QTextMarkdownWriter: Handle lists in blockquotes correctly

But we do not yet handle a blockquote in a list item. Presumably
that's less common anyway.

We now also continue block-quote prefixes onto blank lines
within a block quote, which looks more normal.

Task-number: QTBUG-104997
Change-Id: I2b5642cf3a0c81a94444a33f026a02ad53e7e6bb
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
(cherry picked from commit f3e528b)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/gui/text/qtextmarkdownwriter.cpp

@@ -112,17 +112,22 @@ void QTextMarkdownWriter::writeFrame(const QTextFrame *frame)
             // suppress needless blank lines, when there will be a big change in block format
             bool nextIsDifferent = false;
             bool ending = false;
+            int blockQuoteIndent = 0;
+            int nextBlockQuoteIndent = 0;
             {
                 QTextFrame::iterator next = iterator;
                 ++next;
+                QTextBlockFormat format = iterator.currentBlock().blockFormat();
+                QTextBlockFormat nextFormat = next.currentBlock().blockFormat();
+                blockQuoteIndent = format.intProperty(QTextFormat::BlockQuoteLevel);
+                nextBlockQuoteIndent = nextFormat.intProperty(QTextFormat::BlockQuoteLevel);
                 if (next.atEnd()) {
                     nextIsDifferent = true;
                     ending = true;
                 } else {
-                    QTextBlockFormat format = iterator.currentBlock().blockFormat();
-                    QTextBlockFormat nextFormat = next.currentBlock().blockFormat();
                     if (nextFormat.indent() != format.indent() ||
-                            nextFormat.property(QTextFormat::BlockCodeLanguage) != format.property(QTextFormat::BlockCodeLanguage))
+                        nextFormat.property(QTextFormat::BlockCodeLanguage) !=
+                                format.property(QTextFormat::BlockCodeLanguage))
                         nextIsDifferent = true;
                 }
             }
@@ -139,8 +144,10 @@ void QTextMarkdownWriter::writeFrame(const QTextFrame *frame)
                     tableRow = cell.row();
                 }
             } else if (!block.textList()) {
-                if (lastWasList)
+                if (lastWasList) {
                     m_stream << qtmw_Newline;
+                    m_linePrefixWritten = false;
+                }
             }
             int endingCol = writeBlock(block, !table, table && tableRow == 0,
                                        nextIsDifferent && !block.textList());
@@ -164,8 +171,16 @@ void QTextMarkdownWriter::writeFrame(const QTextFrame *frame)
             } else if (endingCol > 0) {
                 if (block.textList() || block.blockFormat().hasProperty(QTextFormat::BlockCodeLanguage)) {
                     m_stream << qtmw_Newline;
+                    if (block.textList()) {
+                        m_stream << m_linePrefix;
+                        m_linePrefixWritten = true;
+                    }
                 } else {
-                    m_stream << qtmw_Newline << qtmw_Newline;
+                    m_stream << qtmw_Newline;
+                    if (nextBlockQuoteIndent < blockQuoteIndent)
+                        setLinePrefixForBlockQuote(nextBlockQuoteIndent);
+                    m_stream << m_linePrefix;
+                    m_stream << qtmw_Newline;
                     m_doubleNewlineWritten = true;
                 }
             }
@@ -211,6 +226,16 @@ QTextMarkdownWriter::ListInfo QTextMarkdownWriter::listInfo(QTextList *list)
     return m_listInfo.value(list);
 }
 
+void QTextMarkdownWriter::setLinePrefixForBlockQuote(int level)
+{
+    m_linePrefix.clear();
+    if (level > 0) {
+        m_linePrefix.reserve(level * 2);
+        for (int i = 0; i < level; ++i)
+            m_linePrefix += u"> ";
+    }
+}
+
 static int nearestWordWrapIndex(const QString &s, int before)
 {
     before = qMin(before, s.size());
@@ -336,10 +361,20 @@ int QTextMarkdownWriter::writeBlock(const QTextBlock &block, bool wrap, bool ign
     const bool codeBlock = blockFmt.hasProperty(QTextFormat::BlockCodeFence) ||
             blockFmt.stringProperty(QTextFormat::BlockCodeLanguage).size() > 0 ||
             blockFmt.nonBreakableLines();
+    const int blockQuoteLevel = blockFmt.intProperty(QTextFormat::BlockQuoteLevel);
     if (m_fencedCodeBlock && !codeBlock) {
         m_stream << m_linePrefix << m_codeBlockFence << qtmw_Newline;
         m_fencedCodeBlock = false;
         m_codeBlockFence.clear();
+        m_linePrefixWritten = m_linePrefix.size() > 0;
+    }
+    m_linePrefix.clear();
+    if (!blockFmt.headingLevel() && blockQuoteLevel > 0) {
+        setLinePrefixForBlockQuote(blockQuoteLevel);
+        if (!m_linePrefixWritten) {
+            m_stream << m_linePrefix;
+            m_linePrefixWritten = true;
+        }
     }
     if (block.textList()) { // it's a list-item
         auto fmt = block.textList()->format();
@@ -416,31 +451,25 @@ int QTextMarkdownWriter::writeBlock(const QTextBlock &block, bool wrap, bool ign
             if (blockFmt.hasProperty(QTextFormat::BlockIndent))
                 m_codeBlockFence = QString(m_wrappedLineIndent, qtmw_Space) + m_codeBlockFence;
             // A block quote can contain an indented code block, but not vice-versa.
-            m_stream << m_linePrefix << m_codeBlockFence
-                     << blockFmt.stringProperty(QTextFormat::BlockCodeLanguage) << qtmw_Newline;
+            m_stream << m_codeBlockFence << blockFmt.stringProperty(QTextFormat::BlockCodeLanguage)
+                     << qtmw_Newline << m_linePrefix;
             m_fencedCodeBlock = true;
         }
         wrap = false;
     } else if (!blockFmt.indent()) {
         m_wrappedLineIndent = 0;
-        m_linePrefix.clear();
-        if (blockFmt.hasProperty(QTextFormat::BlockQuoteLevel)) {
-            int level = blockFmt.intProperty(QTextFormat::BlockQuoteLevel);
-            QString quoteMarker = QStringLiteral("> ");
-            m_linePrefix.reserve(level * 2);
-            for (int i = 0; i < level; ++i)
-                m_linePrefix += quoteMarker;
-        }
         if (blockFmt.hasProperty(QTextFormat::BlockCodeLanguage)) {
             // A block quote can contain an indented code block, but not vice-versa.
             m_linePrefix += QString(4, qtmw_Space);
             m_indentedCodeBlock = true;
         }
+        if (!m_linePrefixWritten) {
+            m_stream << m_linePrefix;
+            m_linePrefixWritten = true;
+        }
     }
     if (blockFmt.headingLevel())
         m_stream << QByteArray(blockFmt.headingLevel(), '#') << ' ';
-    else
-        m_stream << m_linePrefix;
 
     QString wrapIndentString = m_linePrefix + QString(m_wrappedLineIndent, qtmw_Space);
     // It would be convenient if QTextStream had a lineCharPos() accessor,
@@ -584,6 +613,10 @@ int QTextMarkdownWriter::writeBlock(const QTextBlock &block, bool wrap, bool ign
                     i = j + 1;
                 }
             } else {
+                if (!m_linePrefixWritten && col == wrapIndentString.size()) {
+                    m_stream << m_linePrefix;
+                    col += m_linePrefix.size();
+                }
                 m_stream << markers << fragmentText;
                 col += markers.size() + fragmentText.size();
             }
@@ -615,6 +648,7 @@ int QTextMarkdownWriter::writeBlock(const QTextBlock &block, bool wrap, bool ign
     }
     if (missedBlankCodeBlockLine)
         m_stream << qtmw_Newline;
+    m_linePrefixWritten = false;
     return col;
 }
 

src/gui/text/qtextmarkdownwriter_p.h

@@ -43,6 +43,7 @@ class Q_GUI_EXPORT QTextMarkdownWriter
     };
 
     ListInfo listInfo(QTextList *list);
+    void setLinePrefixForBlockQuote(int level);
 
 private:
     QTextStream &m_stream;
@@ -53,6 +54,7 @@ class Q_GUI_EXPORT QTextMarkdownWriter
     int m_wrappedLineIndent = 0;
     int m_lastListIndent = 1;
     bool m_doubleNewlineWritten = false;
+    bool m_linePrefixWritten = false;
     bool m_indentedCodeBlock = false;
     bool m_fencedCodeBlock = false;
 };

tests/auto/gui/text/qtextmarkdownwriter/data/blockquotes.md

@@ -8,17 +8,17 @@ MacFarlane writes:
 
 > What distinguishes Markdown from many other lightweight markup syntaxes,
 > which are often easier to write, is its readability. As Gruber writes:
-
+> 
 > > The overriding design goal for Markdown's formatting syntax is to make it
 > > as readable as possible. The idea is that a Markdown-formatted document should
 > > be publishable as-is, as plain text, without looking like it's been marked up
 > > with tags or formatting instructions. ( 
 > > <http://daringfireball.net/projects/markdown/> )
-
+> 
 > The point can be illustrated by comparing a sample of AsciiDoc with an
 > equivalent sample of Markdown. Here is a sample of AsciiDoc from the AsciiDoc
 > manual:
-
+> 
 > ```AsciiDoc
 > 1. List item one.
 > +

tests/auto/gui/text/qtextmarkdownwriter/data/blockquotesWithLists.md

@@ -0,0 +1,14 @@
+What if we have a quotation containing a list?
+
+> First some quoted text, and then a list:
+> 
+> - one
+> - two is longer and has enough words to form a paragraph with text continuing
+>   onto the next line
+> 
+> enough of that, let's try a numbered list
+> 
+> 1.  List item one
+> 2.  List item two is longer and has enough words to form a paragraph with
+>     text continuing onto the next line.
+> 

tests/auto/gui/text/qtextmarkdownwriter/data/listItemWithBlockquote.md

@@ -0,0 +1,6 @@
+What if we have a list item containing a block quote?
+
+- one
+- > two is longer and has enough words to form a paragraph with text continuing
+  > onto the next line
+

tests/auto/gui/text/qtextmarkdownwriter/tst_qtextmarkdownwriter.cpp

@@ -530,6 +530,8 @@ void tst_QTextMarkdownWriter::rewriteDocument_data()
     QTest::addColumn<QString>("inputFile");
 
     QTest::newRow("block quotes") << "blockquotes.md";
+    QTest::newRow("block quotes with lists") << "blockquotesWithLists.md";
+    // QTest::newRow("list item with block quote") << "listItemWithBlockquote.md"; // not supported for now
     QTest::newRow("example") << "example.md";
     QTest::newRow("list items after headings") << "headingsAndLists.md";
     QTest::newRow("word wrap") << "wordWrap.md";
@@ -629,6 +631,8 @@ void tst_QTextMarkdownWriter::fromHtml()
     }
 #endif
 
+    output = output.trimmed();
+    expectedOutput = expectedOutput.trimmed();
     if (output != expectedOutput && (isMainFontFixed() || isFixedFontProportional()))
         QEXPECT_FAIL("", "fixed main font or proportional fixed font (QTBUG-103484)", Continue);
     QCOMPARE(output, expectedOutput);