JSON Machine

Json Machine is a Fast, efficient and easy-to-use JSON stream parser based on coroutines developed for unpredictably long JSON streams or documents. Main features are:

Ease of use. Just iterate JSON of any size with foreach. No events and callbacks.
Constant memory footprint for unpredictably large JSON documents.
Speed. Performace critical code contains no unnecessary function calls, no regular expressions and uses native json_decode to decode JSON document chunks.
Supports efficient iteration on any subtree of the document, specified by Json Pointer

Examples

Parsing simple JSON document

Let's say that big.json contains this really big JSON document:

// big.json
{
    "apple": {
        "color": "red"
    },
    "pear": {
        "color": "yellow"
    }
}

It can be parsed this way:

<?php

$jsonStream = \JsonMachine\JsonMachine::fromFile('big.json');

foreach ($jsonStream as $name => $data) {
    // 1st iteration: $name === "apple" and $data === ["color" => "red"]
    // 2nd iteration: $name === "pear" and $data === ["color" => "yellow"]
}

Parsing an array instead of a dictionary follows the same logic. The key in a foreach will be a numeric index of an item.

Parsing JSON document subtree

If you want to iterate only fruits-key subtree in this fruits.json:

// fruits.json
{
    "fruits-key": {
        "apple": {
            "color": "red"
        },
        "pear": {
            "color": "yellow"
        }
    }
}

do it like this:

<?php

$jsonStream = \JsonMachine\JsonMachine::fromFile("fruits.json", "/fruits-key" /* <- Json Pointer */);
foreach ($jsonStream as $name => $data) {
    // The same as above, which means:
    // 1st iteration: $name === "apple" and $data === ["color" => "red"]
    // 2nd iteration: $name === "pear" and $data === ["color" => "yellow"]
}

Note:

Value of fruits-key is not loaded into memory at once, but only one item in fruits-key at a time. It is always one item in memory at a time at the level/subtree you are currently iterating. Thus the memory consumption is constant.

Parsing API responses

If you use this library to parse large API responses, all you need to do is passing the stream resource of your api response to JsonMachine::fromStream($streamResource).

GuzzleHttp example

Guzzle uses its own streams, but they can be converted back to PHP streams by calling \GuzzleHttp\Psr7\StreamWrapper::getResource(). See GuzzleHttp example

Error handling

When any part of the JSON stream is malformed, SyntaxError exception is thrown. Better solution is on the way.

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