JsonRecast

Editable JSON AST with visitor traversal and formatting-preserving printing.

JsonRecast parses JSON into an editable AST, lets you transform it with path-aware visitors, and prints the result while keeping the original formatting where possible. Its traversal model is inspired by nikic/PHP-Parser, applied to JSON documents for tools that update files without creating noisy diffs.

Installation

composer require boundwize/jsonrecast

Example

This example updates a composer.json-style document in one traversal:

1. Parse the JSON into a JsonDocument.
2. Traverse the document with a visitor and return changed nodes.
3. Replace the root name value.
4. Remove the root minimum-stability entry.
5. Add a PSR-4 namespace under autoload.psr-4.
6. Remove a stale value from autoload-dev.classmap.
7. In leaveNode(), remove the now-empty autoload-dev parent.
8. Print the result while preserving the original formatting style.

use Boundwize\JsonRecast\JsonRecast;
use Boundwize\JsonRecast\Node\ArrayNode;
use Boundwize\JsonRecast\Node\NodeJson;
use Boundwize\JsonRecast\Node\ObjectItemNode;
use Boundwize\JsonRecast\Node\ObjectNode;
use Boundwize\JsonRecast\Node\StringNode;
use Boundwize\JsonRecast\NodePath\NodeJsonPath;
use Boundwize\JsonRecast\NodeVisitor\NodeJsonVisitor;
use Boundwize\JsonRecast\NodeVisitor\NodeJsonVisitorAbstract;

$json = <<<'JSON'
{
    "name": "acme/demo",
    "autoload": {
        "psr-4": {
            "App\\": "app/"
        }
    },
    "autoload-dev": {
        "classmap": [
            "tests/Fixtures/App"
        ]
    },
    "minimum-stability": "dev"
}
JSON;

// 1. Parse the source JSON into an editable document node.
$document = JsonRecast::parse($json);

// 2. Traverse the document and return changed nodes so JsonRecast can track edits.
$result = JsonRecast::traverse($document, new class extends NodeJsonVisitorAbstract {
    public function enterNode(NodeJson $node, NodeJsonPath $path): null|NodeJson|int
    {
        if ($node instanceof ObjectItemNode && $path->isRoot()) {
            // 3. Replace the root "name" value.
            if ($node->key->value === 'name') {
                $node->value = new StringNode('boundwize/jsonrecast');

                return $node;
            }

            // 4. Remove an unwanted root object item.
            if ($node->key->value === 'minimum-stability') {
                return NodeJsonVisitor::REMOVE_NODE;
            }
        }

        // 5. Add a new namespace under "autoload.psr-4".
        if ($node instanceof ObjectNode && $path->matches(['autoload', 'psr-4'])) {
            $node->set('Boundwize\\JsonRecast\\', new StringNode('src/'));

            return $node;
        }

        // 6. Remove a stale classmap entry.
        if ($node instanceof ArrayNode && $path->matches(['autoload-dev', 'classmap'])) {
            foreach ($node->items as $index => $item) {
                if ($item->value instanceof StringNode && $item->value->value === 'tests/Fixtures/App') {
                    $node->removeAt($index);

                    return $node;
                }
            }
        }

        return null;
    }

    // 7. After child edits are done, remove the empty "autoload-dev" parent.
    public function leaveNode(NodeJson $node, NodeJsonPath $path): ?int
    {
        if (
            ! $node instanceof ObjectItemNode
            || ! $path->isRoot()
            || $node->key->value !== 'autoload-dev'
            || ! $node->value instanceof ObjectNode
        ) {
            return null;
        }

        $classmapItem = $node->value->get('classmap');

        if (
            $classmapItem instanceof ObjectItemNode
            && $classmapItem->value instanceof ArrayNode
            && $classmapItem->value->items === []
        ) {
            return NodeJsonVisitor::REMOVE_NODE;
        }

        return null;
    }
});

// 8. Print with the original formatting preserved where possible.
echo JsonRecast::print($result);

That will output:

{
    "name": "boundwize/jsonrecast",
    "autoload": {
        "psr-4": {
            "App\\": "app/",
            "Boundwize\\JsonRecast\\": "src/"
        }
    }
}

Documentation

Read the full documentation at https://boundwize.github.io/jsonrecast/.