext.magic:numbers' metric
	Average        : 2.75
	Minimum        : 0
	Maximum        : 7
	Total          : 11.0
	Distribution   : 4 regions in total (including 0 suppressed)
	  Metric value : Ratio : R-sum : Number of regions
	             0 : 0.250 : 0.250 : 1	|||||||||||||||||||||||||
	             1 : 0.250 : 0.500 : 1	|||||||||||||||||||||||||
	             3 : 0.250 : 0.750 : 1	|||||||||||||||||||||||||
	             7 : 0.250 : 1.000 : 1	|||||||||||||||||||||||||

:: info: Directory content:
	Directory      : .
</pre>
          </ol>
          <h4>Extend regular expression incremental counting by smarter logic</h4>
          <ol>
             <li>At this stage the metric counts every number in source code.
                 However, we indent to spot only 'magic' numbers. Declared constant
                 is not a magic number, so it is better to exclude constants from counting.
                 It is easy to change default counter behaviour by implementing 
                 a function with name '_&lt;metric_name&gt;_count'. </li>
             <pre class="prettyprint linenums">
import mpp.api
import re

class Plugin(mpp.api.Plugin,
             mpp.api.IConfigurable,
             mpp.api.Child,
             mpp.api.MetricPluginMixin):
    
    def declare_configuration(self, parser):
        parser.add_option("--myext.magic.numbers", "--mmn",
            action="store_true", default=False,
            help="Enables collection of magic numbers metric [default: %default]")
    
    def configure(self, options):
        self.is_active_numbers = options.__dict__['myext.magic.numbers']
    
    def initialize(self):
        # improve pattern to find declarations of constants
        pattern_to_search = re.compile(
            r'''(const\s+([_a-zA-Z][_a-zA-Z0-9]*\s+)+[=]\s*)?[-+]?[0-9]+''')
        self.declare_metric(self.is_active_numbers,
                            self.Field('numbers', int),
                            pattern_to_search, # and use it here
                            marker_type_mask=mpp.api.Marker.T.CODE,
                            region_type_mask=mpp.api.Region.T.ANY)
        
        super(Plugin, self).initialize(fields=self.get_fields())
        
        if self.is_active() == True:
            self.subscribe_by_parents_interface(mpp.api.ICode)
    
    # implement custom counter behavior:
    # increments counter by 1 only if single number spotted,
    # but not declaration of a constant
    def _numbers_count(self, alias, data, region, marker, match, count, counter_data):
        if match.group(0).startswith('const'):
            return count
        return count + 1
</pre>
             <li>Initialy counter is initialized by zero, but it is possible to 
             	change it as well by implementing a function with name '_&lt;metric_name&gt;_count_initialize'.
             	Plugin we are implementing does not require this.</li>
            <li>Now run Metrix++ to collect and view the results.</li>
          <pre>&gt; python "/path/to/metrix++.py" collect --myext.magic.numbers</pre>
          <pre>&gt; python "/path/to/metrix++.py" view</pre>
          </ol>
          <h4>Language specific regular expressions</h4>
          <ol>
             <li>In the previous step we added matching of constants assuming that identifiers
             	may have symbols '_', 'a-z', 'A-Z' and '0-9'. It is true for C++ but it is not complete for Java.
             	Java identifier may have '$' symbol in the identifier. So, let's add language specific pattern
             	in the declaration of the metric:</li>
             <pre class="prettyprint linenums">
import mpp.api
import re

class Plugin(mpp.api.Plugin,
             mpp.api.IConfigurable,
             mpp.api.Child,
             mpp.api.MetricPluginMixin):
    
    def declare_configuration(self, parser):
        parser.add_option("--myext.magic.numbers", "--mmn",
            action="store_true", default=False,
            help="Enables collection of magic numbers metric [default: %default]")
    
    def configure(self, options):
        self.is_active_numbers = options.__dict__['myext.magic.numbers']
    
    def initialize(self):
        # specialized pattern for java
        pattern_to_search_java = re.compile(
            r'''(const\s+([_$a-zA-Z][_$a-zA-Z0-9]*\s+)+[=]\s*)?[-+]?[0-9]+''')
        # pattern for C++ and C# languages
        pattern_to_search_cpp_cs = re.compile(
            r'''(const\s+([_a-zA-Z][_a-zA-Z0-9]*\s+)+[=]\s*)?[-+]?[0-9]+''')
        # pattern for all other languages
        pattern_to_search = re.compile(
            r'''[0-9]+''')
        self.declare_metric(self.is_active_numbers,
                            self.Field('numbers', int),
                            # dictionary of patterns instead of a single one
                            {
                             'std.code.java': pattern_to_search_java,
                             'std.code.cpp': pattern_to_search_cpp_cs,
                             'std.code.cs': pattern_to_search_cpp_cs,
                             '*': pattern_to_search
                            },
                            marker_type_mask=mpp.api.Marker.T.CODE,
                            region_type_mask=mpp.api.Region.T.ANY)
        
        super(Plugin, self).initialize(fields=self.get_fields())
        
        if self.is_active() == True:
            self.subscribe_by_parents_interface(mpp.api.ICode)

    def _numbers_count(self, alias, data, region, marker, match, count, counter_data):
        if match.group(0).startswith('const'):
            return count
        return count + 1
</pre>
             <li>Keys in the dictionary of patterns are names of parent plugins (references to code parsers).
             	The key '*' refers to any parser.</li>
            <li>Now run Metrix++ to collect and view the results.</li>
          <pre>&gt; python "/path/to/metrix++.py" collect --myext.magic.numbers</pre>
          <pre>&gt; python "/path/to/metrix++.py" view</pre>
          </ol>
          <h4>Store only non-zero metric values</h4>
          <ol>
             <li>Most functions have the metric, which we are implemneting, equal to zero.
             	However, we are interested in finding code blocks having this metric greater than zero.
             	Zeros consumes the space in the data file. So, we can optimise the size of a data file,
             	if we exclude zero metric values. Let's declare this behavior for the metric.</li>
             <pre class="prettyprint linenums">
import mpp.api
import re

class Plugin(mpp.api.Plugin,
             mpp.api.IConfigurable,
             mpp.api.Child,
             mpp.api.MetricPluginMixin):
    
    def declare_configuration(self, parser):
        parser.add_option("--myext.magic.numbers", "--mmn",
            action="store_true", default=False,
            help="Enables collection of magic numbers metric [default: %default]")
    
    def configure(self, options):
        self.is_active_numbers = options.__dict__['myext.magic.numbers']
    
    def initialize(self):
        pattern_to_search_java = re.compile(
            r'''(const\s+([_$a-zA-Z][_$a-zA-Z0-9]*\s+)+[=]\s*)?[-+]?[0-9]+''')
        pattern_to_search_cpp_cs = re.compile(
            r'''(const\s+([_a-zA-Z][_a-zA-Z0-9]*\s+)+[=]\s*)?[-+]?[0-9]+''')
        pattern_to_search = re.compile(
            r'''[0-9]+''')
        self.declare_metric(self.is_active_numbers,
                            self.Field('numbers', int,
                                # optimize the size of datafile:
                                # store only non-zero results
                                non_zero=True),
                            {
                             'std.code.java': pattern_to_search_java,
                             'std.code.cpp': pattern_to_search_cpp_cs,
                             'std.code.cs': pattern_to_search_cpp_cs,
                             '*': pattern_to_search
                            },
                            marker_type_mask=mpp.api.Marker.T.CODE,
                            region_type_mask=mpp.api.Region.T.ANY)
        
        super(Plugin, self).initialize(fields=self.get_fields())
        
        if self.is_active() == True:
            self.subscribe_by_parents_interface(mpp.api.ICode)

    def _numbers_count(self, alias, data, region, marker, match, count, counter_data):
        if match.group(0).startswith('const'):
            return count
        return count + 1
</pre>
            <li>Now run Metrix++ to collect and view the results.</li>
          <pre>&gt; python "/path/to/metrix++.py" collect --myext.magic.numbers</pre>
          <pre>&gt; python "/path/to/metrix++.py" view</pre>
          </ol>
          <h4>Additional per metric configuration options</h4>
          <ol>
             <li>It is typical that most numbers counted by the metric are equal to 0, -1 or 1.
             	They are not necessary magic numbers. 0 or 1 are typical variable initializers.
             	-1 is a typical negative return code. So, let's implement simplified version of the metric,
             	which does not count 0, -1 and 1, if the specific new option is set.</li>
             <pre class="prettyprint linenums">
import mpp.api
import re

class Plugin(mpp.api.Plugin,
             mpp.api.IConfigurable,
             mpp.api.Child,
             mpp.api.MetricPluginMixin):
    
    def declare_configuration(self, parser):
        parser.add_option("--myext.magic.numbers", "--mmn",
            action="store_true", default=False,
            help="Enables collection of magic numbers metric [default: %default]")
        # Add new option
        parser.add_option("--myext.magic.numbers.simplier", "--mmns",
            action="store_true", default=False,
            help="Is set, 0, -1 and 1 numbers are not counted [default: %default]")
    
    def configure(self, options):
        self.is_active_numbers = options.__dict__['myext.magic.numbers']
        # remember the option here
        self.is_active_numbers_simplier = options.__dict__['myext.magic.numbers.simplier']
    
    def initialize(self):
        pattern_to_search_java = re.compile(
            r'''(const\s+([_$a-zA-Z][_$a-zA-Z0-9]*\s+)+[=]\s*)?[-+]?[0-9]+''')
        pattern_to_search_cpp_cs = re.compile(
            r'''(const\s+([_a-zA-Z][_a-zA-Z0-9]*\s+)+[=]\s*)?[-+]?[0-9]+''')
        pattern_to_search = re.compile(
            r'''[0-9]+''')
        self.declare_metric(self.is_active_numbers,
                            self.Field('numbers', int,
                                non_zero=True),
                            {
                             'std.code.java': pattern_to_search_java,
                             'std.code.cpp': pattern_to_search_cpp_cs,
                             'std.code.cs': pattern_to_search_cpp_cs,
                             '*': pattern_to_search
                            },
                            marker_type_mask=mpp.api.Marker.T.CODE,
                            region_type_mask=mpp.api.Region.T.ANY)
        
        super(Plugin, self).initialize(fields=self.get_fields(),
            # remember option settings in data file properties
            # in order to detect changes in settings on iterative re-run
            properties=[self.Property('number.simplier', self.is_active_numbers_simplier)])
        
        if self.is_active() == True:
            self.subscribe_by_parents_interface(mpp.api.ICode)

    def _numbers_count(self, alias, data, region, marker, match, count, counter_data):
        if (match.group(0).startswith('const') or
            # use new option to exclude 0 and 1 numbers
            (self.is_active_numbers_simplier == True and
             match.group(0) in ['0', '1', '-1', '+1'])):
            return count
        return count + 1
</pre>
            <li>Now run Metrix++ to collect and view the results.</li>
          <pre>&gt; python "/path/to/metrix++.py" collect --myext.magic.numbers</pre>
          <pre>&gt; python "/path/to/metrix++.py" view</pre>
          <pre>
:: info: Overall metrics for 'myext.magic:numbers' metric
	Average        : 2.5 (excluding zero metric values)
	Minimum        : 2
	Maximum        : 3
	Total          : 5.0
	Distribution   : 2 regions in total (including 0 suppressed)
	  Metric value : Ratio : R-sum : Number of regions
	             2 : 0.500 : 0.500 : 1	||||||||||||||||||||||||||||||||||||||||||||||||||
	             3 : 0.500 : 1.000 : 1	||||||||||||||||||||||||||||||||||||||||||||||||||

:: info: Directory content:
	Directory      : .
</pre>
          </ol>
          <h4>Summary</h4>
          <p>We have finished with the tutorial. The tutorial explained how to implement simple and advanced metric plugins.
          	We used built-in Metrix++ base classes. If you need to more advanced plugin capabilities,
          	override in your plugin class functions inherited from mpp.api base classes. Check code of standard plugins
          	to learn more techniques.</p>
          <p></p>
          <h2>Analysis tool plugin</h2>
          <p>This tutorial will explain how to build custom Metrix++ command, which is bound to custom post-analysis tool.
          	We will implement the tool, which identifies all new and changed regions and counts number of added lines.
          	We skip calculating number of deleted lines, but it is easy to extend from what we get finally in the tutorial.</p>
          <h4>New Metrix++ command / action</h4>
          <ol>
             <li>As in the tutorial for metric plugin, set the environment and 
             	create new python package 'myext', python lib 'compare.py' and 'compare.ini' file.</li>
             <pre>
+ working_directory (set in METRIXPLUSPLUS_PATH variable)
\--+ myext
   \--- __init__.py
   \--- compare.py
   \--- compare.ini
</pre>
            <li>__init__.py is empty file to make myext considered by python as a package.</li>
            <li>Edit compare.py to have the following content:
             <pre class="prettyprint linenums">
import mpp.api

class Plugin(mpp.api.Plugin, mpp.api.IRunable):
    
    def run(self, args):
        print args
        return 0
</pre>
            Inheritance from mpp.api.IRunable declares that the plugin is runable and requires implementation of 'run' interface.</li>
            <li>Edit compare.ini to have the following content:
             <pre class="prettyprint linenums">

[Plugin]
version: 1.0
package: myext
module:  compare
class:   Plugin
depends: None
actions: compare
enabled: True
</pre>
            This file is a manifest for Metrix++ plugin loader. Actions field has got new value 'compare'.
            Metrix++ engine will automatically pick this action and will add it to the list of available commands.
            This plugin will be loaded on 'compare' action.
            </li>
            <li>Now run Metrix++ to see how this new plugin works:</li>
          <pre>&gt; python "/path/to/metrix++.py" compare -- path1 path2 path3</pre>
          <pre>["path1", "path2", "path3"]</pre>
          </ol>
          <h4>Access data file loader and its' interfaces</h4>
          <ol>
             <li>By default, all post-analysis tools have got --db-file and --db-file-prev options. It is 
             	because 'mpp.dbf' plugin is loaded for any action, including our new one 'compare'. In order to continue
             	the tutorial, we need to have 2 data files with 'std.code.lines:total' metric collected.
             	So, write to files by running:</li>
             <pre>cd my_project_version_1
&gt; python "/path/to/metrix++.py" collect --std.code.lines.total</pre>
             <pre>cd my_project_version_2
&gt; python "/path/to/metrix++.py" collect --std.code.lines.total</pre>
            <li>Edit compare.py file to get the loader and iterate collected file paths:</li>
             <pre class="prettyprint linenums">
import mpp.api
# load common utils for post processing tools
import mpp.utils

class Plugin(mpp.api.Plugin, mpp.api.IRunable):
    
    def run(self, args):
        # get data file reader using standard metrix++ plugin
        loader = self.get_plugin('mpp.dbf').get_loader()
        
        # iterate and print file length for every path in args
        exit_code = 0
        for path in (args if len(args) > 0 else [""]):
            file_iterator = loader.iterate_file_data(path)
            if file_iterator == None:
                mpp.utils.report_bad_path(path)
                exit_code += 1
                continue
            for file_data in file_iterator:
                print file_data.get_path()
        return exit_code
</pre>
            <li>Now run Metrix++ to see how it works:</li>
          <pre>&gt; python "/path/to/metrix++.py" compare --db-file=my_project_version_2/metrixpp.db --db-file-prev=my_project_version_1/metrixpp.db</pre>
          </ol>

          <h4>Identify added, modified files/regions and read metric data</h4>
          <ol>
            <li>Let's extend the logic of the tool to compare files and regions, read 'std.code.lines:total' metric
            	and calcuate the summary of number of added lines. mpp.utils.FileRegionsMatcher is helper class
            	which does matching and comparison of regions for 2 given mpp.api.FileData objects.</li>
             <pre class="prettyprint linenums">
import mpp.api
import mpp.utils
import mpp.cout

class Plugin(mpp.api.Plugin, mpp.api.IRunable):
    
    def run(self, args):
        loader = self.get_plugin('mpp.dbf').get_loader()
        # get previous db file loader
        loader_prev = self.get_plugin('mpp.dbf').get_loader_prev()
        
        exit_code = 0
        for path in (args if len(args) > 0 else [""]):
            added_lines = 0
            file_iterator = loader.iterate_file_data(path)
            if file_iterator == None:
                mpp.utils.report_bad_path(path)
                exit_code += 1
                continue
            for file_data in file_iterator:
                added_lines += self._compare_file(file_data, loader, loader_prev)
            mpp.cout.notify(path, '', mpp.cout.SEVERITY_INFO,
                            "Change trend report",
                            [('Added lines', added_lines)])
        return exit_code

    def _compare_file(self, file_data, loader, loader_prev):
        # compare file with previous and return number of new lines
        file_data_prev = loader_prev.load_file_data(file_data.get_path())
        if file_data_prev == None:
            return self._sum_file_regions_lines(file_data)
        elif file_data.get_checksum() != file_data_prev.get_checksum():
            return self._compare_file_regions(file_data, file_data_prev)

    def _sum_file_regions_lines(self, file_data):
        # just sum up the metric for all regions
        result = 0
        for region in file_data.iterate_regions():
            result += region.get_data('std.code.lines', 'total')
    
    def _compare_file_regions(self, file_data, file_data_prev):
        # compare every region with previous and return number of new lines
        matcher = mpp.utils.FileRegionsMatcher(file_data, file_data_prev)
        result = 0
        for region in file_data.iterate_regions():
            if matcher.is_matched(region.get_id()) == False:
                # if added region, just add the lines
                result += region.get_data('std.code.lines', 'total')
            elif matcher.is_modified(region.get_id()):
                # if modified, add the difference in lines
                region_prev = file_data_prev.get_region(
                    matcher.get_prev_id(region.get_id()))
                result += (region.get_data('std.code.lines', 'total') -
                           region_prev.get_data('std.code.lines', 'total'))
        return result
</pre>
            <li>Now run Metrix++ to see how it works:</li>
          <pre>&gt; python "/path/to/metrix++.py" compare --db-file=my_project_version_2/metrixpp.db --db-file-prev=my_project_version_1/metrixpp.db</pre>
          <pre>
:: info: Change trend report
	Added lines    : 7
</pre>
          </ol>

          <h4>Summary</h4>
          <p>We have finished with the tutorial. The tutorial explained how to read Metrix++ data files and 
          	implement custom post-processing tools. Even if some existing Metrix++ code requires clean-up and refactoring,
          	check code of standard tool plugins to learn more techniques.</p>
          <h2>Language parser plugin</h2>

                <p>Unfortunately, there is no good documentation at this stage for this part.
                Briefly, if metric plugin counts and stores data into FileData object,
                tool plugin reads this data, language plugin construct the original structure of
                FileData object. The orginal structure includes regions (like functions, classes, etc.)
                 and markers (like comments, strings, preprocessor, etc.). 
                 Check code of existing parsers.</p>
                <ul>
                  <li>a language parser plugin is registered in the same way as a metric plugin</li>
                  <li>it registers parser's callback in 'std.tools.collect' plugin</li>
                  <li>parses a file in a callback, called by 'std.tools.collect'</li>
                  <li>parser needs to identify markers  and regions 
                    and tell about this to file data object passed as an
                    argument for the callback.</li>
                </ul>

                <p>There are useful options and tools avaialble for
                trobuleshooting purposes during development:</p>
                <ul>
                  <li>metrix++.py debug generates html code showing parsed code structures and their boundaries</li>
                  <li>--nest-regions for view tool forces the viewer to indent subregions.</li>
                  <li>--general.log-level option is available for any command and is helpful to trace execution.</li>
                </ul>

                <p>Finally, if there are any questions or enquires, please,
                feel free to <a href="https://sourceforge.net/p/metrixplusplus/tickets/new/">submit new question</a>.</p>

        </section>

        <section id="contribute_section">
          <div class="page-header">
            <h1>Feeback and contribute</h1>
          </div>
          <p>Now it is your turn. There are multiple ways how you can contribute and help to improve and progress Metrix++ project:</p>
          <ul>
          	<li>Try Metrix++ and <a href="https://sourceforge.net/projects/metrixplusplus/reviews/new">post review</a></li>
          	<li><a href="https://sourceforge.net/p/metrixplusplus/tickets/new/">Submit new feature request or bug report</a></li>
          	<li><a href="https://sourceforge.net/p/metrixplusplus/tickets/new/">Ask a question</a></li>
          	<li>Share your patch files and ideas, colloborate by email to 
          		<a href="mailto:avkonst@users.sourceforge.net?subject=Metrix%2B%2B Project Request">project administrator</a></li>
          	<li>Create and publish your plugin. 
          		<a href="mailto:avkonst@users.sourceforge.net?subject=Metrix%2B%2B Plugin Reference">Request to refer</a>
          			 to it from Metrix++ project space.</li>
          	<li><a href="mailto:avkonst@users.sourceforge.net?subject=Metrix%2B%2B Plugin Submission">Submit your plugin</a>
          		 to include to the standard set</li>
          	<li>... and consider to
          		<a href="mailto:avkonst@users.sourceforge.net?subject=Metrix%2B%2B Join Request">join the project</a>!</li>
          </ul>
        </section>

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