Fix examples

1 files changed, 11 insertions, 0 deletions

diff --git a/example/math_expression/rpn.go b/example/math_expression/rpn.go
index b65983d..84de59c 100644
--- a/example/math_expression/rpn.go
+++ b/example/math_expression/rpn.go
@@ -1,3 +1,5 @@
+// +build example
+
 package main
 
 // Helper functions to convert infix notation to RPN and calculates expression result.
@@ -10,6 +12,15 @@ import (
 	"github.com/neonxp/unilex"
 )
 
+var opPriority = map[string]int{
+	"^": 3,
+	"!": 3,
+	"*": 2,
+	"/": 2,
+	"+": 1,
+	"-": 1,
+}
+
 func infixToRPNotation(l *unilex.Lexer) []unilex.Lexem {
 	output := []unilex.Lexem{}
 	stack := lexemStack{}