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   1 JSON representation
   2 ===================
   3
   4 Nodes (and comments) implement the `JsonSerializable` interface. As such, it is possible to JSON
   5 encode the AST directly using `json_encode()`:
   6
   7 ```php
   8 <?php
   9
  10 use PhpParser\ParserFactory;
  11
  12 $code = <<<'CODE'
  13 <?php
  14
  15 /** @param string $msg */
  16 function printLine($msg) {
  17     echo $msg, "\n";
  18 }
  19 CODE;
  20
  21 $parser = (new ParserFactory)->create(ParserFactory::PREFER_PHP7);
  22
  23 try {
  24     $stmts = $parser->parse($code);
  25
  26     echo json_encode($stmts, JSON_PRETTY_PRINT), "\n";
  27 } catch (PhpParser\Error $e) {
  28     echo 'Parse Error: ', $e->getMessage();
  29 }
  30 ```
  31
  32 This will result in the following output (which includes attributes):
  33
  34 ```json
  35 [
  36     {
  37         "nodeType": "Stmt_Function",
  38         "byRef": false,
  39         "name": {
  40             "nodeType": "Identifier",
  41             "name": "printLine",
  42             "attributes": {
  43                 "startLine": 4,
  44                 "endLine": 4
  45             }
  46         },
  47         "params": [
  48             {
  49                 "nodeType": "Param",
  50                 "type": null,
  51                 "byRef": false,
  52                 "variadic": false,
  53                 "var": {
  54                     "nodeType": "Expr_Variable",
  55                     "name": "msg",
  56                     "attributes": {
  57                         "startLine": 4,
  58                         "endLine": 4
  59                     }
  60                 },
  61                 "default": null,
  62                 "attributes": {
  63                     "startLine": 4,
  64                     "endLine": 4
  65                 }
  66             }
  67         ],
  68         "returnType": null,
  69         "stmts": [
  70             {
  71                 "nodeType": "Stmt_Echo",
  72                 "exprs": [
  73                     {
  74                         "nodeType": "Expr_Variable",
  75                         "name": "msg",
  76                         "attributes": {
  77                             "startLine": 5,
  78                             "endLine": 5
  79                         }
  80                     },
  81                     {
  82                         "nodeType": "Scalar_String",
  83                         "value": "\n",
  84                         "attributes": {
  85                             "startLine": 5,
  86                             "endLine": 5,
  87                             "kind": 2
  88                         }
  89                     }
  90                 ],
  91                 "attributes": {
  92                     "startLine": 5,
  93                     "endLine": 5
  94                 }
  95             }
  96         ],
  97         "attributes": {
  98             "startLine": 4,
  99             "comments": [
 100                 {
 101                     "nodeType": "Comment_Doc",
 102                     "text": "\/** @param string $msg *\/",
 103                     "line": 3,
 104                     "filePos": 9,
 105                     "tokenPos": 2
 106                 }
 107             ],
 108             "endLine": 6
 109         }
 110     }
 111 ]
 112 ```
 113
 114 The JSON representation may be converted back into an AST using the `JsonDecoder`:
 115
 116 ```php
 117 <?php
 118
 119 $nodeDecoder = new PhpParser\NodeDecoder();
 120 $ast = $nodeDecoder->decode($json);
 121 ```
 122
 123 Note that not all ASTs can be represented using JSON. In particular:
 124
 125  * JSON only supports UTF-8 strings.
 126  * JSON does not support non-finite floating-point numbers. This can occur if the original source
 127    code contains non-representable floating-pointing literals such as `1e1000`.
 128
 129 If the node tree is not representable in JSON, the initial `json_encode()` call will fail.
 130
 131 From the command line, a JSON dump can be obtained using `vendor/bin/php-parse -j file.php`.