highlighter.cpp

#include "highlighter.h"

#include <utility>  // std::as_const

Highlighter::Highlighter(QObject *parent)
    : QSyntaxHighlighter(parent), initialised(false)
{
}

void Highlighter::highlightBlock(const QString &text)
{
    if (!initialised)
        return;

    for (const HighlightingRule &rule : std::as_const(highlightingRules))
    {
        QRegularExpressionMatchIterator matchIterator =
            rule.pattern.globalMatch(text);
        while (matchIterator.hasNext())
        {
            const QRegularExpressionMatch match = matchIterator.next();
            setFormat(match.capturedStart(), match.capturedLength(),
                      rule.format);
        }
    }
    setCurrentBlockState(0);

    // Multi-line /* ... */ comments.
    int startIndex = 0;
    if (previousBlockState() != 1)
        startIndex = text.indexOf(commentStartExpression);

    while (startIndex >= 0)
    {
        const QRegularExpressionMatch match =
            commentEndExpression.match(text, startIndex);
        const int endIndex = match.capturedStart();
        int commentLength = 0;
        if (endIndex == -1)
        {
            setCurrentBlockState(1);
            commentLength = text.length() - startIndex;
        }
        else
        {
            commentLength = endIndex - startIndex + match.capturedLength();
        }
        setFormat(startIndex, commentLength, multiLineCommentFormat);
        startIndex =
            text.indexOf(commentStartExpression, startIndex + commentLength);
    }

    // Search highlight. Skip when the pattern is empty / invalid, otherwise
    // an empty regex would match every position and paint the whole document.
    if (!searchMatchExpression.pattern().isEmpty() &&
        searchMatchExpression.isValid())
    {
        QRegularExpressionMatchIterator searchMatchIterator =
            searchMatchExpression.globalMatch(text);
        while (searchMatchIterator.hasNext())
        {
            const QRegularExpressionMatch match = searchMatchIterator.next();
            if (match.capturedLength() == 0)
                continue;
            setFormat(match.capturedStart(), match.capturedLength(),
                      searchMatchFormat);
        }
    }
}

void Highlighter::initColors()
{
    // Clear previous rules so re-initialisation (theme change) does not
    // keep appending duplicate rules.
    highlightingRules.clear();

    HighlightingRule rule;

    keywordFormat.setForeground(syntaxColor.keyword);
    keywordFormat.setFontWeight(QFont::Bold);

    const QString keywordPatterns[] = {
        QStringLiteral("\\bchar\\b"),      QStringLiteral("\\bclass\\b"),
        QStringLiteral("\\bconst\\b"),     QStringLiteral("\\bdouble\\b"),
        QStringLiteral("\\benum\\b"),      QStringLiteral("\\bexplicit\\b"),
        QStringLiteral("\\bfriend\\b"),    QStringLiteral("\\binline\\b"),
        QStringLiteral("\\bint\\b"),       QStringLiteral("\\blong\\b"),
        QStringLiteral("\\bnamespace\\b"), QStringLiteral("\\boperator\\b"),
        QStringLiteral("\\bprivate\\b"),   QStringLiteral("\\bprotected\\b"),
        QStringLiteral("\\bpublic\\b"),    QStringLiteral("\\bshort\\b"),
        QStringLiteral("\\bsignals\\b"),   QStringLiteral("\\bsigned\\b"),
        QStringLiteral("\\bslots\\b"),     QStringLiteral("\\bstatic\\b"),
        QStringLiteral("\\bstruct\\b"),    QStringLiteral("\\btemplate\\b"),
        QStringLiteral("\\btypedef\\b"),   QStringLiteral("\\btypename\\b"),
        QStringLiteral("\\bunion\\b"),     QStringLiteral("\\bunsigned\\b"),
        QStringLiteral("\\bvirtual\\b"),   QStringLiteral("\\bvoid\\b"),
        QStringLiteral("\\bvolatile\\b"),  QStringLiteral("\\bbool\\b"),
        QStringLiteral("\\bcmake\\b")};
    for (const QString &pattern : keywordPatterns)
    {
        rule.pattern = QRegularExpression(pattern);
        rule.format = keywordFormat;
        highlightingRules.append(rule);
    }

    classFormat.setFontWeight(QFont::Bold);
    classFormat.setForeground(syntaxColor.argument);
    rule.pattern =
        QRegularExpression(QStringLiteral("(?<=\\s)--?[a-zA-Z0-9_]+"));
    rule.format = classFormat;
    highlightingRules.append(rule);

    tickMarkFormat.setForeground(QColor(60, 179, 113));
    tickMarkFormat.setFontWeight(QFont::ExtraBold);
    rule.pattern = QRegularExpression(QStringLiteral("(☑|-\\s\\[x]\\s)"));
    rule.format = tickMarkFormat;
    highlightingRules.append(rule);

    unTickMarkFormat.setForeground(QColor(219, 112, 147));
    unTickMarkFormat.setFontWeight(QFont::ExtraBold);
    rule.pattern = QRegularExpression(QStringLiteral("(☐|-\\s\\[\\s\\]\\s)"));
    rule.format = unTickMarkFormat;
    highlightingRules.append(rule);

    singleLineCommentFormat.setForeground(syntaxColor.comment);
    rule.pattern = QRegularExpression(QStringLiteral("//[^\n]*"));
    rule.format = singleLineCommentFormat;
    highlightingRules.append(rule);

    multiLineCommentFormat.setForeground(syntaxColor.comment);

    quotationFormat.setForeground(syntaxColor.quote);
    rule.pattern = QRegularExpression(QStringLiteral("\"(.*?)\""));
    rule.format = quotationFormat;
    highlightingRules.append(rule);

    functionFormat.setFontItalic(true);
    functionFormat.setForeground(syntaxColor.method);
    rule.pattern =
        QRegularExpression(QStringLiteral("\\b[A-Za-z0-9_]+(?=\\()"));
    rule.format = functionFormat;
    highlightingRules.append(rule);

    commentStartExpression = QRegularExpression(QStringLiteral("/\\*"));
    commentEndExpression = QRegularExpression(QStringLiteral("\\*/"));

    regexCodeBlock.setPattern(QStringLiteral("^```+.*"));

    searchMatchFormat.setBackground(syntaxColor.searchMatch);

    initialised = true;
}

void Highlighter::syntaxColorUpdateHandler(HighlightColor &colors)
{
    syntaxColor.argument = colors.argument;
    syntaxColor.keyword = colors.keyword;
    syntaxColor.method = colors.method;
    syntaxColor.comment = colors.comment;
    syntaxColor.quote = colors.quote;
    syntaxColor.type = colors.type;
    syntaxColor.searchMatch = colors.searchMatch;

    // initColors() clears highlightingRules before re-populating,
    // so repeated theme changes no longer duplicate rules.
    initColors();
    rehighlight();
}

void Highlighter::updateSearchText(const QString &text)
{
    if (text.isEmpty())
    {
        // Clearing the search box must remove all search highlighting.
        searchMatchExpression.setPattern(QString());
        rehighlight();
        return;
    }

    QRegularExpression re(QRegularExpression::escape(text),
                          QRegularExpression::CaseInsensitiveOption);
    searchMatchExpression = re;
    rehighlight();
}