Add "@abstract" tag support

Author: SerafimArts

Diff for: README.md

@@ -32,7 +32,7 @@ composer require type-lang/phpdoc
 
 ## Supported Tags
 
-- [ ] `@abstract` - TODO
+- [x] `@abstract` - Declare a class-like _Symbol_ or method as abstract
 - [ ] `@api` - TODO
 - [ ] `@author` - TODO
 - [ ] `@category` - TODO
@@ -49,7 +49,8 @@ composer require type-lang/phpdoc
 - [x] `@inherits` - An alias of `@extends` tag
 - [ ] `@internal` - TODO
 - [ ] `@license` - TODO
-- [x] `@link` - Indicates a custom relation between the associated _Symbol_ and a website, which is identified by an absolute URI
+- [x] `@link` - Indicates a custom relation between the associated _Symbol_ 
+      and a website, which is identified by an absolute URI
 - [x] `@method` - Allows a class to know which "_magic_" methods are callable
 - [ ] `@mixin` - TODO
 - [ ] `@no-named-arguments` - TODO
@@ -71,19 +72,24 @@ composer require type-lang/phpdoc
 - [x] `@returns` - An alias of `@return` tag
 - [ ] `@seal-methods` - TODO
 - [ ] `@seal-properties` - TODO
-- [x] `@see` - Indicates a reference from the associated _Symbol(s)_ to a website or other _Symbol(s)_
+- [x] `@see` - Indicates a reference from the associated _Symbol(s)_ to a 
+      website or other _Symbol(s)_
 - [ ] `@since` - TODO
 - [ ] `@source` - TODO
 - [ ] `@subpackage` - TODO
 - [ ] `@suppress` - TODO
-- [x] `@template` - Allows classes (and class-like entries), functions and methods to declare a generic type parameter
-- [x] `@template-contravariant` - Allows classes (and class-like entries), functions and methods to declare a generic contravariant type parameter
-- [x] `@template-covariant` - Allows classes (and class-like entries), functions and methods to declare a generic covariant type parameter
+- [x] `@template` - Allows classes (and class-like entries), functions and
+      methods to declare a generic type parameter
+- [x] `@template-contravariant` - Allows classes (and class-like entries),
+      functions and methods to declare a generic contravariant type parameter
+- [x] `@template-covariant` - Allows classes (and class-like entries), functions
+      and methods to declare a generic covariant type parameter
 - [x] `@template-extends` - An alias of `@extends` tag
 - [x] `@template-implements` - An alias of `@implements` tag
 - [x] `@template-use` - Allows to extend templated traits
 - [x] `@throw` - An alias of `@throws` tag
-- [x] `@throws` - Used to indicate whether _Symbol_ throw a specific type of `\Throwable` (exception or error)
+- [x] `@throws` - Used to indicate whether _Symbol_ throw a specific type 
+      of `\Throwable` (exception or error)
 - [ ] `@todo` - TODO
 - [ ] `@unused-param` - TODO
 - [x] `@use` - An alias of `@template-use` tag
@@ -200,7 +206,7 @@ composer require type-lang/phpdoc
 
 ### Phan Tags
 
-- [ ] `@phan-abstract` - TODO
+- [x] `@phan-abstract` - Vendor-specific `@abstract` alias
 - [ ] `@phan-assert` - TODO
 - [ ] `@phan-assert-false-condition` - TODO
 - [ ] `@phan-assert-if-false` - TODO

Diff for: src/DocBlock/Tag/AbstractTag/AbstractTag.php

@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace TypeLang\PHPDoc\DocBlock\Tag\AbstractTag;
+
+use TypeLang\PHPDoc\DocBlock\Tag\Tag;
+
+/**
+ * Declare a class-like or method as abstract, as well as for declaring
+ * what methods must be redefined in a child class.
+ *
+ * ```
+ * "@abstract" [<description>]
+ * ```
+ */
+final class AbstractTag extends Tag
+{
+    public function __construct(
+        string $name,
+        \Stringable|string|null $description = null,
+    ) {
+        parent::__construct($name, $description);
+    }
+}

Diff for: src/DocBlock/Tag/AbstractTag/AbstractTagFactory.php

@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+namespace TypeLang\PHPDoc\DocBlock\Tag\AbstractTag;
+
+use TypeLang\PHPDoc\DocBlock\Tag\Factory\TagFactoryInterface;
+use TypeLang\PHPDoc\Parser\Content\Stream;
+use TypeLang\PHPDoc\Parser\Description\DescriptionParserInterface;
+
+/**
+ * This class is responsible for creating "`@abstract`" tags.
+ *
+ * See {@see AbstractTag} for details about this tag.
+ */
+final class AbstractTagFactory implements TagFactoryInterface
+{
+    public function create(string $tag, string $content, DescriptionParserInterface $descriptions): AbstractTag
+    {
+        $stream = new Stream($tag, $content);
+
+        return new AbstractTag(
+            name: $tag,
+            description: $stream->toOptionalDescription($descriptions),
+        );
+    }
+}

Diff for: src/Parser.php

@@ -19,7 +19,6 @@
 use TypeLang\PHPDoc\Parser\Tag\RegexTagParser;
 use TypeLang\PHPDoc\Parser\Tag\TagParserInterface;
 use TypeLang\PHPDoc\Platform\CompoundPlatform;
-use TypeLang\PHPDoc\Platform\FallbacksPlatform;
 use TypeLang\PHPDoc\Platform\PhanPlatform;
 use TypeLang\PHPDoc\Platform\PHPStanPlatform;
 use TypeLang\PHPDoc\Platform\PlatformInterface;
@@ -42,7 +41,6 @@ public function __construct(
             new PsalmPlatform(),
             new PHPStanPlatform(),
             new PhanPlatform(),
-            new FallbacksPlatform(),
         ]),
     ) {
         $this->factories = new TagFactory($platform->getTags());

Diff for: src/Platform/FallbacksPlatform.php

@@ -5,6 +5,7 @@
 namespace TypeLang\PHPDoc\Platform;
 
 use TypeLang\Parser\ParserInterface as TypesParserInterface;
+use TypeLang\PHPDoc\DocBlock\Tag\AbstractTag\AbstractTagFactory;
 use TypeLang\PHPDoc\DocBlock\Tag\MethodTag\MethodTagFactory;
 use TypeLang\PHPDoc\DocBlock\Tag\ParamTag\ParamTagFactory;
 use TypeLang\PHPDoc\DocBlock\Tag\PropertyTag\PropertyReadTagFactory;
@@ -24,6 +25,7 @@ public function getName(): string
 
     protected function load(TypesParserInterface $types): iterable
     {
+        yield 'phan-abstract' => new AbstractTagFactory();
         yield 'phan-method' => new MethodTagFactory($types);
         yield 'phan-param' => new ParamTagFactory($types);
         yield 'phan-property' => new PropertyTagFactory($types);

Diff for: src/Platform/PhanPlatform.php

@@ -5,6 +5,8 @@
 namespace TypeLang\PHPDoc\Platform;
 
 use TypeLang\Parser\ParserInterface as TypesParserInterface;
+use TypeLang\PHPDoc\DocBlock\Tag\AbstractTag\AbstractTagFactory;
+use TypeLang\PHPDoc\DocBlock\Tag\Factory\TagFactoryInterface;
 use TypeLang\PHPDoc\DocBlock\Tag\LinkTag\LinkTagFactory;
 use TypeLang\PHPDoc\DocBlock\Tag\MethodTag\MethodTagFactory;
 use TypeLang\PHPDoc\DocBlock\Tag\ParamTag\ParamTagFactory;
@@ -30,6 +32,9 @@ public function getName(): string
 
     protected function load(TypesParserInterface $types): iterable
     {
+        yield 'abstract' => new AbstractTagFactory();
+        yield 'extends' => new TemplateExtendsTagFactory($types);
+        yield 'implements' => new TemplateImplementsTagFactory($types);
         yield 'link' => new LinkTagFactory();
         yield 'method' => new MethodTagFactory($types);
         yield 'param' => new ParamTagFactory($types);
@@ -39,12 +44,25 @@ protected function load(TypesParserInterface $types): iterable
         yield 'return' => new ReturnTagFactory($types);
         yield 'see' => new SeeTagFactory($types);
         yield 'template' => new TemplateTagFactory($types);
-        yield 'implements' => new TemplateImplementsTagFactory($types);
-        yield 'extends' => new TemplateExtendsTagFactory($types);
-        yield 'use' => new TemplateExtendsTagFactory($types);
-        yield 'template-covariant' => new TemplateCovariantTagFactory($types);
         yield 'template-contravariant' => new TemplateContravariantTagFactory($types);
+        yield 'template-covariant' => new TemplateCovariantTagFactory($types);
+        yield 'use' => new TemplateExtendsTagFactory($types);
         yield 'throws' => new ThrowsTagFactory($types);
         yield 'var' => new VarTagFactory($types);
+
+        yield from $this->loadAliases($types);
+    }
+
+    /**
+     * @return iterable<non-empty-string|iterable<mixed, non-empty-string>, TagFactoryInterface>
+     */
+    protected function loadAliases(TypesParserInterface $types): iterable
+    {
+        yield 'inherits' => $extends = new TemplateExtendsTagFactory($types);
+        yield 'returns' => new ReturnTagFactory($types);
+        yield 'template-extends' => $extends;
+        yield 'template-implements' => new TemplateImplementsTagFactory($types);
+        yield 'template-use' => new TemplateExtendsTagFactory($types);
+        yield 'throw' => new ThrowsTagFactory($types);
     }
 }