highlight_syntax.cpp

/* ****************************************************************************
 * -------------------------------------------------------------------------- *
 *                                                                            *
 * Copyright © 2021 Kalynovsky Valentin. All rights reserved.                 *
 * Licensed under the Apache License, Version 2.0                             *
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 * Licensed under the Apache License, Version 2.0 (the "License");            *
 * you may not use this file except in compliance with the License.           *
 * You may obtain a copy of the License at                                    *
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 *     http://www.apache.org/licenses/LICENSE-2.0                             *
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 * Unless required by applicable law or agreed to in writing, software        *
 * distributed under the License is distributed on an "AS IS" BASIS,          *
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   *
 * See the License for the specific language governing permissions and        *
 * limitations under the License.                                             *
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 * -------------------------------------------------------------------------- *
 * ************************************************************************** */

#include "highlight_syntax.h"

highlight_syntax::highlight_syntax(QTextDocument *parent) :
    QSyntaxHighlighter(parent)
{
    HighlightRule rule;

    keywordFormat.setForeground(Qt::darkBlue);
    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")
    };

    for(const QString &pattern : keywordPatterns)
    {
        rule.pattern = QRegularExpression(pattern);
        rule.form = keywordFormat;
        highlightingRules.append(rule);
    }

    classFormat.setForeground(Qt::darkMagenta);
    classFormat.setFontWeight(QFont::Bold);
    rule.pattern = QRegularExpression("\\bQ[A-Za-z]+\\b");
    rule.form = classFormat;
    highlightingRules.append(rule);

    quotationFormat.setForeground(Qt::darkGreen);
    rule.pattern = QRegularExpression("\".*\"");
    rule.form = quotationFormat;
    highlightingRules.append(rule);

    functionFormat.setFontItalic(true);
    functionFormat.setForeground(Qt::blue);
    rule.pattern = QRegularExpression("\\b[A-Za-z0-9_]+(?=\\()");
    rule.form = functionFormat;
    highlightingRules.append(rule);

    singleLineCommentFormat.setForeground(Qt::red);
    rule.pattern = QRegularExpression("//[^\n]*");
    rule.form = singleLineCommentFormat;
    highlightingRules.append(rule);

    multiLineCommentFormat.setForeground(Qt::red);

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

void highlight_syntax::highlightBlock(const QString &text)
{
    for(const HighlightRule &rule : qAsConst(highlightingRules)) {
        QRegularExpressionMatchIterator matchIterator = rule.pattern.globalMatch(text);
        while (matchIterator.hasNext()) {
            QRegularExpressionMatch match = matchIterator.next();
            setFormat(match.capturedStart(), match.capturedLength(), rule.form);
        }
    }

    setCurrentBlockState(0);

    int startIndex = 0;
    if (previousBlockState() != 1)
        startIndex = text.indexOf(commentStartExpression);

    while (startIndex >= 0) {
        QRegularExpressionMatch match = commentEndExpression.match(text, startIndex);
        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);
    }
}