LeetCode/go/parsing-a-boolean-expression.go

package main

import (
	arraystack "github.com/emirpasic/gods/v2/stacks/arraystack"
)

func parseBoolExpr(expression string) bool {
	getRune := func(result bool) rune {
		if result {
			return 't'
		}
		return 'f'
	}

	st := arraystack.New[rune]()

	for _, token := range expression {
		if token == ',' || token == '(' {
			// ignore delimiters and opening brackets
			continue
		}

		// Handle closing of the operation
		if token == ')' {
			hasTrue, hasFalse := false, false

			for top, has := st.Peek(); has && top != '!' && top != '&' && top != '|'; top, has = st.Peek() {
				if top == 't' {
					hasTrue = true
				} else if top == 'f' {
					hasFalse = true
				}
				st.Pop()
			}

			// evaluate the operator
			op, _ := st.Pop()
			if op == '!' {
				st.Push(getRune(!hasTrue))
			} else if op == '&' {
				st.Push(getRune(!hasFalse))
			} else {
				st.Push(getRune(hasTrue))
			}

			continue
		}

		st.Push(token)
	}

	result, _ := st.Peek()
	return result == 't'
}