File: src/eMacros/Runtime/Symbol/SymbolExists.php

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File: src/eMacros/Runtime/Symbol/SymbolExists.php
Role: Class source
Content type: text/plain
Description: Class source
Class: eMacros
PHP LISP language interpreter
Author: By
Last change:
Date: 7 years ago
Size: 788 bytes
 

Contents

Class file image Download
<?php
namespace eMacros\Runtime\Symbol;

use
eMacros\Applicable;
use
eMacros\Scope;
use
eMacros\GenericList;

class
SymbolExists implements Applicable {
   
/**
     * Checks if the given symbol exists on current environment
     * Usage: (sym-exists "true") (sym-exists "_value")
     * Returns: boolean
     * (non-PHPdoc)
     * @see \eMacros\Applicable::apply()
     */
   
public function apply(Scope $scope, GenericList $arguments) {
        if (
count($arguments) == 0) {
            throw new \
BadFunctionCallException("SymbolExists: No parameters found.");
        }
       
       
$ref = $arguments[0]->evaluate($scope);
       
        if (!
is_string($ref) || empty($ref)) {
            throw new \
InvalidArgumentException("SymbolExists: Symbol must be specified as a non-empty string.");
        }
       
        return
array_key_exists($ref, $scope->symbols);
    }
}
?>

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