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ccbikai/brainfuck.js

Created December 4, 2014 06:38
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Revisions

  1. 不给力的面条 created this gist Dec 4, 2014.
    78 changes: 78 additions & 0 deletions brainfuck.js
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,78 @@
    function getMatchingBra(code) {
    var stack = [];
    var bra = [];
    for(var i = 0; i < code.length; i++) bra.push(-1);
    for(var i = 0; i < code.length; i++) {
    if(code[i] === '[') {
    stack.push(i);
    } else if(code[i] === ']') {
    bra[i] = stack.pop();
    bra[bra[i]] = i;
    }
    }
    return bra;
    }

    function brainFuck(code, input) {
    var inputPos = 0;
    var commandPos = 0;
    var pointerPos = 0;
    var bytes = [ 0 ];
    var output = "";
    var matching = getMatchingBra(code);

    while(commandPos < code.length) {
    switch(code[commandPos]) {
    case '>': {
    pointerPos++;
    if(undefined === bytes[pointerPos]) {
    bytes.push(0);
    }
    break;
    }
    case '<': {
    pointerPos--;
    if(0 > pointerPos) {
    bytes.unshift(0);
    pointerPos = 0;
    }
    break;
    }
    case '+': {
    bytes[pointerPos] = (bytes[pointerPos] + 1) % 256;
    break;
    }
    case '-': {
    bytes[pointerPos]--;
    if(bytes[pointerPos] < 0) bytes[pointerPos] = 0;
    break;
    }
    case '.': {
    output += String.fromCharCode(bytes[pointerPos]);
    break;
    }
    case ',': {
    var temp = input.charCodeAt(inputPos++);
    bytes[pointerPos] = temp;
    break;
    }
    case '[': {
    if(!bytes[pointerPos]) {
    commandPos = matching[commandPos];
    }
    break;
    }
    case ']': {
    if(bytes[pointerPos]) {
    commandPos = matching[commandPos];
    }
    break;
    }
    }
    commandPos++;
    }

    return output;
    }
    var out = brainFuck('+++++++[>+++++[>++>+<<-]>>>+>++>++<<<<<<-]>>+++.[->+<]>.+++.[->+<]>.>[-<->]<---.>>[-<<->>]<<--.');
    console.log(out);