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