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More robust link highlighting
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@tim-gromeyer
tim-gromeyer committed Aug 22, 2023
1 parent bb3bcd3 commit b597cbf
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Showing 2 changed files with 193 additions and 139 deletions.
323 changes: 184 additions & 139 deletions markdownhighlighter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -117,15 +117,6 @@ void MarkdownHighlighter::addDirtyBlock(const QTextBlock &block) {
* /usr/share/kde4/apps/katepart/syntax/markdown.xml
*/
void MarkdownHighlighter::initHighlightingRules() {
// highlight the reference of reference links
{
HighlightingRule rule(HighlighterState::MaskedSyntax);
rule.pattern =
QRegularExpression(QStringLiteral(R"(^\[.+?\]: \w+://.+$)"));
rule.shouldContain = QStringLiteral("://");
_highlightingRules.append(rule);
}

// highlight block quotes
{
HighlightingRule rule(HighlighterState::BlockQuote);
Expand All @@ -144,98 +135,6 @@ void MarkdownHighlighter::initHighlightingRules() {
// rule.pattern = QRegularExpression("^.+? \\| .+? \\| .+$");
// rule.state = HighlighterState::Table;
// _highlightingRulesPre.append(rule);

// highlight urls
{
HighlightingRule rule(HighlighterState::Link);

// highlight urls without any other markup like http://www.github.com
rule.pattern =
QRegularExpression(QStringLiteral(R"(\b\w+?:\/\/[^\s>]+)"));
rule.capturingGroup = 0;
rule.shouldContain = QStringLiteral("://");
_highlightingRules.append(rule);

// highlight urls without any other markup like www.github.com
rule.pattern =
QRegularExpression(QStringLiteral(R"(\bwww\.[^\s]+\.[^\s]+\b)"));
rule.capturingGroup = 0;
rule.shouldContain = QStringLiteral("www.");
_highlightingRules.append(rule);

// highlight urls with <> but without any . in it
rule.pattern =
QRegularExpression(QStringLiteral(R"(<(\w+?:\/\/[^\s]+)>)"));
rule.capturingGroup = 1;
rule.shouldContain = QStringLiteral("://");
_highlightingRules.append(rule);

// highlight links with <> that have a .in it
// rule.pattern = QRegularExpression("<(.+?:\\/\\/.+?)>");
rule.pattern = QRegularExpression(
QStringLiteral("<([^\\s`][^`]*?\\.[^`]*?[^\\s`])>"));
rule.capturingGroup = 1;
rule.shouldContain = QStringLiteral("<");
_highlightingRules.append(rule);

// highlight urls with title
// rule.pattern = QRegularExpression("\\[(.+?)\\]\\(.+?://.+?\\)");
// rule.pattern = QRegularExpression("\\[(.+?)\\]\\(.+\\)\\B");
rule.pattern = QRegularExpression(
QStringLiteral(R"(\[([^\[\]]+)\]\((\S+|.+?)\)\B)"));
rule.shouldContain = QStringLiteral("](");
_highlightingRules.append(rule);

// highlight urls with empty title
// rule.pattern = QRegularExpression("\\[\\]\\((.+?://.+?)\\)");
rule.pattern = QRegularExpression(QStringLiteral(R"(\[\]\((.+?)\))"));
rule.shouldContain = QStringLiteral("[](");
_highlightingRules.append(rule);

// highlight email links
rule.pattern = QRegularExpression(QStringLiteral("<(.+?@.+?)>"));
rule.shouldContain = QStringLiteral("@");
_highlightingRules.append(rule);

// highlight reference links
rule.pattern =
QRegularExpression(QStringLiteral(R"(\[(.+?)\]\[.+?\])"));
rule.shouldContain = QStringLiteral("[");
_highlightingRules.append(rule);
}

// Images
{
// highlight images with text
HighlightingRule rule(HighlighterState::Image);
rule.pattern =
QRegularExpression(QStringLiteral(R"(!\[(.+?)\]\(.+?\))"));
rule.shouldContain = QStringLiteral("![");
rule.capturingGroup = 1;
_highlightingRules.append(rule);

// highlight images without text
rule.pattern = QRegularExpression(QStringLiteral(R"(!\[\]\((.+?)\))"));
rule.shouldContain = QStringLiteral("![]");
_highlightingRules.append(rule);
}

// highlight images links
{
HighlightingRule rule(HighlighterState::Link);
rule.pattern = QRegularExpression(
QStringLiteral(R"(\[!\[(.+?)\]\(.+?\)\]\(.+?\))"));
rule.shouldContain = QStringLiteral("[![");
rule.capturingGroup = 1;
_highlightingRules.append(rule);

// highlight images links without text
rule.pattern =
QRegularExpression(QStringLiteral(R"(\[!\[\]\(.+?\)\]\((.+?)\))"));
rule.shouldContain = QStringLiteral("[![](");
_highlightingRules.append(rule);
}

// highlight trailing spaces
{
HighlightingRule rule(HighlighterState::TrailingSpace);
Expand Down Expand Up @@ -669,10 +568,8 @@ void MarkdownHighlighter::highlightIndentedCodeBlock(const QString &text) {
const QString prevTrimmed = currentBlock().previous().text().trimmed();
// previous line must be empty according to CommonMark except if it is a
// heading https://spec.commonmark.org/0.29/#indented-code-block
if (!prevTrimmed.isEmpty() &&
previousBlockState() != CodeBlockIndented &&
(previousBlockState() < H1 || previousBlockState() > H6) &&
previousBlockState() != HeadlineEnd)
if (!prevTrimmed.isEmpty() && previousBlockState() != CodeBlockIndented &&
!isHeading(previousBlockState()) && previousBlockState() != HeadlineEnd)
return;

const QString trimmed = text.trimmed();
Expand Down Expand Up @@ -1913,7 +1810,6 @@ void MarkdownHighlighter::setHeadingStyles(HighlighterState rule,
void MarkdownHighlighter::highlightAdditionalRules(
const QVector<HighlightingRule> &rules, const QString &text) {
const auto &maskedFormat = _formats[HighlighterState::MaskedSyntax];
_linkRanges.clear();

for (const HighlightingRule &rule : rules) {
// continue if another current block state was already set if
Expand Down Expand Up @@ -1943,26 +1839,16 @@ void MarkdownHighlighter::highlightAdditionalRules(
format.fontPointSize());
}

if (currentBlockState() >= H1 && currentBlockState() <= H6) {
if (isHeading(currentBlockState())) {
// setHeadingStyles(format, match, maskedGroup);

} else {
// store masked part of the link as a range
if (rule.state == Link) {
const int start = match.capturedStart(maskedGroup);
const int end = match.capturedStart(maskedGroup) +
match.capturedLength(maskedGroup);
if (!_linkRanges.contains({start, end})) {
_linkRanges.append({start, end});
}
}

setFormat(match.capturedStart(maskedGroup),
match.capturedLength(maskedGroup),
currentMaskedFormat);
}
}
if (currentBlockState() >= H1 && currentBlockState() <= H6) {
if (isHeading(currentBlockState())) {
setHeadingStyles(rule.state, match, capturingGroup);

} else {
Expand Down Expand Up @@ -1995,42 +1881,201 @@ int isInLinkRange(int pos, QVector<QPair<int, int>> &range) {

/**
* @brief highlight inline rules aka Emphasis, bolds, inline code spans,
* underlines, strikethrough.
* underlines, strikethrough, links, and images.
*/
void MarkdownHighlighter::highlightInlineRules(const QString &text) {
bool isEmStrongDone = false;

// TODO: Add Links and Images parsing
for (int i = 0; i < text.length(); ++i) {
// make sure we are not in a link range
if (!_linkRanges.isEmpty()) {
const int res = isInLinkRange(i, _linkRanges);
if (res > -1) {
i += res - 1;
continue;
}
QChar currentChar = text.at(i);

if (currentChar == QLatin1Char('`') ||
currentChar == QLatin1Char('~')) {
i = highlightInlineSpans(text, i, currentChar);
} else if (currentChar == QLatin1Char('<') &&
MH_SUBSTR(i, 4) == QLatin1String("<!--")) {
i = highlightInlineComment(text, i);
} else if (!isEmStrongDone && (currentChar == QLatin1Char('*') ||
currentChar == QLatin1Char('_'))) {
highlightEmAndStrong(text, i);
isEmStrongDone = true;
} else if (currentChar == QLatin1Char('[') ||
currentChar == QLatin1Char('<') || // <>
currentChar == QLatin1Char('h') || // http
currentChar == QLatin1Char('w') // www
) {
i = highlightLinkOrImage(text, i);
}
}
}

if ((text.at(i) == QLatin1Char('`') ||
text.at(i) == QLatin1Char('~'))) {
// Helper function for MarkdownHighlighter::highlightLinkOrImage
bool isLink(const QString &text) {
static const QLatin1String supportedSchemes[] = {
QLatin1String("http://"), QLatin1String("https://"),
QLatin1String("file://"), QLatin1String("www."),
QLatin1String("ftp://"), QLatin1String("mailto:"),
QLatin1String("tel:"), QLatin1String("sms:"),
QLatin1String("smsto:"), QLatin1String("data:"),
QLatin1String("irc://"), QLatin1String("gopher://"),
QLatin1String("spotify:"), QLatin1String("steam:"),
QLatin1String("bitcoin:"), QLatin1String("magnet:"),
QLatin1String("ed2k://"), QLatin1String("news:"),
QLatin1String("ssh://")};

for (const QLatin1String &scheme : supportedSchemes) {
if (text.startsWith(scheme)) {
return true;
}
}

i = highlightInlineSpans(text, i, text.at(i));
return false;
}

} else if (text.at(i) == QLatin1Char('<') && i + 3 < text.length() &&
text.at(i + 1) == QLatin1Char('!') &&
text.at(i + 2) == QLatin1Char('-') &&
text.at(i + 3) == QLatin1Char('-')) {
void MarkdownHighlighter::formatAndMaskRemaining(
int formatBegin, int formatLength, int beginningText, int endText,
const QTextCharFormat &format) {
int afterFormat = formatBegin + formatLength;

i = highlightInlineComment(text, i);
setFormat(beginningText, formatBegin - beginningText,
_formats[MaskedSyntax]);
setFormat(formatBegin, formatLength, format);
setFormat(afterFormat, endText - afterFormat, _formats[MaskedSyntax]);
}

} else if (!isEmStrongDone && (text.at(i) == QLatin1Char('*') ||
text.at(i) == QLatin1Char('_'))) {
/**
* @brief This function highlights images and links in Markdown text.
*
* @param text The input Markdown text.
* @param startIndex The starting index from where to begin processing.
* @return The index where processing should continue.
*/
int MarkdownHighlighter::highlightLinkOrImage(const QString &text,
qsizetype startIndex) {
// If the current blockis a heading, don't process further
if (isHeading(currentBlockState())) return startIndex;

// Get the character at the starting index
QChar startChar = text.at(startIndex);

// If it starts with '<', it indicates a link, or an email
// enclosed in angle brackets
if (startChar == QLatin1Char('<')) {
// Find the closing '>' character to identify the end of the link
int closingChar = text.indexOf(QLatin1Char('>'), startIndex);
if (closingChar == -1) return startIndex;

// Extract the content between '<' and '>'
QString linkContent =
text.mid(startIndex + 1, closingChar - startIndex - 1);

// Check if it's a valid link or email
if (!isLink(linkContent) && !linkContent.contains(QLatin1Char('@')))
return startIndex;

// Apply formatting to highlight the link
formatAndMaskRemaining(startIndex + 1, closingChar - startIndex - 1,
startIndex, closingChar, _formats[Link]);

return closingChar;
}
// Highlight http and www links
else if (startChar == QLatin1Char('h') || startChar == QLatin1Char('w')) {
int space = text.indexOf(QLatin1Char(' '), startIndex);
if (space == -1) space = text.length();

// Allow to highlight the href in HTML tags
if (MH_SUBSTR(startIndex, 6) == QLatin1String("href=\"")) {
int hrefEnd = text.indexOf(QLatin1Char('"'), startIndex + 6);
if (hrefEnd == -1) return space;

setFormat(startIndex + 6, hrefEnd - startIndex - 6, _formats[Link]);
return hrefEnd;
}

highlightEmAndStrong(text, i);
isEmStrongDone = true;
QString link = text.mid(startIndex, space - startIndex - 1);
if (!isLink(link)) return startIndex;

setFormat(startIndex, link.length() + 1, _formats[Link]);
return space;
}

// Find the index of the closing ']' character to identify the end of link
// or image text.
int endIndex = text.indexOf(QLatin1Char(']'), startIndex);

// If endIndex is not found or at the end of the text, the link is invalid
if (endIndex == -1 || endIndex == text.size() - 1) return startIndex;

// If there is an '!' preceding the starting character, it's an image
if (startIndex != 0 && text.at(startIndex - 1) == QLatin1Char('!')) {
// Find the index of the closing ')' character after the image link
int closingIndex = text.indexOf(QLatin1Char(')'), endIndex);
if (closingIndex == -1) return startIndex;
++closingIndex;

// Apply formatting to highlight the image.
formatAndMaskRemaining(startIndex + 1, endIndex - startIndex - 1,
startIndex, closingIndex, _formats[Image]);
return closingIndex;
}
// If the character after the closing ']' is '(', it's a regular link
else if (text.at(endIndex + 1) == QLatin1Char('(')) {
// Find the index of the closing ')' character after the link
int closingParenIndex = text.indexOf(QLatin1Char(')'), endIndex);
if (closingParenIndex == -1) return startIndex;
++closingParenIndex;

// If the substring starting from the current index matches "[![",
// It's a image with link
if (MH_SUBSTR(startIndex, 3) == QLatin1String("[![")) {
// Apply formatting to highlight the image alt text (inside the
// first ']')
int altEndIndex = text.indexOf(QLatin1Char(']'), endIndex + 1);
if (altEndIndex == -1) return startIndex;

// Find the last `)` (href) [![Image alt](Image src)](Link href)
int hrefIndex = text.indexOf(QLatin1Char(')'), altEndIndex);
if (hrefIndex == -1) return startIndex;
++hrefIndex;

formatAndMaskRemaining(startIndex + 3, endIndex - startIndex - 3,
startIndex, hrefIndex, _formats[Link]);

return hrefIndex;
}

// Apply formatting to highlight the link
formatAndMaskRemaining(startIndex + 1, endIndex - startIndex - 1,
startIndex, closingParenIndex, _formats[Link]);
return closingParenIndex;
}
// Reference links
else if (text.at(endIndex + 1) == QLatin1Char('[')) {
// Image with reference
int origIndex = startIndex;
if (text.at(startIndex + 1) == QLatin1Char('!')) {
startIndex = text.indexOf(QLatin1Char('['), startIndex + 1);
if (startIndex == -1) return origIndex;
}

int closingChar = text.indexOf(QLatin1Char(']'), endIndex + 1);
if (closingChar == -1) return startIndex;
++closingChar;

formatAndMaskRemaining(startIndex + 1, endIndex - startIndex - 1,
origIndex, closingChar, _formats[Link]);
return closingChar;
}
// If the character after the closing ']' is ':', it's a reference link
// reference
else if (text.at(endIndex + 1) == QLatin1Char(':')) {
formatAndMaskRemaining(0, 0, startIndex, endIndex + 1, {});
return endIndex + 1;
}

return startIndex; // If none of the conditions are met, continue
// processing from the same index
}

/** @brief highlight inline code spans -> `code` and highlight strikethroughs
Expand Down
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