Add HeaderSlug configurable

Adds HeaderSlug configurable, with the option for the slug function
to be customised.

Co-authored-by: netniV <netniv@hotmail.com>

src/Components/Blocks/Header.php

@@ -5,6 +5,7 @@ namespace Erusev\Parsedown\Components\Blocks;
 use Erusev\Parsedown\AST\Handler;
 use Erusev\Parsedown\AST\StateRenderable;
 use Erusev\Parsedown\Components\Block;
+use Erusev\Parsedown\Configurables\HeaderSlug;
 use Erusev\Parsedown\Configurables\StrictMode;
 use Erusev\Parsedown\Html\Renderables\Element;
 use Erusev\Parsedown\Parsedown;
@@ -96,9 +97,16 @@ final class Header implements Block
         return new Handler(
             /** @return Element */
             function (State $State) {
+                $HeaderSlug = $State->get(HeaderSlug::class);
+                $attributes = (
+                    $HeaderSlug->isEnabled()
+                    ? ['id' => $HeaderSlug->transform($this->text())]
+                    : []
+                );
+
                 return new Element(
                     'h' . \strval($this->level()),
-                    [],
+                    $attributes,
                     $State->applyTo(Parsedown::line($this->text(), $State))
                 );
             }

src/Components/Blocks/SetextHeader.php

@@ -6,6 +6,7 @@ use Erusev\Parsedown\AST\Handler;
 use Erusev\Parsedown\AST\StateRenderable;
 use Erusev\Parsedown\Components\AcquisitioningBlock;
 use Erusev\Parsedown\Components\Block;
+use Erusev\Parsedown\Configurables\HeaderSlug;
 use Erusev\Parsedown\Html\Renderables\Element;
 use Erusev\Parsedown\Parsedown;
 use Erusev\Parsedown\Parsing\Context;
@@ -88,9 +89,16 @@ final class SetextHeader implements AcquisitioningBlock
         return new Handler(
             /** @return Element */
             function (State $State) {
+                $HeaderSlug = $State->get(HeaderSlug::class);
+                $attributes = (
+                    $HeaderSlug->isEnabled()
+                    ? ['id' => $HeaderSlug->transform($this->text())]
+                    : []
+                );
+
                 return new Element(
                     'h' . \strval($this->level()),
-                    [],
+                    $attributes,
                     $State->applyTo(Parsedown::line($this->text(), $State))
                 );
             }

src/Configurables/HeaderSlug.php

@@ -0,0 +1,64 @@
+<?php
+
+namespace Erusev\Parsedown\Configurables;
+
+use Erusev\Parsedown\Configurable;
+
+final class HeaderSlug implements Configurable
+{
+    /** @var bool */
+    private $enabled = false;
+
+    /** @var \Closure(string):string */
+    private $slugCallback;
+
+    /**
+     * @param bool $enabled
+     * @param (\Closure(string):string)|null $slugCallback
+     */
+    public function __construct($enabled, $slugCallback = null)
+    {
+        $this->enabled = $enabled;
+
+        if (! isset($slugCallback)) {
+            $this->slugCallback = function (string $text): string {
+                $slug = \mb_strtolower($text);
+                $slug = \str_replace(' ', '-', $slug);
+                $slug = \preg_replace('/[^\p{L}\p{N}\p{M}-]+/u', '', $slug);
+
+                return $slug;
+            };
+        } else {
+            $this->slugCallback = $slugCallback;
+        }
+    }
+
+    /** @return bool */
+    public function isEnabled()
+    {
+        return $this->enabled;
+    }
+
+    public function transform(string $text): string
+    {
+        return ($this->slugCallback)($text);
+    }
+
+    /** @param \Closure(string):string $slugCallback */
+    public static function withCallback($slugCallback): self
+    {
+        return new self(true, $slugCallback);
+    }
+
+    /** @return self */
+    public static function enabled()
+    {
+        return new self(true);
+    }
+
+    /** @return self */
+    public static function initial()
+    {
+        return new self(false);
+    }
+}

tests/ParsedownTest.php

@@ -6,6 +6,7 @@ use Erusev\Parsedown\Components\Blocks\Markup as BlockMarkup;
 use Erusev\Parsedown\Components\Inlines\Markup as InlineMarkup;
 use Erusev\Parsedown\Configurables\BlockTypes;
 use Erusev\Parsedown\Configurables\Breaks;
+use Erusev\Parsedown\Configurables\HeaderSlug;
 use Erusev\Parsedown\Configurables\InlineTypes;
 use Erusev\Parsedown\Configurables\SafeMode;
 use Erusev\Parsedown\Configurables\StrictMode;
@@ -59,6 +60,7 @@ class ParsedownTest extends TestCase
             new SafeMode(\substr($test, 0, 3) === 'xss'),
             new StrictMode(\substr($test, 0, 6) === 'strict'),
             new Breaks(\substr($test, 0, 14) === 'breaks_enabled'),
+            new HeaderSlug(\substr($test, 0, 4) === 'slug'),
         ]));
 
         $actualMarkup = $Parsedown->toHtml($markdown);

tests/data/slug_heading.html

@@ -0,0 +1,10 @@
+<h1 id="foo">foo</h1>
+<h1 id="foo-bar">foo bar</h1>
+<h1 id="foobar">foo_bar</h1>
+<h1 id="foobar">foo+bar</h1>
+<h1 id="2rer0ගම්මැද්ද-v-force-ඉනොවේශන්-නේෂන්-සඳහා-එවූ-නි">2rer*(0👍ගම්මැද්ද V FORCE ඉනොවේශන් නේෂන් සඳහා එවූ නි</h1>
+<h2 id="foo">foo</h2>
+<h2 id="foo-bar">foo bar</h2>
+<h2 id="foobar">foo_bar</h2>
+<h2 id="foobar">foo+bar</h2>
+<h2 id="2rer0ගම්මැද්ද-v-force-ඉනොවේශන්-නේෂන්-සඳහා-එවූ-නි">2rer*(0👍ගම්මැද්ද V FORCE ඉනොවේශන් නේෂන් සඳහා එවූ නි</h2>

tests/data/slug_heading.md

@@ -0,0 +1,24 @@
+# foo
+
+# foo bar
+
+# foo_bar
+
+# foo+bar
+
+# 2rer*(0👍ගම්මැද්ද V FORCE ඉනොවේශන් නේෂන් සඳහා එවූ නි
+
+foo
+---
+
+foo bar
+---
+
+foo_bar
+---
+
+foo+bar
+---
+
+2rer*(0👍ගම්මැද්ද V FORCE ඉනොවේශන් නේෂන් සඳහා එවූ නි
+---

tests/src/Configurables/HeaderSlugTest.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace Erusev\Parsedown\Tests\Configurables;
+
+use Erusev\Parsedown\Configurables\HeaderSlug;
+use Erusev\Parsedown\State;
+use PHPUnit\Framework\TestCase;
+
+final class HeaderSlugTest extends TestCase
+{
+    /**
+     * @return void
+     * @throws \PHPUnit\Framework\ExpectationFailedException
+     * @throws \SebastianBergmann\RecursionContext\InvalidArgumentException
+     */
+    public function testNamedConstructor()
+    {
+        $State = new State([HeaderSlug::enabled()]);
+
+        $this->assertSame(true, $State->get(HeaderSlug::class)->isEnabled());
+    }
+    /**
+     * @return void
+     * @throws \PHPUnit\Framework\ExpectationFailedException
+     * @throws \SebastianBergmann\RecursionContext\InvalidArgumentException
+     */
+    public function testCustomCallback()
+    {
+        $HeaderSlug = HeaderSlug::withCallback(function (string $t): string {
+            return \preg_replace('/[^A-Za-z0-9]++/', '_', $t);
+        });
+
+        $this->assertSame(
+            'foo_bar',
+            $HeaderSlug->transform('foo bar')
+        );
+    }
+}