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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| 13 | class FileInputStream extends InputStream  | 
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| 14 | { | 
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| 15 | /**  | 
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| 16 | * @var File ファイルオブジェクト  | 
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| 17 | */  | 
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| 18 | protected $file;  | 
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| 19 | |||
| 20 | /**  | 
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| 21 | * constructor  | 
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| 22 | * @param mixed $file ファイルオブジェクトまたはファイルパス  | 
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| 23 | * @throws InvalidArgumentException  | 
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| 24 | * @throws IOException  | 
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| 25 | */  | 
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| 26 | public function __construct($file)  | 
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| 27 |     { | 
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| 28 |         if ($file instanceof File) { | 
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| 29 | $this->file = $file;  | 
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| 30 |         } elseif (is_string($file)) { | 
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| 31 | $this->file = new File($file);  | 
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| 32 |         } else { | 
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| 33 |             throw new InvalidArgumentException("Unable to open file: " . $file); | 
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| 34 | }  | 
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| 35 | |||
| 36 | // 読み込みはロックを掛けずダーティーリード  | 
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| 37 | $stream = fopen($this->file->getAbsoluteFilePath(), 'r');  | 
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| 38 |         if (!is_resource($stream) || $stream === false) { | 
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| 39 |             throw new IOException("Unable open " . $this->file->getAbsoluteFilePath()); | 
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| 40 | }  | 
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| 41 | |||
| 42 | parent::__construct($stream);  | 
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| 43 | }  | 
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| 44 | |||
| 45 | /**  | 
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| 46 | * 入力ストリームを閉じる  | 
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| 47 | */  | 
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| 48 | public function close()  | 
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| 49 |     { | 
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| 50 |         if ($this->stream === null) { | 
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| 51 | return;  | 
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| 52 | }  | 
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| 53 | |||
| 54 |         if (get_resource_type($this->stream) !== 'Unknown' && fclose($this->stream) === false) { | 
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| 55 |             throw new IOException("Cannot close input stream."); | 
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| 56 | }  | 
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| 57 | |||
| 58 | $this->stream = null;  | 
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| 59 | }  | 
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| 60 | |||
| 61 | /**  | 
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| 62 |      * {@inheritdoc} | 
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| 63 | */  | 
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| 64 | public function read($length = null)  | 
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| 65 |     { | 
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| 66 |         if ($this->stream === null) { | 
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| 67 | return null;  | 
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| 68 | }  | 
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| 69 | |||
| 70 |         if ($this->eof()) { | 
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| 71 | return null;  | 
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| 72 | }  | 
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| 73 | |||
| 74 | $out = null;  | 
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| 75 |         if ($length === null) { | 
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| 76 |             if (($out = @fread($this->stream, 1)) === false) { | 
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| 77 |                 throw new IOException("Failed to read stream."); | 
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| 78 | }  | 
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| 79 |         } else { | 
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| 80 |             if (!is_int($length)) { | 
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| 81 |                 throw new InvalidArgumentException("Stream read must be a numeric value."); | 
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| 82 | }  | 
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| 83 | // ポインタ位置が負になった場合、警告が出てfalseを返す  | 
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| 84 | // ポインタの終端を越えた場合、読み込みを終了する  | 
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| 85 | // すでに終端位置の場合、空文字を返す  | 
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| 86 |             if (($out = @fread($this->stream, $length)) === false) { | 
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| 87 |                 throw new IOException("Failed to read stream."); | 
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| 88 | }  | 
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| 89 | }  | 
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| 90 | |||
| 91 | return $out;  | 
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| 92 | }  | 
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| 93 | |||
| 94 | /**  | 
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| 95 | * 入力ストリームから行単位でデータを読み込む  | 
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| 96 | * 末尾に改行コードは含まない  | 
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| 97 | * @return string 読み込みデータ  | 
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| 98 | */  | 
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| 99 | public function readLine()  | 
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| 100 |     { | 
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| 101 |         if ($this->stream === null) { | 
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| 102 | return null;  | 
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| 103 | }  | 
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| 104 | |||
| 105 |         if ($this->eof()) { | 
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| 106 | return null;  | 
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| 107 | }  | 
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| 108 | |||
| 109 | $out = fgets($this->stream);  | 
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| 110 |         if ($out === false) { | 
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| 111 | return null;  | 
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| 112 | }  | 
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| 113 | |||
| 114 | $this->cursorPosition = ftell($this->stream);  | 
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| 115 | |||
| 116 | return trim($out);  | 
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| 117 | }  | 
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| 118 | |||
| 119 | /**  | 
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| 120 |      * {@inheritdoc} | 
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| 121 | */  | 
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| 122 | public function skip(int $pos)  | 
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| 123 |     { | 
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| 124 |         if ($this->stream === null) { | 
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| 125 | return -1;  | 
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| 126 | }  | 
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| 127 | |||
| 128 | // 現在のポインタ位置から$posだけ後方へ移動  | 
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| 129 | // シークに対応していないファイルシステムの場合、-1を返す  | 
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| 130 |         if (fseek($this->stream, $pos, SEEK_CUR) === -1) { | 
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| 131 | return -1;  | 
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| 132 | }  | 
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| 133 | |||
| 134 | $start = $this->cursorPosition;  | 
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| 135 | $this->cursorPosition = ftell($this->stream);  | 
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| 136 | |||
| 137 | $skipNum = 0;  | 
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| 138 |         if ($start > $this->cursorPosition) { | 
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| 139 | // 後方へ移動  | 
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| 140 | $skipNum = $start - $this->cursorPosition;  | 
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| 141 |         } else { | 
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| 142 | // 前方へ移動  | 
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| 143 | $skipNum = $this->cursorPosition - $start;  | 
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| 144 | }  | 
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| 145 | |||
| 146 | return $skipNum;  | 
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| 147 | }  | 
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| 148 | |||
| 149 | /**  | 
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| 150 |      * {@inheritdoc} | 
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| 151 | */  | 
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| 152 | public function reset()  | 
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| 153 |     { | 
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| 154 |         if (!$this->isMarkSupported()) { | 
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| 155 | throw new IOException(get_class($this) . " does not support mark and reset.");  | 
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| 156 | }  | 
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| 157 | |||
| 158 |         if ($this->stream === null) { | 
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| 159 | return;  | 
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| 160 | }  | 
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| 161 | |||
| 162 | // ポインタ位置をmark位置に移動  | 
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| 163 | fseek($this->stream, $this->markedPosition, SEEK_SET);  | 
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| 164 | // mark位置を初期値に戻す  | 
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| 165 | $this->cursorPosition = $this->markedPosition;  | 
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| 166 | $this->markedPosition = 0;  | 
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| 167 | }  | 
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| 168 | |||
| 169 | /**  | 
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| 170 |      * {@inheritdoc} | 
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| 171 | */  | 
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| 172 | public function eof()  | 
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| 173 |     { | 
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| 174 | return feof($this->stream);  | 
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| 175 | }  | 
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| 176 | |||
| 177 | /**  | 
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| 178 |      * {@inheritdoc} | 
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| 179 | */  | 
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| 180 | public function isMarkSupported()  | 
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| 181 |     { | 
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| 182 | return true;  | 
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| 183 | }  | 
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| 184 | }  | 
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| 185 |