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我有以下Brainfuck解释器通过最小测试套件。除了像打印斐波那契序列这样的大问题似乎失败(套件中的最后一个测试)。我解释失误执行的brainfuck斐波那契代码是从http://esoteric.sange.fi/brainfuck/bf-source/prog/fibonacci.txt。 我的解释有什么问题? 这里是一个小提琴:https://jsfiddle.net/rt017kpz/Brainfuck解释器错误行为
function brainLuck(code, input) {
// "Infinite" heap of memory initialized as 0 for bf to store program values
let data = new Proxy([], {get: (arr, i) => arr[i] ? arr[i] : 0 })
let ptr = 0;
let inputPtr = 0;
let codePtr = 0;
let output = '';
let loopStack = []
const op = {
'+' :() => {
if (data[ptr] === 255) { data[ptr] = 0; }
else { data[ptr]++; }
codePtr++;
},
'-' :() => {
if (data[ptr] === 0) { data[ptr] = 255; }
else { data[ptr]--; }
codePtr++;
},
'.' :() => {
output += String.fromCharCode(data[ptr]);
codePtr++;
},
',' :() => {
data[ptr] = input.charCodeAt(inputPtr++);
codePtr++;
},
'>' :() => {
ptr++; codePtr++;
},
'<' :() => {
if (ptr > 0) { ptr--; }
codePtr++;
},
'[' :() => {
if (data[ptr] === 0) {
while(code[codePtr] !== ']') codePtr++;
} else {
loopStack.unshift(codePtr);
}
codePtr++
},
']' :() => {
if (data[ptr] === 0) { loopStack.shift(); }
else { codePtr = loopStack[0] }
codePtr++
}
}
while(codePtr < code.length) {
if(op[code[codePtr]]) op[code[codePtr]]()
else codePtr++
}
return output;
}
////////// TESTS //////////////
it('handles `+` and `.` operants',() => {
expect(
brainLuck('+++.')
).to.equal(
String.fromCharCode(3)
)
})
it('handles `-` operant and underflows from 0 to 255',() => {
expect(
brainLuck('+++----.')
).to.equal(
String.fromCharCode(255)
)
})
it('handles `,` the input operand',() => {
expect(
brainLuck(',.', 'A')
).to.equal(
'A'
)
})
it('handles input in conjuction with arithmetic',() => {
expect(
brainLuck(',+.', 'A')
).to.equal(
'B'
)
})
it('handles looping (`[`, `]`) and shift (`<`, `>`) operants',() => {
expect(
brainLuck(',>+++[<.>-]', 'A')
).to.equal(
'AAA'
)
})
it('only parses known symbols',() => {
expect(
brainLuck(',nothing>++else+[<.>matters!-]', 'A')
).to.equal(
'AAA'
)
})
it('handles nested loops',() => {
expect(
brainLuck(',>+++[->+++[<<.>>-]<]', 'A')
).to.equal(
'AAAAAAAAA'
)
})
it('can multiply two numbers',() => {
expect(
brainLuck(',>,<[>[->+>+<<]>>[-<<+>>]<<<-]>>.', String.fromCharCode(8,9))
).to.equal(
String.fromCharCode(72)
)
})
it('can print the fibonacci sequence',() => {
expect(
brainLuck('++++>+>>>>++++++++++++++++++++++++++++++++++++++++++++>++++++++++++++++++++++++++++++++<<<<<<[>[>>>>>>+>+<<<<<<<-]>>>>>>>[<<<<<<<+>>>>>>>-]<[>++++++++++[-<-[>>+>+<<<-]>>>[<<<+>>>-]+<[>[-]<[-]]>[<<[>>>+<<<-]>>[-]]<<]>>>[>>+>+<<<-]>>>[<<<+>>>-]+<[>[-]<[-]]>[<<+>>[-]]<<<<<<<]>>>>>[++++++++++++++++++++++++++++++++++++++++++++++++.[-]]++++++++++<[->-<]>++++++++++++++++++++++++++++++++++++++++++++++++.[-]<<<<<<<<<<<<[>>>+>+<<<<-]>>>>[<<<<+>>>>-]<-[>>.>.<<<[-]]<<[>>+>+<<<-]>>>[<<<+>>>-]<<[<+>-]>[<+>-]<<<-]')
).to.equal(
'1, 1, 2, 3'
)
})
mocha.run();
<html>
<head>
<meta charset="utf-8">
<title>Mocha Tests</title>
<link href="https://cdn.rawgit.com/mochajs/mocha/2.2.5/mocha.css" rel="stylesheet" />
</head>
<body>
<div id="mocha"></div>
<script src="https://cdn.rawgit.com/Automattic/expect.js/0.3.1/index.js"></script>
<script src="https://cdn.rawgit.com/mochajs/mocha/2.2.5/mocha.js"></script>
<script>mocha.setup('bdd')</script>
</body>
</html>
您是否尝试过通过代码在调试器步进找出它可能是什么? * *测试失败了吗?它会“崩溃”吗?意想不到的结果?还有别的吗? –
感谢您的回应,如果您运行我的代码片段,您可以看到'错误:预期':',等于'1,1,2,3''。至于使用调试器进行调试,我已经尝试过,但是bf代码是如此严重混淆。到目前为止我没有运气。斐波那契bf代码非常大。不幸的是,这是我唯一知道的不能正确执行的人。 –
你的']'实现是否正确?我希望看到像'if(data [ptr]!== 0){while(code [codePtr]!=='[')codePtr - ;'(我认为可能没关系)数组作为堆栈)。 –