Chris@0: JSON representation
Chris@0: ===================
Chris@0: 
Chris@0: Nodes (and comments) implement the `JsonSerializable` interface. As such, it is possible to JSON
Chris@0: encode the AST directly using `json_encode()`:
Chris@0: 
Chris@0: ```php
Chris@0: <?php
Chris@0: 
Chris@0: use PhpParser\ParserFactory;
Chris@0: 
Chris@0: $code = <<<'CODE'
Chris@0: <?php
Chris@0: 
Chris@0: /** @param string $msg */
Chris@0: function printLine($msg) {
Chris@0:     echo $msg, "\n";
Chris@0: }
Chris@0: CODE;
Chris@0: 
Chris@0: $parser = (new ParserFactory)->create(ParserFactory::PREFER_PHP7);
Chris@0: 
Chris@0: try {
Chris@0:     $stmts = $parser->parse($code);
Chris@0: 
Chris@0:     echo json_encode($stmts, JSON_PRETTY_PRINT), "\n";
Chris@0: } catch (PhpParser\Error $e) {
Chris@0:     echo 'Parse Error: ', $e->getMessage();
Chris@0: }
Chris@0: ```
Chris@0: 
Chris@0: This will result in the following output (which includes attributes):
Chris@0: 
Chris@0: ```json
Chris@0: [
Chris@0:     {
Chris@0:         "nodeType": "Stmt_Function",
Chris@0:         "byRef": false,
Chris@0:         "name": {
Chris@0:             "nodeType": "Identifier",
Chris@0:             "name": "printLine",
Chris@0:             "attributes": {
Chris@0:                 "startLine": 4,
Chris@0:                 "endLine": 4
Chris@0:             }
Chris@0:         },
Chris@0:         "params": [
Chris@0:             {
Chris@0:                 "nodeType": "Param",
Chris@0:                 "type": null,
Chris@0:                 "byRef": false,
Chris@0:                 "variadic": false,
Chris@0:                 "var": {
Chris@0:                     "nodeType": "Expr_Variable",
Chris@0:                     "name": "msg",
Chris@0:                     "attributes": {
Chris@0:                         "startLine": 4,
Chris@0:                         "endLine": 4
Chris@0:                     }
Chris@0:                 },
Chris@0:                 "default": null,
Chris@0:                 "attributes": {
Chris@0:                     "startLine": 4,
Chris@0:                     "endLine": 4
Chris@0:                 }
Chris@0:             }
Chris@0:         ],
Chris@0:         "returnType": null,
Chris@0:         "stmts": [
Chris@0:             {
Chris@0:                 "nodeType": "Stmt_Echo",
Chris@0:                 "exprs": [
Chris@0:                     {
Chris@0:                         "nodeType": "Expr_Variable",
Chris@0:                         "name": "msg",
Chris@0:                         "attributes": {
Chris@0:                             "startLine": 5,
Chris@0:                             "endLine": 5
Chris@0:                         }
Chris@0:                     },
Chris@0:                     {
Chris@0:                         "nodeType": "Scalar_String",
Chris@0:                         "value": "\n",
Chris@0:                         "attributes": {
Chris@0:                             "startLine": 5,
Chris@0:                             "endLine": 5,
Chris@0:                             "kind": 2
Chris@0:                         }
Chris@0:                     }
Chris@0:                 ],
Chris@0:                 "attributes": {
Chris@0:                     "startLine": 5,
Chris@0:                     "endLine": 5
Chris@0:                 }
Chris@0:             }
Chris@0:         ],
Chris@0:         "attributes": {
Chris@0:             "startLine": 4,
Chris@0:             "comments": [
Chris@0:                 {
Chris@0:                     "nodeType": "Comment_Doc",
Chris@0:                     "text": "\/** @param string $msg *\/",
Chris@0:                     "line": 3,
Chris@0:                     "filePos": 9,
Chris@0:                     "tokenPos": 2
Chris@0:                 }
Chris@0:             ],
Chris@0:             "endLine": 6
Chris@0:         }
Chris@0:     }
Chris@0: ]
Chris@0: ```
Chris@0: 
Chris@0: The JSON representation may be converted back into an AST using the `JsonDecoder`:
Chris@0: 
Chris@0: ```php
Chris@0: <?php
Chris@0: 
Chris@0: $nodeDecoder = new PhpParser\NodeDecoder();
Chris@0: $ast = $nodeDecoder->decode($json);
Chris@0: ```
Chris@0: 
Chris@0: Note that not all ASTs can be represented using JSON. In particular:
Chris@0: 
Chris@0:  * JSON only supports UTF-8 strings.
Chris@0:  * JSON does not support non-finite floating-point numbers. This can occur if the original source
Chris@0:    code contains non-representable floating-pointing literals such as `1e1000`.
Chris@0: 
Chris@0: If the node tree is not representable in JSON, the initial `json_encode()` call will fail.
Chris@0: 
Chris@0: From the command line, a JSON dump can be obtained using `vendor/bin/php-parse -j file.php`.