File: src/eMacros/Symbol.php

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File: src/eMacros/Symbol.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: 1,199 bytes
 

Contents

Class file image Download
<?php
namespace eMacros;

class
Symbol implements Expression {
   
/**
     * Symbol expression
     * @var string
     */
   
public $symbol;
   
   
/**
     * Symbol package
     * @var NULL|string
     */
   
public $package;
   
   
/**
     * Package prefix regex
     * @var string
     */
   
const PACKAGE_PREFIX = '/^([a-z|A-Z|_][\w]+)::/';
   
   
/**
     * Symbol validation regex
     * @var string
     */
   
const PATTERN = '{^[^\s\d(){}\[\]"\';][^\s\'"(){}\[\];]*$}';

    public static function
validateSymbol($symbol) {
        if (!
is_string($symbol)) {
            throw new \
UnexpectedValueException(sprintf("Symbol: unexpected value of type '%s'.", gettype($symbol)));
        }
       
        if (!
preg_match(self::PATTERN, $symbol)) {
            throw new \
UnexpectedValueException(sprintf("Symbol: '%s' is not a valid symbol.", $symbol));
        }
   
        return
$symbol;
    }
   
    public function
__construct($symbol) {
       
//obtain package, if any
       
if (preg_match(self::PACKAGE_PREFIX, $symbol, $matches)) {
           
$this->package = $matches[1];
           
$symbol = substr($symbol, strlen($this->package) + 2);
        }

       
$this->symbol = self::validateSymbol($symbol);
    }
   
    public function
evaluate(Scope $scope) {
        return
$scope[$this];
    }
   
    public function
__toString() {
        return
$this->symbol;
    }
}
?>

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