PHP JSON TO CSV Listener using salsify/jsonstreamingparser

JSON2CSV.php

<?php
namespace App\Test\JSONListener;

use \JsonStreamingParser\Listener;

class JSON2CSV implements Listener
{
    private $_current_row;
    private $_outfile;
    private $_key;
    private $_header_written;

    public function __construct($outputFileName)
    {
        $this->_outfile = fopen($outputFileName, 'w');
    }


    public function startDocument()
    {
        $this->_current_row = array();
        $this->_key = null;
        $this->_header_written = false;
    }

    public function endDocument()
    {
        fclose($this->_outfile);
    }

    public function startObject()
    {
        $this->_current_row = array();
    }

    public function endObject()
    {
        if (!$this->_header_written) {
            fputcsv($this->_outfile, array_keys($this->_current_row));
            $this->_header_written = true;
        }
        fputcsv($this->_outfile, $this->_current_row);

    }

    public function startArray()
    {
        $this->startObject();
    }

    public function endArray()
    {
        $this->endObject();
    }

    // Key will always be a string
    public function key($key)
    {
        $this->_key = $key;
    }

    // Note that value may be a string, integer, boolean, null
    public function value($value)
    {

        if ($this->_key) {
            $this->_current_row[$this->_key] = $value;
            $this->_key = null;
        }
    }

    public function whitespace($whitespace)
    {

    }
}