Working on syntax highlighting

Author: dcwhite

src/Interface/Modules/Python/InterfaceWithPythonDialog.cc

@@ -139,6 +139,8 @@ CodeEditor::CodeEditor(QWidget *parent) : QPlainTextEdit(parent)
 
     updateLineNumberAreaWidth(0);
     highlightCurrentLine();
+
+    highlighter_ = new Highlighter(document());
 }
 
 int CodeEditor::lineNumberAreaWidth()
@@ -220,3 +222,88 @@ void CodeEditor::lineNumberAreaPaintEvent(QPaintEvent *event)
     ++blockNumber;
 }
 }
+
+Highlighter::Highlighter(QTextDocument *parent)
+    : QSyntaxHighlighter(parent)
+{
+    HighlightingRule rule;
+
+    keywordFormat.setForeground(Qt::green);
+    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" << "\\bfor\\b" << "\\bin\\b"
+                    << "\\bTrue\\b" << "\\bFalse\\b";
+    for (const auto& 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);
+
+quotationFormat.setForeground(Qt::darkGreen);
+rule.pattern = QRegExp("\".*\"");
+rule.format = quotationFormat;
+highlightingRules.append(rule);
+
+functionFormat.setFontItalic(true);
+functionFormat.setForeground(Qt::cyan);
+rule.pattern = QRegExp("\\b[A-Za-z0-9_]+(?=\\()");
+rule.format = functionFormat;
+highlightingRules.append(rule);
+
+singleLineCommentFormat.setForeground(Qt::yellow);
+rule.pattern = QRegExp("#[^\n]*");
+rule.format = singleLineCommentFormat;
+highlightingRules.append(rule);
+
+multiLineCommentFormat.setForeground(Qt::yellow);
+
+commentStartExpression = QRegExp("/\\*");
+commentEndExpression = QRegExp("\\*/");
+}
+
+void Highlighter::highlightBlock(const QString &text)
+{
+    for (const auto& 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);
+}
+}

src/Interface/Modules/Python/InterfaceWithPythonDialog.h

@@ -74,6 +74,7 @@ private Q_SLOTS:
 
 private:
   QWidget* lineNumberArea_;
+  class Highlighter* highlighter_;
 };
 
 class LineNumberArea : public QWidget
@@ -96,6 +97,35 @@ class LineNumberArea : public QWidget
     CodeEditor *codeEditor;
 };
 
+class Highlighter : public QSyntaxHighlighter
+{
+    Q_OBJECT
+
+public:
+    Highlighter(QTextDocument* parent = nullptr);
+
+protected:
+    void highlightBlock(const QString &text) override;
+
+private:
+    struct HighlightingRule
+    {
+        QRegExp pattern;
+        QTextCharFormat format;
+    };
+    QVector<HighlightingRule> highlightingRules;
+
+    QRegExp commentStartExpression;
+    QRegExp commentEndExpression;
+
+    QTextCharFormat keywordFormat;
+    QTextCharFormat classFormat;
+    QTextCharFormat singleLineCommentFormat;
+    QTextCharFormat multiLineCommentFormat;
+    QTextCharFormat quotationFormat;
+    QTextCharFormat functionFormat;
+};
+
 }
 }