Complex classes like ListDiffNew 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 ListDiffNew, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 8 | class ListDiffNew extends AbstractDiff |
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| 9 | { |
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| 10 | protected static $listTypes = array('ul', 'ol', 'dl'); |
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| 11 | |||
| 12 | 4 | public function build() |
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| 21 | |||
| 22 | 4 | protected function diffLists(DiffList $oldList, DiffList $newList) |
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| 23 | { |
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| 24 | 4 | $oldMatchData = array(); |
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| 25 | 4 | $newMatchData = array(); |
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| 26 | 4 | $oldListIndices = array(); |
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| 27 | 4 | $newListIndices = array(); |
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| 28 | 4 | $oldListItems = array(); |
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| 29 | 4 | $newListItems = array(); |
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| 30 | |||
| 31 | 4 | foreach ($oldList->getListItems() as $oldIndex => $oldListItem) { |
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| 32 | 4 | if ($oldListItem instanceof DiffListItem) { |
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| 33 | 4 | $oldListItems[$oldIndex] = $oldListItem; |
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| 34 | |||
| 35 | 4 | $oldListIndices[] = $oldIndex; |
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| 36 | 4 | $oldMatchData[$oldIndex] = array(); |
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| 37 | |||
| 38 | // Get match percentages |
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| 39 | 4 | foreach ($newList->getListItems() as $newIndex => $newListItem) { |
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| 40 | 4 | if ($newListItem instanceof DiffListItem) { |
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| 41 | 4 | if (!in_array($newListItem, $newListItems)) { |
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| 42 | 4 | $newListItems[$newIndex] = $newListItem; |
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| 43 | 4 | } |
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| 44 | 4 | if (!in_array($newIndex, $newListIndices)) { |
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| 45 | 4 | $newListIndices[] = $newIndex; |
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| 46 | 4 | } |
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| 47 | 4 | if (!array_key_exists($newIndex, $newMatchData)) { |
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| 48 | 4 | $newMatchData[$newIndex] = array(); |
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| 49 | 4 | } |
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| 50 | |||
| 51 | 4 | $oldText = implode('', $oldListItem->getText()); |
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| 52 | 4 | $newText = implode('', $newListItem->getText()); |
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| 53 | |||
| 54 | // similar_text |
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| 55 | 4 | $percentage = null; |
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| 56 | 4 | similar_text($oldText, $newText, $percentage); |
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| 57 | |||
| 58 | 4 | $oldMatchData[$oldIndex][$newIndex] = $percentage; |
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| 59 | 4 | $newMatchData[$newIndex][$oldIndex] = $percentage; |
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| 60 | 4 | } |
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| 61 | 4 | } |
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| 62 | 4 | } |
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| 63 | 4 | } |
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| 64 | |||
| 65 | 4 | $currentIndexInOld = 0; |
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| 66 | 4 | $currentIndexInNew = 0; |
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| 67 | 4 | $oldCount = count($oldListIndices); |
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| 68 | 4 | $newCount = count($newListIndices); |
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| 69 | 4 | $difference = max($oldCount, $newCount) - min($oldCount, $newCount); |
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| 70 | |||
| 71 | 4 | $diffOutput = ''; |
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| 72 | |||
| 73 | 4 | foreach ($newList->getListItems() as $newIndex => $newListItem) { |
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| 74 | 4 | if ($newListItem instanceof DiffListItem) { |
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| 75 | 4 | $operation = null; |
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| 76 | |||
| 77 | 4 | $oldListIndex = array_key_exists($currentIndexInOld, $oldListIndices) ? $oldListIndices[$currentIndexInOld] : null; |
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| 78 | 4 | $class = 'normal'; |
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| 79 | |||
| 80 | 4 | if (null !== $oldListIndex && array_key_exists($oldListIndex, $oldMatchData)) { |
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| 81 | // Check percentage matches of upcoming list items in old. |
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| 82 | 4 | $matchPercentage = $oldMatchData[$oldListIndex][$newIndex]; |
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| 83 | |||
| 84 | // does the old list item match better? |
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| 85 | 4 | $otherMatchBetter = false; |
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| 86 | 4 | foreach ($oldMatchData[$oldListIndex] as $index => $percentage) { |
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| 87 | 4 | if ($index > $newIndex && $percentage > $matchPercentage) { |
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| 88 | 2 | $otherMatchBetter = $index; |
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| 89 | 2 | } |
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| 90 | 4 | } |
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| 91 | |||
| 92 | 4 | if (false !== $otherMatchBetter && $newCount > $oldCount && $difference > 0) { |
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| 93 | 1 | $diffOutput .= sprintf('%s', $newListItem->getHtml('normal new', 'ins')); |
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| 94 | 1 | $currentIndexInNew++; |
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| 95 | 1 | $difference--; |
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| 96 | |||
| 97 | 1 | continue; |
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| 98 | } |
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| 99 | |||
| 100 | 4 | $nextOldListIndex = array_key_exists($currentIndexInOld + 1, $oldListIndices) ? $oldListIndices[$currentIndexInOld + 1] : null; |
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| 101 | |||
| 102 | 4 | $replacement = false; |
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| 103 | |||
| 104 | 4 | if ($nextOldListIndex !== null && $oldMatchData[$nextOldListIndex][$newIndex] > $matchPercentage && $oldMatchData[$nextOldListIndex][$newIndex] > $this->matchThreshold) { |
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| 105 | // Following list item in old is better match, use that. |
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| 106 | $diffOutput .= sprintf('%s', $oldListItems[$oldListIndex]->getHtml('removed', 'del')); |
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| 107 | |||
| 108 | $currentIndexInOld++; |
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| 109 | $oldListIndex = $nextOldListIndex; |
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| 110 | $matchPercentage = $oldMatchData[$oldListIndex]; |
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| 111 | $replacement = true; |
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| 112 | } |
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| 113 | |||
| 114 | 4 | if ($matchPercentage > $this->matchThreshold || $currentIndexInNew === $currentIndexInOld) { |
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| 115 | // Diff the two lists. |
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| 116 | 4 | $htmlDiff = new HtmlDiff($oldListItems[$oldListIndex]->getInnerHtml(), $newListItem->getInnerHtml(), $this->encoding, $this->specialCaseTags, $this->groupDiffs); |
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| 117 | 4 | $diffContent = $htmlDiff->build(); |
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| 118 | |||
| 119 | 4 | $diffOutput .= sprintf('%s%s%s', $newListItem->getStartTagWithDiffClass($replacement ? 'replacement' : 'normal'), $diffContent, $newListItem->getEndTag()); |
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| 120 | |||
| 121 | 4 | } else { |
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| 122 | $diffOutput .= sprintf('%s', $oldListItems[$oldListIndex]->getHtml('removed', 'del')); |
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| 123 | $diffOutput .= sprintf('%s', $newListItem->getHtml('replacement', 'ins')); |
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| 124 | } |
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| 125 | 4 | $currentIndexInOld++; |
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| 126 | 4 | } else { |
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| 127 | $diffOutput .= sprintf('%s', $newListItem->getHtml('normal new', 'ins')); |
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| 128 | } |
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| 129 | |||
| 130 | 4 | $currentIndexInNew++; |
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| 131 | 4 | } |
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| 132 | 4 | } |
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| 133 | |||
| 134 | // Output any additional list items |
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| 135 | 4 | while (array_key_exists($currentIndexInOld, $oldListIndices)) { |
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| 136 | 2 | $oldListIndex = $oldListIndices[$currentIndexInOld]; |
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| 137 | 2 | $diffOutput .= sprintf('%s', $oldListItems[$oldListIndex]->getHtml('removed', 'del')); |
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| 138 | 2 | $currentIndexInOld++; |
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| 139 | 2 | } |
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| 140 | |||
| 141 | 4 | return sprintf('%s%s%s', $newList->getStartTagWithDiffClass(), $diffOutput, $newList->getEndTag()); |
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| 142 | } |
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| 143 | |||
| 144 | 4 | protected function buildDiffList($words) |
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| 219 | |||
| 220 | 4 | protected function isOpeningListTag($word, $type = null) |
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| 225 | |||
| 226 | 4 | protected function isClosingListTag($word, $type = null) |
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| 232 | |||
| 233 | 4 | protected function isOpeningListItemTag($word, $type = null) |
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| 239 | |||
| 240 | 4 | protected function isClosingListItemTag($word, $type = null) |
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| 246 | } |
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| 247 |
This check looks for variable assignements that are either overwritten by other assignments or where the variable is not used subsequently.
Both the
$myVarassignment in line 1 and the$higherassignment in line 2 are dead. The first because$myVaris never used and the second because$higheris always overwritten for every possible time line.