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  <title>rcov/ruby/1.8/gems/diff-lcs-1.1.2/lib/diff/lcs/callbacks.rb</title>
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  <h1>Rspec Steps C0 Coverage Information - RCov</h1>
  <h2>rcov/ruby/1.8/gems/diff-lcs-1.1.2/lib/diff/lcs/callbacks.rb</h2>

  <div class="report_table_wrapper">
    <table class='report' id='report_table'>
      <thead>
        <tr>
          <th class="left_align">Name</th>
          <th class="right_align">Total Lines</th>
          <th class="right_align">Lines of Code</th>
          <th class="left_align">Total Coverage</th>
          <th class="left_align">Code Coverage</th>
        </tr>
      </thead>
      <tbody>
        <tr>
          <td class="left_align"><a href="rcov-ruby-1_8-gems-diff-lcs-1_1_2-lib-diff-lcs-callbacks_rb.html">rcov/ruby/1.8/gems/diff-lcs-1.1.2/lib/diff/lcs/callbacks.rb</a></td>
          <td class='right_align'><tt>322</tt></td>
          <td class='right_align'><tt>83</tt></td>
          <td class="left_align"><div class="percent_graph_legend"><tt class=''>84.47%</tt></div>
        <div class="percent_graph">
          <div class="covered" style="width:84px"></div>
          <div class="uncovered" style="width:16px"></div>
        </div></td>
          <td class="left_align"><div class="percent_graph_legend"><tt class=''>40.96%</tt></div>
        <div class="percent_graph">
          <div class="covered" style="width:41px"></div>
          <div class="uncovered" style="width:59px"></div>
        </div></td>
        </tr>
      </tbody>
    </table>
  </div>

  <h3>Key</h3>

  <div class="key"><pre><span class='marked'>Code reported as executed by Ruby looks like this...</span><span class='marked1'>and this: this line is also marked as covered.</span><span class='inferred'>Lines considered as run by rcov, but not reported by Ruby, look like this,</span><span class='inferred1'>and this: these lines were inferred by rcov (using simple heuristics).</span><span class='uncovered'>Finally, here's a line marked as not executed.</span></pre></div>

  <h3>Coverage Details</h3>

  <table class="details">
    <tbody>

        <tr class="inferred">
          <td><pre><a name="line1">1</a> #! /usr/env/bin ruby</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line2">2</a> #--</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line3">3</a> # Copyright 2004 Austin Ziegler &lt;diff-lcs@halostatue.ca&gt;</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line4">4</a> #   adapted from:</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line5">5</a> #     Algorithm::Diff (Perl) by Ned Konz &lt;perl@bike-nomad.com&gt;</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line6">6</a> #     Smalltalk by Mario I. Wolczko &lt;mario@wolczko.com&gt;</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line7">7</a> #   implements McIlroy-Hunt diff algorithm</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line8">8</a> #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line9">9</a> # This program is free software. It may be redistributed and/or modified under</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line10">10</a> # the terms of the GPL version 2 (or later), the Perl Artistic licence, or the</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line11">11</a> # Ruby licence.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line12">12</a> # </pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line13">13</a> # $Id: callbacks.rb,v 1.4 2004/09/14 18:51:26 austin Exp $</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line14">14</a> #++</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line15">15</a> # Contains definitions for all default callback objects.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line16">16</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line17">17</a> require 'diff/lcs/change'</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line18">18</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line19">19</a> module Diff::LCS</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line20">20</a>     # This callback object implements the default set of callback events, which</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line21">21</a>     # only returns the event itself. Note that #finished_a and #finished_b are</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line22">22</a>     # not implemented -- I haven't yet figured out where they would be useful.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line23">23</a>     #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line24">24</a>     # Note that this is intended to be called as is, e.g.,</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line25">25</a>     #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line26">26</a>     #     Diff::LCS.LCS(seq1, seq2, Diff::LCS::DefaultCallbacks)</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line27">27</a>   class DefaultCallbacks</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line28">28</a>     class &lt;&lt; self</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line29">29</a>         # Called when two items match.</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line30">30</a>       def match(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line31">31</a>         event</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line32">32</a>       end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line33">33</a>         # Called when the old value is discarded in favour of the new value.</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line34">34</a>       def discard_a(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line35">35</a>         event</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line36">36</a>       end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line37">37</a>         # Called when the new value is discarded in favour of the old value.</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line38">38</a>       def discard_b(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line39">39</a>         event</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line40">40</a>       end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line41">41</a>         # Called when both the old and new values have changed.</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line42">42</a>       def change(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line43">43</a>         event</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line44">44</a>       end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line45">45</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line46">46</a>       private :new</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line47">47</a>     end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line48">48</a>   end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line49">49</a> </pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line50">50</a>     # An alias for DefaultCallbacks that is used in Diff::LCS#traverse_sequences.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line51">51</a>     #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line52">52</a>     #     Diff::LCS.LCS(seq1, seq2, Diff::LCS::SequenceCallbacks)</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line53">53</a>   SequenceCallbacks = DefaultCallbacks</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line54">54</a>     # An alias for DefaultCallbacks that is used in Diff::LCS#traverse_balanced.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line55">55</a>     #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line56">56</a>     #     Diff::LCS.LCS(seq1, seq2, Diff::LCS::BalancedCallbacks)</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line57">57</a>   BalancedCallbacks = DefaultCallbacks</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line58">58</a> end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line59">59</a> </pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line60">60</a>   # This will produce a compound array of simple diff change objects. Each</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line61">61</a>   # element in the #diffs array is a +hunk+ or +hunk+ array, where each</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line62">62</a>   # element in each +hunk+ array is a single Change object representing the</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line63">63</a>   # addition or removal of a single element from one of the two tested</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line64">64</a>   # sequences. The +hunk+ provides the full context for the changes.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line65">65</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line66">66</a>   #     diffs = Diff::LCS.diff(seq1, seq2)</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line67">67</a>   #       # This example shows a simplified array format.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line68">68</a>   #       # [ [ [ '-',  0, 'a' ] ],   # 1</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line69">69</a>   #       #   [ [ '+',  2, 'd' ] ],   # 2</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line70">70</a>   #       #   [ [ '-',  4, 'h' ],     # 3</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line71">71</a>   #       #     [ '+',  4, 'f' ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line72">72</a>   #       #   [ [ '+',  6, 'k' ] ],   # 4</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line73">73</a>   #       #   [ [ '-',  8, 'n' ],     # 5</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line74">74</a>   #       #     [ '-',  9, 'p' ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line75">75</a>   #       #     [ '+',  9, 'r' ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line76">76</a>   #       #     [ '+', 10, 's' ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line77">77</a>   #       #     [ '+', 11, 't' ] ] ]</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line78">78</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line79">79</a>   # There are five hunks here. The first hunk says that the +a+ at position 0</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line80">80</a>   # of the first sequence should be deleted (&lt;tt&gt;'-'&lt;/tt&gt;). The second hunk</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line81">81</a>   # says that the +d+ at position 2 of the second sequence should be inserted</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line82">82</a>   # (&lt;tt&gt;'+'&lt;/tt&gt;). The third hunk says that the +h+ at position 4 of the</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line83">83</a>   # first sequence should be removed and replaced with the +f+ from position 4</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line84">84</a>   # of the second sequence. The other two hunks are described similarly.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line85">85</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line86">86</a>   # === Use</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line87">87</a>   # This callback object must be initialised and is used by the Diff::LCS#diff</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line88">88</a>   # method.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line89">89</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line90">90</a>   #     cbo = Diff::LCS::DiffCallbacks.new</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line91">91</a>   #     Diff::LCS.LCS(seq1, seq2, cbo)</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line92">92</a>   #     cbo.finish</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line93">93</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line94">94</a>   # Note that the call to #finish is absolutely necessary, or the last set of</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line95">95</a>   # changes will not be visible. Alternatively, can be used as:</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line96">96</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line97">97</a>   #     cbo = Diff::LCS::DiffCallbacks.new { |tcbo| Diff::LCS.LCS(seq1, seq2, tcbo) }</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line98">98</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line99">99</a>   # The necessary #finish call will be made.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line100">100</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line101">101</a>   # === Simplified Array Format</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line102">102</a>   # The simplified array format used in the example above can be obtained</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line103">103</a>   # with:</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line104">104</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line105">105</a>   #     require 'pp'</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line106">106</a>   #     pp diffs.map { |e| e.map { |f| f.to_a } }</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line107">107</a> class Diff::LCS::DiffCallbacks</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line108">108</a>     # Returns the difference set collected during the diff process.</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line109">109</a>   attr_reader :diffs</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line110">110</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line111">111</a>   def initialize # :yields self:</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line112">112</a>     @hunk = []</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line113">113</a>     @diffs = []</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line114">114</a> </pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line115">115</a>     if block_given?</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line116">116</a>       begin</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line117">117</a>         yield self</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line118">118</a>       ensure</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line119">119</a>         self.finish</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line120">120</a>       end</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line121">121</a>     end</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line122">122</a>   end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line123">123</a> </pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line124">124</a>     # Finalizes the diff process. If an unprocessed hunk still exists, then it</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line125">125</a>     # is appended to the diff list.</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line126">126</a>   def finish</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line127">127</a>     add_nonempty_hunk</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line128">128</a>   end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line129">129</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line130">130</a>   def match(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line131">131</a>     add_nonempty_hunk</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line132">132</a>   end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line133">133</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line134">134</a>   def discard_a(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line135">135</a>     @hunk &lt;&lt; Diff::LCS::Change.new('-', event.old_position, event.old_element)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line136">136</a>   end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line137">137</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line138">138</a>   def discard_b(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line139">139</a>     @hunk &lt;&lt; Diff::LCS::Change.new('+', event.new_position, event.new_element)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line140">140</a>   end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line141">141</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line142">142</a> private</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line143">143</a>   def add_nonempty_hunk</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line144">144</a>     @diffs &lt;&lt; @hunk unless @hunk.empty?</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line145">145</a>     @hunk = []</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line146">146</a>   end</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line147">147</a> end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line148">148</a> </pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line149">149</a>   # This will produce a compound array of contextual diff change objects. Each</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line150">150</a>   # element in the #diffs array is a &quot;hunk&quot; array, where each element in each</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line151">151</a>   # &quot;hunk&quot; array is a single change. Each change is a Diff::LCS::ContextChange</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line152">152</a>   # that contains both the old index and new index values for the change. The</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line153">153</a>   # &quot;hunk&quot; provides the full context for the changes. Both old and new objects</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line154">154</a>   # will be presented for changed objects. +nil+ will be substituted for a</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line155">155</a>   # discarded object.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line156">156</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line157">157</a>   #     seq1 = %w(a b c e h j l m n p)</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line158">158</a>   #     seq2 = %w(b c d e f j k l m r s t)</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line159">159</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line160">160</a>   #     diffs = Diff::LCS.diff(seq1, seq2, Diff::LCS::ContextDiffCallbacks)</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line161">161</a>   #       # This example shows a simplified array format.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line162">162</a>   #       # [ [ [ '-', [  0, 'a' ], [  0, nil ] ] ],   # 1</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line163">163</a>   #       #   [ [ '+', [  3, nil ], [  2, 'd' ] ] ],   # 2</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line164">164</a>   #       #   [ [ '-', [  4, 'h' ], [  4, nil ] ],     # 3</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line165">165</a>   #       #     [ '+', [  5, nil ], [  4, 'f' ] ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line166">166</a>   #       #   [ [ '+', [  6, nil ], [  6, 'k' ] ] ],   # 4</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line167">167</a>   #       #   [ [ '-', [  8, 'n' ], [  9, nil ] ],     # 5</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line168">168</a>   #       #     [ '+', [  9, nil ], [  9, 'r' ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line169">169</a>   #       #     [ '-', [  9, 'p' ], [ 10, nil ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line170">170</a>   #       #     [ '+', [ 10, nil ], [ 10, 's' ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line171">171</a>   #       #     [ '+', [ 10, nil ], [ 11, 't' ] ] ] ]</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line172">172</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line173">173</a>   # The five hunks shown are comprised of individual changes; if there is a</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line174">174</a>   # related set of changes, they are still shown individually.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line175">175</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line176">176</a>   # This callback can also be used with Diff::LCS#sdiff, which will produce</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line177">177</a>   # results like:</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line178">178</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line179">179</a>   #     diffs = Diff::LCS.sdiff(seq1, seq2, Diff::LCS::ContextCallbacks)</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line180">180</a>   #       # This example shows a simplified array format.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line181">181</a>   #       # [ [ [ &quot;-&quot;, [  0, &quot;a&quot; ], [  0, nil ] ] ],  # 1</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line182">182</a>   #       #   [ [ &quot;+&quot;, [  3, nil ], [  2, &quot;d&quot; ] ] ],  # 2</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line183">183</a>   #       #   [ [ &quot;!&quot;, [  4, &quot;h&quot; ], [  4, &quot;f&quot; ] ] ],  # 3</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line184">184</a>   #       #   [ [ &quot;+&quot;, [  6, nil ], [  6, &quot;k&quot; ] ] ],  # 4</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line185">185</a>   #       #   [ [ &quot;!&quot;, [  8, &quot;n&quot; ], [  9, &quot;r&quot; ] ],    # 5</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line186">186</a>   #       #     [ &quot;!&quot;, [  9, &quot;p&quot; ], [ 10, &quot;s&quot; ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line187">187</a>   #       #     [ &quot;+&quot;, [ 10, nil ], [ 11, &quot;t&quot; ] ] ] ]</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line188">188</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line189">189</a>   # The five hunks are still present, but are significantly shorter in total</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line190">190</a>   # presentation, because changed items are shown as changes (&quot;!&quot;) instead of</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line191">191</a>   # potentially &quot;mismatched&quot; pairs of additions and deletions.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line192">192</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line193">193</a>   # The result of this operation is similar to that of</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line194">194</a>   # Diff::LCS::SDiffCallbacks. They may be compared as:</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line195">195</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line196">196</a>   #     s = Diff::LCS.sdiff(seq1, seq2).reject { |e| e.action == &quot;=&quot; }</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line197">197</a>   #     c = Diff::LCS.sdiff(seq1, seq2, Diff::LCS::ContextDiffCallbacks).flatten</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line198">198</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line199">199</a>   #     s == c # -&gt; true</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line200">200</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line201">201</a>   # === Use</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line202">202</a>   # This callback object must be initialised and can be used by the</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line203">203</a>   # Diff::LCS#diff or Diff::LCS#sdiff methods.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line204">204</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line205">205</a>   #     cbo = Diff::LCS::ContextDiffCallbacks.new</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line206">206</a>   #     Diff::LCS.LCS(seq1, seq2, cbo)</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line207">207</a>   #     cbo.finish</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line208">208</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line209">209</a>   # Note that the call to #finish is absolutely necessary, or the last set of</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line210">210</a>   # changes will not be visible. Alternatively, can be used as:</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line211">211</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line212">212</a>   #     cbo = Diff::LCS::ContextDiffCallbacks.new { |tcbo| Diff::LCS.LCS(seq1, seq2, tcbo) }</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line213">213</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line214">214</a>   # The necessary #finish call will be made.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line215">215</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line216">216</a>   # === Simplified Array Format</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line217">217</a>   # The simplified array format used in the example above can be obtained</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line218">218</a>   # with:</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line219">219</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line220">220</a>   #     require 'pp'</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line221">221</a>   #     pp diffs.map { |e| e.map { |f| f.to_a } }</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line222">222</a> class Diff::LCS::ContextDiffCallbacks &lt; Diff::LCS::DiffCallbacks</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line223">223</a>   def discard_a(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line224">224</a>     @hunk &lt;&lt; Diff::LCS::ContextChange.simplify(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line225">225</a>   end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line226">226</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line227">227</a>   def discard_b(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line228">228</a>     @hunk &lt;&lt; Diff::LCS::ContextChange.simplify(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line229">229</a>   end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line230">230</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line231">231</a>   def change(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line232">232</a>     @hunk &lt;&lt; Diff::LCS::ContextChange.simplify(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line233">233</a>   end</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line234">234</a> end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line235">235</a> </pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line236">236</a>   # This will produce a simple array of diff change objects. Each element in</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line237">237</a>   # the #diffs array is a single ContextChange. In the set of #diffs provided</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line238">238</a>   # by SDiffCallbacks, both old and new objects will be presented for both</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line239">239</a>   # changed &lt;strong&gt;and unchanged&lt;/strong&gt; objects. +nil+ will be substituted</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line240">240</a>   # for a discarded object.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line241">241</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line242">242</a>   # The diffset produced by this callback, when provided to Diff::LCS#sdiff,</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line243">243</a>   # will compute and display the necessary components to show two sequences</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line244">244</a>   # and their minimized differences side by side, just like the Unix utility</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line245">245</a>   # +sdiff+.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line246">246</a>   # </pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line247">247</a>   #     same             same</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line248">248</a>   #     before     |     after</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line249">249</a>   #     old        &lt;     -</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line250">250</a>   #     -          &gt;     new</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line251">251</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line252">252</a>   #     seq1 = %w(a b c e h j l m n p)</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line253">253</a>   #     seq2 = %w(b c d e f j k l m r s t)</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line254">254</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line255">255</a>   #     diffs = Diff::LCS.sdiff(seq1, seq2)</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line256">256</a>   #       # This example shows a simplified array format.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line257">257</a>   #       # [ [ &quot;-&quot;, [  0, &quot;a&quot;], [  0, nil ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line258">258</a>   #       #   [ &quot;=&quot;, [  1, &quot;b&quot;], [  0, &quot;b&quot; ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line259">259</a>   #       #   [ &quot;=&quot;, [  2, &quot;c&quot;], [  1, &quot;c&quot; ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line260">260</a>   #       #   [ &quot;+&quot;, [  3, nil], [  2, &quot;d&quot; ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line261">261</a>   #       #   [ &quot;=&quot;, [  3, &quot;e&quot;], [  3, &quot;e&quot; ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line262">262</a>   #       #   [ &quot;!&quot;, [  4, &quot;h&quot;], [  4, &quot;f&quot; ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line263">263</a>   #       #   [ &quot;=&quot;, [  5, &quot;j&quot;], [  5, &quot;j&quot; ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line264">264</a>   #       #   [ &quot;+&quot;, [  6, nil], [  6, &quot;k&quot; ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line265">265</a>   #       #   [ &quot;=&quot;, [  6, &quot;l&quot;], [  7, &quot;l&quot; ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line266">266</a>   #       #   [ &quot;=&quot;, [  7, &quot;m&quot;], [  8, &quot;m&quot; ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line267">267</a>   #       #   [ &quot;!&quot;, [  8, &quot;n&quot;], [  9, &quot;r&quot; ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line268">268</a>   #       #   [ &quot;!&quot;, [  9, &quot;p&quot;], [ 10, &quot;s&quot; ] ],</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line269">269</a>   #       #   [ &quot;+&quot;, [ 10, nil], [ 11, &quot;t&quot; ] ] ]</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line270">270</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line271">271</a>   # The result of this operation is similar to that of</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line272">272</a>   # Diff::LCS::ContextDiffCallbacks. They may be compared as:</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line273">273</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line274">274</a>   #     s = Diff::LCS.sdiff(seq1, seq2).reject { |e| e.action == &quot;=&quot; }</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line275">275</a>   #     c = Diff::LCS.sdiff(seq1, seq2, Diff::LCS::ContextDiffCallbacks).flatten</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line276">276</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line277">277</a>   #     s == c # -&gt; true</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line278">278</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line279">279</a>   # === Use</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line280">280</a>   # This callback object must be initialised and is used by the Diff::LCS#sdiff</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line281">281</a>   # method.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line282">282</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line283">283</a>   #     cbo = Diff::LCS::SDiffCallbacks.new</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line284">284</a>   #     Diff::LCS.LCS(seq1, seq2, cbo)</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line285">285</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line286">286</a>   # As with the other initialisable callback objects, Diff::LCS::SDiffCallbacks</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line287">287</a>   # can be initialised with a block. As there is no &quot;fininishing&quot; to be done,</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line288">288</a>   # this has no effect on the state of the object.</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line289">289</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line290">290</a>   #     cbo = Diff::LCS::SDiffCallbacks.new { |tcbo| Diff::LCS.LCS(seq1, seq2, tcbo) }</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line291">291</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line292">292</a>   # === Simplified Array Format</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line293">293</a>   # The simplified array format used in the example above can be obtained</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line294">294</a>   # with:</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line295">295</a>   #</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line296">296</a>   #     require 'pp'</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line297">297</a>   #     pp diffs.map { |e| e.to_a }</pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line298">298</a> class Diff::LCS::SDiffCallbacks</pre></td>
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        <tr class="inferred">
          <td><pre><a name="line299">299</a>     # Returns the difference set collected during the diff process.</pre></td>
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        <tr class="marked">
          <td><pre><a name="line300">300</a>   attr_reader :diffs</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line301">301</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line302">302</a>   def initialize #:yields self:</pre></td>
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        <tr class="uncovered">
          <td><pre><a name="line303">303</a>     @diffs = []</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line304">304</a>     yield self if block_given?</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line305">305</a>   end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line306">306</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line307">307</a>   def match(event)</pre></td>
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        <tr class="uncovered">
          <td><pre><a name="line308">308</a>     @diffs &lt;&lt; Diff::LCS::ContextChange.simplify(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line309">309</a>   end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line310">310</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line311">311</a>   def discard_a(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line312">312</a>     @diffs &lt;&lt; Diff::LCS::ContextChange.simplify(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line313">313</a>   end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line314">314</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line315">315</a>   def discard_b(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line316">316</a>     @diffs &lt;&lt; Diff::LCS::ContextChange.simplify(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line317">317</a>   end</pre></td>
        </tr>

        <tr class="inferred">
          <td><pre><a name="line318">318</a> </pre></td>
        </tr>

        <tr class="marked">
          <td><pre><a name="line319">319</a>   def change(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line320">320</a>     @diffs &lt;&lt; Diff::LCS::ContextChange.simplify(event)</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line321">321</a>   end</pre></td>
        </tr>

        <tr class="uncovered">
          <td><pre><a name="line322">322</a> end</pre></td>
        </tr>

    </tbody>
  </table>

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