Syntax Highlighter Foundation

CMakeLists.txt

@@ -54,8 +54,10 @@ add_executable(${TARGET_NAME}
     src/main.cpp
     src/MainWindow.cpp
     src/CodeEditor.cpp
+    src/Syntax.cpp
     include/MainWindow.h
     include/CodeEditor.h
+    include/Syntax.h
 )
 
 qt_add_resources(APP_RESOURCES resources.qrc)

include/MainWindow.h

@@ -2,6 +2,7 @@
 #define MAINWINDOW_H
 
 #include "CodeEditor.h"
+#include "Syntax.h"
 #include <QMainWindow>
 #include <QMenu>
 #include <QAction>
@@ -34,6 +35,7 @@ private slots:
                           void (MainWindow::*slot)());
     CodeEditor *editor;
     QString currentFileName;
+    Syntax *syntax;
 };
 
 #endif // MAINWINDOW_H

include/Syntax.h

@@ -0,0 +1,37 @@
+#ifndef SYNTAX_H
+#define SYNTAX_H
+
+#include <QTextCharFormat>
+#include <QRegularExpression>
+#include <QSyntaxHighlighter>
+#include <QTextDocument>
+
+class Syntax : public QSyntaxHighlighter
+{
+    Q_OBJECT
+
+public:
+    Syntax(QTextDocument *parent = nullptr);
+
+protected:
+    void highlightBlock(const QString &text) override;
+
+private:
+    struct SyntaxRule
+    {
+        QRegularExpression pattern;
+        QTextCharFormat format;
+    };
+    QList<SyntaxRule> syntaxRules;
+
+    QTextCharFormat keywordFormat;
+    QTextCharFormat singleLineCommentFormat;
+    QTextCharFormat quotationMark;
+    QTextCharFormat functionFormat;
+    QTextCharFormat parenthesisFormat;
+    QTextCharFormat charFormat;
+
+    void addPattern(const QString &pattern, const QTextCharFormat &format);
+};
+
+#endif // SYNTAX_H

src/MainWindow.cpp

@@ -1,4 +1,5 @@
 #include "MainWindow.h"
+#include "Syntax.h"
 
 #include <QMenuBar>
 #include <QFileDialog>
@@ -15,8 +16,9 @@ MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent)
     resize(800, 600);
 
     editor = new CodeEditor(this);
-    setCentralWidget(editor);
+    syntax = new Syntax(editor->document());
 
+    setCentralWidget(editor);
     createMenuBar();
 }
 

src/Syntax.cpp

@@ -0,0 +1,66 @@
+#include "Syntax.h"
+
+Syntax::Syntax(QTextDocument *parent) : QSyntaxHighlighter(parent)
+{
+  keywordFormat.setForeground(Qt::blue);
+  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" << "\\bforeach\\b";
+  foreach (const QString &pattern, keywordPatterns)
+  {
+    addPattern(pattern, keywordFormat);
+  }
+
+  // Single line comment format expression
+  singleLineCommentFormat.setForeground(Qt::darkGray);
+  addPattern("//[^\n]*", singleLineCommentFormat);
+
+  // Double quotation mark for string
+  quotationMark.setForeground(Qt::darkGreen);
+  addPattern("\".*\"", quotationMark);
+
+  // Function format expression
+  functionFormat.setFontItalic(true);
+  functionFormat.setForeground(Qt::darkYellow);
+  addPattern("\\b[a-zA-Z_][a-zA-Z0-9_]*(?=\\s*\\()", functionFormat);
+
+  // Color pattern for parenthesis
+  QColor parenthesisColor("#6495ED");
+  parenthesisFormat.setForeground(parenthesisColor);
+  addPattern("[()]", parenthesisFormat);
+
+  // Regex for single character format 'a', '\n', etc
+  charFormat.setForeground(Qt::darkCyan);
+  addPattern("'(\\\\.|[^'])'", charFormat);
+}
+
+// Add syntax highlighting patterns
+void Syntax::addPattern(const QString &pattern, const QTextCharFormat &format)
+{
+    SyntaxRule rule;
+    rule.pattern = QRegularExpression(pattern);
+    rule.format  = format;
+    syntaxRules.append(rule);
+}
+
+void Syntax::highlightBlock(const QString &text)
+{
+  foreach (const SyntaxRule &rule, syntaxRules)
+  {
+    QRegularExpressionMatchIterator matchIterator = rule.pattern.globalMatch(text);
+    while (matchIterator.hasNext())
+    {
+      QRegularExpressionMatch match = matchIterator.next();
+      setFormat(match.capturedStart(), match.capturedLength(), rule.format);
+    }
+  }
+}