Allow multi-line content in setext headings (api break, spec 0.24, #28)

This changes the MatchedBlockParser API to return the full paragraph
content instead of just the first line. Extensions might be affected.

Author: robinst

commonmark-ext-gfm-tables/src/main/java/org/commonmark/ext/gfm/tables/internal/TableBlockParser.java

@@ -157,14 +157,14 @@ public static class Factory extends AbstractBlockParserFactory {
         @Override
         public BlockStart tryStart(ParserState state, MatchedBlockParser matchedBlockParser) {
             CharSequence line = state.getLine();
-            CharSequence paragraphStartLine = matchedBlockParser.getParagraphStartLine();
-            if (paragraphStartLine != null && paragraphStartLine.toString().contains("|")) {
+            CharSequence paragraph = matchedBlockParser.getParagraphContent();
+            if (paragraph != null && paragraph.toString().contains("|") && !paragraph.toString().contains("\n")) {
                 CharSequence separatorLine = line.subSequence(state.getIndex(), line.length());
                 if (TABLE_HEADER_SEPARATOR.matcher(separatorLine).matches()) {
-                    List<String> headParts = split(paragraphStartLine);
+                    List<String> headParts = split(paragraph);
                     List<String> separatorParts = split(separatorLine);
                     if (separatorParts.size() >= headParts.size()) {
-                        return BlockStart.of(new TableBlockParser(paragraphStartLine))
+                        return BlockStart.of(new TableBlockParser(paragraph))
                                 .atIndex(state.getIndex())
                                 .replaceActiveBlockParser();
                     }

commonmark-ext-gfm-tables/src/test/java/org/commonmark/ext/gfm/tables/TablesTest.java

@@ -32,6 +32,11 @@ public void separatorCanNotHaveLeadingSpaceThenPipe() {
         assertRendering("Abc|Def\n |---|---", "<p>Abc|Def\n|---|---</p>\n");
     }
 
+    @Test
+    public void headerMustBeOneLine() {
+        assertRendering("No\nAbc|Def\n---|---", "<p>No\nAbc|Def\n---|---</p>\n");
+    }
+
     @Test
     public void oneHeadNoBody() {
         assertRendering("Abc|Def\n---|---", "<table>\n" +

commonmark/src/main/java/org/commonmark/internal/DocumentParser.java

@@ -511,12 +511,10 @@ public BlockParser getMatchedBlockParser() {
         }
 
         @Override
-        public CharSequence getParagraphStartLine() {
+        public CharSequence getParagraphContent() {
             if (matchedBlockParser instanceof ParagraphParser) {
                 ParagraphParser paragraphParser = (ParagraphParser) matchedBlockParser;
-                if (paragraphParser.hasSingleLine()) {
-                    return paragraphParser.getContentString();
-                }
+                return paragraphParser.getContentString();
             }
             return null;
         }

commonmark/src/main/java/org/commonmark/internal/HeadingParser.java

@@ -47,7 +47,7 @@ public BlockStart tryStart(ParserState state, MatchedBlockParser matchedBlockPar
             }
             CharSequence line = state.getLine();
             int nextNonSpace = state.getNextNonSpaceIndex();
-            CharSequence paragraphStartLine = matchedBlockParser.getParagraphStartLine();
+            CharSequence paragraph = matchedBlockParser.getParagraphContent();
             Matcher matcher;
             if ((matcher = ATX_HEADING.matcher(line.subSequence(nextNonSpace, line.length()))).find()) {
                 // ATX heading
@@ -58,12 +58,12 @@ public BlockStart tryStart(ParserState state, MatchedBlockParser matchedBlockPar
                 return BlockStart.of(new HeadingParser(level, content))
                         .atIndex(line.length());
 
-            } else if (paragraphStartLine != null &&
+            } else if (paragraph != null &&
                     ((matcher = SETEXT_HEADING.matcher(line.subSequence(nextNonSpace, line.length()))).find())) {
                 // setext heading line
 
                 int level = matcher.group(0).charAt(0) == '=' ? 1 : 2;
-                String content = paragraphStartLine.toString();
+                String content = paragraph.toString();
                 return BlockStart.of(new HeadingParser(level, content))
                         .atIndex(line.length())
                         .replaceActiveBlockParser();

commonmark/src/main/java/org/commonmark/parser/block/MatchedBlockParser.java

@@ -10,9 +10,11 @@ public interface MatchedBlockParser {
     BlockParser getMatchedBlockParser();
 
     /**
-     * @return the first line of the paragraph if the matched block is a paragraph and we're on the second line,
-     * null otherwise
+     * Returns the current content of the paragraph if the matched block is a paragraph. The content can be multiple
+     * lines separated by {@code '\n'}.
+     *
+     * @return paragraph content or {@code null}
      */
-    CharSequence getParagraphStartLine();
+    CharSequence getParagraphContent();
 
 }