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 Parser 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 Parser, and based on these observations, apply Extract Interface, too.
1 | <?php |
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26 | class Parser extends Tokenizer |
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27 | { |
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28 | |||
29 | /** @var array */ |
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30 | private $data = []; |
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31 | |||
32 | 98 | public function parse($source = null) |
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67 | |||
68 | 98 | private function init($source = null) |
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81 | |||
82 | 96 | protected function parseBody($token = Token::TYPE_QUERY, $highLevel = true) |
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115 | |||
116 | 13 | protected function parseVariables() |
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117 | { |
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118 | 13 | $this->eat(Token::TYPE_LPAREN); |
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119 | |||
120 | 13 | while (!$this->match(Token::TYPE_RPAREN) && !$this->end()) { |
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121 | 13 | $variableToken = $this->eat(Token::TYPE_VARIABLE); |
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122 | 13 | $nameToken = $this->eatIdentifierToken(); |
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123 | 13 | $this->eat(Token::TYPE_COLON); |
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124 | |||
125 | 13 | $isArray = false; |
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126 | 13 | $arrayElementNullable = true; |
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127 | |||
128 | 13 | if ($this->match(Token::TYPE_LSQUARE_BRACE)) { |
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129 | 3 | $isArray = true; |
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130 | |||
131 | 3 | $this->eat(Token::TYPE_LSQUARE_BRACE); |
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132 | 3 | $type = $this->eatIdentifierToken()->getData(); |
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133 | |||
134 | 3 | if ($this->match(Token::TYPE_REQUIRED)) { |
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135 | 2 | $arrayElementNullable = false; |
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136 | 2 | $this->eat(Token::TYPE_REQUIRED); |
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137 | } |
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138 | |||
139 | 3 | $this->eat(Token::TYPE_RSQUARE_BRACE); |
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140 | } else { |
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141 | 12 | $type = $this->eatIdentifierToken()->getData(); |
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142 | } |
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143 | |||
144 | 13 | $required = false; |
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145 | 13 | if ($this->match(Token::TYPE_REQUIRED)) { |
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146 | 2 | $required = true; |
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147 | 2 | $this->eat(Token::TYPE_REQUIRED); |
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148 | } |
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149 | |||
150 | 13 | $variable = new Variable( |
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151 | 13 | $nameToken->getData(), |
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152 | $type, |
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153 | $required, |
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154 | $isArray, |
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155 | 13 | new Location($variableToken->getLine(), $variableToken->getColumn()), |
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156 | 13 | $arrayElementNullable |
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157 | ); |
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158 | |||
159 | 13 | if ($this->match(Token::TYPE_EQUAL)) { |
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160 | 1 | $this->eat(Token::TYPE_EQUAL); |
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161 | 1 | $variable->setDefaultValue($this->parseValue()); |
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162 | } |
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163 | |||
164 | 13 | $this->data['variables'][] = $variable; |
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165 | } |
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166 | |||
167 | 13 | $this->expect(Token::TYPE_RPAREN); |
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168 | 13 | } |
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169 | |||
170 | 93 | protected function expectMulti($types) |
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178 | |||
179 | 12 | protected function parseVariableReference() |
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180 | { |
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181 | 12 | $startToken = $this->expectMulti([Token::TYPE_VARIABLE]); |
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182 | |||
183 | 12 | if ($this->match(Token::TYPE_NUMBER) || $this->match(Token::TYPE_IDENTIFIER) || $this->match(Token::TYPE_QUERY)) { |
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184 | 12 | $name = $this->lex()->getData(); |
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185 | |||
186 | 12 | $variable = $this->findVariable($name); |
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187 | 12 | if ($variable) { |
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188 | 12 | $variable->setUsed(true); |
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189 | } |
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190 | |||
191 | 12 | $variableReference = new VariableReference($name, $variable, new Location($startToken->getLine(), $startToken->getColumn())); |
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192 | |||
193 | 12 | $this->data['variableReferences'][] = $variableReference; |
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194 | |||
195 | 12 | return $variableReference; |
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196 | } |
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197 | |||
198 | throw $this->createUnexpectedException($this->peek()); |
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199 | } |
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200 | |||
201 | 12 | protected function findVariable($name) |
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202 | { |
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203 | 12 | foreach ($this->data['variables'] as $variable) { |
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204 | /** @var $variable Variable */ |
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205 | 12 | if ($variable->getName() == $name) { |
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206 | 12 | return $variable; |
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207 | } |
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208 | } |
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209 | |||
210 | return null; |
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211 | } |
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212 | |||
213 | 8 | protected function parseFragmentReference() |
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222 | |||
223 | 93 | protected function eatIdentifierToken() |
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224 | { |
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225 | 93 | return $this->expectMulti([ |
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226 | 93 | Token::TYPE_IDENTIFIER, |
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227 | 93 | Token::TYPE_MUTATION, |
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228 | 93 | Token::TYPE_QUERY, |
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229 | 93 | Token::TYPE_FRAGMENT, |
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230 | ]); |
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231 | } |
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232 | |||
233 | 93 | protected function parseBodyItem($type = Token::TYPE_QUERY, $highLevel = true) |
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234 | { |
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235 | 93 | $nameToken = $this->eatIdentifierToken(); |
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236 | 93 | $alias = null; |
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237 | |||
238 | 93 | if ($this->eat(Token::TYPE_COLON)) { |
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239 | 17 | $alias = $nameToken->getData(); |
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240 | 17 | $nameToken = $this->eatIdentifierToken(); |
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241 | } |
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242 | |||
243 | 93 | $bodyLocation = new Location($nameToken->getLine(), $nameToken->getColumn()); |
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244 | 93 | $arguments = $this->match(Token::TYPE_LPAREN) ? $this->parseArgumentList() : []; |
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245 | |||
246 | 86 | if ($this->match(Token::TYPE_LBRACE)) { |
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247 | 57 | $fields = $this->parseBody($type == Token::TYPE_TYPED_FRAGMENT ? Token::TYPE_QUERY : $type, false); |
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248 | |||
249 | 56 | if (!$fields) { |
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250 | 3 | throw $this->createUnexpectedTokenTypeException($this->lookAhead->getType()); |
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251 | } |
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252 | |||
253 | 55 | View Code Duplication | if ($type == Token::TYPE_QUERY) { |
254 | 53 | return new Query($nameToken->getData(), $alias, $arguments, $fields, $bodyLocation); |
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255 | 6 | } elseif ($type == Token::TYPE_TYPED_FRAGMENT) { |
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256 | 3 | return new TypedFragmentReference($nameToken->getData(), $fields, $bodyLocation); |
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257 | } else { |
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258 | 3 | return new Mutation($nameToken->getData(), $alias, $arguments, $fields, $bodyLocation); |
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259 | } |
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260 | View Code Duplication | } else { |
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261 | 84 | if ($highLevel && $type == Token::TYPE_MUTATION) { |
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262 | 10 | return new Mutation($nameToken->getData(), $alias, $arguments, [], $bodyLocation); |
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263 | 75 | } elseif ($highLevel && $type == Token::TYPE_QUERY) { |
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264 | 24 | return new Query($nameToken->getData(), $alias, $arguments, [], $bodyLocation); |
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265 | } |
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266 | |||
267 | 55 | return new Field($nameToken->getData(), $alias, $arguments, $bodyLocation); |
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268 | } |
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269 | } |
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270 | |||
271 | 56 | protected function parseArgumentList() |
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272 | { |
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273 | 56 | $args = []; |
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274 | |||
275 | 56 | $this->expect(Token::TYPE_LPAREN); |
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276 | |||
277 | 56 | while (!$this->match(Token::TYPE_RPAREN) && !$this->end()) { |
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278 | 56 | $args[] = $this->parseArgument(); |
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279 | } |
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280 | |||
281 | 50 | $this->expect(Token::TYPE_RPAREN); |
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282 | |||
283 | 49 | return $args; |
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284 | } |
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285 | |||
286 | 56 | protected function parseArgument() |
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294 | |||
295 | /** |
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296 | * @return array|InputList|InputObject|Literal|VariableReference |
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297 | * |
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298 | * @throws SyntaxErrorException |
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299 | */ |
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300 | 55 | protected function parseValue() |
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301 | { |
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302 | 55 | switch ($this->lookAhead->getType()) { |
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303 | 55 | case Token::TYPE_LSQUARE_BRACE: |
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304 | 7 | return $this->parseList(); |
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305 | |||
306 | 48 | case Token::TYPE_LBRACE: |
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307 | 8 | return $this->parseObject(); |
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308 | |||
309 | 40 | case Token::TYPE_VARIABLE: |
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310 | 12 | return $this->parseVariableReference(); |
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311 | |||
312 | 33 | case Token::TYPE_NUMBER: |
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313 | 25 | case Token::TYPE_STRING: |
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314 | 11 | case Token::TYPE_IDENTIFIER: |
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315 | 8 | case Token::TYPE_NULL: |
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316 | 5 | case Token::TYPE_TRUE: |
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317 | 1 | case Token::TYPE_FALSE: |
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318 | 32 | $token = $this->lex(); |
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319 | |||
320 | 32 | return new Literal($token->getData(), new Location($token->getLine(), $token->getColumn())); |
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321 | } |
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322 | |||
323 | 1 | throw $this->createUnexpectedException($this->lookAhead); |
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324 | } |
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325 | |||
326 | 9 | protected function parseList($createType = true) |
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327 | { |
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328 | 9 | $startToken = $this->eat(Token::TYPE_LSQUARE_BRACE); |
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329 | |||
330 | 9 | $list = []; |
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331 | 9 | while (!$this->match(Token::TYPE_RSQUARE_BRACE) && !$this->end()) { |
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332 | 9 | $list[] = $this->parseListValue(); |
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333 | } |
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334 | |||
335 | 8 | $this->expect(Token::TYPE_RSQUARE_BRACE); |
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336 | |||
337 | 8 | return $createType ? new InputList($list, new Location($startToken->getLine(), $startToken->getColumn())) : $list; |
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338 | } |
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339 | |||
340 | 15 | protected function parseListValue() |
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341 | { |
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342 | 15 | switch ($this->lookAhead->getType()) { |
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343 | 15 | case Token::TYPE_NUMBER: |
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344 | 11 | case Token::TYPE_STRING: |
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345 | 9 | case Token::TYPE_TRUE: |
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346 | 9 | case Token::TYPE_FALSE: |
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347 | 9 | case Token::TYPE_NULL: |
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348 | 6 | case Token::TYPE_IDENTIFIER: |
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349 | 14 | return $this->expect($this->lookAhead->getType())->getData(); |
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350 | |||
351 | 5 | case Token::TYPE_VARIABLE: |
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352 | return $this->parseVariableReference(); |
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353 | |||
354 | 5 | case Token::TYPE_LBRACE: |
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355 | 4 | return $this->parseObject(true); |
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356 | |||
357 | 3 | case Token::TYPE_LSQUARE_BRACE: |
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358 | 2 | return $this->parseList(false); |
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359 | } |
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360 | |||
361 | 1 | throw new SyntaxErrorException('Can\'t parse argument', $this->getLocation()); |
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362 | } |
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363 | |||
364 | 9 | protected function parseObject($createType = true) |
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365 | { |
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366 | 9 | $startToken = $this->eat(Token::TYPE_LBRACE); |
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367 | |||
368 | 9 | $object = []; |
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369 | 9 | while (!$this->match(Token::TYPE_RBRACE) && !$this->end()) { |
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370 | 9 | $key = $this->expectMulti([Token::TYPE_STRING, Token::TYPE_IDENTIFIER])->getData(); |
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371 | 9 | $this->expect(Token::TYPE_COLON); |
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372 | 9 | $value = $this->parseListValue(); |
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373 | |||
374 | 9 | $object[$key] = $value; |
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375 | } |
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376 | |||
377 | 7 | $this->eat(Token::TYPE_RBRACE); |
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378 | |||
379 | 7 | return $createType ? new InputObject($object, new Location($startToken->getLine(), $startToken->getColumn())) : $object; |
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380 | } |
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381 | |||
382 | 8 | protected function parseFragment() |
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394 | |||
395 | 95 | protected function eat($type) |
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403 | |||
404 | protected function eatMulti($types) |
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412 | |||
413 | 93 | protected function matchMulti($types) |
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414 | { |
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415 | 93 | foreach ($types as $type) { |
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416 | 93 | if ($this->peek()->getType() == $type) { |
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417 | 93 | return true; |
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418 | } |
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419 | } |
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420 | |||
421 | 2 | return false; |
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422 | } |
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423 | } |
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424 |
This check marks implicit conversions of arrays to boolean values in a comparison. While in PHP an empty array is considered to be equal (but not identical) to false, this is not always apparent.
Consider making the comparison explicit by using
empty(..)
or! empty(...)
instead.