Initial

1 files changed, 54 insertions, 0 deletions

diff --git a/example/math_expression/main.go b/example/math_expression/main.go
new file mode 100644
index 0000000..35f7c3b
--- /dev/null
+++ b/example/math_expression/main.go
@@ -0,0 +1,54 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/neonxp/unilex"
+)
+
+var output []unilex.Lexem = []unilex.Lexem{}
+var opPriority = map[string]int{
+	"^": 3,
+	"!": 3,
+	"*": 2,
+	"/": 2,
+	"+": 1,
+	"-": 1,
+}
+
+func main() {
+
+	l := unilex.New("10 * (20.0 + 30.0)")
+
+	go l.Run(lexExpression) // Start lexer
+
+	// Read infix expression lexems from lexer and convert them to RPN (reverse polish notation)
+	rpn := infixToRPNotation(l)
+	fmt.Println("RPN:", rpn)
+
+	// Calculate RPN
+	result := calculateRPN(rpn)
+	fmt.Println("Result:", result)
+}
+
+func lexExpression(l *unilex.Lexer) unilex.StateFunc {
+	l.AcceptWhile(" \t")
+	l.Ignore() // Ignore whitespaces
+
+	switch {
+	case l.Accept("("):
+		l.Emit("LP")
+	case l.Accept(")"):
+		l.Emit("RP")
+	case unilex.ScanNumber(l):
+		l.Emit("NUMBER")
+	case l.Accept("+-*/^!"):
+		l.Emit("OPERATOR")
+	case l.Peek() == unilex.EOF:
+		return nil
+	default:
+		return l.Errorf("Unexpected symbol")
+	}
+
+	return lexExpression
+}