Qt 5.6 | Qt Widgets | Syntax Highlighter Example | highlighter.cpp Example File

Qt 5.6.2 Reference Documentation

# highlighter.cpp Example File

richtext/syntaxhighlighter/highlighter.cpp

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

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

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

          multiLineCommentFormat.setForeground(Qt::red);

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

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

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

      void Highlighter::highlightBlock(const QString &text)
      {
          foreach (const HighlightingRule &rule, highlightingRules) {
              QRegExp expression(rule.pattern);
              int index = expression.indexIn(text);
              while (index >= 0) {
                  int length = expression.matchedLength();
                  setFormat(index, length, rule.format);
                  index = expression.indexIn(text, index + length);
              }
          }
          setCurrentBlockState(0);

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

          while (startIndex >= 0) {
              int endIndex = commentEndExpression.indexIn(text, startIndex);
              int commentLength;
              if (endIndex == -1) {
                  setCurrentBlockState(1);
                  commentLength = text.length() - startIndex;
              } else {
                  commentLength = endIndex - startIndex
                                  + commentEndExpression.matchedLength();
              }
              setFormat(startIndex, commentLength, multiLineCommentFormat);
              startIndex = commentStartExpression.indexIn(text, startIndex + commentLength);
          }
      }