brainf.swift

// First Brainf*** Interpreter in Swift

import Cocoa

func input() -> String {
    var keyboard = NSFileHandle.fileHandleWithStandardInput()
    var inputData = keyboard.availableData
    return NSString(data: inputData, encoding:NSUTF8StringEncoding)
}

func interpret(program_str: String) {
    var program = String[]()
    for char in program_str {
        program.append(String(char))
    }
    print(program)
    var loop = Dictionary<Int, Int>(),
        stack = Int[](),
        ptr = 0,
        pc = 0,
        env = Dictionary<Int, Int>()
    
    for (i, token) in enumerate(program) {
        if token == "[" {
            stack += i
        }
        if token == "]" {
            if stack.isEmpty {
                println("ERROR: Parser: Unmatched bracket at character \(i).")
                exit(-1)
            }
            var end = stack.removeLast()
            loop[end] = i
            loop[i] = end
        }
    }
    if !stack.isEmpty {
        println("ERROR: Parser: \(stack.count) unterminated loop(s).")
        exit(-1)
    }
    while pc < countElements(program) {
        var token = program[pc]
        if token == ">" {
            ptr++
        } else if token == "<" {
            ptr--
        } else if token == "+" {
            env[ptr] = env[ptr]! + 1
        } else if token == "-" {
            env[ptr] = env[ptr]! - 1
        } else if token == "." {
            var c = String(env[ptr]!)
            print(c)
        } else if token == "," {
            var in_str = input()
            env[ptr] = in_str.toInt()
        } else if (token == "[" && env[ptr] == 0) || (token == "]" && env[ptr] != 0) {
            pc = loop[pc]!
        }
        pc++
        
    }
}

interpret("++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.")