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QTextMarkdownWriter: escape special characters (line or word prefix) 

Try to avoid writing anything that the parser would misinterpret.
Escape pre-existing backslashes, but not those that are already escaped.
Optimize maybeEscapeFirstChar() slightly and apply it to every line
of output (except in code blocks), not only to new lines created by
word-wrapping.

Since it would be hard to do this without using regular expressions,
the markdown writer feature now depends on the regex feature.

Fixes: QTBUG-96051
Fixes: QTBUG-122083
Pick-to: 6.7
Change-Id: I8d95366501fd31441829081c668f11a3a3a23fe2
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
bb10
Shawn Rutledge 2024-03-01 00:39:50 -07:00
parent 5670d5f7e1
commit ca4774131b
4 changed files with 115 additions and 8 deletions
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1
src/gui/configure.cmake
View File

@ -1012,6 +1012,7 @@ qt_feature("system-textmarkdownreader" PUBLIC
qt_feature("textmarkdownwriter" PUBLIC
SECTION "Kernel"
LABEL "MarkdownWriter"
CONDITION QT_FEATURE_regularexpression
PURPOSE "Provides a Markdown (CommonMark and GitHub) writer"
)
qt_feature("textodfwriter" PUBLIC

54
src/gui/text/qtextmarkdownwriter.cpp
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@ -12,6 +12,7 @@
#include "qtextimagehandler_p.h"
#include "qtextmarkdownimporter_p.h"
#include "qloggingcategory.h"
#include <QtCore/QRegularExpression>
#if QT_CONFIG(itemmodel)
#include "qabstractitemmodel.h"
#endif
@ -286,15 +287,58 @@ static int adjacentBackticksCount(const QString &s)
return ret;
}
/*! \internal
Escape anything at the beginning of a line of markdown that would be
misinterpreted by a markdown parser, including any period that follows a
number (to avoid misinterpretation as a numbered list item).
https://spec.commonmark.org/0.31.2/#backslash-escapes
*/
static void maybeEscapeFirstChar(QString &s)
{
static const QRegularExpression numericListRe(uR"(\d+([\.)])\s)"_s);
static const QLatin1StringView specialFirstCharacters("#*+-");
QString sTrimmed = s.trimmed();
if (sTrimmed.isEmpty())
return;
char firstChar = sTrimmed.at(0).toLatin1();
if (firstChar == '*' || firstChar == '+' || firstChar == '-') {
int i = s.indexOf(QLatin1Char(firstChar));
QChar firstChar = sTrimmed.at(0);
if (specialFirstCharacters.contains(firstChar)) {
int i = s.indexOf(firstChar); // == 0 unless s got trimmed
s.insert(i, u'\\');
} else {
auto match = numericListRe.match(s, 0, QRegularExpression::NormalMatch,
QRegularExpression::AnchorAtOffsetMatchOption);
if (match.hasMatch())
s.insert(match.capturedStart(1), qtmw_Backslash);
}
}
/*! \internal
Escape unescaped backslashes. Then escape any special character that stands
alone or prefixes a "word", including the \c < that starts an HTML tag.
https://spec.commonmark.org/0.31.2/#backslash-escapes
*/
static void escapeSpecialCharacters(QString &s)
{
static const QRegularExpression backslashRe(uR"([^\\]\\)"_s);
static const QRegularExpression spaceRe(uR"(\s+)"_s);
static const QRegularExpression specialRe(uR"([<!*[`&]+[/\w])"_s);
int i = 0;
while (i >= 0) {
if (int j = s.indexOf(backslashRe, i); j >= 0) {
++j; // we found some char before the backslash that needs escaping
if (s.size() == j + 1 || s.at(j + 1) != qtmw_Backslash)
s.insert(j, qtmw_Backslash);
i = j + 3;
}
if (int j = s.indexOf(specialRe, i); j >= 0 && (j == 0 || s.at(j - 1) != u'\\')) {
s.insert(j, qtmw_Backslash);
i = j + 3;
}
i = s.indexOf(spaceRe, i);
if (i >= 0)
++i; // past the whitespace, if found
}
}
@ -504,6 +548,10 @@ int QTextMarkdownWriter::writeBlock(const QTextBlock &block, bool wrap, bool ign
QString fragmentText = frag.fragment().text();
while (fragmentText.endsWith(qtmw_Newline))
fragmentText.chop(1);
if (!(m_fencedCodeBlock || m_indentedCodeBlock)) {
escapeSpecialCharacters(fragmentText);
maybeEscapeFirstChar(fragmentText);
}
if (block.textList()) { // <li>first line</br>continuation</li>
QString newlineIndent =
QString(qtmw_Newline) + QString(m_wrappedLineIndent, qtmw_Space);

2
tests/auto/gui/text/qtextmarkdownimporter/tst_qtextmarkdownimporter.cpp
View File

@ -253,7 +253,7 @@ void tst_QTextMarkdownImporter::lists_data()
QTest::newRow("hyphen space newline") << "- \n" << 0 << 1 << 1 << true << "- \n";
QTest::newRow("hyphen space letter newline") << "- a\n" << 0 << 1 << 1 << false << "- a\n";
QTest::newRow("hyphen nbsp newline") <<
QString::fromUtf8("-\u00A0\n") << 0 << 1 << 0 << true << "-\u00A0\n\n";
QString::fromUtf8("-\u00A0\n") << 0 << 1 << 0 << true << "\\-\u00A0\n\n";
QTest::newRow("nested empty lists") << "*\n *\n *\n" << 0 << 1 << 1 << true << " * \n";
QTest::newRow("list nested in empty list") << "-\n * a\n" << 0 << 1 << 2 << false << "- \n * a\n";
QTest::newRow("lists nested in empty lists")

66
tests/auto/gui/text/qtextmarkdownwriter/tst_qtextmarkdownwriter.cpp
View File

@ -45,6 +45,8 @@ private slots:
void rewriteDocument();
void fromHtml_data();
void fromHtml();
void escapeSpecialCharacters_data();
void escapeSpecialCharacters();
private:
bool isMainFontFixed();
@ -822,16 +824,21 @@ void tst_QTextMarkdownWriter::fromHtml_data()
QTest::newRow("code") <<
"<pre class=\"language-pseudocode\">\n#include \"foo.h\"\n\nblock {\n statement();\n}\n\n</pre>" <<
"```pseudocode\n#include \"foo.h\"\n\nblock {\n statement();\n}\n\n```\n\n";
// TODO
// QTest::newRow("escaped number and paren after double newline") <<
// "<p>(The first sentence of this paragraph is a line, the next paragraph has a number</p>13) but that's not part of an ordered list" <<
// "(The first sentence of this paragraph is a line, the next paragraph has a number\n\n13\\) but that's not part of an ordered list\n\n";
QTest::newRow("escaped number and paren after single newline") <<
"<p>(The first sentence of this paragraph is a line, next paragraph has a number 13) but that's not part of an ordered list</p>" <<
"(The first sentence of this paragraph is a line, next paragraph has a number\n13\\) but that's not part of an ordered list\n\n";
QTest::newRow("escaped number and paren after double newline") <<
"<p>(The first sentence of this paragraph is a line, the next paragraph has a number</p>13) but that's not part of an ordered list" <<
"(The first sentence of this paragraph is a line, the next paragraph has a number\n\n13\\) but that's not part of an ordered list\n\n";
QTest::newRow("preformats with embedded backticks") <<
"<pre>none `one` ``two``</pre>plain<pre>```three``` ````four````</pre>plain" <<
"```\nnone `one` ``two``\n\n```\nplain\n\n```\n```three``` ````four````\n\n```\nplain\n\n";
QTest::newRow("list items with and without checkboxes") <<
"<ul><li>bullet</li><li class=\"unchecked\">unchecked item</li><li class=\"checked\">checked item</li></ul>" <<
"- bullet\n- [ ] unchecked item\n- [x] checked item\n";
QTest::newRow("table with backslash in cell") << // QTBUG-96051
"<table><tr><td>1011011 [</td><td>1011100 backslash \\</td></tr></table>" <<
"|1011011 [|1011100 backslash \\\\|";
}
void tst_QTextMarkdownWriter::fromHtml()
@ -858,5 +865,56 @@ void tst_QTextMarkdownWriter::fromHtml()
QCOMPARE(output, expectedOutput);
}
void tst_QTextMarkdownWriter::escapeSpecialCharacters_data()
{
QTest::addColumn<QString>("input");
QTest::addColumn<QString>("expectedOutput");
QTest::newRow("backslash") << "foo \\ bar \\\\ baz \\" << "foo \\\\ bar \\\\ baz \\\\";
QTest::newRow("not emphasized") << "*normal* **normal too**" << "\\*normal* \\**normal too**";
QTest::newRow("not code") << "`normal` `normal too`" << "\\`normal` \\`normal too`";
QTest::newRow("code fence") << "```not a fence; ``` no risk here; ```not a fence" // TODO slightly inconsistent
<< "\\```not a fence; ``` no risk here; \\```not a fence";
QTest::newRow("not html") << "<p>not a tag: <br/> nope</p>" << "\\<p>not a tag: \\<br/> nope\\</p>";
QTest::newRow("not a link") << "text [not a link](/foo)" << "text \\[not a link](/foo)";
QTest::newRow("not a circle") << "* polaris" << "\\* polaris";
QTest::newRow("not a square") << "+ groovy" << "\\+ groovy";
QTest::newRow("not a bullet") << "- stayin alive" << "\\- stayin alive";
QTest::newRow("arithmetic") << "1 + 2 - 3 * 4" << "1 + 2 - 3 * 4";
QTest::newRow("not a list") << "1. not a list" << "1\\. not a list";
QTest::newRow("not a list either") << "Jupiter and 10." << "Jupiter and 10.";
QTest::newRow("not a heading") << "# not a heading" << "\\# not a heading";
QTest::newRow("a non-entity") << "&ouml; not a character entity" << "\\&ouml; not a character entity";
}
/*! \internal
If the user types into a Qt-based editor plain text that the
markdown parser would misinterpret, escape it when we save to markdown
to clarify that it's plain text.
https://spec.commonmark.org/0.31.2/#backslash-escapes
*/
void tst_QTextMarkdownWriter::escapeSpecialCharacters() // QTBUG-96051, QTBUG-122083
{
QFETCH(QString, input);
QFETCH(QString, expectedOutput);
document->setPlainText(input);
QString output = documentToUnixMarkdown();
#ifdef DEBUG_WRITE_OUTPUT
{
QFile out("/tmp/" + QLatin1String(QTest::currentDataTag()) + ".md");
out.open(QFile::WriteOnly);
out.write(output.toUtf8());
out.close();
}
#endif
output = output.trimmed();
if (output != expectedOutput && (isMainFontFixed() || isFixedFontProportional()))
QEXPECT_FAIL("", "fixed main font or proportional fixed font (QTBUG-103484)", Continue);
QCOMPARE(output, expectedOutput);
}
QTEST_MAIN(tst_QTextMarkdownWriter)
#include "tst_qtextmarkdownwriter.moc"