Add a GitHub extension preset

README.md

@@ -313,6 +313,20 @@ HtmlRenderer renderer = HtmlRenderer.builder()
 
 To configure another extension in the above example, just add it to the list.
 
+To enable tables, strikethrough, autolinks, task list items, alerts, and footnotes
+together, use the `org.commonmark:commonmark-ext-github` dependency. Pass its preset
+to both builders:
+
+```java
+import org.commonmark.ext.github.GitHubExtensions;
+
+List<Extension> extensions = GitHubExtensions.create();
+Parser parser = Parser.builder().extensions(extensions).build();
+HtmlRenderer renderer = HtmlRenderer.builder().extensions(extensions).build();
+```
+
+Other extensions can still be enabled individually.
+
 The following extensions are developed with this library, each in their
 own artifact.
 

commonmark-android-test/app/build.gradle

@@ -36,10 +36,14 @@ android {
                 [
                         '../../commonmark',
                         '../../commonmark-ext-autolink',
+                        '../../commonmark-ext-footnotes',
+                        '../../commonmark-ext-gfm-alerts',
                         '../../commonmark-ext-gfm-strikethrough',
                         '../../commonmark-ext-gfm-tables',
+                        '../../commonmark-ext-github',
                         '../../commonmark-ext-heading-anchor',
                         '../../commonmark-ext-ins',
+                        '../../commonmark-ext-task-list-items',
                         '../../commonmark-ext-yaml-front-matter'
                 ].forEach { d ->
                     // don't include module-info files, otherwise we get

commonmark-ext-gfm-alerts/src/main/java/org/commonmark/ext/gfm/alerts/AlertsExtension.java

@@ -63,13 +63,17 @@ public class AlertsExtension
      * The standard GitHub Flavored Markdown (GFM) types that the extension enables by default.
      * These can be overwritten with {@link Builder#setAllowedTypes(Map)}.
      */
-    public static final Map<String, String> STANDARD_TYPES =
-            Map.ofEntries(
-                    Map.entry("NOTE", "Note"),
-                    Map.entry("TIP", "Tip"),
-                    Map.entry("IMPORTANT", "Important"),
-                    Map.entry("WARNING", "Warning"),
-                    Map.entry("CAUTION", "Caution"));
+    public static final Map<String, String> STANDARD_TYPES;
+
+    static {
+        Map<String, String> types = new HashMap<>();
+        types.put("NOTE", "Note");
+        types.put("TIP", "Tip");
+        types.put("IMPORTANT", "Important");
+        types.put("WARNING", "Warning");
+        types.put("CAUTION", "Caution");
+        STANDARD_TYPES = Collections.unmodifiableMap(types);
+    }
 
     /** A map of alert marker ({@code [!TYPE]}) to the default title for that marker. */
     private final Map<String, String> allowedTypes;

commonmark-ext-github/pom.xml

@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.commonmark</groupId>
+        <artifactId>commonmark-parent</artifactId>
+        <version>0.32.1-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>commonmark-ext-github</artifactId>
+    <name>commonmark-java GitHub extensions</name>
+    <description>A bundle of extensions for GitHub Markdown features</description>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.commonmark</groupId>
+            <artifactId>commonmark</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.commonmark</groupId>
+            <artifactId>commonmark-ext-autolink</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.commonmark</groupId>
+            <artifactId>commonmark-ext-footnotes</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.commonmark</groupId>
+            <artifactId>commonmark-ext-gfm-alerts</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.commonmark</groupId>
+            <artifactId>commonmark-ext-gfm-strikethrough</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.commonmark</groupId>
+            <artifactId>commonmark-ext-gfm-tables</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.commonmark</groupId>
+            <artifactId>commonmark-ext-task-list-items</artifactId>
+        </dependency>
+    </dependencies>
+</project>

commonmark-ext-github/src/main/java/module-info.java

@@ -0,0 +1,11 @@
+module org.commonmark.ext.github {
+    exports org.commonmark.ext.github;
+
+    requires transitive org.commonmark;
+    requires org.commonmark.ext.autolink;
+    requires org.commonmark.ext.footnotes;
+    requires org.commonmark.ext.gfm.alerts;
+    requires org.commonmark.ext.gfm.strikethrough;
+    requires org.commonmark.ext.gfm.tables;
+    requires org.commonmark.ext.task.list.items;
+}

commonmark-ext-github/src/main/java/org/commonmark/ext/github/GitHubExtensions.java

@@ -0,0 +1,34 @@
+package org.commonmark.ext.github;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import org.commonmark.Extension;
+import org.commonmark.ext.autolink.AutolinkExtension;
+import org.commonmark.ext.footnotes.FootnotesExtension;
+import org.commonmark.ext.gfm.alerts.AlertsExtension;
+import org.commonmark.ext.gfm.strikethrough.StrikethroughExtension;
+import org.commonmark.ext.gfm.tables.TablesExtension;
+import org.commonmark.ext.task.list.items.TaskListItemsExtension;
+
+/** A preset for tables, strikethrough, autolinks, task lists, alerts and footnotes. */
+public final class GitHubExtensions {
+    private GitHubExtensions() {}
+
+    /**
+     * Creates the extensions with their default settings. Use the same list when building the
+     * parser and renderer.
+     *
+     * @return an unmodifiable list of extensions
+     */
+    public static List<Extension> create() {
+        return Collections.unmodifiableList(
+                Arrays.asList(
+                        AutolinkExtension.create(),
+                        FootnotesExtension.create(),
+                        AlertsExtension.create(),
+                        StrikethroughExtension.create(),
+                        TablesExtension.create(),
+                        TaskListItemsExtension.create()));
+    }
+}

commonmark-ext-github/src/main/java/org/commonmark/ext/github/package-info.java

@@ -0,0 +1,2 @@
+/** A preset for Markdown features supported by GitHub. */
+package org.commonmark.ext.github;

commonmark-integration-test/pom.xml

@@ -16,6 +16,10 @@
             <groupId>org.commonmark</groupId>
             <artifactId>commonmark</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.commonmark</groupId>
+            <artifactId>commonmark-ext-github</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.commonmark</groupId>
             <artifactId>commonmark-ext-autolink</artifactId>

commonmark-integration-test/src/test/java/org/commonmark/integration/GitHubExtensionsTest.java

@@ -0,0 +1,85 @@
+package org.commonmark.integration;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.util.List;
+import org.commonmark.Extension;
+import org.commonmark.ext.autolink.AutolinkExtension;
+import org.commonmark.ext.footnotes.FootnotesExtension;
+import org.commonmark.ext.gfm.alerts.AlertsExtension;
+import org.commonmark.ext.gfm.strikethrough.StrikethroughExtension;
+import org.commonmark.ext.gfm.tables.TablesExtension;
+import org.commonmark.ext.github.GitHubExtensions;
+import org.commonmark.ext.task.list.items.TaskListItemsExtension;
+import org.commonmark.parser.Parser;
+import org.commonmark.renderer.html.HtmlRenderer;
+import org.junit.jupiter.api.Test;
+
+class GitHubExtensionsTest {
+    @Test
+    void rendersTheSixBundledFeaturesTogether() {
+        String markdown =
+                """
+                | column |
+                | ------ |
+                | ~~old~~ |
+
+                - [x] See https://example.com
+
+                > [!NOTE]
+                > See the note[^one].
+
+                [^one]: A footnote.
+                """;
+        List<Extension> manual =
+                List.of(
+                        AutolinkExtension.create(),
+                        FootnotesExtension.create(),
+                        AlertsExtension.create(),
+                        StrikethroughExtension.create(),
+                        TablesExtension.create(),
+                        TaskListItemsExtension.create());
+        List<Extension> preset = GitHubExtensions.create();
+        assertEquals(
+                manual.stream().map(Object::getClass).toList(),
+                preset.stream().map(Object::getClass).toList());
+        String html = render(markdown, preset);
+        assertEquals(render(markdown, manual), html);
+        for (String feature :
+                List.of(
+                        "<th>column</th>",
+                        "<del>old</del>",
+                        "type=\"checkbox\"",
+                        "<a href=\"https://example.com\">",
+                        "markdown-alert-note",
+                        "class=\"footnote-ref\"")) {
+            assertTrue(html.contains(feature), feature);
+        }
+    }
+
+    @Test
+    void preservesCoreRenderingForOtherExtensions() {
+        String markdown =
+                """
+                ---
+                title: example
+                ---
+
+                # Heading
+
+                ++insert++ ![text](/img.png){width=6}
+                """;
+        assertEquals(render(markdown, List.of()), render(markdown, GitHubExtensions.create()));
+    }
+
+    @Test
+    void callersCannotChangeThePreset() {
+        assertThrows(UnsupportedOperationException.class, () -> GitHubExtensions.create().clear());
+        assertEquals(6, GitHubExtensions.create().size());
+    }
+
+    private static String render(String markdown, List<Extension> extensions) {
+        Parser parser = Parser.builder().extensions(extensions).build();
+        return HtmlRenderer.builder().extensions(extensions).build().render(parser.parse(markdown));
+    }
+}

pom.xml

@@ -20,6 +20,7 @@
         <module>commonmark-ext-gfm-alerts</module>
         <module>commonmark-ext-gfm-strikethrough</module>
         <module>commonmark-ext-gfm-tables</module>
+        <module>commonmark-ext-github</module>
         <module>commonmark-ext-heading-anchor</module>
         <module>commonmark-ext-image-attributes</module>
         <module>commonmark-ext-ins</module>
@@ -183,6 +184,11 @@
                 <artifactId>commonmark-ext-gfm-tables</artifactId>
                 <version>0.32.1-SNAPSHOT</version>
             </dependency>
+            <dependency>
+                <groupId>org.commonmark</groupId>
+                <artifactId>commonmark-ext-github</artifactId>
+                <version>0.32.1-SNAPSHOT</version>
+            </dependency>
             <dependency>
                 <groupId>org.commonmark</groupId>
                 <artifactId>commonmark-ext-heading-anchor</artifactId>