Complex classes like MarkdownParser 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 MarkdownParser, and based on these observations, apply Extract Interface, too.
1 | <?php |
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34 | final class MarkdownParser implements MarkdownParserInterface |
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35 | { |
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36 | /** |
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37 | * @var EnvironmentInterface |
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38 | * |
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39 | * @psalm-readonly |
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40 | */ |
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41 | private $environment; |
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42 | |||
43 | /** |
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44 | * @var int|float |
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45 | * |
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46 | * @psalm-readonly |
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47 | */ |
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48 | private $maxNestingLevel; |
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49 | |||
50 | /** |
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51 | * @var ReferenceMap |
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52 | * |
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53 | * @psalm-readonly-allow-private-mutation |
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54 | */ |
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55 | private $referenceMap; |
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56 | |||
57 | /** |
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58 | * @var int |
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59 | * |
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60 | * @psalm-readonly-allow-private-mutation |
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61 | */ |
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62 | private $lineNumber = 0; |
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63 | |||
64 | /** |
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65 | * @var Cursor |
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66 | * |
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67 | * @psalm-readonly-allow-private-mutation |
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68 | */ |
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69 | private $cursor; |
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70 | |||
71 | /** |
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72 | * @var array<int, BlockContinueParserInterface> |
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73 | * |
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74 | * @psalm-readonly-allow-private-mutation |
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75 | */ |
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76 | private $allBlockParsers = []; |
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77 | |||
78 | /** |
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79 | * @var array<int, BlockContinueParserInterface> |
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80 | * |
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81 | * @psalm-readonly-allow-private-mutation |
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82 | */ |
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83 | private $activeBlockParsers = []; |
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84 | |||
85 | 2511 | public function __construct(EnvironmentInterface $environment) |
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90 | |||
91 | 2502 | private function initialize(): void |
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98 | |||
99 | /** |
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100 | * @throws \RuntimeException |
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101 | */ |
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102 | 2502 | public function parse(string $input): Document |
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125 | |||
126 | /** |
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127 | * Analyze a line of text and update the document appropriately. We parse markdown text by calling this on each |
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128 | * line of input, then finalizing the document. |
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129 | */ |
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130 | 2496 | private function incorporateLine(string $line): void |
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131 | { |
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132 | 2496 | $this->cursor = new Cursor($line); |
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133 | |||
134 | 2496 | $matches = 1; |
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135 | 2496 | foreach ($this->getActiveBlockParsers(1) as $blockParser) { |
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136 | \assert($blockParser instanceof BlockContinueParserInterface); |
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137 | 1302 | $blockContinue = $blockParser->tryContinue(clone $this->cursor, $this->getActiveBlockParser()); |
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138 | 1302 | if ($blockContinue === null) { |
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139 | 828 | break; |
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140 | } |
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141 | |||
142 | 900 | if ($blockContinue->isFinalize()) { |
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143 | 87 | $this->finalizeAndClose($blockParser, $this->lineNumber); |
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144 | |||
145 | 87 | return; |
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146 | } |
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147 | |||
148 | 894 | if (($state = $blockContinue->getCursorState()) !== null) { |
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149 | 894 | $this->cursor->restoreState($state); |
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150 | } |
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151 | |||
152 | 894 | $matches++; |
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153 | } |
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154 | |||
155 | 2496 | $unmatchedBlockParsers = $this->getActiveBlockParsers($matches); |
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156 | 2496 | $lastMatchedBlockParser = $this->getActiveBlockParsers()[$matches - 1]; |
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157 | 2496 | $blockParser = $lastMatchedBlockParser; |
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158 | 2496 | $allClosed = empty($unmatchedBlockParsers); |
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159 | |||
160 | // Unless last matched container is a code block, try new container starts |
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161 | 2496 | $tryBlockStarts = $blockParser->getBlock() instanceof Paragraph || $blockParser->isContainer(); |
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162 | 2496 | while ($tryBlockStarts) { |
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163 | // this is a little performance optimization |
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164 | 2496 | if ($this->cursor->isBlank()) { |
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165 | 630 | $this->cursor->advanceToEnd(); |
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166 | 630 | break; |
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167 | } |
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168 | |||
169 | 2496 | if (! $this->cursor->isIndented() && RegexHelper::isLetter($this->cursor->getNextNonSpaceCharacter())) { |
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170 | 1023 | $this->cursor->advanceToNextNonSpaceOrTab(); |
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171 | 1023 | break; |
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172 | } |
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173 | |||
174 | 2112 | if ($blockParser->getBlock()->getDepth() >= $this->maxNestingLevel) { |
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175 | 3 | break; |
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176 | } |
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177 | |||
178 | 2112 | $blockStart = $this->findBlockStart($blockParser); |
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179 | 2112 | if ($blockStart === null) { |
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180 | 1299 | $this->cursor->advanceToNextNonSpaceOrTab(); |
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181 | 1299 | break; |
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182 | } |
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183 | |||
184 | 954 | if (($state = $blockStart->getCursorState()) !== null) { |
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185 | 954 | $this->cursor->restoreState($state); |
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186 | } |
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187 | |||
188 | 954 | if (! $allClosed) { |
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189 | 210 | $this->finalizeBlocks($unmatchedBlockParsers, $this->lineNumber - 1); |
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190 | 210 | $allClosed = true; |
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191 | } |
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192 | |||
193 | 954 | if ($blockStart->isReplaceActiveBlockParser()) { |
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194 | 132 | $this->prepareActiveBlockParserForReplacement(); |
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195 | } |
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196 | |||
197 | 954 | foreach ($blockStart->getBlockParsers() as $newBlockParser) { |
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198 | 954 | $blockParser = $this->addChild($newBlockParser); |
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199 | 954 | $tryBlockStarts = $newBlockParser->isContainer(); |
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200 | } |
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201 | } |
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202 | |||
203 | // What remains ath the offset is a text line. Add the text to the appropriate block. |
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204 | |||
205 | // First check for a lazy paragraph continuation: |
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206 | 2496 | if (! $allClosed && ! $this->cursor->isBlank() && $this->getActiveBlockParser()->canHaveLazyContinuationLines()) { |
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207 | 48 | $this->getActiveBlockParser()->addLine($this->cursor->getRemainder()); |
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208 | } else { |
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209 | // finalize any blocks not matched |
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210 | 2496 | if (! $allClosed) { |
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211 | 669 | $this->finalizeBlocks($unmatchedBlockParsers, $this->lineNumber); |
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212 | } |
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213 | |||
214 | 2496 | if (! $blockParser->isContainer()) { |
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215 | 981 | $this->getActiveBlockParser()->addLine($this->cursor->getRemainder()); |
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216 | 2181 | } elseif (! $this->cursor->isBlank()) { |
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217 | 2133 | $this->addChild(new ParagraphParser()); |
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218 | 2133 | $this->getActiveBlockParser()->addLine($this->cursor->getRemainder()); |
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219 | } |
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220 | } |
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221 | 2496 | } |
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222 | |||
223 | 2112 | private function findBlockStart(BlockContinueParserInterface $lastMatchedBlockParser): ?BlockStart |
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224 | { |
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225 | 2112 | $matchedBlockParser = new MarkdownParserState($this->getActiveBlockParser(), $lastMatchedBlockParser); |
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226 | |||
227 | 2112 | foreach ($this->environment->getBlockStartParsers() as $blockStartParser) { |
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228 | \assert($blockStartParser instanceof BlockStartParserInterface); |
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229 | 2109 | if (($result = $blockStartParser->tryStart(clone $this->cursor, $matchedBlockParser)) !== null) { |
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230 | 954 | return $result; |
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231 | } |
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232 | } |
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233 | |||
234 | 1299 | return null; |
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235 | } |
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236 | |||
237 | /** |
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238 | * @param array<int, BlockContinueParserInterface> $blockParsers |
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239 | */ |
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240 | 2496 | private function finalizeBlocks(array $blockParsers, int $endLineNumber): void |
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246 | |||
247 | /** |
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248 | * Finalize a block. Close it and do any necessary postprocessing, e.g. creating string_content from strings, |
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249 | * setting the 'tight' or 'loose' status of a list, and parsing the beginnings of paragraphs for reference |
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250 | * definitions. |
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251 | */ |
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252 | 2496 | private function finalizeAndClose(BlockContinueParserInterface $blockParser, int $endLineNumber): void |
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265 | |||
266 | /** |
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267 | * Walk through a block & children recursively, parsing string content into inline content where appropriate. |
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268 | */ |
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269 | 2496 | private function processInlines(): void |
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270 | { |
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271 | 2496 | $p = new InlineParserEngine($this->environment, $this->referenceMap); |
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272 | |||
273 | 2496 | foreach ($this->allBlockParsers as $blockParser) { |
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274 | \assert($blockParser instanceof BlockContinueParserInterface); |
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275 | 2496 | $blockParser->parseInlines($p); |
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276 | } |
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277 | 2496 | } |
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278 | |||
279 | /** |
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280 | * Add block of type tag as a child of the tip. If the tip can't accept children, close and finalize it and try |
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281 | * its parent, and so on til we find a block that can accept children. |
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282 | */ |
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283 | 2496 | private function addChild(BlockContinueParserInterface $blockParser): BlockContinueParserInterface |
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296 | |||
297 | 2502 | private function activateBlockParser(BlockContinueParserInterface $blockParser): void |
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302 | |||
303 | 2496 | private function deactivateBlockParser(): BlockContinueParserInterface |
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312 | |||
313 | 132 | private function prepareActiveBlockParserForReplacement(): void |
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325 | |||
326 | /** |
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327 | * @param ReferenceInterface[] $references |
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328 | */ |
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329 | 2133 | private function updateReferenceMap(iterable $references): void |
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337 | |||
338 | /** |
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339 | * @return array<int, BlockContinueParserInterface> |
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340 | */ |
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341 | 2496 | private function getActiveBlockParsers(?int $offset = 0): array |
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349 | |||
350 | 2496 | public function getActiveBlockParser(): BlockContinueParserInterface |
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359 | } |
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360 |
PHP Analyzer performs a side-effects analysis of your code. A side-effect is basically anything that might be visible after the scope of the method is left.
Let’s take a look at an example:
If we look at the
getEmail()
method, we can see that it has no side-effect. Whether you call this method or not, no future calls to other methods are affected by this. As such code as the following is useless:On the hand, if we look at the
setEmail()
, this method _has_ side-effects. In the following case, we could not remove the method call: