Parser for json-like format in PHP

Question

At work they use a format similar to JSON but without quotes that looks like this:

{foo:{qux:1,quux:0}, bar:{}}

The reason they don't just use json is because the C# package Newtonsoft.Json can deserialize this like if it was regular json and it works. I need to use it in Php but json_decode is not as forgiving.

So here's my attempt at a simple parser:

<?php
namespace Foo\Bar;
class NotJsonParser
{
 const STEP_NAME = 0;
 const STEP_VALUE = 1;
 /**
 * @param $string
 * @return array
 */
 public static function parseNotJSON($string)
 {
 $generator = self::stringIterator($string);
 $data = self::parser($generator);
 return $data[''];
 }
 /**
 * @param \Generator $generator
 * @return array
 */
 private static function parser(\Generator $generator)
 {
 $data = [];
 $step = self::STEP_NAME;
 $name = '';
 $value = '';
 while ($generator->valid()) {
 $i = $generator->current();
 switch ($i) {
 case ' ':
 case "\n":
 continue;
 case '{':
 $generator->next();
 $value = self::parser($generator);
 $data[$name] = $value;
 $step = self::STEP_NAME;
 $name = '';
 $value = '';
 break;
 case '}':
 if ($name) {
 $data[$name] = $value;
 }
 return $data;
 case ',':
 if ($name) {
 $data[$name] = $value;
 }
 $step = self::STEP_NAME;
 $name = '';
 $value = '';
 break;
 case ':':
 $step = self::STEP_VALUE;
 break;
 default:
 if ($step === self::STEP_NAME) {
 $name .= $i;
 } else {
 $value .= $i;
 }
 }
 $generator->next();
 }
 return $data;
 }
 /**
 * @param string $str
 * @return \Generator
 */
 private static function stringIterator($str)
 {
 for ($i = 0; $i < strlen($str); $i++) {
 yield $str[$i];
 }
 }
}

And here's the usage:

>>> $result = \Foo\Bar\NotJsonParser::parseNotJSON("{foo:{qux:1,quux:0}, bar:{}}");
=> [
 "foo" => [
 "qux" => "1",
 "quux" => "0",
 ],
 "bar" => [],
 ]

How could I improve this? I know it really lacks error handling. I don't mind that the numbers stay as strings. Also the format never goes more than 2 levels deep. Whitespace between tokens is non important but there shouldn't be whitespace inside the keys (e.g.: {foo bar: baz} should be an error).

Also how should I encode it back from an array to a string? I was thinking just using json_encode and then removing the quote characters.

Answer 1

The following workaround will wrap your keys and values with double quotes. Such hacks will always be vulnerable to edge cases. To avoid sprinting down a rabbit hole of possibilities (I can think of a few cases off the top of my head -- 1. keys/values already containing quotes 2. declared empty/null keys ...there will be more), I'll just provide a solution for your sample input.

For now, I'm using \w to ensure that the space before bar is not included. There are several ways to do this action, but I would need to have intimate knowledge of your project data to develop the expression that I feel is "best / most robust".

If you discover any fringe cases that break this simple regex pattern, please update your question and I can create a patch.

Code: (Demo)

$unquoted_json = <<<NOTJSON
{foo:{qux:1,quux:0}, bar:{}}
NOTJSON;
$quoted_json = preg_replace('~\w[^:{},]*~', '"0ドル"', $unquoted_json);
$array = json_decode($quoted_json, true);
var_export($array);
echo "\n---\n";
echo json_encode($array);

Output:

array (
 'foo' => 
 array (
 'qux' => '1',
 'quux' => '0',
 ),
 'bar' => 
 array (
 ),
)
---
{"foo":{"qux":"1","quux":"0"},"bar":[]}

• solarc: That's an interesting take on it. I'll try it and see if it is better than the other approach. Thanks.
• mickmackusa: The difficult thing about fabricated sample input is that we don't have a lot of certainty that the fabricated data is a true indicator of the quality of characters/data that can potentially exist in your actual project. Does your project data only use letters and numbers as key/value substrings? Might you have floats? indexed arrays? quotes? Might your keys/values contain one of the delimiting characters ({}:,)? Please improve your question by further clarifying the range of known/expected formats that the data may have. I want to see you find resolution. Some feedback would help me.