php-parser/README.md

<!--
  Title: PHP Parser
  Description: A Parser for PHP written in Go.
  Author: Slizov Vadim
  Keywords: go golang php php-parser ast
  -->

<img src="./parser.jpg" alt="PHP Parser written in Go" width="980"/>

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#### Try it online: [demo](https://php-parser.com)

## Features:
- Fully support PHP 5 and PHP 7 syntax
- Abstract syntax tree (AST) representation
- Traversing AST
- Namespace resolver
- Able to parse syntax-invalid PHP files

## Roadmap

- Control Flow Graph (CFG)
- PhpDocComment parser
- Stabilize api

## Install

```
go get github.com/z7zmey/php-parser
```

## CLI

```
php-parser [-php5] <path> ...
```

Dump AST to stdout.

## Example
```Golang
package main

import (
	"fmt"
	"bytes"
	"os"

	"github.com/z7zmey/php-parser/php7"
	"github.com/z7zmey/php-parser/visitor"
)

func main() {
	src := bytes.NewBufferString(`<? echo "Hello world";`)

	parser := php7.NewParser(src, "example.php")
	parser.Parse()

	for _, e := range parser.GetErrors() {
		fmt.Println(e)
	}

	visitor := visitor.Dumper{
		Writer:    os.Stdout,
		Indent:    "",
		Comments:  parser.GetComments(),
		Positions: parser.GetPositions(),
	}

	rootNode := parser.GetRootNode()
	rootNode.Walk(visitor)
}
```

## Namespace resolver

Namespace resolver is a visitor that resolves nodes fully qualified name and saves into `map[node.Node]string` structure

- For `Class`, `Interface`, `Trait`, `Function`, `Constant` nodes it saves name with current namespace.
- For `Name`, `Relative`, `FullyQualified` nodes it resolves `use` aliases and saves a fully qualified name.

## Parsing syntax-invalid PHP files

If we try to parse `$a$b;` then the parser triggers error 'syntax error: unexpected T_VARIABLE'. Token `$b` is unexpected, but parser recovers parsing process and returns `$b;` statement to AST, because it is syntactically correct.

## Pretty printer

```Golang
nodes := &stmt.StmtList{
	Stmts: []node.Node{
		&stmt.Namespace{
			NamespaceName: &name.Name{Parts: []node.Node{&name.NamePart{Value: "Foo"}}},
		},
		&stmt.Class{
			Modifiers: []node.Node{&node.Identifier{Value: "abstract"}},
			ClassName: &name.Name{Parts: []node.Node{&name.NamePart{Value: "Bar"}}},
			Extends: &name.Name{Parts: []node.Node{&name.NamePart{Value: "Baz"}}},
			Stmts: []node.Node{
				&stmt.ClassMethod{
					Modifiers:  []node.Node{&node.Identifier{Value: "public"}},
					MethodName: &node.Identifier{Value: "greet"},
					Stmts: []node.Node{
						&stmt.Echo{
							Exprs: []node.Node{
								&scalar.String{Value: "'Hello world'"},
							},
						},
					},
				},
			},
		},
	},
}

file := os.Stdout
p := printer.NewPrinter(file, "    ")
p.PrintFile(nodes)
```

Output:
```PHP
<?php
namespace Foo;
abstract class Bar extends Baz
{
    public function greet()
    {
        echo 'Hello world';
    }
}
```