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#include "highlighter.h"

Highlighter::Highlighter(QTextDocument *parent)
	: QSyntaxHighlighter(parent)
{
	HighlightingRule rule;

	keywordFormat.setForeground(Qt::darkBlue);
	keywordFormat.setFontWeight(QFont::Bold);
	QStringList keywordPatterns;

	// Lua keywords
	keywordPatterns << "\\band\\b" << "\\bbreak\\b" << "\\bdo\\b"
	                << "\\belse\\b" << "\\belseif\\b"
	                << "\\bend\\b" << "\\bfalse\\b" << "\\bfor\\b"
	                << "\\bfunction\\b" << "\\bif\\b"
	                << "\\bin\\b" << "\\blocal\\b" << "\\bnil\\b"
	                << "\\bnot\\b" << "\\bor\\b"
	                << "\\brepeat\\b"<< "\\breturn\\b" << "\\bthen\\b"
	                << "\\btrue\\b" << "\\buntil\\b" << "\\bwhile\\b";
	foreach(const QString &pattern, keywordPatterns)
	{
		rule.pattern = QRegularExpression(pattern);
		rule.format = keywordFormat;
		highlightingRules.append(rule);
	}

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

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

	multiLineCommentFormat.setForeground(Qt::red);

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

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

	commentStartExpression = QRegularExpression("--\\[\\[");
	commentEndExpression = QRegularExpression("--\\]\\]");
}

void Highlighter::highlightBlock(const QString &text)
{
	foreach (const HighlightingRule &rule, highlightingRules)
	{
		QRegularExpressionMatchIterator matchIterator =
			rule.pattern.globalMatch(text);
		while(matchIterator.hasNext())
		{
			QRegularExpressionMatch match = matchIterator.next();
			setFormat(match.capturedStart(), match.capturedLength(), rule.format);
		}
	}
	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);
	}
}