File: src/eMacros/Runtime/Collection/Car.php

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File: src/eMacros/Runtime/Collection/Car.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: 1,279 bytes
 

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

use
eMacros\Runtime\GenericFunction;

class
Car extends GenericFunction {
   
/**
     * Returns the head element on a list
     * Usage: (Array:car (array 1 2 3))
     * Returns: mixed
     * (non-PHPdoc)
     * @see \eMacros\Runtime\GenericFunction::execute()
     */
   
public function execute(array $arguments) {
        if (empty(
$arguments)) {
            throw new \
BadFunctionCallException("Car: No parameters found.");
        }
       
        list(
$list) = $arguments;
       
        if (
$list instanceof \Iterator) {
           
$list->rewind();
           
$value = $list->valid() ? $list->current() : null;
        }
        elseif (
$list instanceof \IteratorAggregate) {
           
$iter = $list->getIterator();
           
$iter->rewind();
           
$value = $iter->valid() ? $iter->current() : null;
        }
        elseif (
is_array($list)) {
           
$value = !empty($list) ? array_shift($list) : null;
        }
        elseif (
$list instanceof \ArrayAccess) {
           
//cannot ensure which is the first element, return index 0
           
$value = isset($list[0]) ? $list[0] : null;
        }
        else {
            throw new \
InvalidArgumentException('Car: Parameter is not a list.');
        }
       
        return
$value;
    }
}

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