# PHP Parser

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This is a PHP parser written in PHP. Its purpose is to simplify static code analysis and
manipulation.

[**Documentation for version 5.x**][doc_master] (current; for running on PHP >= 7.4; for parsing PHP 7.0 to PHP 8.3, with limited support for parsing PHP 5.x).

[Documentation for version 4.x][doc_4_x] (supported; for running on PHP >= 7.0; for parsing PHP 5.2 to PHP 8.3).

## Features

The main features provided by this library are:

- Parsing PHP 7, and PHP 8 code into an abstract syntax tree (AST).
  - Invalid code can be parsed into a partial AST.
  - The AST contains accurate location information.
- Dumping the AST in human-readable form.
- Converting an AST back to PHP code.
  - Formatting can be preserved for partially changed ASTs.
- Infrastructure to traverse and modify ASTs.
- Resolution of namespaced names.
- Evaluation of constant expressions.
- Builders to simplify AST construction for code generation.
- Converting an AST into JSON and back.

## Quick Start

Install the library using [composer](https://getcomposer.org):

    php composer.phar require nikic/php-parser

Parse some PHP code into an AST and dump the result in human-readable form:

```php
<?php
use PhpParser\Error;
use PhpParser\NodeDumper;
use PhpParser\ParserFactory;

$code = <<<'CODE'
<?php

function test($foo)
{
    var_dump($foo);
}
CODE;

$parser = (new ParserFactory())->createForNewestSupportedVersion();
try {
    $ast = $parser->parse($code);
} catch (Error $error) {
    echo "Parse error: {$error->getMessage()}\n";
    return;
}

$dumper = new NodeDumper;
echo $dumper->dump($ast) . "\n";
```

This dumps an AST looking something like this:

```
array(
    0: Stmt_Function(
        attrGroups: array(
        )
        byRef: false
        name: Identifier(
            name: test
        )
        params: array(
            0: Param(
                attrGroups: array(
                )
                flags: 0
                type: null
                byRef: false
                variadic: false
                var: Expr_Variable(
                    name: foo
                )
                default: null
            )
        )
        returnType: null
        stmts: array(
            0: Stmt_Expression(
                expr: Expr_FuncCall(
                    name: Name(
                        name: var_dump
                    )
                    args: array(
                        0: Arg(
                            name: null
                            value: Expr_Variable(
                                name: foo
                            )
                            byRef: false
                            unpack: false
                        )
                    )
                )
            )
        )
    )
)
```

Let's traverse the AST and perform some kind of modification. For example, drop all function bodies:

```php
use PhpParser\Node;
use PhpParser\Node\Stmt\Function_;
use PhpParser\NodeTraverser;
use PhpParser\NodeVisitorAbstract;

$traverser = new NodeTraverser();
$traverser->addVisitor(new class extends NodeVisitorAbstract {
    public function enterNode(Node $node) {
        if ($node instanceof Function_) {
            // Clean out the function body
            $node->stmts = [];
        }
    }
});

$ast = $traverser->traverse($ast);
echo $dumper->dump($ast) . "\n";
```

This gives us an AST where the `Function_::$stmts` are empty:

```
array(
    0: Stmt_Function(
        attrGroups: array(
        )
        byRef: false
        name: Identifier(
            name: test
        )
        params: array(
            0: Param(
                attrGroups: array(
                )
                type: null
                byRef: false
                variadic: false
                var: Expr_Variable(
                    name: foo
                )
                default: null
            )
        )
        returnType: null
        stmts: array(
        )
    )
)
```

Finally, we can convert the new AST back to PHP code:

```php
use PhpParser\PrettyPrinter;

$prettyPrinter = new PrettyPrinter\Standard;
echo $prettyPrinter->prettyPrintFile($ast);
```

This gives us our original code, minus the `var_dump()` call inside the function:

```php
<?php

function test($foo)
{
}
```

For a more comprehensive introduction, see the documentation.

## Documentation

1.  [Introduction](doc/0_Introduction.markdown)
2.  [Usage of basic components](doc/2_Usage_of_basic_components.markdown)

Component documentation:

- [Walking the AST](doc/component/Walking_the_AST.markdown)
  - Node visitors
  - Modifying the AST from a visitor
  - Short-circuiting traversals
  - Interleaved visitors
  - Simple node finding API
  - Parent and sibling references
- [Name resolution](doc/component/Name_resolution.markdown)
  - Name resolver options
  - Name resolution context
- [Pretty printing](doc/component/Pretty_printing.markdown)
  - Converting AST back to PHP code
  - Customizing formatting
  - Formatting-preserving code transformations
- [AST builders](doc/component/AST_builders.markdown)
  - Fluent builders for AST nodes
- [Lexer](doc/component/Lexer.markdown)
  - Emulation
  - Tokens, positions and attributes
- [Error handling](doc/component/Error_handling.markdown)
  - Column information for errors
  - Error recovery (parsing of syntactically incorrect code)
- [Constant expression evaluation](doc/component/Constant_expression_evaluation.markdown)
  - Evaluating constant/property/etc initializers
  - Handling errors and unsupported expressions
- [JSON representation](doc/component/JSON_representation.markdown)
  - JSON encoding and decoding of ASTs
- [Performance](doc/component/Performance.markdown)
  - Disabling Xdebug
  - Reusing objects
  - Garbage collection impact
- [Frequently asked questions](doc/component/FAQ.markdown)
  - Parent and sibling references

[doc_3_x]: https://github.com/nikic/PHP-Parser/tree/3.x/doc
[doc_4_x]: https://github.com/nikic/PHP-Parser/tree/4.x/doc
[doc_master]: https://github.com/nikic/PHP-Parser/tree/master/doc