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:
| 1 | <?php |
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| 7 | final class StdRangesCalculator implements RangesCalculator |
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| 8 | { |
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| 9 | /** |
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| 10 | * @inheritdoc |
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| 11 | */ |
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| 12 | 4 | public function sum(Range ...$ranges): array |
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| 13 | { |
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| 14 | 4 | if (\count($ranges) === 0) { |
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| 15 | 1 | return []; |
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| 16 | } |
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| 17 | |||
| 18 | 3 | $this->sortRanges($ranges); |
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| 19 | 3 | return $this->mergeRanges($ranges); |
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| 20 | } |
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| 21 | |||
| 22 | /** |
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| 23 | * @param Range[] $ranges |
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| 24 | */ |
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| 25 | private function sortRanges(array &$ranges): void |
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| 31 | |||
| 32 | /** |
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| 33 | * @inheritdoc |
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| 34 | * @throws \Exception |
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| 35 | */ |
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| 36 | 6 | public function sub(Range $minuend, Range ...$subtrahends): array |
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| 44 | |||
| 45 | /** |
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| 46 | * @param Range $range |
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| 47 | * @param Range[] $ranges |
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| 48 | * @return Range[] |
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| 49 | * @throws \Exception |
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| 50 | */ |
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| 51 | 6 | private function removeRangeFromRanges(Range $range, array $ranges): array |
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| 87 | |||
| 88 | /** |
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| 89 | * @param Range[] $ranges |
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| 90 | * @return array |
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| 91 | */ |
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| 92 | 3 | private function mergeRanges(array $ranges): array |
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| 115 | } |
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| 116 |
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.