Consider EuropeanNumberTerminator property when determining text direction

Also, use EuropeanNumberSeparator information rather than relying on an
own (incomplete) list of number separators.

Fixes: #4057

src/Text.cpp

@@ -971,14 +971,19 @@ void Text::insertChar(Cursor & cur, char_type c)
 	if (lyxrc.auto_number) {
 		static docstring const number_operators = from_ascii("+-/*");
 		static docstring const number_unary_operators = from_ascii("+-");
-		static docstring const number_separators = from_ascii(".,:");
 
+		// European Number Separators: comma, dot etc.
+		// European Number Terminators: percent, permille, degree, euro etc.
 		if (cur.current_font.fontInfo().number() == FONT_ON) {
 			if (!isDigitASCII(c) && !contains(number_operators, c) &&
-			    !(contains(number_separators, c) &&
+			    !(isEuropeanNumberSeparator(c) &&
 			      cur.pos() != 0 &&
 			      cur.pos() != cur.lastpos() &&
 			      tm.displayFont(pit, cur.pos()).fontInfo().number() == FONT_ON &&
+			      tm.displayFont(pit, cur.pos() - 1).fontInfo().number() == FONT_ON) &&
+			    !(isEuropeanNumberTerminator(c) &&
+			      cur.pos() != 0 &&
+			      tm.displayFont(pit, cur.pos()).fontInfo().number() == FONT_ON &&
 			      tm.displayFont(pit, cur.pos() - 1).fontInfo().number() == FONT_ON)
 			   )
 				number(cur); // Set current_font.number to OFF
@@ -996,7 +1001,7 @@ void Text::insertChar(Cursor & cur, char_type c)
 				  ) {
 					setCharFont(pit, cur.pos() - 1, cur.current_font,
 						tm.font_);
-				} else if (contains(number_separators, ch)
+				} else if (isEuropeanNumberSeparator(ch)
 				     && cur.pos() >= 2
 				     && tm.displayFont(pit, cur.pos() - 2).fontInfo().number() == FONT_ON) {
 					setCharFont(pit, cur.pos() - 1, cur.current_font,

src/support/lstrings.cpp

@@ -164,6 +164,26 @@ bool isNumber(char_type c)
 }
 
 
+bool isEuropeanNumberSeparator(char_type c)
+{
+	if (!is_utf16(c))
+		// assume that no non-utf16 character is a numeral
+		// c outside the UCS4 range is catched as well
+		return false;
+	return ucs4_to_qchar(c).direction() == QChar::DirES;
+}
+
+
+bool isEuropeanNumberTerminator(char_type c)
+{
+	if (!is_utf16(c))
+		// assume that no non-utf16 character is a numeral
+		// c outside the UCS4 range is catched as well
+		return false;
+	return ucs4_to_qchar(c).direction() == QChar::DirET;
+}
+
+
 bool isDigitASCII(char_type c)
 {
 	return '0' <= c && c <= '9';

src/support/textutils.h

@@ -44,6 +44,14 @@ bool isSpace(char_type c);
 /// return true if a unicode char is a numeral.
 bool isNumber(char_type c);
 
+/// return true if a unicode char has the direction attribute
+/// European Number Separator [ES]
+bool isEuropeanNumberSeparator(char_type c);
+
+/// return true if a unicode char has the direction attribute
+/// European Number Terminator [ET]
+bool isEuropeanNumberTerminator(char_type c);
+
 /// return whether \p c is a digit in the ASCII range
 bool isDigitASCII(char_type c);