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 Markdown 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 Markdown, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 27 | class Markdown extends \cebe\markdown\Parser |
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| 28 | { |
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| 29 | // include block element parsing using traits |
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| 30 | use CodeTrait; |
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| 31 | use HeadlineTrait; |
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| 32 | use ListTrait { |
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| 33 | // Check Ul List before headline |
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| 34 | identifyUl as protected identifyBUl; |
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| 35 | consumeUl as protected consumeBUl; |
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| 36 | } |
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| 37 | use QuoteTrait; |
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| 38 | use RuleTrait { |
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| 39 | // Check Hr before checking lists |
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| 40 | identifyHr as protected identifyAHr; |
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| 41 | consumeHr as protected consumeAHr; |
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| 42 | } |
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| 43 | |||
| 44 | // include inline element parsing using traits |
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| 45 | use InlineCodeTrait; |
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| 46 | use EmphStrongTrait; |
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| 47 | use LinkTrait; |
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| 48 | |||
| 49 | /** |
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| 50 | * @var string this string will be prefixed to all auto generated labels. |
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| 51 | * This can be used to disambiguate labels when combining multiple markdown files into one document. |
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| 52 | */ |
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| 53 | public $labelPrefix = ''; |
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| 54 | |||
| 55 | /** |
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| 56 | * @var array these are "escapeable" characters. When using one of these prefixed with a |
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| 57 | * backslash, the character will be outputted without the backslash and is not interpreted |
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| 58 | * as markdown. |
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| 59 | */ |
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| 60 | protected $escapeCharacters = [ |
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| 61 | '\\', // backslash |
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| 62 | '`', // backtick |
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| 63 | '*', // asterisk |
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| 64 | '_', // underscore |
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| 65 | '{', '}', // curly braces |
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| 66 | '[', ']', // square brackets |
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| 67 | '(', ')', // parentheses |
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| 68 | '#', // hash mark |
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| 69 | '+', // plus sign |
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| 70 | '-', // minus sign (hyphen) |
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| 71 | '.', // dot |
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| 72 | '!', // exclamation mark |
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| 73 | '<', '>', |
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| 74 | ]; |
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| 75 | |||
| 76 | |||
| 77 | /** |
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| 78 | * @inheritDoc |
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| 79 | */ |
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| 80 | 21 | protected function prepare() |
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| 85 | |||
| 86 | /** |
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| 87 | * Consume lines for a paragraph |
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| 88 | * |
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| 89 | * Allow headlines and code to break paragraphs |
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| 90 | */ |
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| 91 | 7 | protected function consumeParagraph($lines, $current) |
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| 112 | |||
| 113 | |||
| 114 | // rendering adjusted for LaTeX output |
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| 115 | |||
| 116 | |||
| 117 | /** |
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| 118 | * @inheritdoc |
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| 119 | */ |
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| 120 | 19 | protected function renderParagraph($block) |
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| 124 | |||
| 125 | /** |
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| 126 | * @inheritdoc |
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| 127 | */ |
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| 128 | 2 | protected function renderQuote($block) |
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| 132 | |||
| 133 | /** |
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| 134 | * @inheritdoc |
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| 135 | */ |
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| 136 | 3 | protected function renderCode($block) |
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| 141 | |||
| 142 | /** |
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| 143 | * @inheritdoc |
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| 144 | */ |
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| 145 | 2 | protected function renderList($block) |
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| 156 | |||
| 157 | /** |
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| 158 | * @inheritdoc |
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| 159 | */ |
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| 160 | 3 | protected function renderHeadline($block) |
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| 170 | |||
| 171 | /** |
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| 172 | * @inheritdoc |
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| 173 | */ |
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| 174 | 2 | protected function renderHr($block) |
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| 178 | |||
| 179 | /** |
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| 180 | * @inheritdoc |
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| 181 | */ |
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| 182 | 2 | protected function renderLink($block) |
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| 205 | |||
| 206 | /** |
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| 207 | * @inheritdoc |
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| 208 | */ |
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| 209 | protected function renderImage($block) |
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| 223 | |||
| 224 | /** |
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| 225 | * Parses <a name="..."></a> tags as reference labels |
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| 226 | */ |
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| 227 | 2 | private function parseInlineHtml($text) |
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| 240 | |||
| 241 | /** |
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| 242 | * renders a reference label |
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| 243 | */ |
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| 244 | 2 | protected function renderLabel($block) |
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| 248 | |||
| 249 | /** |
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| 250 | * @inheritdoc |
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| 251 | */ |
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| 252 | 2 | protected function renderEmail($block) |
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| 257 | |||
| 258 | /** |
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| 259 | * @inheritdoc |
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| 260 | */ |
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| 261 | 2 | protected function renderUrl($block) |
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| 265 | |||
| 266 | /** |
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| 267 | * @inheritdoc |
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| 268 | */ |
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| 269 | 1 | protected function renderInlineCode($block) |
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| 277 | |||
| 278 | /** |
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| 279 | * @inheritdoc |
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| 280 | */ |
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| 281 | 1 | protected function renderStrong($block) |
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| 285 | |||
| 286 | /** |
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| 287 | * @inheritdoc |
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| 288 | */ |
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| 289 | 1 | protected function renderEmph($block) |
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| 293 | |||
| 294 | /** |
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| 295 | * Parses escaped special characters. |
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| 296 | * This allow a backslash to be interpreted as LaTeX |
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| 297 | * @marker \ |
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| 298 | */ |
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| 299 | 1 | protected function parseEscape($text) |
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| 300 | { |
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| 301 | 1 | if (isset($text[1]) && in_array($text[1], $this->escapeCharacters)) { |
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| 302 | 1 | if ($text[1] === '\\') { |
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| 303 | return [['backslash'], 2]; |
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| 304 | } |
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| 305 | 1 | return [['text', $text[1]], 2]; |
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| 306 | } |
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| 307 | return [['text', $text[0]], 1]; |
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| 308 | } |
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| 309 | |||
| 310 | protected function renderBackslash() |
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| 311 | { |
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| 312 | return '\\'; |
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| 313 | } |
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| 314 | |||
| 315 | private $_escaper; |
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| 316 | |||
| 317 | /** |
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| 318 | * Escape special characters in URLs |
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| 319 | */ |
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| 320 | 4 | protected function escapeUrl($string) |
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| 324 | |||
| 325 | /** |
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| 326 | * Escape special LaTeX characters |
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| 327 | */ |
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| 328 | 19 | protected function escapeLatex($string) |
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| 335 | |||
| 336 | /** |
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| 337 | * @inheritdocs |
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| 338 | * |
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| 339 | * Parses a newline indicated by two spaces on the end of a markdown line. |
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| 340 | */ |
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| 341 | 19 | protected function renderText($text) |
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| 352 | } |
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| 353 |
This check looks from parameters that have been defined for a function or method, but which are not used in the method body.