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JSON representation
===================
Nodes (and comments) implement the `JsonSerializable` interface. As such, it is possible to JSON
encode the AST directly using `json_encode()`:
```php
<?php
use PhpParser\ParserFactory;
$code = <<<'CODE'
<?php
/** @param string $msg */
function printLine($msg) {
echo $msg, "\n";
}
CODE;
$parser = (new ParserFactory())->createForHostVersion();
try {
$stmts = $parser->parse($code);
echo json_encode($stmts, JSON_PRETTY_PRINT), "\n";
} catch (PhpParser\Error $e) {
echo 'Parse Error: ', $e->getMessage();
}
```
This will result in the following output (which includes attributes):
```json
[
{
"nodeType": "Stmt_Function",
"attributes": {
"startLine": 4,
"comments": [
{
"nodeType": "Comment_Doc",
"text": "\/** @param string $msg *\/",
"line": 3,
"filePos": 7,
"tokenPos": 2,
"endLine": 3,
"endFilePos": 31,
"endTokenPos": 2
}
],
"endLine": 6
},
"byRef": false,
"name": {
"nodeType": "Identifier",
"attributes": {
"startLine": 4,
"endLine": 4
},
"name": "printLine"
},
"params": [
{
"nodeType": "Param",
"attributes": {
"startLine": 4,
"endLine": 4
},
"type": null,
"byRef": false,
"variadic": false,
"var": {
"nodeType": "Expr_Variable",
"attributes": {
"startLine": 4,
"endLine": 4
},
"name": "msg"
},
"default": null,
"flags": 0,
"attrGroups": []
}
],
"returnType": null,
"stmts": [
{
"nodeType": "Stmt_Echo",
"attributes": {
"startLine": 5,
"endLine": 5
},
"exprs": [
{
"nodeType": "Expr_Variable",
"attributes": {
"startLine": 5,
"endLine": 5
},
"name": "msg"
},
{
"nodeType": "Scalar_String",
"attributes": {
"startLine": 5,
"endLine": 5,
"kind": 2,
"rawValue": "\"\\n\""
},
"value": "\n"
}
]
}
],
"attrGroups": [],
"namespacedName": null
}
]
```
The JSON representation may be converted back into an AST using the `JsonDecoder`:
```php
<?php
$jsonDecoder = new PhpParser\JsonDecoder();
$ast = $jsonDecoder->decode($json);
```
Note that not all ASTs can be represented using JSON. In particular:
* JSON only supports UTF-8 strings.
* JSON does not support non-finite floating-point numbers. This can occur if the original source
code contains non-representable floating-pointing literals such as `1e1000`.
If the node tree is not representable in JSON, the initial `json_encode()` call will fail.
From the command line, a JSON dump can be obtained using `vendor/bin/php-parse -j file.php`.
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