add color highlighting during token post-processing

src/syntaxer.cpp

@@ -420,7 +420,7 @@ static void write_operation(
 	mp.erase(mp.begin() + position, mp.begin() + position + 1);
 }
 
-static void add_bracket_to(std::vector<Expression::Token>& tv, const int location, const int direction)
+static int add_bracket_to(std::vector<Expression::Token>& tv, const int location, const int direction)
 {
 	int i = location + direction, l = tv.size(), lv = 0;
 
@@ -438,7 +438,7 @@ static void add_bracket_to(std::vector<Expression::Token>& tv, const int locatio
 				if (!lv)
 				{
 					tv.insert(tv.begin() + i + 1, Expression::Token(Expression::Token::OPA));
-					return;
+					return i + 1;
 				}
 
 				if (tv[i].v.o == Expression::Token::OPA)
@@ -449,6 +449,7 @@ static void add_bracket_to(std::vector<Expression::Token>& tv, const int locatio
 		}
 
 		tv.insert(tv.begin(), Expression::Token(Expression::Token::OPA));
+		return 0;
 	}
 	else if (direction == 1)
 	{
@@ -464,7 +465,7 @@ static void add_bracket_to(std::vector<Expression::Token>& tv, const int locatio
 				if (!lv)
 				{
 					tv.insert(tv.begin() + i, Expression::Token(Expression::Token::CPA));
-					return;
+					return i;
 				}
 
 				if (tv[i].v.o == Expression::Token::CPA)
@@ -475,6 +476,12 @@ static void add_bracket_to(std::vector<Expression::Token>& tv, const int locatio
 		}
 
 		tv.emplace_back(Expression::Token::CPA);
+		return i;
+	}
+	else
+	{
+		pr_warn("Invalid direction given, this is a big bug!");
+		return -1;
 	}
 }
 
@@ -699,8 +706,10 @@ void apply_corrections(std::vector<Expression::Token>& tv)
 							}
 
 							// inverse order to keep location valid between calls
-							add_bracket_to(tv, i,  1);
-							add_bracket_to(tv, i, -1);
+							std::vector<int> highlight_locations;
+							highlight_locations.emplace_back(i+1);
+							highlight_locations.emplace_back(add_bracket_to(tv, i,  1) + 1);
+							highlight_locations.emplace(highlight_locations.begin(), add_bracket_to(tv, i, -1));
 
 							// advance one step to compensate for inserted left bracket
 							i++;
@@ -709,7 +718,7 @@ void apply_corrections(std::vector<Expression::Token>& tv)
 							relative_level++;
 
 							pr_debug("Updated vector:");
-							Parser::print_math_vector(tv);
+							Parser::print_math_vector(tv, highlight_locations);
 						}
 					}
 				}