Other node tree representations
It is possible to convert the AST into several textual representations, which serve different uses.
Simple serialization
It is possible to serialize the node tree using serialize() and also unserialize it using
unserialize(). The output is not human readable and not easily processable from anything
but PHP, but it is compact and generates quickly. The main application thus is in caching.
Human readable dumping
Furthermore it is possible to dump nodes into a human readable format using the dump method of
PhpParser\NodeDumper. This can be used for debugging.
$code = <<<'CODE'
<?php
function printLine($msg) {
echo $msg, "\n";
}
printLine('Hello World!!!');
CODE;
$parser = (new PhpParser\ParserFactory)->create(PhpParser\ParserFactory::PREFER_PHP7);
$nodeDumper = new PhpParser\NodeDumper;
try {
$stmts = $parser->parse($code);
echo $nodeDumper->dump($stmts), "\n";
} catch (PhpParser\Error $e) {
echo 'Parse Error: ', $e->getMessage();
}
The above script will have an output looking roughly like this:
array(
0: Stmt_Function(
byRef: false
params: array(
0: Param(
name: msg
default: null
type: null
byRef: false
)
)
stmts: array(
0: Stmt_Echo(
exprs: array(
0: Expr_Variable(
name: msg
)
1: Scalar_String(
value:
)
)
)
)
name: printLine
)
1: Expr_FuncCall(
name: Name(
parts: array(
0: printLine
)
)
args: array(
0: Arg(
value: Scalar_String(
value: Hello World!!!
)
byRef: false
)
)
)
)
JSON encoding
Nodes (and comments) implement the JsonSerializable interface. As such, it is possible to JSON
encode the AST directly using json_encode():
$code = <<<'CODE'
<?php
function printLine($msg) {
echo $msg, "\n";
}
printLine('Hello World!!!');
CODE;
$parser = (new PhpParser\ParserFactory)->create(PhpParser\ParserFactory::PREFER_PHP7);
$nodeDumper = new PhpParser\NodeDumper;
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):
[
{
"nodeType": "Stmt_Function",
"byRef": false,
"name": "printLine",
"params": [
{
"nodeType": "Param",
"type": null,
"byRef": false,
"variadic": false,
"name": "msg",
"default": null,
"attributes": {
"startLine": 3,
"endLine": 3
}
}
],
"returnType": null,
"stmts": [
{
"nodeType": "Stmt_Echo",
"exprs": [
{
"nodeType": "Expr_Variable",
"name": "msg",
"attributes": {
"startLine": 4,
"endLine": 4
}
},
{
"nodeType": "Scalar_String",
"value": "\n",
"attributes": {
"startLine": 4,
"endLine": 4,
"kind": 2
}
}
],
"attributes": {
"startLine": 4,
"endLine": 4
}
}
],
"attributes": {
"startLine": 3,
"endLine": 5
}
},
{
"nodeType": "Expr_FuncCall",
"name": {
"nodeType": "Name",
"parts": [
"printLine"
],
"attributes": {
"startLine": 7,
"endLine": 7
}
},
"args": [
{
"nodeType": "Arg",
"value": {
"nodeType": "Scalar_String",
"value": "Hello World!!!",
"attributes": {
"startLine": 7,
"endLine": 7,
"kind": 1
}
},
"byRef": false,
"unpack": false,
"attributes": {
"startLine": 7,
"endLine": 7
}
}
],
"attributes": {
"startLine": 7,
"endLine": 7
}
}
]
There is currently no mechanism to convert JSON back into a node tree. Furthermore, not all ASTs can be JSON encoded. In particular, JSON only supports UTF-8 strings.
Serialization to XML
It is also possible to serialize the node tree to XML using PhpParser\Serializer\XML->serialize()
and to unserialize it using PhpParser\Unserializer\XML->unserialize(). This is useful for
interfacing with other languages and applications or for doing transformation using XSLT.
<?php
$code = <<<'CODE'
<?php
function printLine($msg) {
echo $msg, "\n";
}
printLine('Hello World!!!');
CODE;
$parser = (new PhpParser\ParserFactory)->create(PhpParser\ParserFactory::PREFER_PHP7);
$serializer = new PhpParser\Serializer\XML;
try {
$stmts = $parser->parse($code);
echo $serializer->serialize($stmts);
} catch (PhpParser\Error $e) {
echo 'Parse Error: ', $e->getMessage();
}
Produces:
<?xml version="1.0" encoding="UTF-8"?>
<AST xmlns:node="http://nikic.github.com/PHPParser/XML/node" xmlns:subNode="http://nikic.github.com/PHPParser/XML/subNode" xmlns:scalar="http://nikic.github.com/PHPParser/XML/scalar">
<scalar:array>
<node:Stmt_Function line="2">
<subNode:byRef>
<scalar:false/>
</subNode:byRef>
<subNode:params>
<scalar:array>
<node:Param line="2">
<subNode:name>
<scalar:string>msg</scalar:string>
</subNode:name>
<subNode:default>
<scalar:null/>
</subNode:default>
<subNode:type>
<scalar:null/>
</subNode:type>
<subNode:byRef>
<scalar:false/>
</subNode:byRef>
</node:Param>
</scalar:array>
</subNode:params>
<subNode:stmts>
<scalar:array>
<node:Stmt_Echo line="3">
<subNode:exprs>
<scalar:array>
<node:Expr_Variable line="3">
<subNode:name>
<scalar:string>msg</scalar:string>
</subNode:name>
</node:Expr_Variable>
<node:Scalar_String line="3">
<subNode:value>
<scalar:string>
</scalar:string>
</subNode:value>
</node:Scalar_String>
</scalar:array>
</subNode:exprs>
</node:Stmt_Echo>
</scalar:array>
</subNode:stmts>
<subNode:name>
<scalar:string>printLine</scalar:string>
</subNode:name>
</node:Stmt_Function>
<node:Expr_FuncCall line="6">
<subNode:name>
<node:Name line="6">
<subNode:parts>
<scalar:array>
<scalar:string>printLine</scalar:string>
</scalar:array>
</subNode:parts>
</node:Name>
</subNode:name>
<subNode:args>
<scalar:array>
<node:Arg line="6">
<subNode:value>
<node:Scalar_String line="6">
<subNode:value>
<scalar:string>Hello World!!!</scalar:string>
</subNode:value>
</node:Scalar_String>
</subNode:value>
<subNode:byRef>
<scalar:false/>
</subNode:byRef>
</node:Arg>
</scalar:array>
</subNode:args>
</node:Expr_FuncCall>
</scalar:array>
</AST>