errant/tacit

<?php
namespace Tacit;
/**
 * Implements a basic Stack
 *
 * @author Tom Morton
 */
class Stack {

    protected $size;
    protected $stack = array();
    protected $memory;

    /**
     * @param Memory\Store $memory
     */
    public function __construct($memory, $stackSize=128) {

        if(!is_integer($stackSize)) {
            throw new \Exception('Stack size must be specified as an integer');
        }

        $this->size = $stackSize;
        $this->memory = $memory;
    }

    public function push($value)
    {
        if(count($this->stack) >= $this->size) {
            throw new \Exception('Stack Overflow');
        }

        $this->memory->reserveBytes(count($value));

        $this->stack[] = $value;
    }

    public function pop()
    {
        if(count($this->stack) == 0) {
            throw new \Exception('Stack Empty');
        }

        $value = array_pop($this->stack);

        $this->memory->releaseBytes(count($value));

        return $value;
    }

    public function clear()
    {
        $data = $this->stack;
        $this->stack = array();
        $this->memory->releaseBytes(count($data));
        return $data;
    }

    public function describe()
    {
        return $this->stack;
    }
}