LaTeX highlighter: make at a letter in the user preamble

Syntax highlighting now provides the appropriate cue that the user preamble is
inside \makeatletter…\makeatother.

(cherry picked from commit 10f6eb2e7e)

src/frontends/qt4/GuiDocument.cpp

@@ -452,7 +452,8 @@ PreambleModule::PreambleModule() : current_id_(0)
 {
 	// This is not a memory leak. The object will be destroyed
 	// with this.
-	(void) new LaTeXHighlighter(preambleTE->document());
+	// @ is letter in the LyX user preamble
+	(void) new LaTeXHighlighter(preambleTE->document(), true);
 	preambleTE->setFont(guiApp->typewriterSystemFont());
 	preambleTE->setWordWrapMode(QTextOption::NoWrap);
 	setFocusProxy(preambleTE);

src/frontends/qt4/LaTeXHighlighter.cpp

@@ -31,8 +31,8 @@ QColor blend(QColor color1, QColor color2) {
 }
 
 
-LaTeXHighlighter::LaTeXHighlighter(QTextDocument * parent)
-	: QSyntaxHighlighter(parent)
+LaTeXHighlighter::LaTeXHighlighter(QTextDocument * parent, bool at_letter)
+	: QSyntaxHighlighter(parent), at_letter_(at_letter)
 {
 	QPalette palette = QPalette();
 	QColor text_color = palette.color(QPalette::Active, QPalette::Text);
@@ -96,7 +96,11 @@ void LaTeXHighlighter::highlightBlock(QString const & text)
 		startIndex = exprStartDispMath.indexIn(text, startIndex + length);
 	}
 	// \whatever
-	static const QRegExp exprKeyword("\\\\[A-Za-z]+");
+	static const QRegExp exprKeywordAtOther("\\\\[A-Za-z]+");
+	// \wh@tever
+	static const QRegExp exprKeywordAtLetter("\\\\[A-Za-z@]+");
+	QRegExp const & exprKeyword = at_letter_ ? exprKeywordAtLetter
+	                                         : exprKeywordAtOther;
 	index = exprKeyword.indexIn(text);
 	while (index >= 0) {
 		int length = exprKeyword.matchedLength();

src/frontends/qt4/LaTeXHighlighter.h

@@ -25,7 +25,7 @@ namespace frontend {
 class LaTeXHighlighter : public QSyntaxHighlighter
 {
 public:
-	LaTeXHighlighter(QTextDocument * parent);
+	explicit LaTeXHighlighter(QTextDocument * parent, bool at_letter = false);
 
 protected:
 	void highlightBlock(QString const & text);
@@ -35,6 +35,8 @@ private:
 	QTextCharFormat keywordFormat;
 	QTextCharFormat mathFormat;
 	QTextCharFormat warningFormat;
+	// is at a letter? (as in the preamble)
+	bool const at_letter_;
 };
 
 } // namespace frontend

status.22x

@@ -21,9 +21,12 @@ What's new
 
 * USER INTERFACE
 
-* When changing zoom level, show current value in status bar (bug
+- When changing zoom level, show current value in status bar (bug
   10212).
 
+- Names containing @ are now recognised by the syntax highlighter in the
+  preamble.
+
 
 * DOCUMENTATION AND LOCALIZATION