A JSON encoder class to encode and process large data sets

LargeJSONEncode.php

<?php

namespace LargeJson;

class JSONEncoder {
  protected static $whiteSpace = ' ';
  protected static $indentation = 2;
  protected static $inline = false;

  /**
   * Globally set to use tabs
   *
   * Call with `false` to switch to spaces back.
   *
   */
  public static function tabs(bool $useTabs = true) {
    static::$whiteSpace = $useTabs ? "\t" : ' ';
  }

  /**
   * Globally set how much to indent for pretty print
   *
   * Use `0` to disable pretty print.
   *
   */
  public static function indent(int $indentation) {
    assert($indentation >= 0, 'indentation is non-negative failed');

    static::$indentation = $indentation;
  }

  protected static function paddingByLevel(int $level) {
    if (static::$inline) {
      return '';
    }

    return str_repeat(static::$whiteSpace, $level * static::$indentation);
  }

  protected static function newLine() {
    return static::$indentation > 0 && !static::$inline ? "\n" : '';
  }

  protected static function allScallar(array $array) {
    foreach ($array as &$value) {
      if (is_array($value) || is_object($value)) {
        return false;
      }
    }

    return true;
  }

  /**
   * Encode data to JSON with callback
   *
   * Use callback function to further process part of the encoded JSON string.
   * Callback is expected to have 1 string attribute.
   */
  public static function encode($data, callable $append, int $level = 0) {
    if (!is_array($data) && !is_object($data)) {
      $append(json_encode($data));
    }

    $padding = static::paddingByLevel($level);
    $innerPadding = static::paddingByLevel($level + 1);
    $newLine = static::newLine();

    if ($level === 200) {
      $append(str_replace($newLine, "${$newLine}${padding}  ", json_encode($data, JSON_PRETTY_PRINT)));
    }

    $isObject = is_object($data);

    $keys = array_keys((array) $data);
    $hasKeys = $isObject || is_string($keys[0]);

    $append(($hasKeys ? "{" : "[").$newLine);

      foreach ($keys as $index => $key) {
        $append($hasKeys
        ? "${innerPadding}\"${key}\":".($newLine ? ' ' : '')
        : "${innerPadding}"
      );

      if ($isObject) {
        $value =& $data->{$key};
      } else {
        $value =& $data[$key];
      }

      if (is_array($value) || is_object($value)) {
        if (is_array($value) && static::allScallar($value)) {
          static::$inline = true;
          static::encode($value, $append, 0);
          static::$inline = false;
        } else {
          static::encode($value, $append, $level + 1);
        }
      } else {
        $append(json_encode($value));
      }

      if ($index <= count($keys) - 2) {
        $append(",".(static::$inline ? ' ' : ''));
      }

      $append($newLine);
    }

    $append($hasKeys ? "${padding}}" : "${padding}]");
  }
}