Add support for Markdown tables.

This is very basic, and the main intent is just to avoid mangling tables. We essentially preserve the formatting of any table we find, without attempting to adjust it in any way.

PiperOrigin-RevId: 906574344

Author: eamonnmcmanus

core/pom.xml

@@ -39,11 +39,6 @@
       <groupId>com.google.guava</groupId>
       <artifactId>guava</artifactId>
     </dependency>
-    <dependency>
-      <groupId>org.commonmark</groupId>
-      <artifactId>commonmark</artifactId>
-      <version>0.28.0</version>
-    </dependency>
 
     <!-- Compile-time dependencies -->
     <dependency>
@@ -66,6 +61,16 @@
       <artifactId>auto-service-annotations</artifactId>
       <optional>true</optional>
     </dependency>
+    <dependency>
+      <groupId>org.commonmark</groupId>
+      <artifactId>commonmark</artifactId>
+      <version>0.28.0</version>
+    </dependency>
+    <dependency>
+      <groupId>org.commonmark</groupId>
+      <artifactId>commonmark-ext-gfm-tables</artifactId>
+      <version>0.28.0</version>
+    </dependency>
 
     <!-- Test dependencies -->
     <dependency>

core/src/main/java/com/google/googlejavaformat/java/javadoc/JavadocFormatter.java

@@ -44,6 +44,7 @@
 import com.google.googlejavaformat.java.javadoc.Token.MarkdownCodeSpanStart;
 import com.google.googlejavaformat.java.javadoc.Token.MarkdownFencedCodeBlock;
 import com.google.googlejavaformat.java.javadoc.Token.MarkdownHardLineBreak;
+import com.google.googlejavaformat.java.javadoc.Token.MarkdownTable;
 import com.google.googlejavaformat.java.javadoc.Token.MoeBeginStripComment;
 import com.google.googlejavaformat.java.javadoc.Token.MoeEndStripComment;
 import com.google.googlejavaformat.java.javadoc.Token.OptionalLineBreak;
@@ -137,6 +138,7 @@ private static String render(List<Token> input, int blockIndent, boolean classic
         case MarkdownHardLineBreak unused -> output.writeMarkdownHardLineBreak();
         case Literal t -> output.writeLiteral(t);
         case MarkdownFencedCodeBlock t -> output.writeMarkdownFencedCodeBlock(t);
+        case MarkdownTable t -> output.writeMarkdownTable(t);
         case ListItemCloseTag unused -> {}
         case OptionalLineBreak unused -> {}
         case ParagraphCloseTag unused -> {}

core/src/main/java/com/google/googlejavaformat/java/javadoc/JavadocWriter.java

@@ -35,6 +35,7 @@
 import com.google.googlejavaformat.java.javadoc.Token.ListOpenTag;
 import com.google.googlejavaformat.java.javadoc.Token.Literal;
 import com.google.googlejavaformat.java.javadoc.Token.MarkdownFencedCodeBlock;
+import com.google.googlejavaformat.java.javadoc.Token.MarkdownTable;
 import com.google.googlejavaformat.java.javadoc.Token.MoeBeginStripComment;
 import com.google.googlejavaformat.java.javadoc.Token.MoeEndStripComment;
 import com.google.googlejavaformat.java.javadoc.Token.PreCloseTag;
@@ -44,6 +45,7 @@
 import com.google.googlejavaformat.java.javadoc.Token.StartOfLineToken;
 import com.google.googlejavaformat.java.javadoc.Token.TableCloseTag;
 import com.google.googlejavaformat.java.javadoc.Token.TableOpenTag;
+import java.util.List;
 
 /**
  * Stateful object that accepts "requests" and "writes," producing formatted Javadoc.
@@ -354,6 +356,20 @@ void writeMarkdownFencedCodeBlock(MarkdownFencedCodeBlock token) {
     requestBlankLine();
   }
 
+  void writeMarkdownTable(MarkdownTable token) {
+    if (wroteAnythingSignificant && !atStartOfLine) {
+      requestBlankLine();
+    }
+    flushWhitespace();
+    List<String> lines = token.value().lines().toList();
+    output.append(lines.get(0));
+    for (String line : lines.subList(1, lines.size())) {
+      writeNewline(AutoIndent.NO_AUTO_INDENT);
+      output.append(line);
+    }
+    requestBlankLine();
+  }
+
   @Override
   public String toString() {
     return output.toString();

core/src/main/java/com/google/googlejavaformat/java/javadoc/MarkdownPositions.java

@@ -28,11 +28,14 @@
 import com.google.googlejavaformat.java.javadoc.Token.MarkdownCodeSpanEnd;
 import com.google.googlejavaformat.java.javadoc.Token.MarkdownCodeSpanStart;
 import com.google.googlejavaformat.java.javadoc.Token.MarkdownFencedCodeBlock;
+import com.google.googlejavaformat.java.javadoc.Token.MarkdownTable;
 import com.google.googlejavaformat.java.javadoc.Token.ParagraphCloseTag;
 import com.google.googlejavaformat.java.javadoc.Token.ParagraphOpenTag;
 import java.util.Objects;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import org.commonmark.ext.gfm.tables.TableBlock;
+import org.commonmark.ext.gfm.tables.TablesExtension;
 import org.commonmark.node.BulletList;
 import org.commonmark.node.Code;
 import org.commonmark.node.FencedCodeBlock;
@@ -93,6 +96,10 @@ void visit(Node node) {
         case OrderedList orderedList -> addSpan(orderedList, LIST_OPEN_TOKEN, LIST_CLOSE_TOKEN);
         case ListItem listItem -> alreadyVisitedChildren = visitListItem(listItem);
         case FencedCodeBlock fencedCodeBlock -> visitFencedCodeBlock(fencedCodeBlock);
+        case TableBlock tableBlock -> {
+          visitTableBlock(tableBlock);
+          alreadyVisitedChildren = true;
+        }
         case Code code -> visitCodeSpan(code);
         // TODO: others
         default -> {}
@@ -143,6 +150,12 @@ private void visitFencedCodeBlock(FencedCodeBlock fencedCodeBlock) {
       positionToToken.get(start).addLast(token);
     }
 
+    private void visitTableBlock(TableBlock tableBlock) {
+      int start = startPosition(tableBlock);
+      int end = endPosition(tableBlock);
+      positionToToken.get(start).addLast(new MarkdownTable(input.substring(start, end)));
+    }
+
     private void visitCodeSpan(Code code) {
       int start = startPosition(code);
       int end = endPosition(code);
@@ -200,7 +213,10 @@ public String toString() {
   }
 
   private static final Parser PARSER =
-      Parser.builder().includeSourceSpans(IncludeSourceSpans.BLOCKS_AND_INLINES).build();
+      Parser.builder()
+          .includeSourceSpans(IncludeSourceSpans.BLOCKS_AND_INLINES)
+          .extensions(ImmutableList.of(TablesExtension.create()))
+          .build();
 
   private static final HeaderOpenTag HEADER_OPEN_TOKEN = new HeaderOpenTag("");
   private static final HeaderCloseTag HEADER_CLOSE_TOKEN = new HeaderCloseTag("");

core/src/main/java/com/google/googlejavaformat/java/javadoc/Token.java

@@ -140,6 +140,20 @@ record MarkdownCodeSpanEnd(String value) implements Token {}
   record MarkdownFencedCodeBlock(String value, String start, String end, String literal)
       implements Token {}
 
+  /**
+   * A Markdown table, like:
+   *
+   * {@snippet :
+   * | foo | bar |
+   * | --- | --- |
+   * | baz | qux |
+   * }
+   *
+   * @param value the full text of the table as it appeared in the input, including the delimiters
+   *     and the literal content.
+   */
+  record MarkdownTable(String value) implements Token {}
+
   /**
    * Whitespace that is not in a {@code <pre>} or {@code <table>} section. Whitespace includes
    * leading newlines, asterisks, and tabs and spaces. In the output, it is translated to newlines

core/src/test/java/com/google/googlejavaformat/java/JavadocFormattingTest.java

@@ -1516,15 +1516,6 @@ class Test {}
     doFormatTest(input, expected);
   }
 
-  private void doFormatTest(String input, String expected) {
-    try {
-      String actual = formatter.formatSource(input);
-      assertThat(actual).isEqualTo(expected);
-    } catch (FormatterException e) {
-      throw new AssertionError(e);
-    }
-  }
-
   @Test
   public void windowsLineSeparator() throws FormatterException {
     String input =
@@ -2016,25 +2007,37 @@ public void markdownTables() {
     assume().that(MARKDOWN_JAVADOC_SUPPORTED).isTrue();
     String input =
 """
+/// Table McTableface
+///
 /// | foo | bar |
 /// | --- | --- |
 /// | baz | qux |
 ///
 /// - |foo|bar|
 ///   |--:|:--|
 ///   |baz|qux|
+///
+/// - Another list.
+///
+///   | which | contains |
+///   | ----- | -------- |
+///   | a | table |
 class Test {}
 """;
-    // TODO: unmangle the tables
-    String expected =
-"""
-/// | foo | bar | | --- | --- | | baz | qux |
-/// - |foo|bar| |--:|:--| |baz|qux|
-class Test {}
-""";
+    // We don't currently try to align the column markers in the rows of the last table.
+    String expected = input;
     doFormatTest(input, expected);
   }
 
+  private void doFormatTest(String input, String expected) {
+    try {
+      String actual = formatter.formatSource(input);
+      assertThat(actual).isEqualTo(expected);
+    } catch (FormatterException e) {
+      throw new AssertionError(e);
+    }
+  }
+
   // TODO: b/346668798 - Test the following Markdown constructs, and make the tests work as needed.
   // We can assume that the CommonMark parser correctly handles Markdown, so the question is whether
   // they are subsequently mishandled by our formatting logic. So for example the CommonMark parser
@@ -2074,10 +2077,4 @@ class Test {}
   //
   // - Autolinks
   //   <http://example.com> should be preserved. https://spec.commonmark.org/0.31.2/#autolink
-  //
-  // - Tables
-  //   | foo | bar |
-  //   | --- | --- |
-  //   | baz | qux |
-  //   Probably we should just try not to mangle them. https://spec.commonmark.org/0.31.2/#tables
 }