unify operator weights, add recursive weight method to TreeNode

inc/expression.hpp

@@ -5,6 +5,8 @@
 #include <memory>
 #include <string>
 
+#include "print.h"
+
 namespace Expression {
 
 class Token {
@@ -28,6 +30,31 @@ public:
 		NOP  // not an operator
 	};
 
+	static int weight_op(Operator o)
+	{
+		switch (o)
+		{
+		case Expression::Token::OPA:
+		case Expression::Token::CPA:
+		case Expression::Token::NOP:
+			pr_warn("Unweightable operator - this is probably a bug!");
+			return 0;
+		case Expression::Token::ADD:
+			return 1;
+		case Expression::Token::SUB:
+			return 1;
+		case Expression::Token::MUL:
+			return 2;
+		case Expression::Token::DIV:
+			return 2;
+		case Expression::Token::POW:
+			return 3;
+		default:
+			pr_warn("Impossible operator - this is a bug!");
+			return 0;
+		}
+	}
+
 	union TokenValue {
 		std::shared_ptr<std::string> s;
 		double d;
@@ -380,6 +407,28 @@ public:
 			delete r;
 		}
 	}
+
+	int weight()
+	{
+		int w = 0;
+
+		if (l != nullptr)
+		{
+			w += l->weight();
+		}
+
+		if (r != nullptr)
+		{
+			w += r->weight();
+		}
+
+		if (o.t == Token::OPERATOR)
+		{
+			Token::weight_op(o.v.o);
+		}
+
+		return w;
+	}
 };
 
 }