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<h1>Source code for stetl.component</h1><div class="highlight"><pre>
<span></span><span class="c1"># -*- coding: utf-8 -*-</span>
<span class="c1">#</span>
<span class="c1"># Component base class for ETL.</span>
<span class="c1">#</span>
<span class="c1"># Author: Just van den Broecke</span>
<span class="c1">#</span>
<span class="kn">import</span> <span class="nn">os</span>
<span class="kn">from</span> <span class="nn">util</span> <span class="k">import</span> <span class="n">Util</span><span class="p">,</span> <span class="n">ConfigSection</span>
<span class="kn">from</span> <span class="nn">packet</span> <span class="k">import</span> <span class="n">FORMAT</span>
<span class="n">log</span> <span class="o">=</span> <span class="n">Util</span><span class="o">.</span><span class="n">get_log</span><span class="p">(</span><span class="s1">'component'</span><span class="p">)</span>
<div class="viewcode-block" id="Config"><a class="viewcode-back" href="../../code.html#stetl.component.Config">[docs]</a><span class="k">class</span> <span class="nc">Config</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Decorator class to tie config values from the .ini file to object instance</span>
<span class="sd"> property values. Somewhat like the Python standard @property but with</span>
<span class="sd"> the possibility to define default values, typing and making properties required.</span>
<span class="sd"> Each property is defined by @Config(type, default, required).</span>
<span class="sd"> Basic idea comes from: https://wiki.python.org/moin/PythonDecoratorLibrary#Cached_Properties</span>
<span class="sd"> """</span>
<span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">ptype</span><span class="o">=</span><span class="nb">str</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">required</span><span class="o">=</span><span class="kc">False</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> If there are no decorator arguments, the function</span>
<span class="sd"> to be decorated is passed to the constructor.</span>
<span class="sd"> """</span>
<span class="c1"># print "Inside __init__()"</span>
<span class="bp">self</span><span class="o">.</span><span class="n">ptype</span> <span class="o">=</span> <span class="n">ptype</span>
<span class="bp">self</span><span class="o">.</span><span class="n">default</span> <span class="o">=</span> <span class="n">default</span>
<span class="bp">self</span><span class="o">.</span><span class="n">required</span> <span class="o">=</span> <span class="n">required</span>
<span class="k">def</span> <span class="nf">__call__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">fget</span><span class="p">,</span> <span class="n">doc</span><span class="o">=</span><span class="s1">''</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> The __call__ method is not called until the</span>
<span class="sd"> decorated function is called. self is returned such that __get__ below is called</span>
<span class="sd"> with the Component instance. That allows us to cache the actual property value</span>
<span class="sd"> in the Component itself.</span>
<span class="sd"> """</span>
<span class="c1"># Save the property name (is the name of the function calling us).</span>
<span class="bp">self</span><span class="o">.</span><span class="n">property_name</span> <span class="o">=</span> <span class="n">fget</span><span class="o">.</span><span class="vm">__name__</span>
<span class="c1"># print "Inside __call__() name=%s" % self.property_name</span>
<span class="c1"># For Spinx documentation build we need the original function with docstring.</span>
<span class="n">IS_SPHINX_BUILD</span> <span class="o">=</span> <span class="nb">bool</span><span class="p">(</span><span class="n">os</span><span class="o">.</span><span class="n">getenv</span><span class="p">(</span><span class="s1">'SPHINX_BUILD'</span><span class="p">))</span>
<span class="k">if</span> <span class="n">IS_SPHINX_BUILD</span><span class="p">:</span>
<span class="n">doc</span> <span class="o">=</span> <span class="n">doc</span><span class="o">.</span><span class="n">strip</span><span class="p">()</span>
<span class="c1"># TODO more detail, example below</span>
<span class="c1"># doc = '``Parameter`` - %s\n\n' % doc</span>
<span class="n">doc</span> <span class="o">+=</span> <span class="s1">'* type: </span><span class="si">%s</span><span class="se">\n</span><span class="s1">'</span> <span class="o">%</span> <span class="nb">str</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">ptype</span><span class="p">)</span><span class="o">.</span><span class="n">split</span><span class="p">(</span><span class="s2">"'"</span><span class="p">)[</span><span class="mi">1</span><span class="p">]</span>
<span class="n">doc</span> <span class="o">+=</span> <span class="s1">'* required: </span><span class="si">%s</span><span class="se">\n</span><span class="s1">'</span> <span class="o">%</span> <span class="bp">self</span><span class="o">.</span><span class="n">required</span>
<span class="n">doc</span> <span class="o">+=</span> <span class="s1">'* default: </span><span class="si">%s</span><span class="se">\n</span><span class="s1">'</span> <span class="o">%</span> <span class="bp">self</span><span class="o">.</span><span class="n">default</span>
<span class="c1"># if self.value:</span>
<span class="c1"># doc += '* value: %s\n' % self.value</span>
<span class="c1"># else:</span>
<span class="c1"># doc += '* required: %s\n' % self.required</span>
<span class="c1"># doc += '* default: %s\n' % self.default</span>
<span class="c1"># doc += '* value_range: %s\n' % self.value_range</span>
<span class="n">fget</span><span class="o">.</span><span class="vm">__doc__</span> <span class="o">=</span> <span class="s1">'``CONFIG`` </span><span class="si">%s</span><span class="se">\n</span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="p">(</span><span class="n">fget</span><span class="o">.</span><span class="vm">__doc__</span><span class="p">,</span> <span class="n">doc</span><span class="p">)</span>
<span class="k">return</span> <span class="n">fget</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">return</span> <span class="bp">self</span>
<span class="k">def</span> <span class="nf">__get__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">comp_inst</span><span class="p">,</span> <span class="n">owner</span><span class="p">):</span>
<span class="c1"># print "Inside __get__() owner=%s" % owner</span>
<span class="sd">""" descr.__get__(obj[, type]) -> value """</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">property_name</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">comp_inst</span><span class="o">.</span><span class="n">cfg_vals</span><span class="p">:</span>
<span class="n">cfg</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">default_value</span> <span class="o">=</span> <span class="n">comp_inst</span><span class="o">.</span><span class="n">cfg</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">property_name</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">default</span>
<span class="c1"># Do type conversion where needed from the string values</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">ptype</span> <span class="ow">is</span> <span class="nb">str</span><span class="p">:</span>
<span class="n">value</span> <span class="o">=</span> <span class="n">cfg</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="n">default_value</span><span class="p">)</span>
<span class="k">elif</span> <span class="bp">self</span><span class="o">.</span><span class="n">ptype</span> <span class="ow">is</span> <span class="nb">bool</span><span class="p">:</span>
<span class="n">value</span> <span class="o">=</span> <span class="n">cfg</span><span class="o">.</span><span class="n">get_bool</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="n">default_value</span><span class="p">)</span>
<span class="k">elif</span> <span class="bp">self</span><span class="o">.</span><span class="n">ptype</span> <span class="ow">is</span> <span class="nb">list</span><span class="p">:</span>
<span class="n">value</span> <span class="o">=</span> <span class="n">cfg</span><span class="o">.</span><span class="n">get_list</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="n">default_value</span><span class="p">)</span>
<span class="k">elif</span> <span class="bp">self</span><span class="o">.</span><span class="n">ptype</span> <span class="ow">is</span> <span class="nb">dict</span><span class="p">:</span>
<span class="n">value</span> <span class="o">=</span> <span class="n">cfg</span><span class="o">.</span><span class="n">get_dict</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="n">default_value</span><span class="p">)</span>
<span class="k">elif</span> <span class="bp">self</span><span class="o">.</span><span class="n">ptype</span> <span class="ow">is</span> <span class="nb">int</span><span class="p">:</span>
<span class="n">value</span> <span class="o">=</span> <span class="n">cfg</span><span class="o">.</span><span class="n">get_int</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="n">default_value</span><span class="p">)</span>
<span class="k">elif</span> <span class="bp">self</span><span class="o">.</span><span class="n">ptype</span> <span class="ow">is</span> <span class="nb">tuple</span><span class="p">:</span>
<span class="n">value</span> <span class="o">=</span> <span class="n">cfg</span><span class="o">.</span><span class="n">get_tuple</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="n">default_value</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">value</span> <span class="o">=</span> <span class="n">cfg</span><span class="o">.</span><span class="n">get</span><span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="n">default_value</span><span class="p">)</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">required</span> <span class="ow">is</span> <span class="kc">True</span> <span class="ow">and</span> <span class="n">value</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">Exception</span><span class="p">(</span><span class="s1">'Config property: </span><span class="si">%s</span><span class="s1"> is required in config for </span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="nb">str</span><span class="p">(</span><span class="n">comp_inst</span><span class="p">)))</span>
<span class="n">comp_inst</span><span class="o">.</span><span class="n">cfg_vals</span><span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">property_name</span><span class="p">]</span> <span class="o">=</span> <span class="n">value</span>
<span class="k">return</span> <span class="n">comp_inst</span><span class="o">.</span><span class="n">cfg_vals</span><span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">property_name</span><span class="p">]</span></div>
<div class="viewcode-block" id="Component"><a class="viewcode-back" href="../../code.html#stetl.component.Component">[docs]</a><span class="k">class</span> <span class="nc">Component</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Abstract Base class for all Input, Filter and Output Components.</span>
<span class="sd"> """</span>
<div class="viewcode-block" id="Component.input_format"><a class="viewcode-back" href="../../code.html#stetl.component.Component.input_format">[docs]</a> <span class="nd">@Config</span><span class="p">(</span><span class="n">ptype</span><span class="o">=</span><span class="nb">str</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">required</span><span class="o">=</span><span class="kc">False</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">input_format</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> The specific input format if the consumes parameter is a list or the format to be converted to the output_format.</span>
<span class="sd"> """</span>
<span class="k">pass</span></div>
<div class="viewcode-block" id="Component.output_format"><a class="viewcode-back" href="../../code.html#stetl.component.Component.output_format">[docs]</a> <span class="nd">@Config</span><span class="p">(</span><span class="n">ptype</span><span class="o">=</span><span class="nb">str</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">required</span><span class="o">=</span><span class="kc">False</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">output_format</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> The specific output format if the produces parameter is a list or the format to which the input format is converted.</span>
<span class="sd"> """</span>
<span class="k">pass</span></div>
<span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">configdict</span><span class="p">,</span> <span class="n">section</span><span class="p">,</span> <span class="n">consumes</span><span class="o">=</span><span class="n">FORMAT</span><span class="o">.</span><span class="n">none</span><span class="p">,</span> <span class="n">produces</span><span class="o">=</span><span class="n">FORMAT</span><span class="o">.</span><span class="n">none</span><span class="p">):</span>
<span class="c1"># The raw config values from the cfg file</span>
<span class="bp">self</span><span class="o">.</span><span class="n">cfg</span> <span class="o">=</span> <span class="n">ConfigSection</span><span class="p">(</span><span class="n">configdict</span><span class="o">.</span><span class="n">items</span><span class="p">(</span><span class="n">section</span><span class="p">))</span>
<span class="c1"># The actual typed values as populated within Config Decorator</span>
<span class="bp">self</span><span class="o">.</span><span class="n">cfg_vals</span> <span class="o">=</span> <span class="nb">dict</span><span class="p">()</span>
<span class="bp">self</span><span class="o">.</span><span class="n">next</span> <span class="o">=</span> <span class="kc">None</span>
<span class="bp">self</span><span class="o">.</span><span class="n">section</span> <span class="o">=</span> <span class="n">section</span>
<span class="c1"># First assume single output provided by derived class</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_output_format</span> <span class="o">=</span> <span class="n">produces</span>
<span class="c1"># We may have a configured output_format: use that value, when multiple formats it should be in that list</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">output_format</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_output_format</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">output_format</span>
<span class="k">if</span> <span class="nb">type</span><span class="p">(</span><span class="n">produces</span><span class="p">)</span> <span class="ow">is</span> <span class="nb">list</span> <span class="ow">and</span> <span class="bp">self</span><span class="o">.</span><span class="n">_output_format</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">produces</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s1">'Configured output_format </span><span class="si">%s</span><span class="s1"> not in list: </span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">_output_format</span><span class="p">,</span> <span class="nb">str</span><span class="p">(</span><span class="n">produces</span><span class="p">)))</span>
<span class="k">elif</span> <span class="nb">type</span><span class="p">(</span><span class="n">produces</span><span class="p">)</span> <span class="ow">is</span> <span class="nb">list</span><span class="p">:</span>
<span class="c1"># No output_format configured and a list: use the first as default</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_output_format</span> <span class="o">=</span> <span class="n">produces</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span>
<span class="c1"># First assume single input provided by derived class</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_input_format</span> <span class="o">=</span> <span class="n">consumes</span>
<span class="c1"># We may have a configured input_format: use that value, when multiple formats it should be in that list</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">input_format</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_input_format</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">input_format</span>
<span class="k">if</span> <span class="nb">type</span><span class="p">(</span><span class="n">consumes</span><span class="p">)</span> <span class="ow">is</span> <span class="nb">list</span> <span class="ow">and</span> <span class="bp">self</span><span class="o">.</span><span class="n">_input_format</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">consumes</span><span class="p">:</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span><span class="s1">'Configured input_format </span><span class="si">%s</span><span class="s1"> not in list: </span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">_input_format</span><span class="p">,</span> <span class="nb">str</span><span class="p">(</span><span class="n">consumes</span><span class="p">)))</span>
<span class="k">elif</span> <span class="nb">type</span><span class="p">(</span><span class="n">consumes</span><span class="p">)</span> <span class="ow">is</span> <span class="nb">list</span><span class="p">:</span>
<span class="c1"># No input_format configured and a list: use the first as default</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_input_format</span> <span class="o">=</span> <span class="n">consumes</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span>
<span class="k">def</span> <span class="nf">add_next</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">next_component</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">next</span> <span class="o">=</span> <span class="n">next_component</span>
<span class="k">if</span> <span class="ow">not</span> <span class="bp">self</span><span class="o">.</span><span class="n">is_compatible</span><span class="p">():</span>
<span class="k">raise</span> <span class="ne">ValueError</span><span class="p">(</span>
<span class="s1">'Incompatible components are linked: </span><span class="si">%s</span><span class="s1"> and </span><span class="si">%s</span><span class="s1">'</span> <span class="o">%</span> <span class="p">(</span><span class="nb">str</span><span class="p">(</span><span class="bp">self</span><span class="p">),</span> <span class="nb">str</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">next</span><span class="p">)))</span>
<span class="c1"># Get our id: currently the [section] name</span>
<span class="k">def</span> <span class="nf">get_id</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">section</span>
<span class="c1"># Get last Component in Chain</span>
<span class="k">def</span> <span class="nf">get_last</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">last</span> <span class="o">=</span> <span class="bp">self</span>
<span class="k">while</span> <span class="n">last</span><span class="o">.</span><span class="n">next</span><span class="p">:</span>
<span class="n">last</span> <span class="o">=</span> <span class="n">last</span><span class="o">.</span><span class="n">next</span>
<span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">last</span><span class="p">,</span> <span class="nb">list</span><span class="p">):</span>
<span class="n">last</span> <span class="o">=</span> <span class="n">last</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span>
<span class="k">return</span> <span class="n">last</span>
<span class="c1"># Check our compatibility with the next Component in the Chain</span>
<span class="k">def</span> <span class="nf">is_compatible</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="c1"># Ok, nothing next in Chain</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">next</span> <span class="ow">is</span> <span class="kc">None</span> <span class="ow">or</span> <span class="bp">self</span><span class="o">.</span><span class="n">_output_format</span> <span class="ow">is</span> <span class="n">FORMAT</span><span class="o">.</span><span class="n">none</span> <span class="ow">or</span> <span class="bp">self</span><span class="o">.</span><span class="n">next</span><span class="o">.</span><span class="n">_input_format</span> <span class="o">==</span> <span class="n">FORMAT</span><span class="o">.</span><span class="n">any</span><span class="p">:</span>
<span class="k">return</span> <span class="kc">True</span>
<span class="c1"># return if our Output is compatible with the next Component's Input</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">_output_format</span> <span class="o">==</span> <span class="bp">self</span><span class="o">.</span><span class="n">next</span><span class="o">.</span><span class="n">_input_format</span>
<span class="k">def</span> <span class="nf">__str__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="s2">"</span><span class="si">%s</span><span class="s2">: in=</span><span class="si">%s</span><span class="s2"> out=</span><span class="si">%s</span><span class="s2">"</span> <span class="o">%</span> <span class="p">(</span><span class="nb">str</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="vm">__class__</span><span class="p">),</span> <span class="bp">self</span><span class="o">.</span><span class="n">_input_format</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">_output_format</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">process</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">packet</span><span class="p">):</span>
<span class="c1"># Current processor of packet</span>
<span class="n">packet</span><span class="o">.</span><span class="n">component</span> <span class="o">=</span> <span class="bp">self</span>
<span class="c1"># Do something with the data</span>
<span class="n">result</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">before_invoke</span><span class="p">(</span><span class="n">packet</span><span class="p">)</span>
<span class="k">if</span> <span class="n">result</span> <span class="ow">is</span> <span class="kc">False</span><span class="p">:</span>
<span class="c1"># Component indicates it does not want the chain to proceed</span>
<span class="k">return</span> <span class="n">packet</span>
<span class="c1"># Do component-specific processing, e.g. read or write or filter</span>
<span class="n">packet</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">invoke</span><span class="p">(</span><span class="n">packet</span><span class="p">)</span>
<span class="n">result</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">after_invoke</span><span class="p">(</span><span class="n">packet</span><span class="p">)</span>
<span class="k">if</span> <span class="n">result</span> <span class="ow">is</span> <span class="kc">False</span><span class="p">:</span>
<span class="c1"># Component indicates it does not want the chain to proceed</span>
<span class="k">return</span> <span class="n">packet</span>
<span class="c1"># If there is a next component, let it process</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">next</span><span class="p">:</span>
<span class="c1"># Hand-over data (line, doc whatever) to the next component</span>
<span class="n">packet</span><span class="o">.</span><span class="n">format</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_output_format</span>
<span class="n">packet</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">next</span><span class="o">.</span><span class="n">process</span><span class="p">(</span><span class="n">packet</span><span class="p">)</span>
<span class="n">result</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">after_chain_invoke</span><span class="p">(</span><span class="n">packet</span><span class="p">)</span>
<span class="k">return</span> <span class="n">packet</span>
<span class="k">def</span> <span class="nf">do_init</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="c1"># Some components may do one-time init</span>
<span class="bp">self</span><span class="o">.</span><span class="n">init</span><span class="p">()</span>
<span class="c1"># If there is a next component, let it do its init()</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">next</span><span class="p">:</span>
<span class="bp">self</span><span class="o">.</span><span class="n">next</span><span class="o">.</span><span class="n">do_init</span><span class="p">()</span>
<span class="k">def</span> <span class="nf">do_exit</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="c1"># Notify all comps that we exit</span>
<span class="bp">self</span><span class="o">.</span><span class="n">exit</span><span class="p">()</span>
<span class="c1"># If there is a next component, let it do its exit()</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">next</span><span class="p">:</span>
<span class="bp">self</span><span class="o">.</span><span class="n">next</span><span class="o">.</span><span class="n">do_exit</span><span class="p">()</span>
<div class="viewcode-block" id="Component.before_invoke"><a class="viewcode-back" href="../../code.html#stetl.component.Component.before_invoke">[docs]</a> <span class="k">def</span> <span class="nf">before_invoke</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">packet</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Called just before Component invoke.</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="kc">True</span></div>
<div class="viewcode-block" id="Component.after_invoke"><a class="viewcode-back" href="../../code.html#stetl.component.Component.after_invoke">[docs]</a> <span class="k">def</span> <span class="nf">after_invoke</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">packet</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Called right after Component invoke.</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="kc">True</span></div>
<div class="viewcode-block" id="Component.after_chain_invoke"><a class="viewcode-back" href="../../code.html#stetl.component.Component.after_chain_invoke">[docs]</a> <span class="k">def</span> <span class="nf">after_chain_invoke</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">packet</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Called right after entire Component Chain invoke.</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="kc">True</span></div>
<div class="viewcode-block" id="Component.invoke"><a class="viewcode-back" href="../../code.html#stetl.component.Component.invoke">[docs]</a> <span class="k">def</span> <span class="nf">invoke</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">packet</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Components override for Component-specific behaviour, typically read, filter or write actions.</span>
<span class="sd"> """</span>
<span class="k">return</span> <span class="n">packet</span></div>
<div class="viewcode-block" id="Component.init"><a class="viewcode-back" href="../../code.html#stetl.component.Component.init">[docs]</a> <span class="k">def</span> <span class="nf">init</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Allows derived Components to perform a one-time init.</span>
<span class="sd"> """</span>
<span class="k">pass</span></div>
<div class="viewcode-block" id="Component.exit"><a class="viewcode-back" href="../../code.html#stetl.component.Component.exit">[docs]</a> <span class="k">def</span> <span class="nf">exit</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""</span>
<span class="sd"> Allows derived Components to perform a one-time exit/cleanup.</span>
<span class="sd"> """</span>
<span class="k">pass</span></div></div>
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