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<?php |
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namespace Desmond; |
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use Exception; |
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class Environment |
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{ |
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public $values = []; |
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private $upperEnv = null; |
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343 |
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public function __construct(Environment $upperEnvironment=null) |
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{ |
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343 |
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$this->upperEnv = $upperEnvironment; |
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343 |
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} |
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340 |
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public function set($key, $val) |
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{ |
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$this->values[$key] = $val; |
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340 |
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} |
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334 |
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public function exists($key) |
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{ |
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return null !== $this->find($key); |
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} |
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public function get($key) |
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{ |
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if ($this->exists($key)) { |
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$envWithKey = $this->find($key); |
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return $envWithKey->values[$key]; |
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} else { |
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throw new Exception('Symbol "' . $key . '" not found in environment.'); |
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} |
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} |
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334 |
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public function find($key) |
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{ |
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if (array_key_exists($key, $this->values)) { |
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return $this; |
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} else if (null !== $this->upperEnv) { |
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return $this->upperEnv->find($key); |
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} else { |
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return null; |
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} |
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} |
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public function makeChild() |
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{ |
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$newEnvId = Environment::getNewEnvId($this->values); |
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$newEnv = new Environment($this); |
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$this->set($newEnvId, $newEnv); |
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return $newEnvId; |
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} |
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public function getParent() |
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{ |
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return $this->upperEnv; |
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} |
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public function destroyChild($child) |
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{ |
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unset($this->values[$child]); |
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} |
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public static function getNewEnvId($values) |
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{ |
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do { |
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$envId = 'let_' . mt_rand(); // Most probably, this will only happen once. |
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} while (array_key_exists($envId, $values)); |
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return $envId; |
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} |
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} |
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Archer70 /
desmond
