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Thread: Highlight with two different syntaxes with QSyntaxHighlighter

  1. 8th November 2009, 20:20 #1
    codemonkey
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    Default Highlight with two different syntaxes with QSyntaxHighlighter

    Hello.

    I have a working class that highlights fine right now.
    Straight from the docs
    Qt Code: 
    1. void myClass::highlightBlock(const QString &text)
    2. {
    3.     int length ;
    4.     int index = text.indexOf(this->m_pattern);
    5.     while (index >= 0)
    6.     {
    7.         length = this->m_pattern.matchedLength();
    8.         setFormat(index, length, this->m_format);
    9.         index = text.indexOf(this->m_pattern, index + length);
    10.     }
    11. }
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    But now I wish to add another pattern and highlight with that. So I wonder how one should do this: Something like this?

    Qt Code: 
    1. void myClass::highlightBlock(const QString &text)
    2. {
    3.     int index,index2,length;
    4.     index = text.indexOf(this->m_pattern);
    5.     index2 = text.indexOf(this->m_pattern2);
    6.     while (index >= 0 && index2 >=0)
    7.     {
    8.         if (index2 < index  && index2>0=0)
    9.         {
    10.             length = this->m_pattern2.matchedLength();
    11.             setFormat(index, length, this->m_format2);
    12.         }
    13.         else if (index < index2 && index>=0)
    14.         {
    15.            length = this->m_pattern.matchedLength();
    16.            setFormat(index, length, this->m_format);
    17.         }
    18.  
    19.         // perhaps some clever check to see that the matches do not overlap
    20.  
    21.         index = text.indexOf(this->m_pattern, index + length);
    22.         index = text.indexOf(this->m_pattern2, index + length);
    23.     }
    24. }
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    Will this work?

    And how do you do really do this if one would write an editor with proper syntax highlighting for a language for example c++, how do you separate all the different kind of patterns to highlight with different formats?
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  2. 8th November 2009, 20:50 #2
    lasher
    lasher is offline Novice
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    Default Re: Highlight with two different syntaxes with QSyntaxHighlighter

    Hi,

    Please check syntaxhighlighter example from Qt, It shows how to make
    syntax highlighting for C++. It's not perfect example because highlighting
    doesn't work well, but you will understand how to add many highligh rules.


    Regards
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  3. 9th November 2009, 16:40 #3
    JohannesMunk
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    Default Re: Highlight with two different syntaxes with QSyntaxHighlighter

    Maybe this will help you! I have pimped the syntaxhighlighter example a bit:

    Now the rules have names, so that you can add/replace a search-highlight rule with varying patterns. The map returns the rules sorted by keys. The order is relevant because for example strings in comments or function calls in comments should not be highlighted..

    Header-File:

    Qt Code: 
    1. #ifndef SYNTAXHIGHLIGHTER_H #define SYNTAXHIGHLIGHTER_H
    2.   #include <QSyntaxHighlighter>
    3.  #include <QTextCharFormat>
    4.   QT_BEGIN_NAMESPACE
    6.  QT_END_NAMESPACE
    7.   class Highlighter : public QSyntaxHighlighter
    8.  {    Q_OBJECT
    9.  public:
    10.      Highlighter(QTextDocument *parent = 0);
    11.      void SetRule(QString name,QString pattern,QTextCharFormat format);
    12.  protected:
    13.      void highlightBlock(const QString &text);
    14.       struct HighlightingRule
    15.      {
    16.          HighlightingRule() {}
    17.          HighlightingRule(QRegExp _pattern,QTextCharFormat _format) {pattern = _pattern;format = _format;}
    18.          QRegExp pattern;
    20.      };
    21.      QMap<QString,HighlightingRule> highlightingRules;
    22.  };
    23.   class MultiLineCommentHighlighter : public Highlighter
    24.  {    Q_OBJECT
    25.  public:
    26.      MultiLineCommentHighlighter(QTextDocument *parent = 0);
    27.  protected:
    28.      void highlightBlock(const QString &text);
    29.      QRegExp commentStartExpression;
    30.      QRegExp commentEndExpression;
    31.      QTextCharFormat multiLineCommentFormat;
    32.  };
    33.   class CppHighlighter : public MultiLineCommentHighlighter
    34.  {    Q_OBJECT
    35.  public:
    36.      CppHighlighter(QTextDocument *parent = 0);
    37.  };
    38.   #endif // SYNTAXHIGHLIGHTER_H
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    SyntaxHighlighter.cpp:
    Qt Code: 
    1. #include "SyntaxHighlighter.h"  #include <QtGui>
    2.   /****************************************************************************************
    3.   ****************************************************************************************
    4.   **** Highlighter ***********************************************************************
    5.   ****************************************************************************************
    6.   ****************************************************************************************/
    7.   Highlighter::Highlighter(QTextDocument *parent) : QSyntaxHighlighter(parent)
    8.  {
    9.  }
    10.   void Highlighter::SetRule(QString name,QString pattern,QTextCharFormat format)
    11.  {
    12.      if (pattern != "")
    13.          highlightingRules.insert(name,HighlightingRule(QRegExp(pattern),format));
    14.      else
    15.          highlightingRules.remove(name);
    16.      rehighlight();
    17.  }
    18.   void Highlighter::highlightBlock(const QString &text)
    19.  {
    20.      foreach (const HighlightingRule &rule, highlightingRules) {
    21.          QRegExp expression(rule.pattern);
    22.          int index = expression.indexIn(text);
    23.          while (index >= 0) {
    24.              int length = expression.matchedLength();
    25.              setFormat(index, length, rule.format);
    26.              index = expression.indexIn(text, index + length);
    27.          }
    28.      }
    29.      setCurrentBlockState(0);
    30.  }
    31.   /****************************************************************************************
    32.   ****************************************************************************************
    33.   **** MultiLineCommentHighlighter *******************************************************
    34.   ****************************************************************************************
    35.   ****************************************************************************************/
    36.   MultiLineCommentHighlighter::MultiLineCommentHighlighter(QTextDocument *parent) : Highlighter(parent)
    37.  {
    38.      multiLineCommentFormat.setForeground(Qt::red);
    39.      commentStartExpression = QRegExp("/\\*");
    40.      commentEndExpression = QRegExp("\\*/");
    41.  }
    42.   void MultiLineCommentHighlighter::highlightBlock(const QString &text)
    43.  {
    44.      Highlighter::highlightBlock(text);
    45.      int startIndex = 0;
    46.      if (previousBlockState() != 1)
    47.          startIndex = commentStartExpression.indexIn(text);
    48.       while (startIndex >= 0) {
    49.          int endIndex = commentEndExpression.indexIn(text, startIndex);
    50.          int commentLength;
    51.          if (endIndex == -1) {
    52.              setCurrentBlockState(1);
    53.              commentLength = text.length() - startIndex;
    54.          } else {
    55.              commentLength = endIndex - startIndex
    56.                              + commentEndExpression.matchedLength();
    57.          }
    58.          setFormat(startIndex, commentLength, multiLineCommentFormat);
    59.          startIndex = commentStartExpression.indexIn(text, startIndex + commentLength);
    60.      }
    61.  }
    62.   /****************************************************************************************
    63.   ****************************************************************************************
    64.   **** CppHighlighter ********************************************************************
    65.   ****************************************************************************************
    66.   ****************************************************************************************/
    67.   CppHighlighter::CppHighlighter(QTextDocument *parent) : MultiLineCommentHighlighter(parent)
    68.  {
    69.      QTextCharFormat keywordFormat;
    70.      QTextCharFormat classFormat;
    71.      QTextCharFormat singleLineCommentFormat;
    72.      QTextCharFormat quotationFormat;
    73.      QTextCharFormat functionFormat;
    74.       keywordFormat.setForeground(Qt::darkBlue);
    75.      keywordFormat.setFontWeight(QFont::Bold);
    76.      QStringList keywordPatterns;
    77.      keywordPatterns << "\\bchar\\b" << "\\bclass\\b" << "\\bconst\\b"
    78.                      << "\\bdouble\\b" << "\\benum\\b" << "\\bexplicit\\b"
    79.                      << "\\bfriend\\b" << "\\binline\\b" << "\\bint\\b"
    80.                      << "\\blong\\b" << "\\bnamespace\\b" << "\\boperator\\b"
    81.                      << "\\bprivate\\b" << "\\bprotected\\b" << "\\bpublic\\b"
    82.                      << "\\bshort\\b" << "\\bsignals\\b" << "\\bsigned\\b"
    83.                      << "\\bslots\\b" << "\\bstatic\\b" << "\\bstruct\\b"
    84.                      << "\\btemplate\\b" << "\\btypedef\\b" << "\\btypename\\b"
    85.                      << "\\bunion\\b" << "\\bunsigned\\b" << "\\bvirtual\\b"
    86.                      << "\\bvoid\\b" << "\\bvolatile\\b";
    87.      int i = 0;
    88.      foreach (const QString &pattern, keywordPatterns) {
    89.          SetRule(QString("00_KeyWord_%1").arg(i),pattern,keywordFormat);
    90.          ++i;
    91.      }
    92.       classFormat.setFontWeight(QFont::Bold);
    93.      classFormat.setForeground(Qt::darkMagenta);
    94.      SetRule("01_QtClasses","\\bQ[A-Za-z]+\\b",classFormat);
    95.       singleLineCommentFormat.setForeground(Qt::red);
    96.      SetRule("02_SingleLineComment","//[^\n]*",singleLineCommentFormat);
    97.       quotationFormat.setForeground(Qt::darkGreen);
    98.      SetRule("03_Quotation","\".*\"",quotationFormat);
    99.       functionFormat.setFontItalic(true);
    100.      functionFormat.setForeground(Qt::blue);
    101.      SetRule("04_Functions","\\b[A-Za-z0-9_]+(?=\\()",functionFormat);
    102.  }
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    HIH

    Johannes
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