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/*
* routing-stream.js: A Stream focused on connecting an arbitrary RequestStream and
* ResponseStream through a given Router.
*
* (C) 2011, Charlie Robbins & the Contributors
* MIT LICENSE
*
*/
var util = require('util'),
union = require('./index'),
RequestStream = require('./request-stream'),
ResponseStream = require('./response-stream');
//
// ### function RoutingStream (options)
//
//
var RoutingStream = module.exports = function (options) {
options = options || {};
RequestStream.call(this, options);
this.before = options.before || [];
this.after = options.after || [];
this.response = options.response || options.res;
this.headers = options.headers || {
'x-powered-by': 'union ' + union.version
};
this.target = new ResponseStream({
response: this.response,
headers: this.headers
});
this.once('pipe', this.route);
};
util.inherits(RoutingStream, RequestStream);
//
// Called when this instance is piped to **by another stream**
//
RoutingStream.prototype.route = function (req) {
//
// When a `RoutingStream` is piped to:
//
// 1. Setup the pipe-chain between the `after` middleware, the abstract response
// and the concrete response.
// 2. Attempt to dispatch to the `before` middleware, which represent things such as
// favicon, static files, application routing.
// 3. If no match is found then pipe to the 404Stream
//
var self = this,
after,
error,
i;
//
// Don't allow `this.target` to be writable on HEAD requests
//
this.target.writable = req.method !== 'HEAD';
//
// 1. Setup the pipe-chain between the `after` middleware, the abstract response
// and the concrete response.
//
after = [this.target].concat(this.after, this.response);
for (i = 0; i < after.length - 1; i++) {
//
// attach req and res to all streams
//
after[i].req = req;
after[i + 1].req = req;
after[i].res = this.response;
after[i + 1].res = this.response;
after[i].pipe(after[i + 1]);
//
// prevent multiple responses and memory leaks
//
after[i].on('error', this.onError);
}
//
// Helper function for dispatching to the 404 stream.
//
function notFound() {
error = new Error('Not found');
error.status = 404;
self.onError(error);
}
//
// 2. Attempt to dispatch to the `before` middleware, which represent things such as
// favicon, static files, application routing.
//
(function dispatch(i) {
if (self.target.modified) {
return;
}
else if (++i === self.before.length) {
//
// 3. If no match is found then pipe to the 404Stream
//
return notFound();
}
self.target.once('next', dispatch.bind(null, i));
if (self.before[i].length === 3) {
self.before[i](self, self.target, function (err) {
if (err) {
self.onError(err);
} else {
self.target.emit('next');
}
});
}
else {
self.before[i](self, self.target);
}
})(-1);
};
RoutingStream.prototype.onError = function (err) {
this.emit('error', err);
};
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