ntwb /
wordpress
Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like Text_Diff_Engine_string often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Text_Diff_Engine_string, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 23 | class Text_Diff_Engine_string { |
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| 24 | |||
| 25 | /** |
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| 26 | * Parses a unified or context diff. |
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| 27 | * |
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| 28 | * First param contains the whole diff and the second can be used to force |
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| 29 | * a specific diff type. If the second parameter is 'autodetect', the |
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| 30 | * diff will be examined to find out which type of diff this is. |
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| 31 | * |
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| 32 | * @param string $diff The diff content. |
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| 33 | * @param string $mode The diff mode of the content in $diff. One of |
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| 34 | * 'context', 'unified', or 'autodetect'. |
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| 35 | * |
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| 36 | * @return array List of all diff operations. |
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| 37 | */ |
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| 38 | function diff($diff, $mode = 'autodetect') |
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| 83 | |||
| 84 | /** |
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| 85 | * Parses an array containing the unified diff. |
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| 86 | * |
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| 87 | * @param array $diff Array of lines. |
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| 88 | * |
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| 89 | * @return array List of all diff operations. |
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| 90 | */ |
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| 91 | function parseUnifiedDiff($diff) |
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| 92 | { |
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| 93 | $edits = array(); |
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| 94 | $end = count($diff) - 1; |
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| 95 | for ($i = 0; $i < $end;) { |
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| 96 | $diff1 = array(); |
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| 97 | switch (substr($diff[$i], 0, 1)) { |
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| 98 | case ' ': |
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| 99 | do { |
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| 100 | $diff1[] = substr($diff[$i], 1); |
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| 101 | } while (++$i < $end && substr($diff[$i], 0, 1) == ' '); |
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| 102 | $edits[] = new Text_Diff_Op_copy($diff1); |
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| 103 | break; |
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| 104 | |||
| 105 | View Code Duplication | case '+': |
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| 106 | // get all new lines |
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| 107 | do { |
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| 108 | $diff1[] = substr($diff[$i], 1); |
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| 109 | } while (++$i < $end && substr($diff[$i], 0, 1) == '+'); |
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| 110 | $edits[] = new Text_Diff_Op_add($diff1); |
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| 111 | break; |
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| 112 | |||
| 113 | case '-': |
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| 114 | // get changed or removed lines |
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| 115 | $diff2 = array(); |
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| 116 | do { |
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| 117 | $diff1[] = substr($diff[$i], 1); |
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| 118 | } while (++$i < $end && substr($diff[$i], 0, 1) == '-'); |
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| 119 | |||
| 120 | while ($i < $end && substr($diff[$i], 0, 1) == '+') { |
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| 121 | $diff2[] = substr($diff[$i++], 1); |
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| 122 | } |
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| 123 | if (count($diff2) == 0) { |
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| 124 | $edits[] = new Text_Diff_Op_delete($diff1); |
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| 125 | } else { |
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| 126 | $edits[] = new Text_Diff_Op_change($diff1, $diff2); |
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| 127 | } |
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| 128 | break; |
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| 129 | |||
| 130 | default: |
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| 131 | $i++; |
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| 132 | break; |
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| 133 | } |
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| 134 | } |
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| 135 | |||
| 136 | return $edits; |
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| 137 | } |
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| 138 | |||
| 139 | /** |
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| 140 | * Parses an array containing the context diff. |
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| 141 | * |
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| 142 | * @param array $diff Array of lines. |
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| 143 | * |
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| 144 | * @return array List of all diff operations. |
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| 145 | */ |
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| 146 | function parseContextDiff(&$diff) |
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| 247 | |||
| 248 | } |
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| 249 |
