A simple brainfuck interpreter.

brainfuck.go

package brainfuck

func Interpreter(code string, input string) string {
	memory := make([]int, 30000)

	var (
		output                string
		pointer, inputPointer int
		loopStack             []int
	)

	for i := 0; i < len(code); i++ {
		switch code[i] {
		case '>':
			pointer++
		case '<':
			pointer--
		case '+':
			memory[pointer]++
		case '-':
			memory[pointer]--
		case '.':
			output += string(rune(memory[pointer]))
		case ',':
			if inputPointer < len(input) {
				memory[pointer] = int(input[inputPointer])
				inputPointer++
			}
		case '[':
			if memory[pointer] == 0 {
				i = loopStack[len(loopStack)-1]
			} else {
				loopStack = append(loopStack, i)
			}
		case ']':
			if memory[pointer] != 0 {
				i = loopStack[len(loopStack)-1]
			} else {
				loopStack = loopStack[:len(loopStack)-1]
			}
		}
	}
	return output
}