Complex classes like AbstractCsv 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 AbstractCsv, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 28 | abstract class AbstractCsv implements ByteSequence  | 
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| 29 | { | 
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| 30 | /**  | 
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| 31 | * The stream filter mode (read or write)  | 
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| 32 | *  | 
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| 33 | * @var int  | 
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| 34 | */  | 
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| 35 | protected $stream_filter_mode;  | 
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| 36 | |||
| 37 | |||
| 38 | /**  | 
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| 39 | * collection of stream filters  | 
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| 40 | *  | 
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| 41 | * @var bool[]  | 
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| 42 | */  | 
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| 43 | protected $stream_filters = [];  | 
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| 44 | |||
| 45 | /**  | 
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| 46 | * The CSV document BOM sequence  | 
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| 47 | *  | 
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| 48 | * @var string|null  | 
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| 49 | */  | 
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| 50 | protected $input_bom = null;  | 
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| 51 | |||
| 52 | /**  | 
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| 53 | * The Output file BOM character  | 
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| 54 | *  | 
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| 55 | * @var string  | 
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| 56 | */  | 
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| 57 | protected $output_bom = '';  | 
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| 58 | |||
| 59 | /**  | 
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| 60 | * the field delimiter (one character only)  | 
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| 61 | *  | 
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| 62 | * @var string  | 
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| 63 | */  | 
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| 64 | protected $delimiter = ',';  | 
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| 65 | |||
| 66 | /**  | 
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| 67 | * the field enclosure character (one character only)  | 
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| 68 | *  | 
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| 69 | * @var string  | 
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| 70 | */  | 
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| 71 | protected $enclosure = '"';  | 
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| 72 | |||
| 73 | /**  | 
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| 74 | * the field escape character (one character only)  | 
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| 75 | *  | 
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| 76 | * @var string  | 
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| 77 | */  | 
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| 78 | protected $escape = '\\';  | 
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| 79 | |||
| 80 | /**  | 
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| 81 | * The CSV document  | 
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| 82 | *  | 
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| 83 | * @var SplFileObject|Stream  | 
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| 84 | */  | 
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| 85 | protected $document;  | 
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| 86 | |||
| 87 | /**  | 
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| 88 | * New instance  | 
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| 89 | *  | 
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| 90 | * @param SplFileObject|Stream $document The CSV Object instance  | 
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| 91 | */  | 
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| 92 | 22 | protected function __construct($document)  | 
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| 93 |     { | 
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| 94 | 22 | $this->document = $document;  | 
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| 95 | 22 | list($this->delimiter, $this->enclosure, $this->escape) = $this->document->getCsvControl();  | 
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| 96 | 22 | }  | 
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| 97 | |||
| 98 | /**  | 
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| 99 | * @inheritdoc  | 
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| 100 | */  | 
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| 101 | 24 | public function __destruct()  | 
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| 102 |     { | 
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| 103 | 24 | unset($this->document);  | 
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| 104 | 24 | }  | 
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| 105 | |||
| 106 | /**  | 
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| 107 | * @inheritdoc  | 
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| 108 | */  | 
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| 109 | 2 | public function __clone()  | 
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| 110 |     { | 
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| 111 | 2 |         throw new Exception(sprintf('An object of class %s cannot be cloned', get_class($this))); | 
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| 112 | }  | 
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| 113 | |||
| 114 | /**  | 
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| 115 | * Return a new instance from a SplFileObject  | 
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| 116 | *  | 
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| 117 | * @param SplFileObject $file  | 
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| 118 | *  | 
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| 119 | * @return static  | 
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| 120 | */  | 
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| 121 | 24 | public static function createFromFileObject(SplFileObject $file): self  | 
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| 122 |     { | 
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| 123 | 24 | return new static($file);  | 
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| 124 | }  | 
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| 125 | |||
| 126 | /**  | 
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| 127 | * Return a new instance from a PHP resource stream  | 
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| 128 | *  | 
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| 129 | * @param resource $stream  | 
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| 130 | *  | 
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| 131 | * @return static  | 
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| 132 | */  | 
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| 133 | 4 | public static function createFromStream($stream): self  | 
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| 134 |     { | 
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| 135 | 4 | return new static(new Stream($stream));  | 
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| 136 | }  | 
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| 137 | |||
| 138 | /**  | 
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| 139 | * Return a new instance from a string  | 
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| 140 | *  | 
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| 141 | * @param string $content the CSV document as a string  | 
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| 142 | *  | 
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| 143 | * @return static  | 
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| 144 | */  | 
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| 145 | 4 | public static function createFromString(string $content): self  | 
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| 146 |     { | 
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| 147 | 4 | return new static(Stream::createFromString($content));  | 
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| 148 | }  | 
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| 149 | |||
| 150 | /**  | 
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| 151 | * Return a new instance from a file path  | 
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| 152 | *  | 
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| 153 | * @param string $path file path  | 
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| 154 | * @param string $open_mode the file open mode flag  | 
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| 155 | * @param resource|null $context the resource context  | 
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| 156 | *  | 
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| 157 | * @return static  | 
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| 158 | */  | 
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| 159 | 4 | public static function createFromPath(string $path, string $open_mode = 'r+', $context = null): self  | 
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| 160 |     { | 
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| 161 | 4 | return new static(Stream::createFromPath($path, $open_mode, $context));  | 
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| 162 | }  | 
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| 163 | |||
| 164 | /**  | 
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| 165 | * Returns the current field delimiter  | 
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| 166 | *  | 
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| 167 | * @return string  | 
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| 168 | */  | 
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| 169 | 10 | public function getDelimiter(): string  | 
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| 170 |     { | 
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| 171 | 10 | return $this->delimiter;  | 
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| 172 | }  | 
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| 173 | |||
| 174 | /**  | 
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| 175 | * Returns the current field enclosure  | 
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| 176 | *  | 
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| 177 | * @return string  | 
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| 178 | */  | 
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| 179 | 2 | public function getEnclosure(): string  | 
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| 180 |     { | 
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| 181 | 2 | return $this->enclosure;  | 
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| 182 | }  | 
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| 183 | |||
| 184 | /**  | 
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| 185 | * Returns the current field escape character  | 
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| 186 | *  | 
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| 187 | * @return string  | 
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| 188 | */  | 
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| 189 | 2 | public function getEscape(): string  | 
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| 190 |     { | 
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| 191 | 2 | return $this->escape;  | 
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| 192 | }  | 
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| 193 | |||
| 194 | /**  | 
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| 195 | * Returns the BOM sequence in use on Output methods  | 
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| 196 | *  | 
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| 197 | * @return string  | 
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| 198 | */  | 
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| 199 | 2 | public function getOutputBOM(): string  | 
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| 200 |     { | 
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| 201 | 2 | return $this->output_bom;  | 
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| 202 | }  | 
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| 203 | |||
| 204 | /**  | 
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| 205 | * Returns the BOM sequence of the given CSV  | 
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| 206 | *  | 
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| 207 | * @return string  | 
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| 208 | */  | 
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| 209 | 16 | public function getInputBOM(): string  | 
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| 210 |     { | 
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| 211 | 16 |         if (null !== $this->input_bom) { | 
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| 212 | 2 | return $this->input_bom;  | 
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| 213 | }  | 
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| 214 | |||
| 215 | 16 | $this->document->setFlags(SplFileObject::READ_CSV);  | 
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| 216 | 16 | $this->document->setCsvControl($this->delimiter, $this->enclosure, $this->escape);  | 
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| 217 | 16 | $this->document->rewind();  | 
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| 218 | 16 |         $this->input_bom = bom_match(implode(',', (array) $this->document->current())); | 
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| 219 | |||
| 220 | 16 | return $this->input_bom;  | 
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| 221 | }  | 
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| 222 | |||
| 223 | /**  | 
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| 224 | * Returns the stream filter mode  | 
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| 225 | *  | 
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| 226 | * @return int  | 
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| 227 | */  | 
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| 228 | 2 | public function getStreamFilterMode(): int  | 
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| 229 |     { | 
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| 230 | 2 | return $this->stream_filter_mode;  | 
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| 231 | }  | 
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| 232 | |||
| 233 | /**  | 
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| 234 | * Tells whether the stream filter capabilities can be used  | 
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| 235 | *  | 
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| 236 | * @return bool  | 
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| 237 | */  | 
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| 238 | 4 | public function supportsStreamFilter(): bool  | 
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| 239 |     { | 
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| 240 | 4 | return $this->document instanceof Stream;  | 
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| 241 | }  | 
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| 242 | |||
| 243 | /**  | 
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| 244 | * Tell whether the specify stream filter is attach to the current stream  | 
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| 245 | *  | 
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| 246 | * @param string $filtername  | 
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| 247 | *  | 
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| 248 | * @return bool  | 
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| 249 | */  | 
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| 250 | 2 | public function hasStreamFilter(string $filtername): bool  | 
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| 254 | |||
| 255 | /**  | 
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| 256 | * Retrieves the CSV content  | 
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| 257 | *  | 
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| 258 | * @return string  | 
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| 259 | */  | 
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| 260 | 12 | public function __toString(): string  | 
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| 269 | |||
| 270 | /**  | 
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| 271 | * Retuns the CSV document as a Generator of string chunk  | 
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| 272 | *  | 
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| 273 | * @param int $length number of bytes read  | 
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| 274 | *  | 
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| 275 | * @return Generator  | 
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| 276 | */  | 
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| 277 | 10 | public function chunk(int $length): Generator  | 
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| 278 |     { | 
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| 279 | 10 |         if ($length < 1) { | 
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| 280 | 2 |             throw new Exception(sprintf('%s() expects the length to be a positive integer %d given', __METHOD__, $length)); | 
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| 281 | }  | 
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| 282 | |||
| 283 | 8 | $input_bom = $this->getInputBOM();  | 
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| 294 | |||
| 295 | /**  | 
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| 296 | * Outputs all data on the CSV file  | 
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| 297 | *  | 
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| 298 | * @param string $filename CSV downloaded name if present adds extra headers  | 
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| 299 | *  | 
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| 300 | * @return int Returns the number of characters read from the handle  | 
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| 301 | * and passed through to the output.  | 
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| 302 | */  | 
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| 303 | 6 | public function output(string $filename = null): int  | 
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| 315 | |||
| 316 | /**  | 
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| 317 | * Send the CSV headers  | 
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| 318 | *  | 
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| 319 | * Adapted from Symfony\Component\HttpFoundation\ResponseHeaderBag::makeDisposition  | 
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| 320 | *  | 
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| 321 | * @param string|null $filename CSV disposition name  | 
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| 322 | *  | 
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| 323 | * @throws Exception if the submitted header is invalid according to RFC 6266  | 
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| 324 | *  | 
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| 325 | * @see https://tools.ietf.org/html/rfc6266#section-4.3  | 
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| 326 | */  | 
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| 327 | 6 | protected function sendHeaders(string $filename)  | 
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| 352 | |||
| 353 | /**  | 
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| 354 | * Sets the field delimiter  | 
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| 355 | *  | 
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| 356 | * @param string $delimiter  | 
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| 357 | *  | 
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| 358 | * @throws Exception If the Csv control character is not one character only.  | 
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| 359 | *  | 
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| 360 | * @return static  | 
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| 361 | */  | 
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| 362 | 12 | public function setDelimiter(string $delimiter): self  | 
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| 377 | |||
| 378 | /**  | 
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| 379 | * Reset dynamic object properties to improve performance  | 
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| 380 | */  | 
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| 381 | 4 | protected function resetProperties()  | 
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| 384 | |||
| 385 | /**  | 
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| 386 | * Sets the field enclosure  | 
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| 387 | *  | 
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| 388 | * @param string $enclosure  | 
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| 389 | *  | 
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| 390 | * @throws Exception If the Csv control character is not one character only.  | 
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| 391 | *  | 
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| 392 | * @return static  | 
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| 393 | */  | 
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| 394 | 2 | public function setEnclosure(string $enclosure): self  | 
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| 409 | |||
| 410 | /**  | 
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| 411 | * Sets the field escape character  | 
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| 412 | *  | 
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| 413 | * @param string $escape  | 
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| 414 | *  | 
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| 415 | * @throws Exception If the Csv control character is not one character only.  | 
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| 416 | *  | 
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| 417 | * @return static  | 
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| 418 | */  | 
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| 419 | 2 | public function setEscape(string $escape): self  | 
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| 434 | |||
| 435 | /**  | 
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| 436 | * Sets the BOM sequence to prepend the CSV on output  | 
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| 437 | *  | 
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| 438 | * @param string $str The BOM sequence  | 
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| 439 | *  | 
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| 440 | * @return static  | 
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| 441 | */  | 
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| 442 | 6 | public function setOutputBOM(string $str): self  | 
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| 448 | |||
| 449 | /**  | 
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| 450 | * append a stream filter  | 
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| 451 | *  | 
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| 452 | * @param string $filtername a string or an object that implements the '__toString' method  | 
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| 453 | * @param mixed $params additional parameters for the filter  | 
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| 454 | *  | 
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| 455 | * @throws Exception If the stream filter API can not be used  | 
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| 456 | *  | 
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| 457 | * @return static  | 
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| 458 | */  | 
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| 459 | 10 | public function addStreamFilter(string $filtername, $params = null): self  | 
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| 472 | }  | 
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| 473 |