async.js

Ajax下日志框架

/***

MochiKit.Async 1.3.1

See <http://mochikit.com/> for documentation, downloads, license, etc.

(c) 2005 Bob Ippolito.  All rights Reserved.

***/

if (typeof(dojo) != 'undefined') {
    dojo.provide("MochiKit.Async");
    dojo.require("MochiKit.Base");
}
if (typeof(JSAN) != 'undefined') {
    JSAN.use("MochiKit.Base", []);
}

try {
    if (typeof(MochiKit.Base) == 'undefined') {
        throw "";
    }
} catch (e) {
    throw "MochiKit.Async depends on MochiKit.Base!";
}

if (typeof(MochiKit.Async) == 'undefined') {
    MochiKit.Async = {};
}

MochiKit.Async.NAME = "MochiKit.Async";
MochiKit.Async.VERSION = "1.3.1";
MochiKit.Async.__repr__ = function () {
    return "[" + this.NAME + " " + this.VERSION + "]";
};
MochiKit.Async.toString = function () {
    return this.__repr__();
};

MochiKit.Async.Deferred = function (/* optional */ canceller) {
    this.chain = [];
    this.id = this._nextId();
    this.fired = -1;
    this.paused = 0;
    this.results = [null, null];
    this.canceller = canceller;
    this.silentlyCancelled = false;
    this.chained = false;
};

MochiKit.Async.Deferred.prototype = {
    repr: function () {
        var state;
        if (this.fired == -1) {
            state = 'unfired';
        } else if (this.fired === 0) {
            state = 'success';
        } else {
            state = 'error';
        }
        return 'Deferred(' + this.id + ', ' + state + ')';
    },

    toString: MochiKit.Base.forwardCall("repr"),

    _nextId: MochiKit.Base.counter(),

    cancel: function () {
        var self = MochiKit.Async;
        if (this.fired == -1) {
            if (this.canceller) {
                this.canceller(this);
            } else {
                this.silentlyCancelled = true;
            }
            if (this.fired == -1) {
                this.errback(new self.CancelledError(this));
            }
        } else if ((this.fired === 0) && (this.results[0] instanceof self.Deferred)) {
            this.results[0].cancel();
        }
    },
            

    _pause: function () {
        /***

        Used internally to signal that it's waiting on another Deferred

        ***/
        this.paused++;
    },

    _unpause: function () {
        /***

        Used internally to signal that it's no longer waiting on another
        Deferred.

        ***/
        this.paused--;
        if ((this.paused === 0) && (this.fired >= 0)) {
            this._fire();
        }
    },

    _continue: function (res) {
        /***

        Used internally when a dependent deferred fires.

        ***/
        this._resback(res);
        this._unpause();
    },

    _resback: function (res) {
        /***

        The primitive that means either callback or errback

        ***/
        this.fired = ((res instanceof Error) ? 1 : 0);
        this.results[this.fired] = res;
        this._fire();
    },

    _check: function () {
        if (this.fired != -1) {
            if (!this.silentlyCancelled) {
                throw new MochiKit.Async.AlreadyCalledError(this);
            }
            this.silentlyCancelled = false;
            return;
        }
    },

    callback: function (res) {
        this._check();
        if (res instanceof MochiKit.Async.Deferred) {
            throw new Error("Deferred instances can only be chained if they are the result of a callback");
        }
        this._resback(res);
    },

    errback: function (res) {
        this._check();
        var self = MochiKit.Async;
        if (res instanceof self.Deferred) {
            throw new Error("Deferred instances can only be chained if they are the result of a callback");
        }
        if (!(res instanceof Error)) {
            res = new self.GenericError(res);
        }
        this._resback(res);
    },

    addBoth: function (fn) {
        if (arguments.length > 1) {
            fn = MochiKit.Base.partial.apply(null, arguments);
        }
        return this.addCallbacks(fn, fn);
    },

    addCallback: function (fn) {
        if (arguments.length > 1) {
            fn = MochiKit.Base.partial.apply(null, arguments);
        }
        return this.addCallbacks(fn, null);
    },

    addErrback: function (fn) {
        if (arguments.length > 1) {
            fn = MochiKit.Base.partial.apply(null, arguments);
        }
        return this.addCallbacks(null, fn);
    },

    addCallbacks: function (cb, eb) {
        if (this.chained) {
            throw new Error("Chained Deferreds can not be re-used");
        }
        this.chain.push([cb, eb]);
        if (this.fired >= 0) {
            this._fire();
        }
        return this;
    },

    _fire: function () {
        /***

        Used internally to exhaust the callback sequence when a result
        is available.

        ***/
        var chain = this.chain;
        var fired = this.fired;
        var res = this.results[fired];
        var self = this;
        var cb = null;
        while (chain.length > 0 && this.paused === 0) {
            // Array
            var pair = chain.shift();
            var f = pair[fired];
            if (f === null) {
                continue;
            }
            try {
                res = f(res);
                fired = ((res instanceof Error) ? 1 : 0);
                if (res instanceof MochiKit.Async.Deferred) {
                    cb = function (res) {
                        self._continue(res);
                    };
                    this._pause();
                }
            } catch (err) {
                fired = 1;
                if (!(err instanceof Error)) {
                    err = new MochiKit.Async.GenericError(err);
                }
                res = err;
            }
        }
        this.fired = fired;
        this.results[fired] = res;
        if (cb && this.paused) {
            // this is for "tail recursion" in case the dependent deferred
            // is already fired
            res.addBoth(cb);
            res.chained = true;
        }
    }
};

MochiKit.Base.update(MochiKit.Async, {
    evalJSONRequest: function (/* req */) {
        return eval('(' + arguments[0].responseText + ')');
    },

    succeed: function (/* optional */result) {
        var d = new MochiKit.Async.Deferred();
        d.callback.apply(d, arguments);
        return d;
    },

    fail: function (/* optional */result) {
        var d = new MochiKit.Async.Deferred();
        d.errback.apply(d, arguments);
        return d;
    },

    getXMLHttpRequest: function () {
        var self = arguments.callee;
        if (!self.XMLHttpRequest) {
            var tryThese = [
                function () { return new XMLHttpRequest(); },
                function () { return new ActiveXObject('Msxml2.XMLHTTP'); },
                function () { return new ActiveXObject('Microsoft.XMLHTTP'); },
                function () { return new ActiveXObject('Msxml2.XMLHTTP.4.0'); },
                function () {
                    throw new MochiKit.Async.BrowserComplianceError("Browser does not support XMLHttpRequest");
                }
            ];
            for (var i = 0; i < tryThese.length; i++) {
                var func = tryThese[i];
                try {
                    self.XMLHttpRequest = func;
                    return func();
                } catch (e) {
                    // pass
                }
            }
        }
        return self.XMLHttpRequest();
    },

    _nothing: function () {},

    _xhr_onreadystatechange: function (d) {
        // MochiKit.Logging.logDebug('this.readyState', this.readyState);
        if (this.readyState == 4) {
            // IE SUCKS
            try {
                this.onreadystatechange = null;
            } catch (e) {
                try {
                    this.onreadystatechange = MochiKit.Async._nothing;
                } catch (e) {
                }
            }
            var status = null;
            try {
                status = this.status;
                if (!status && MochiKit.Base.isNotEmpty(this.responseText)) {
                    // 0 or undefined seems to mean cached or local
                    status = 304;
                }
            } catch (e) {
                // pass
                // MochiKit.Logging.logDebug('error getting status?', repr(items(e)));
            }
            //  200 is OK, 304 is NOT_MODIFIED
            if (status == 200 || status == 304) { // OK
                d.callback(this);
            } else {
                var err = new MochiKit.Async.XMLHttpRequestError(this, "Request failed");
                if (err.number) {
                    // XXX: This seems to happen on page change
                    d.errback(err);
                } else {
                    // XXX: this seems to happen when the server is unreachable
                    d.errback(err);
                }
            }
        }
    },