comment-remover.js

#!/usr/local/bin/js

function commentRemover(str) {
    var _str = str.split("");

    function getNext() { return _str[i++]; }
    function unget()   { i--; }

    function operandp(c) { return c && /[a-zA-Z0-9_$.)\]}/]/.test(c); }

    function getLastConcrete() {
        for (var i = buffer.length - 1; i >=0; --i)
            if (SKIPPABLE.indexOf(buffer[i]) === -1)
                return buffer[i];
        return "";
    }

    const SKIPPABLE  = "\t\n\r ";

    const ST_NEUTRAL = 0;
    const ST_SLASH   = 1;
    const ST_LINECOM = 100;
    const ST_MULCOM  = 1000;
    const ST_MULCOM2 = 1001;
    const ST_REGEXP  = 10000;
    const ST_REGEXP2 = 10001;   // character class
    const ST_STRING  = 100000;
    const ST_ESCAPE  = 1000000;

    var buffer = [];
    var i = 0;
    var c;

    var state  = ST_NEUTRAL;
    var prevst = ST_NEUTRAL;
    var quote  = null;

    while ((c = getNext()))
    {
        if (c === "~")
        {
            print("[=================== " + state + " ==================]");
        }

        // continue means "Skip this char"
        switch (state)
        {
        case ST_NEUTRAL:
            if (c === "/")
            {
                state = ST_SLASH;
                continue;
            }
            else if (c === "\"" || c === "'")
                quote = c, state = ST_STRING;
            break;
        case ST_SLASH:
            if (c === "/")
            {
                state = ST_LINECOM;
                continue;
            }
            else if (c === "*")
            {
                state = ST_MULCOM;
                continue;
            }
            else if (operandp(getLastConcrete()))
                state = ST_NEUTRAL; // division
            else
                state = ST_REGEXP;
            buffer.push("/");
            break;
        case ST_LINECOM:
            if (c === "\n")
                state = ST_NEUTRAL, unget();
            continue;
            break;
        case ST_MULCOM:
            if (c === "*")
                state = ST_MULCOM2;
            continue;
            break;
        case ST_MULCOM2:
            if (c === "/")
                state = ST_NEUTRAL;
            else
                state = ST_MULCOM, unget();
            continue;
            break;
        case ST_REGEXP:
            if (c === "\\")
                prevst = state, state = ST_ESCAPE;
            else if (c === "/")
                state = ST_NEUTRAL;
            else if (c === "[")
                state = ST_REGEXP2;
            break;
        case ST_REGEXP2:
            if (c === "\\")
                prevst = state, state = ST_ESCAPE;
            else if (c === "]")
                state = ST_REGEXP;
            break;
        case ST_STRING:
            if (c === "\\")
                prevst = state, state = ST_ESCAPE;
            else if (c === quote)
                state = ST_NEUTRAL;
            break;
        case ST_ESCAPE:
            state = prevst;
            break;
        }

        buffer.push(c);
    }

    return buffer.join("");
}

let input = [];
let str;

while ((str = readline()) !== null)
    input.push(str);

print(input.join("\n"));

print(commentRemover(input.join("\n")));