Updated README

README.md

@@ -1,4 +1,4 @@
-<h1 align="center">PHPDoc-Parser for PHPStan</h1>
+<h1 align="center">PHPDoc Parser for PHPStan</h1>
 
 <p align="center">
 	<a href="https://github.com/phpstan/phpdoc-parser/actions"><img src="https://github.com/phpstan/phpdoc-parser/workflows/Build/badge.svg" alt="Build Status"></a>
@@ -11,7 +11,99 @@
 
 ------
 
-Next generation phpDoc parser with support for intersection types and generics.
+This library `phpstan/phpdoc-parser` represents PHPDocs with an AST (Abstract Syntax Tree). It supports parsing and modifying PHPDocs.
+
+For the complete list of supported PHPDoc features check out PHPStan documentation. PHPStan is the main (but not the only) user of this library.
+
+* [PHPDoc Basics](https://phpstan.org/writing-php-code/phpdocs-basics) (list of PHPDoc tags)
+* [PHPDoc Types](https://phpstan.org/writing-php-code/phpdoc-types) (list of PHPDoc types)
+* [phpdoc-parser API Reference](https://phpstan.github.io/phpdoc-parser/namespace-PHPStan.PhpDocParser.html) with all the AST node types etc.
+
+## Installation
+
+```
+composer require phpstan/phpdoc-parser
+```
+
+## Basic usage
+
+```php
+<?php
+
+require_once __DIR__ . '/vendor/autoload.php';
+
+use PHPStan\PhpDocParser\Ast\PhpDoc\ParamTagValueNode;
+use PHPStan\PhpDocParser\Ast\PhpDoc\PhpDocNode;
+use PHPStan\PhpDocParser\Ast\Type\IdentifierTypeNode;
+use PHPStan\PhpDocParser\Lexer\Lexer;
+use PHPStan\PhpDocParser\Parser\ConstExprParser;
+use PHPStan\PhpDocParser\Parser\PhpDocParser;
+use PHPStan\PhpDocParser\Parser\TokenIterator;
+use PHPStan\PhpDocParser\Parser\TypeParser;
+
+// basic setup
+
+$lexer = new Lexer();
+$constExprParser = new ConstExprParser();
+$typeParser = new TypeParser($constExprParser);
+$phpDocParser = new PhpDocParser($typeParser, $constExprParser);
+
+// parsing and reading a PHPDoc string
+
+$tokens = new TokenIterator($lexer->tokenize('/** @param Lorem $a */'));
+$phpDocNode = $phpDocParser->parse($tokens); // PhpDocNode
+$paramTags = $phpDocNode->getParamTagValues(); // ParamTagValueNode[]
+echo $paramTags[0]->parameterName; // '$a'
+echo $paramTags[0]->type; // IdentifierTypeNode - 'Lorem'
+```
+
+### Format-preserving printer
+
+This component can be used to modify the AST
+and print it again as close as possible to the original.
+
+It's heavily inspired by format-preserving printer component in [nikic/PHP-Parser](https://github.com/nikic/PHP-Parser).
+
+```php
+<?php
+
+require_once __DIR__ . '/vendor/autoload.php';
+
+use PHPStan\PhpDocParser\Ast\NodeTraverser;
+use PHPStan\PhpDocParser\Ast\NodeVisitor\CloningVisitor;
+use PHPStan\PhpDocParser\Ast\PhpDoc\PhpDocNode;
+use PHPStan\PhpDocParser\Ast\Type\IdentifierTypeNode;
+use PHPStan\PhpDocParser\Lexer\Lexer;
+use PHPStan\PhpDocParser\Parser\ConstExprParser;
+use PHPStan\PhpDocParser\Parser\PhpDocParser;
+use PHPStan\PhpDocParser\Parser\TokenIterator;
+use PHPStan\PhpDocParser\Parser\TypeParser;
+use PHPStan\PhpDocParser\Printer\Printer;
+
+// basic setup with enabled required lexer attributes
+
+$usedAttributes = ['lines' => true, 'indexes' => true];
+
+$lexer = new Lexer();
+$constExprParser = new ConstExprParser(true, true, $usedAttributes);
+$typeParser = new TypeParser($constExprParser, true, $usedAttributes);
+$phpDocParser = new PhpDocParser($typeParser, $constExprParser, true, true, $usedAttributes);
+
+$tokens = new TokenIterator($lexer->tokenize('/** @param Lorem $a */'));
+$phpDocNode = $phpDocParser->parse($tokens); // PhpDocNode
+
+$cloningTraverser = new NodeTraverser([new CloningVisitor()]);
+
+/** @var PhpDocNode $newPhpDocNode */
+$printer = new Printer();
+[$newPhpDocNode] = $cloningTraverser->traverse([$phpDocNode]);
+
+// change something in $newPhpDocNode
+$newPhpDocNode->getParamTagValues()[0]->type = new IdentifierTypeNode('Ipsum');
+
+$newPhpDoc = $printer->printFormatPreserving($newPhpDocNode, $phpDocNode, $tokens);
+echo $newPhpDoc; // '/** @param Ipsum $a */'
+```
 
 ## Code of Conduct