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<?php |
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namespace Desmond; |
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use Desmond\functions\EnvLoader; |
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use Desmond\data_types\ListType; |
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use Desmond\data_types\VectorType; |
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use Desmond\data_types\HashType; |
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use Desmond\data_types\SymbolType; |
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use Desmond\data_types\LambdaType; |
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use Exception; |
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class Evaluator |
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{ |
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private $coreEnv; |
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public $currentEnv; |
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154 |
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public function __construct() |
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{ |
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154 |
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$this->coreEnv = new Environment(); |
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$this->currentEnv = $this->coreEnv; |
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EnvLoader::loadInto($this->coreEnv, 'core'); |
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} |
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public function getReturn($ast) |
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{ |
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if ($ast instanceof ListType) { |
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return $this->evalForm($ast); |
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} else if ($ast instanceof VectorType || $ast instanceof HashType) { |
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return $this->evalCollection($ast); |
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} else { |
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return $this->evalAtom($ast); |
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} |
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} |
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private function evalForm($form) |
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{ |
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if ($form->get(0) instanceof ListType || $this->getReturn($form->get(0)) instanceof LambdaType) { |
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$function = $this->getReturn($form->get(0)); |
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} else { |
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$function = $form->getFunction()->value(); |
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} |
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return $this->doSpecialForm($function, $form->getArgs()); |
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} |
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public function evalCollection($ast) |
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{ |
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$collection = $ast; |
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foreach ($collection->value() as $key => $value) { |
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$collection->set($this->getReturn($value), $key); |
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} |
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return $collection; |
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} |
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private function doSpecialForm($function, $args) |
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{ |
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$possibilities = $this->specialFunctionList($function); |
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$functionName = null; |
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foreach ($possibilities as $possibility) { |
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if ($possibility[0]) { |
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$functionName = $possibility[1]; |
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break; |
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} |
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} |
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$functionName = $functionName ? $functionName : 'EnvironmentFunction'; |
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return call_user_func_array( |
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"Desmond\\functions\\special\\{$functionName}::run", |
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[$args, $function, &$this->currentEnv, $this]); |
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} |
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private function specialFunctionList($function) |
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{ |
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return [ |
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[$function == 'quote', 'Quote'], |
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[$function == 'quasiquote', 'Quasiquote'], |
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[$function == 'define', 'DefineSymbol'], |
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[$function == 'let', 'Let'], |
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[$function == 'do', 'DoBlock'], |
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[$function == 'if', 'Conditional'], |
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[$function == 'lambda', 'CreateLambda'], |
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[($function instanceof LambdaType), 'RunLambda'], |
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[$function == 'load-file', 'LoadFile'], |
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[$function == 'eval', 'EvalBlock'] |
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]; |
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} |
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152 |
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private function evalAtom($atom) |
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{ |
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if (!($atom instanceof SymbolType)) { |
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return $atom; |
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} |
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try { |
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$value = $this->currentEnv->get($atom->value()); |
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return $value; |
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} catch (Exception $exeption) { |
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return $atom; |
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} |
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} |
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} |
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Archer70 /
desmond
