401 lines
12 KiB
Racket
401 lines
12 KiB
Racket
#lang racket/base
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(require racket/list
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web-server/servlet
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web-server/servlet-env)
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;; A hacky way to test the evaluation.
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;;
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;; Sets up a web server and opens a browser window.
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;; The page on screen periodically polls the server to see if a program has
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;; come in to be evaluated. Whenever code does come in, evaluates and returns the
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;; value to the user, along with the time it took to evaluate.
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(provide make-evaluate
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(struct-out error-happened)
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(struct-out evaluated))
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(define-struct error-happened (str t) #:transparent)
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(define-struct evaluated (stdout value t
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browser) #:transparent)
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;; make-evaluate: (Any output-port) -> void
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;; Produce a JavaScript evaluator that cooperates with a browser.
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;; The JavaScript-compiler is expected to write out a thunk. When invoked,
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;; the thunk should return a function that consumes three values, corresponding
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;; to success, failure, and other parameters to evaluation. For example:
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;;
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;; (make-evaluate (lambda (program op)
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;; (fprintf op "(function() {
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;; return function(success, fail, params) {
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;; success('ok');
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;; }})")))
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;;
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;; is a do-nothing evaluator that will always give back 'ok'.
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;;
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;; At the moment, the evaluator will pass in a parameter that binds 'currentDisplayer' to a function
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;; that captures output.
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(define (make-evaluate javascript-compiler)
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(define port (+ 8000 (random 8000)))
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;; This channel's meant to serialize use of the web server.
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(define ch (make-channel))
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;; start up the web server
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;; The web server responds to two types of requests
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;; ?comet Starting up the comet request path.
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;; ?v Getting a value back from evaluation.
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;; ?e Got an error.
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(void
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(thread (lambda ()
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(define (start req)
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(cond
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;; Server-side sync for a program
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[(exists-binding? 'comet (request-bindings req))
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(handle-comet req)]
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;; Normal result came back
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[(exists-binding? 'v (request-bindings req))
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(handle-normal-response req)]
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;; Error occurred
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[(exists-binding? 'e (request-bindings req))
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(handle-error-response req)]
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[else
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(make-on-first-load-response)]))
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(serve/servlet start
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#:banner? #f
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#:launch-browser? #t
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#:quit? #f
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#:port port
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#:servlet-path "/eval"))))
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(define *alarm-timeout* 30000)
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(define (handle-comet req)
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(let/ec return
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(let* ([alarm (alarm-evt (+ (current-inexact-milliseconds) *alarm-timeout*))]
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[program (sync ch alarm)]
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[op (open-output-bytes)])
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(cond
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[(eq? program alarm)
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(try-again-response)]
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[else
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(with-handlers ([exn:fail? (lambda (exn)
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(let ([sentinel
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(format
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#<<EOF
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(function () {
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return function(success, fail, params) {
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fail(~s);
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}
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});
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EOF
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(exn-message exn))])
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(return
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(response/full 200 #"Okay"
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(current-seconds)
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#"text/plain; charset=utf-8"
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empty
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(list #"" (string->bytes/utf-8 sentinel))))))])
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(javascript-compiler program op))
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(response/full 200 #"Okay"
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(current-seconds)
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#"text/plain; charset=utf-8"
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empty
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(list #"" (get-output-bytes op)))]))))
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(define (try-again-response)
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(response/full 200 #"Try again"
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(current-seconds)
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#"text/plain; charset=utf-8"
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empty
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(list #"" #"")))
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(define (ok-response)
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(response/full 200 #"Okay"
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(current-seconds)
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TEXT/HTML-MIME-TYPE
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empty
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(list #"" #"<html><head></head><body><p>ok</p></body></html>")))
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(define (handle-normal-response req)
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(channel-put ch (make-evaluated (extract-binding/single 'o (request-bindings req))
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(extract-binding/single 'v (request-bindings req))
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(string->number
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(extract-binding/single 't (request-bindings req)))
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(extract-binding/single 'b (request-bindings req))))
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(ok-response))
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(define (handle-error-response req)
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(channel-put ch (make-error-happened
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(extract-binding/single 'e (request-bindings req))
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(string->number
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(extract-binding/single 't (request-bindings req)))))
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(ok-response))
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(define (make-on-first-load-response)
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(let ([op (open-output-bytes)])
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(fprintf op #<<EOF
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<html>
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<head>
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<script>
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// http://www.quirksmode.org/js/xmlhttp.html
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//
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// XMLHttpRequest wrapper. Transparently restarts the request
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// if a timeout occurs.
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function sendRequest(url,callback,postData) {
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var req = createXMLHTTPObject(), method;
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if (!req) return;
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method = (postData) ? "POST" : "GET";
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req.open(method,url,true);
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if (postData) {
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req.setRequestHeader('Content-type','application/x-www-form-urlencoded');
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}
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req.onreadystatechange = function () {
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if (req.readyState != 4) return;
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if (req.status !== 200 && req.status !== 304) {
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return;
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}
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if (req.status === 200 && req.statusText === 'Try again') {
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req.abort();
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setTimeout(function() { sendRequest(url, callback, postData); }, 0);
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return;
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}
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callback(req);
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}
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if (req.readyState == 4) return;
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req.send(postData);
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}
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var XMLHttpFactories = [
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function () {return new XMLHttpRequest()},
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function () {return new ActiveXObject("Msxml2.XMLHTTP")},
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function () {return new ActiveXObject("Msxml3.XMLHTTP")},
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function () {return new ActiveXObject("Microsoft.XMLHTTP")}
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];
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function createXMLHTTPObject() {
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var xmlhttp = false;
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for (var i=0;i<XMLHttpFactories.length;i++) {
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try {
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xmlhttp = XMLHttpFactories[i]();
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}
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catch (e) {
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continue;
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}
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break;
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}
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return xmlhttp;
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}
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var comet = function() {
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sendRequest("/eval",
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function(req) {
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// debug:
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if (window.console && typeof(console.log) === 'function') { console.log(req.responseText); }
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var invoke = eval(req.responseText)();
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var output = [];
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var startTime, endTime;
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var params = { currentDisplayer: function(v) {
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var pNode = document.createElement("span");
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pNode.style.whiteSpace = 'pre';
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pNode.appendChild(document.createTextNode(String(v)));
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document.body.appendChild(pNode);
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//console.log(v);
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output.push(String(v)); } };
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var onSuccess = function(v) {
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endTime = new Date();
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sendRequest("/eval", function(req) { setTimeout(comet, 0); },
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"v=" + encodeURIComponent(String(v)) +
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"&o=" + encodeURIComponent(output.join('')) +
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"&t=" + encodeURIComponent(String(endTime - startTime)) +
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"&b=" + encodeURIComponent(String(BrowserDetect.browser + ' ' + BrowserDetect.version + '/' + BrowserDetect.OS)));
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};
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var onFail = function(machine, e) {
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endTime = new Date();
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sendRequest("/eval", function(req) { setTimeout(comet, 0); },
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"e=" + encodeURIComponent(String(e)) +
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"&t=" + encodeURIComponent(String(endTime - startTime)));
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};
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startTime = new Date();
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invoke(onSuccess, onFail, params);
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},
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"comet=t");
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};
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var BrowserDetect = {
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init: function () {
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this.browser = this.searchString(this.dataBrowser) || "An unknown browser";
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this.version = this.searchVersion(navigator.userAgent)
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|| this.searchVersion(navigator.appVersion)
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|| "an unknown version";
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this.OS = this.searchString(this.dataOS) || "an unknown OS";
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},
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searchString: function (data) {
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for (var i=0;i<data.length;i++) {
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var dataString = data[i].string;
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var dataProp = data[i].prop;
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this.versionSearchString = data[i].versionSearch || data[i].identity;
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if (dataString) {
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if (dataString.indexOf(data[i].subString) != -1)
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return data[i].identity;
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}
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else if (dataProp)
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return data[i].identity;
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}
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},
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searchVersion: function (dataString) {
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var index = dataString.indexOf(this.versionSearchString);
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if (index == -1) return;
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return parseFloat(dataString.substring(index+this.versionSearchString.length+1));
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},
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dataBrowser: [
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{
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string: navigator.userAgent,
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subString: "Chrome",
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identity: "Chrome"
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},
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{ string: navigator.userAgent,
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subString: "OmniWeb",
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versionSearch: "OmniWeb/",
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identity: "OmniWeb"
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},
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{
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string: navigator.vendor,
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subString: "Apple",
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identity: "Safari",
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versionSearch: "Version"
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},
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{
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prop: window.opera,
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identity: "Opera"
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},
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{
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string: navigator.vendor,
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subString: "iCab",
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identity: "iCab"
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},
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{
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string: navigator.vendor,
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subString: "KDE",
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identity: "Konqueror"
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},
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{
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string: navigator.userAgent,
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subString: "Firefox",
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identity: "Firefox"
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},
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{
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string: navigator.vendor,
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subString: "Camino",
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identity: "Camino"
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},
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{ // for newer Netscapes (6+)
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string: navigator.userAgent,
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subString: "Netscape",
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identity: "Netscape"
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},
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{
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string: navigator.userAgent,
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subString: "MSIE",
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identity: "Explorer",
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versionSearch: "MSIE"
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},
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{
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string: navigator.userAgent,
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subString: "Gecko",
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identity: "Mozilla",
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versionSearch: "rv"
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},
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{ // for older Netscapes (4-)
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string: navigator.userAgent,
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subString: "Mozilla",
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identity: "Netscape",
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versionSearch: "Mozilla"
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}
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],
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dataOS : [
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{
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string: navigator.platform,
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subString: "Win",
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identity: "Windows"
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},
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{
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string: navigator.platform,
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subString: "Mac",
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identity: "Mac"
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},
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{
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string: navigator.userAgent,
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subString: "iPhone",
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identity: "iPhone/iPod"
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},
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{
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string: navigator.platform,
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subString: "Linux",
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identity: "Linux"
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}
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]
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};
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BrowserDetect.init();
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var whenLoaded = function() {
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setTimeout(comet, 0);
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};
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</script>
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</head>
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<body onload="whenLoaded()">
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<p>Harness loaded. Do not close this window.</p>
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</body>
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</html>
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EOF
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)
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(response/full 200 #"Okay"
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(current-seconds)
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TEXT/HTML-MIME-TYPE
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empty
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(list #"" (get-output-bytes op)))))
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;; evaluate: sexp -> (values string number)
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;; A little driver to test the evalution of expressions, using a browser to help.
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;; Returns the captured result of stdout, plus # of milliseconds it took to execute.
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(define (evaluate e)
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;; Send the program to the web browser, and wait for the thread to send back
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(channel-put ch e)
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(let ([result (channel-get ch)])
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(cond [(error-happened? result)
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(raise result)]
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[else
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result])))
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evaluate) |